JP2009284721A - Power supply device, lighting fixture and vehicle - Google Patents

Abstract

When an output line of a power supply device has a power fault, the device is protected from being broken or broken with a simple configuration.
In a power supply apparatus having a DC-DC converter circuit 1 in which a primary-side current path and a secondary-side current path are separated by a transformer T1, output two terminals c, a of the DC-DC converter circuit 1 are provided. Current limiting resistor R1 for limiting an abnormal current that flows when an abnormality occurs at the output terminal of the power supply device between one terminal a and the primary ground line g or a reference potential line equivalent thereto. , And an output voltage detection unit 3 (series circuit of resistors R2 and R3) for detecting the state of the output terminal of the power supply device, and receives the output voltage detection signal from the output voltage detection unit 3, Output abnormality state determination means 4 that determines that the output is abnormal when the output is out of the predetermined range. When the output end of the power supply device has a power fault, the output abnormality condition determination means 4 receives the determination result and outputs Stop operation.
[Selection] Figure 1

Description

  The present invention relates to a power supply device that converts electric power through a transformer and transmits it to a load, and in particular, a light source lighting device that uses a semiconductor light source composed of a semiconductor light emitting element such as a light emitting diode (LED) as a load, It is suitable for lamps such as headlamps and vehicles using this.

  In a power supply device for a vehicle, even if an output line of the power supply device contacts a live line (positive side) of the power supply (battery) due to some accident (this is called a power supply), there is no failure or destruction. There is a need to provide such devices. Some kind of accident is assumed to be a short circuit due to, for example, erroneous connection, biting or deterioration of wiring.

  In response to such a request, Patent Document 1 (Japanese Patent Application Laid-Open No. 2007-295641) proposes a method for suppressing and stopping output when a power fault occurs in an output line. However, the method disclosed in Patent Document 1 applies a reference voltage to one of the outputs of the DC-DC conversion circuit that constitutes the power supply device, and flows through the output current detection resistor connected to that point. It is premised on a circuit that performs error calculation with the voltage drop generated by the output current and uses the result to control the output to a predetermined current value. For example, for a power supply device that performs constant voltage control of the output Was not applicable.

Further, in addition to the generation and application of the reference voltage, a comparator or the like is further required to detect the power supply state, and there is a problem that the circuit becomes relatively complicated.
JP 2007-295641 A

  In the present invention, in view of the above-described problems of the conventional technology, even when the output line of the power supply device has a power fault, it is possible to protect the device so that the device does not break down or break down with a simple configuration. To provide a power supply device that can protect not only what the output control is performed, that is, the output control is not only current control but also voltage control, open control, etc. For the purpose.

  In order to solve the above problems, the invention of claim 1 is a DC-DC conversion circuit 1 in which a primary-side current path and a secondary-side current path are separated by a transformer T1, as shown in FIG. Of the DC-DC conversion circuit 1, one terminal (a) of the two output terminals (c) and (a) and the primary ground line (g) or a reference potential line equivalent thereto. Between them, a current limiting resistor R1 for limiting an abnormal current that flows when an abnormality occurs at the output terminal of the power supply device is connected, and an output voltage detector 3 (for detecting the state of the output terminal of the power supply device) A series circuit of resistors R2 and R3), an output abnormal state determination that receives an output voltage detection signal from the output voltage detection unit 3 and determines an output abnormality when the signal falls outside a predetermined range If the output end of the power supply device has a power fault, To, upon receiving the determination result of the output abnormal state judging means 4, is characterized in that so as to stop the output operation.

  In the invention of claim 2, in the invention of claim 1, the output operation is continued when the output terminal (a) on the side connected to the current limiting resistor R1 of the power supply device is grounded. It is characterized by.

  According to a third aspect of the present invention, in the first or second aspect of the invention, the value of the current limiting resistor R1 is such that at least the power supply voltage Vi supplied to the power supply device is directly applied across the current limiting resistor R1. However, it is characterized in that it is set to be equal to or less than an allowable loss of the resistor R1 and the power supply device.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, as shown in FIG. 6, a capacitor C2 is connected in parallel with the current limiting resistor R1.

  According to a fifth aspect of the present invention, in any one of the first to fourth aspects of the present invention, the power supply device has a metal casing, and the primary side of the DC-DC conversion circuit 1 is connected to the current limiting resistor R1. The point (g) is characterized in that the casing is grounded (FG in FIG. 6).

  According to a sixth aspect of the present invention, in any one of the first to fifth aspects of the present invention, the output abnormality determination by the output abnormal state determination means 4 is performed when an abnormal state continuously occurs for a predetermined time or more. (Timer circuit 4c in FIG. 6).

  The invention according to claim 7 is a signal for informing the user of the output abnormality when it is determined that the output is abnormal as shown in FIGS. Is provided.

  According to an eighth aspect of the present invention, in the invention according to any one of the first to seventh aspects, the DC-DC conversion circuit 1 is controlled so that the output current becomes a predetermined value as shown in FIGS. The load 2 to be connected is a low impedance load such as a light emitting diode.

  A ninth aspect of the present invention is a lamp having the power supply device according to the eighth aspect mounted thereon (FIG. 10).

  A tenth aspect of the present invention is a vehicle having the lamp according to the ninth aspect mounted thereon (FIG. 11).

  According to the first aspect of the present invention, there is provided a power supply device that can be protected with a simple configuration so that the device will not break down or break down even when a power supply output line of the power supply device occurs. I can do it. In addition, since it can be applied regardless of output control such as constant voltage control and constant current control, it is possible to provide a safe power supply apparatus according to the application. In addition, since it has an output voltage detection unit for detecting the state of the output terminal of the power supply device, it can be shared with other load abnormality protection functions, and there is an advantage that the configuration of the protection circuit can be simplified. .

  According to the second aspect of the present invention, it is possible to provide a power supply device that does not fail even when a ground fault abnormality occurs in the output line of the power supply device and that can continue the output operation as much as possible. . Specifically, although it is a non-insulated type that can be configured cheaply compared to an insulated type in general, it is possible to continuously enable a stable output operation with respect to one of the output lines. I can do it.

  According to a third aspect of the present invention, the value of the current limiting resistor is such that at least the power supply voltage supplied to the power supply device is directly applied between both ends of the current limiting resistor. Since it is set to be equal to or less than the loss, it is possible to suppress the heat generation of the current limiting resistor to prevent the element from being damaged, and to prevent wasteful power consumption from the input power supply.

  According to the invention of claim 4, since the capacitor is connected in parallel with the current limiting resistor, the generation of a transient voltage of the output voltage can be reduced, and the high frequency potential of the output side circuit can be stabilized. It is effective for noise suppression.

  According to the invention of claim 5, the power supply device has a metal casing, and is grounded to the casing at a connection point between the primary side of the DC-DC conversion circuit and the current limiting resistor. Therefore, even when the grounding side of the load is grounded to the heat sink or the like, no potential difference occurs between the terminals of the current limiting resistor, so that the output current feedback control is not adversely affected. Can be controlled to a predetermined value.

  According to the sixth aspect of the present invention, the output abnormality determination by the output abnormality state determination means is determined as an output abnormality when the abnormal state continues for a predetermined time or more, and therefore is affected by noise or the like. This has the effect of making it possible to reliably determine abnormality.

  According to the seventh aspect of the present invention, means for outputting a signal for notifying the user of the output abnormality when the output is determined to be abnormal is provided, so that the user can surely know the occurrence of the abnormality. There is an effect that can be.

  According to the inventions of claims 8 to 10, when the power conversion device of the present invention is used for a lighting device or lamp using a light emitting diode (LED) as a light source, a vehicle headlamp, or the like, the inventions of claims 1 to 7 are used. It is possible to provide a system that takes advantage of the effects of.

(Embodiment 1)
FIG. 1 shows a circuit diagram of a first embodiment of the present invention. FIG. 1 shows a circuit diagram in the case where the protection means of the present invention is applied to a DC-DC conversion circuit 1 constituting a power supply device which is a flyback converter.

  One end of the primary winding of the transformer T1 is connected to the positive electrode of the DC power supply E, and the other end of the primary winding of the transformer T1 is connected to the negative electrode of the DC power supply E via the switching element SW1. The negative electrode of the DC power supply E is grounded, and is connected to one end of the secondary winding of the transformer T1 via the resistor R1. The other end of the secondary winding of the transformer T1 is connected to the anode of the diode D1. The cathode of the diode D1 is connected to the positive electrode of the capacitor C1. The negative electrode of the capacitor C1 is connected to the one end of the secondary winding of the transformer T1. A load 2 is connected in parallel to both ends of the capacitor C1, and a series circuit of resistors R2 and R3 is connected. The main circuit of the DC-DC conversion circuit 1 is configured as described above.

  Next, the configuration of the control circuit will be described. The voltage Vo of the capacitor C1 is input to the output adjustment unit 5. The output adjustment unit 5 generates a PWM signal and supplies an on / off control signal to the switching element SW1 through the gate circuit AND1. The gate circuit AND1 is supplied with the output signal of the output abnormal state determination means 4, and when any of the output signals becomes low level, the on / off control signal of the switching element SW1 is stopped.

  The abnormal output state determination unit 4 includes a first output state determination unit 41 and a second output state determination unit 42. The first output state determination unit 41 includes a first reference voltage Vref1 and a comparator Comp1, and the second output state determination unit 42 includes a second reference voltage Vref2 and a comparator Comp2. The relationship between the first reference voltage Vref1 and the second reference voltage Vref2 is Vref1> Vref2. The detection signal of the output voltage Vo divided by the series circuit of the resistors R2 and R3 is applied to the inverting input terminal of the comparator Comp1 and the non-inverting input terminal of the comparator Comp2.

  The operation of the circuit will be briefly described below. Energy is stored in the transformer T1 when the switching element SW1 is turned on, energy is released from the secondary side of the transformer T1 when the switching element SW1 is turned off, and the smoothing capacitor C1 is charged via the diode D1. The load 2 is mainly supplied with electric power from the smoothing capacitor C1. The output adjustment unit 5 monitors the output voltage Vo and generates a signal for driving the switching element SW1 of the DC-DC conversion circuit 1 so that the output voltage Vo becomes a predetermined value. Since the signal given to the gate circuit AND1 from the output abnormal state determination means 4 is normally at a high level, the switching element SW1 is driven according to the signal generated and generated by the output adjustment unit 5, and the DC-DC conversion circuit 1 performs a voltage conversion operation.

  The features of the present invention are as follows. In the DC-DC conversion circuit 1, one output terminal of the secondary side rectification / smoothing circuit of the transformer T1 is connected to the output terminal (a) of the apparatus, and the other terminal is connected to the output terminal (c) of the apparatus. Has been. Further, the primary side ground line of the DC-DC conversion circuit 1 or the reference potential line (g) equivalent thereto and the output terminal (a) are connected via a resistor R1 (the resistor R1 is described in the claims). Equivalent to a current limiting resistor). Further, a series circuit of a resistor R2 and a resistor R3 is connected between the output terminal (a) and the output terminal (c), and the state of the output voltage Vo is obtained as an output voltage detection signal from the voltage dividing point therebetween. (Corresponding to the output voltage detector 3 described in the claims).

  The abnormal output state determination means 4 receives the output voltage detection signal and determines whether there is an abnormal output. The abnormal output state determination unit 4 includes an output state determination unit 41 and an output state determination unit 42. The output state determination unit 41 is for determining that the output voltage detection signal has become larger than a value that can normally be taken. By comparing the reference voltage Vref1 with the detection signal by the comparator Comp1, the detection signal becomes the reference. When the voltage Vref1 is exceeded, it is regarded as an abnormal state and the output of the comparator Comp1 is set to the Low level. The reference voltage Vref1 is set to a value larger than a value that can normally be taken by the detection signal.

  The output state determination unit 42 is used to determine that the output voltage detection signal has become smaller than a normal value, and the comparison signal is compared with the reference voltage Vref2 by the comparator Comp2 so that the detection signal is the reference value. When the voltage falls below the voltage Vref2, it is regarded as an abnormal state, and the output of the comparator Comp2 is set to the Low level. The reference voltage Vref2 is set to a value smaller than a value that can normally be taken by the detection signal. As a result, when an abnormality that the detection signal is larger or smaller than a normal value is recognized, a low level signal is given from the output abnormality state determination means 4 to the gate circuit AND1, and as a result, the signal to the switching element SW1 is given. The on / off control signal is fixed at the low level, the switching operation is stopped, and the output operation is stopped.

  In addition, after the power is turned on, the output of the output abnormal state determination unit 4 is maintained at a high level for a certain period of time from when the DC-DC conversion circuit 1 starts to operate until the output adjustment operation of the output adjustment unit 5 is stabilized. May be. The same applies to other embodiments.

  Assuming a case where the output terminal (c) side is a power line of the power source E, that is, a power supply that contacts the positive side, the operation will be described below. Since the output terminal (c) is in contact with the positive side of the power supply E, the potential of the output terminal (c) is fixed at the power supply voltage Vi, and when the output voltage Vo rises due to the operation of the DC-DC conversion circuit 1, The potential at the end (a) is (Vi−Vo). When the output voltage Vo is larger than the power supply voltage Vi in absolute value, the potential at the output terminal (a) becomes negative. As a result, the potential at the voltage dividing point between the resistor R2 and the resistor R3 decreases as the output voltage Vo increases. As a result, when the detected voltage decreases, the output state determination unit 42 determines abnormality. Alternatively, when the output state determination unit 41 detects that the potential at the voltage dividing point between the resistor R2 and the resistor R3 has increased due to a power supply on the output end (c) side, an abnormality is determined.

  Next, assuming the case where the output terminal (a) is a live line of the power source E, that is, a power supply that contacts the positive side, the output terminal (a) is in contact with the positive side of the power source E. ) Is fixed to the power supply voltage Vi. As a result, the potential at the voltage dividing point between the resistor R2 and the resistor R3 increases, and as a result, the output state determination unit 41 determines abnormality.

  As described above, according to the present invention, the state of the output voltage Vo is determined from the voltage dividing point between the series circuit of the resistor R2 and the resistor R3 provided between the output terminal (a) and the output terminal (c). Obtained as a detection signal, the output abnormal state determination means 4 determines whether or not the detected value is a value in a normal range. If it is out of the range, it is determined that an abnormal state has occurred. By doing this, it is possible to determine that the output line has a power fault. If it is determined that there is an abnormality, the output operation of the DC-DC conversion circuit 1 is stopped by the output from the output abnormality state determination means 4 to ensure safety.

  By the way, when the output terminal (a) has a power fault with the power source E, the power fault current flows from the power source E through the path of the output terminal (a) → the resistor R1 → the primary side ground line (g). Even after the abnormality is detected by the output abnormal state determination means 4 and the output operation of the circuit is stopped, the power supply current continues to flow unless the power supply fault is resolved. This leads to heat generation of the resistor R1 and the like, wasteful power consumption from the power source E, and the like. In the worst case, a circuit failure such as burning of the resistor R1 can occur. Therefore, in order to suppress and reduce the power supply current, it is desirable to set the resistance R1 to a large value.

  Specifically, it is assumed that at least the voltage Vi of the power source E is the highest in the normal range, and even when the above power fault occurs in that case, the loss of the resistor R1 and the power supply device is the respective allowable loss. What is necessary is just to select the value of resistance R1 so that it may become the following.

  Next, it is assumed that a ground fault has occurred at the output end (c). Assuming that a ground fault occurs at the output terminal (c) (when contacting the ground line side of the power supply E), the ground fault current is output from the rectifying / smoothing circuit on the secondary side of the transformer T1 to the output terminal (c ) → Primary side ground line (g) → Resistor R1. At this time, since the output terminal (c) has the same potential as the primary side ground line (g), the potential at the voltage dividing point between the resistor R2 and the resistor R3 decreases at a stretch. As a result, the output state determination unit 42 Can be used to determine abnormality.

  Next, it is assumed that a ground fault has occurred at the output end (a). In this case, since the potential of the output terminal (a) is basically the same as the potential of the primary ground line (g), the potential of the output terminal (a) changes greatly even if a ground fault occurs. As a result, the potential at the voltage dividing point between the resistor R2 and the resistor R3 is almost the same as normal, so the output abnormal state determination means 4 determines that the output is abnormal, and the output operation of the DC-DC conversion circuit 1 is performed. Never stop. Thereby, when the output terminal (a) has a ground fault, the power supply to the load can be continued.

  As a result, when power can be supplied to the load, the supply is continued. For example, when this power supply device is used to light the light source of a vehicle headlamp (headlamp) For example, there is an advantage that it is rather safe in terms of securing the driver's field of view at night because lighting can be performed continuously when possible. By the way, according to the method described in the prior art, the output operation is stopped even in such a case. Therefore, when this power supply device is applied to a vehicle headlamp (headlamp), the lighting is continued. Can not be done.

  As described above, according to the present embodiment, when the DC-DC conversion circuit 1 is configured by a flyback converter, the output terminal (c) or the output terminal (a) has a power fault, or the output terminal ( When c) has a ground fault, it is possible to immediately detect the occurrence of an abnormality and stop the output operation. In the case of a ground fault at the output terminal (a) where an abnormal current does not flow, the output operation can be continued, so the output operation is not stopped unnecessarily, and the power to the load is not Supply can be continued.

  Further, even when the output terminals of the power supply device are short-circuited, according to the present configuration, it is possible to detect an abnormality and to provide an effect of protection. Furthermore, if the load is short-circuited or in a low impedance (low voltage) state, or if the load is open, on the contrary, if it is recognized as abnormal beyond the normal range, the abnormality is There is also an effect that the circuit can be protected by detection.

  In the present embodiment, the present invention is applied to an example of an output control circuit that monitors the output voltage and drives the switching element SW1 of the DC-DC conversion circuit 1 so that the output voltage becomes a predetermined value. However, the present invention can be applied to other circuits that perform output control such as constant current control in which the output current is set to a predetermined value.

  As described above, by using the present invention, a power supply that can be protected with a simple configuration so that the device will not break down or break down even when a power supply output line has a power fault or ground fault. A device can be provided. Further, the present invention can be applied to any output control.

  By the way, in the present embodiment, the output voltage detection unit 3 is configured as a series circuit of the resistor R2 and the resistor R3 connected between the output terminals of the power supply device, and the output voltage detection signal is obtained from the voltage dividing point therebetween. Although not shown in the drawings, the output voltage detection signal is obtained directly only from the output terminal (c) of the power supply device, and the output abnormal state determination means 4 determines whether the value of the signal is out of the predetermined range. (The wiring from the output terminal (c) corresponds to the output voltage detection unit described in the claims). However, in this case, it cannot also serve as a protection function such as whether or not the output terminals of the power supply device are short-circuited.

(Embodiment 2)
FIG. 2 shows a circuit diagram of the second embodiment of the present invention. FIG. 2 shows a circuit diagram in the case where the protection means of the present invention is applied to the DC-DC conversion circuit 1 constituting the power supply device being a forward converter. The forward converter generates, on the secondary side of the transformer T1, the voltage applied to the primary side of the transformer T1 when the switching element SW1 is on, as a voltage increased by a turns ratio by the transformer T1. The voltage is rectified and smoothed by a circuit including a diode D1, a diode D2, a coil L1, and a capacitor C1, and a voltage obtained by converting the input voltage Vi into the output voltage Vo is generated. When the switching element SW1 is on, the diode D1 is on, and a current flows through the path of the secondary winding of the transformer T1, the diode D1, the coil L1, and the capacitor C1. When the switching element SW1 is off, the diode D1 is off, and a regenerative current flows through the path of the coil L1, the capacitor C1, and the diode D2. The operation of the output adjustment unit 5 is basically the same as that of the first embodiment.

  The features of the present invention are as follows. In the DC-DC conversion circuit 1, one output terminal of the secondary side rectification / smoothing circuit of the transformer T1 is connected to the output terminal (a) of the apparatus, and the other terminal is connected to the output terminal (c) of the apparatus. Has been. Further, the primary side ground line of the DC-DC conversion circuit 1 or a reference potential line (g) equivalent thereto and the output terminal (a) are connected via a resistor R1. Further, a series circuit of a resistor R2 and a resistor R3 is connected between the output terminal (a) and the output terminal (c), and the state of the output voltage is obtained as an output voltage detection signal from the voltage dividing point therebetween. The output abnormal state determination means 4 determines whether or not the value of the output voltage detection signal is a value that can be normally obtained. If the value is not a value that can be normally obtained, a low level signal is given to the gate circuit AND1. The output operation of the DC-DC conversion circuit 1 is stopped.

  As described above, the present invention can be applied to the case where the DC-DC conversion circuit 1 is configured by a forward converter, and a power supply device having the same effect as described in the first embodiment is provided. Is possible.

(Embodiment 3)
FIG. 3 shows a circuit diagram of the third embodiment of the present invention. FIG. 3 shows a circuit diagram in the case where the protection means of the present invention is applied to the DC-DC conversion circuit 1 constituting the power supply device being a push-pull converter. The push-pull converter is composed of a diode D1, a diode D2, a coil L1, and a capacitor C1 by alternately switching on and off the switching elements SW1 and SW2, thereby generating a voltage generated on the secondary side of the transformer T1. Is rectified and smoothed by a circuit to generate a voltage obtained by converting the input voltage Vi into the output voltage Vo. The operation of the output adjustment unit 5 is basically the same as that of the first embodiment.

  The features of the present invention are as follows. In the DC-DC conversion circuit 1, one output terminal of the secondary side rectification / smoothing circuit of the transformer T1 is connected to the output terminal (a) of the apparatus, and the other terminal is connected to the output terminal (c) of the apparatus. Has been. Further, the primary side ground line of the DC-DC conversion circuit 1 or a reference potential line (g) equivalent thereto and the output terminal (a) are connected via a resistor R1. Further, a series circuit of a resistor R2 and a resistor R3 is connected between the output terminal (a) and the output terminal (c), and the state of the output voltage is obtained as an output voltage detection signal from the voltage dividing point therebetween. The output abnormal state determination means 4 determines whether or not the value of the output voltage detection signal is a value that can be normally obtained. If the value is not a value that can be normally obtained, a low level signal is given to the gate circuit AND1. The output operation of the DC-DC conversion circuit 1 is stopped.

  As described above, the present invention can be applied to the case where the DC-DC conversion circuit 1 is configured by a push-pull converter, and a power supply device that provides the same effect as described in the first embodiment is provided. Is possible.

  In addition, although the circuit in which the present invention is applied to the DC-DC conversion circuit 1 of each system shown in FIGS. 1, 2, and 3 is shown, the present invention is similarly applied to circuits of other systems. It is possible.

(Embodiment 4)
FIG. 4 shows a circuit diagram of the fourth embodiment of the present invention. In the present embodiment, a configuration in which the present invention is applied to a power supply device having a flyback converter configuration, in which current control is performed so that the output current becomes a predetermined value, will be described in detail.

  Energy is stored in the transformer T1 when the switching element SW1 is turned on, energy is released from the secondary side of the transformer T1 when the switching element SW1 is turned off, and the smoothing capacitor C1 is charged via the diode D1. The load 2 is mainly supplied with electric power from the smoothing capacitor C1. The current flowing through the load 2 is detected as an output current signal by the current detection resistor R4, the signal amplification unit 51 amplifies the signal, the error calculation unit 52 compares it with the reference voltage Vref3, and the result is used as a PWM command signal as a PWM signal. Input to the generator 53. The PWM signal generator 53 generates a PWM signal, supplies it as an on / off control signal to the switching element SW1, and a feedback control system is configured to adjust the output. The signal amplifier 51, the error calculator 52, and the PWM signal generator 53 constitute an output current control unit 50.

  In the present embodiment, the signal amplifier 51 includes a differential amplifier circuit composed of an operational amplifier Amp2 and its peripheral resistors R12 to R15, and the error calculator 52 includes an operational amplifier Amp1, peripheral resistors R10 and R11, and a capacitor C10. Proportional integration circuit. The PWM signal generation unit 53 includes a comparator Comp3 and an oscillator OSC1, and uses a method in which a result obtained by comparing the triangular wave generated by the oscillator OSC1 with a command value by the comparator Comp3 is a PWM signal (a rectangular wave signal having a variable pulse width). Show.

  In the power supply device having the flyback converter configuration, one output end (b) of the secondary side rectification / smoothing circuit of the transformer T1 is connected to the output end (a) of the device via the current detection resistor R4. The other is connected to the output end (c) of the apparatus. In FIG. 4, the output potential at the output terminal (c) is higher than the output potential at the output terminal (b). The primary side ground line or a reference potential line (g) equivalent thereto and the output terminal (a) are connected via a resistor R1. Further, a series circuit of a resistor R2 and a resistor R3 is connected between the output terminal (a) and the output terminal (c), and the state of the output voltage is detected as an output voltage detection signal from the voltage dividing point therebetween.

  The abnormal output state determination means 4 receives the output voltage detection signal and determines whether there is an abnormal output. The abnormal output state determination means 4 includes an overvoltage detection circuit 4a and an undervoltage detection circuit 4b. Here, the overvoltage detection circuit 4a corresponds to the output state determination unit 41 of the above-described embodiment, and the low voltage detection circuit 4b corresponds to the output state determination unit 42.

  In this embodiment, since constant current control is used, the range that the output voltage can normally take is wider than in the first to third embodiments using constant voltage control. Therefore, the overvoltage detection circuit 4a and the low voltage detection circuit 4b are designed to be adapted to the case of constant current control.

  The overvoltage detection circuit 4a is for determining that the output voltage detection signal has become larger than a normal value in the case of constant current control. By comparing the reference voltage Vref1 with the detection signal by the comparator Comp1. When an abnormality is detected in the detection signal, the output of the comparator Comp1 is set to a low level. The reference voltage Vref1 is set to a value larger than a value that can normally be taken by the detection signal.

  The low voltage detection circuit 4b is for determining that the output voltage detection signal has become smaller than a normal value in the case of constant current control, and the comparator Comp2 compares the reference voltage Vref2 with the detection signal. Thus, if an abnormality is detected in the detection signal, the output of the comparator Comp2 is set to the low level. The reference voltage Vref2 is set to a value smaller than a value that can normally be taken by the detection signal.

  As a result, when an abnormality that the detection signal is larger or smaller than a normal value is recognized, a low level signal is given from the output abnormality state determination means 4 to the gate circuit AND1, and as a result, the signal to the switching element SW1 is given. The on / off control signal becomes low level, the switching operation is stopped, and the output operation is stopped.

  Assuming a case where the output terminal (c) side is a live line of the power source E, that is, a power supply that contacts the positive side, the output terminal (c) is in contact with the positive side of the power source E. Is fixed at the power supply voltage Vi, and when the output voltage Vo rises due to the operation of the power conversion circuit 1, the potential of the output terminal (b) becomes (Vi−Vo). When the output voltage Vo becomes higher than the power supply voltage Vi, the potentials at the output terminal (b) and the output terminal (a) become negative. As a result, the potential at the voltage dividing point between the resistor R2 and the resistor R3 decreases as the output voltage Vo increases, and as a result, when the detected voltage decreases, the low voltage detection circuit 4b determines abnormality. Alternatively, when the overvoltage detection circuit 4a detects that the potential at the voltage dividing point between the resistor R2 and the resistor R3 has risen due to a power fault on the output end (c) side, an abnormality is determined.

  Next, assuming the case where the output terminal (a) is a live line of the power source E, that is, a power supply that contacts the positive side, the output terminal (a) is in contact with the positive side of the power source E. ) Is fixed to the power supply voltage Vi. As a result, the potential at the voltage dividing point between the resistor R2 and the resistor R3 increases, and as a result, the overvoltage detection circuit 4a can determine abnormality.

  Assuming that a ground fault occurs at the output terminal (c) (when contacting the ground line side of the power supply E), the ground fault current is output from the rectifying / smoothing circuit on the secondary side of the transformer T1 to the output terminal (c ) → Primary side ground line (g) → Resistor R1 → Resistor R4. At this time, since the output terminal (c) has the same potential as the primary side ground line (g), the potential at the voltage dividing point between the resistor R2 and the resistor R3 decreases at a stretch, and as a result, the low voltage detection circuit 4b. Can be used to determine abnormality.

  By the way, in the case of assuming the protection from the ground fault due to the impedance reduction such as the carbonization of the wiring or the insulation deterioration under the ground fault condition, the resistance having a value larger than the resistance value corresponding to the ground fault impedance assumed to be protected is R1. It is good to use for.

  Next, it is assumed that a ground fault has occurred at the output end (a). In this case, since the potential of the output terminal (a) is basically the same as the potential of the primary ground line (g), the potential of the output terminal (a) changes greatly even if a ground fault occurs. As a result, the potential at the voltage dividing point between the resistor R2 and the resistor R3 is almost the same as normal, so the output abnormal state determination means 4 determines that the output is abnormal, and the output operation of the DC-DC conversion circuit 1 is performed. Never stop. Thereby, when the output terminal (a) has a ground fault, the power supply to the load 2 can be continued.

  As described above, according to the present embodiment, when the output terminal (c) or the output terminal (a) has a power fault or when the output terminal (c) has a ground fault, the occurrence of an abnormality is promptly detected. Thus, the output operation is stopped, and the protection and safety of the device can be ensured. In the case of a ground fault at the output terminal (a) where an abnormal current does not flow continuously, the output operation can be performed continuously, so that the output operation is not unnecessarily stopped and the load is stopped. 2 electric power can be supplied.

  In addition, according to the configuration described in the present embodiment, it is possible to combine a protection function at the time of a load abnormality that determines and protects against an abnormality such as a short circuit or an open load, thereby simplifying the configuration of the protection circuit. There are also advantages. That is, when the load 2 is in the open state, the overvoltage detection circuit 4a can detect an increase in the output voltage detection signal to stop the output operation of the circuit. When the load 2 is in the short circuit state, the low voltage detection circuit With 4b, it is possible to detect a drop in the output voltage detection signal and stop the output operation of the circuit.

(Embodiment 5)
FIG. 5 shows a circuit diagram of the fifth embodiment of the present invention. The difference between the present embodiment and the fourth embodiment is that the output potential is not positive but negative. Specifically, in the power converter having the flyback converter configuration, one output terminal (b) of the secondary side rectification / smoothing circuit of the transformer T1 is connected to the output terminal (a) of the apparatus through the current detection resistor R4. The other is connected to the output end (c) of the apparatus. In FIG. 5, since the output potential at the output end (c) is lower than the output potential at the output end (b), the potential output to the load 2 is negative. The primary side ground line or a reference potential line (g) equivalent thereto and the output terminal (a) are connected via a resistor R1. Other configurations are basically the same as those in the fourth embodiment, but the reference voltages Vref1 and Vref2 of the overvoltage detection circuit 4a and the low voltage detection circuit 4b are set in correspondence with the negative output potential. It is given as a negative voltage.

  The following describes the operation when each output terminal has a power fault or a ground fault. When the output terminal (c) has a power fault, the potential of the output terminal (c) is fixed to the power supply voltage Vi. When the output voltage Vo rises due to the operation of the DC-DC conversion circuit 1, the potential of the output terminal (b) is Vi + Vo is a higher value. Similarly, the potential at the voltage dividing point between the resistor R2 and the resistor R3 also rises. As a result, the overvoltage detection circuit 4a can determine abnormality.

  When the output terminal (a) has a power fault, the potential of the output terminal (a) is fixed to the power supply voltage Vi, and the potential at the voltage dividing point between the resistors R2 and R3 also rises. As a result, the overvoltage detection circuit 4a Can be used to determine abnormality.

  When the output terminal (c) is grounded, the ground fault current is routed from the secondary side rectifying / smoothing circuit of the transformer T1 to the resistor R4 → the resistor R1 → the primary side ground line (g) → the output terminal (c). It flows in. At this time, although the potential of the output terminal (c) is normally negative, the potential at the voltage dividing point between the resistor R2 and the resistor R3 is increased because the potential is the same as that of the primary side ground line (g). As a result, an abnormality can be determined by the overvoltage detection circuit 4a.

  Next, it is assumed that a ground fault has occurred at the output end (a). In this case, since the potential of the output terminal (a) is basically the same as the potential of the primary ground line (g), the potential of the output terminal (a) changes greatly even if a ground fault occurs. As a result, the potential at the voltage dividing point between the resistor R2 and the resistor R3 is almost the same as normal, so the output abnormal state determination means 4 determines that the output is abnormal, and the output operation of the DC-DC conversion circuit 1 is performed. Never stop. Thereby, when the output terminal (a) has a ground fault, the power supply to the load 2 is continued.

  From the above, it can be seen that the present invention can be applied to a power converter having a negative output and is effective. According to the present embodiment, when the output terminal (c) or the output terminal (a) has a power fault, or when the output terminal (c) has a ground fault, the occurrence of an abnormality is promptly detected and an output operation is performed. It is possible to protect the device and ensure safety. Also, in the case of a ground fault at the output end (a) where no abnormal current continues to flow, the output operation can be continued, so the output operation is not unnecessarily stopped and the load 2 It is possible to supply power to.

  In addition, according to the configuration described in the present embodiment, it is possible to combine a protection function at the time of a load abnormality that determines and protects against an abnormality such as a short circuit or an open load, thereby simplifying the configuration of the protection circuit. There are also advantages. Incidentally, the overvoltage detection circuit 4a shown in FIG. 5 is for detecting an abnormality when the load 2 is opened and protecting the circuit, and the low voltage detection circuit 4b shown in FIG. This is to protect the circuit by detecting an abnormality in the event of failure.

  By the way, in this embodiment, the output voltage detection signal obtained from the voltage dividing point between the resistors R2 and R3 is directly input to the comparators Comp1 and Comp2, and compared with the negative reference voltages Vref1 and Vref2. Although illustrated, in this case, the comparators Comp1 and Comp2 require two positive and negative power supplies, and the configuration becomes complicated. Therefore, the output voltage signal may be once inverted and amplified by a circuit composed of an operational amplifier or the like and then compared with a positive reference voltage by a single power source comparator. By doing so, the power supply on the negative side of the control circuit required in the configuration of FIG. 5 can be eliminated.

(Embodiment 6)
FIG. 6 shows a circuit diagram of a sixth embodiment of the present invention. Basically, an example is shown in which power is supplied to a semiconductor light source in which a plurality of light emitting diodes (LEDs) are connected in series using the power supply device shown in the fourth embodiment. Since the LED load is a low impedance load having a predetermined forward voltage, it is one of the loads suitable for output current control. Other differences from the fourth embodiment are that the input filter 6 is illustrated, the output filter 7 is illustrated, the grounding point FG to the housing is illustrated, and the capacitor C2 is provided in parallel with the resistor R1. In other words, the output abnormal state determination means 4 is provided with a timer circuit (timer circuit and latch circuit).

  The output filter 7 is provided for suppressing noise from the power supply device. FIG. 6 shows an output filter having a configuration in which each of the output terminal (c) and the output terminal (a) is grounded by capacitors C3 and C4.

  Now, assuming that the circuit starts operating with the load 2 open, for example, when the circuit starts, the charge of the capacitor C3 constituting the output filter 7 is zero, so the voltage of the capacitor C1 A current for charging the capacitor C3 in accordance with the rise of Vo flows from the secondary side rectification / smoothing circuit of the transformer T1 through the path of the capacitor C3 → the primary side ground line (g) → the resistor R1 → the resistor R4. Due to the charging current to the capacitor C3, a potential difference is generated between both ends of the resistor R1, and the potential of the output terminal (a) temporarily decreases.

  On the other hand, when the load 2 is in the open state, the overvoltage detection circuit 4a detects the rise of the output voltage detection signal and controls to stop the operation of the circuit. At this time, the potential of the output terminal (a) is temporarily changed. When the voltage is lowered, the value of the output voltage detection signal is also lowered temporarily, and as a result, a transient voltage equal to or higher than the set voltage value for overvoltage stop is generated as the output voltage Vo. The generation of a transient voltage of the output voltage Vo leads to an increase in the voltage applied to the elements constituting the circuit. Therefore, it is necessary to select an element that takes the stress into consideration, and the size and cost of the apparatus are reduced. From the viewpoint of, it is not preferable.

  Therefore, in the present embodiment, the generation of a transient voltage of the output voltage Vo can be reduced by providing the capacitor C2 in parallel with the resistor R1. By setting the capacitor C2 to have a sufficiently large capacitance value with respect to the capacitor C3, it is possible to reduce a potential difference generated between both ends of the resistor R1 at the start of circuit operation. In addition, providing the capacitor C2 in parallel with the resistor R1 leads to stabilization of the high frequency potential of the output side circuit, which is effective in suppressing noise.

  The input filter 6 is provided for suppressing noise leaking from the power supply device and reducing noise entering the power supply device from the outside. Capacitors C5 and C6 function as a high-frequency component bypass, and coils L2 and L3 function as a high-frequency component block, and function as a low-pass filter as a whole.

  Further, as shown in FIG. 10 described later, the power supply device 95 has a metal casing, and in this embodiment, the connection (ground) to the casing is connected to a ground point FG (shown), that is, DC−. A connection point between the primary side of the DC conversion circuit 1 and the resistor R1 is used.

  In the case of a high-power LED load, it is generally used by being attached to a heat sink 92 in order to handle the heat generated from the LED itself, but the housing of the power supply device 95 and the heat sink 92 of the LED load 2 are used. Is fixed or is electrically connected for reasons of noise reduction or the like, it is assumed that an accident occurs in which the output terminal of the power supply device 95 is grounded to the heat sink 92 of the LED load 2. When the output terminal (a) is grounded to the heat sink 2 of the LED load 2, the housing is temporarily grounded on the power source E side of the input filter 6 (that is, the grounding point FG in FIG. 6 is illustrated). Is the opposite of the power source E side of the input filter), the current flowing in the circuit from the primary side ground line (g) by the impedance of the element constituting the input filter 6 (coil L3 in FIG. 6). Therefore, a potential difference that cannot be ignored is generated between both ends of the resistor R1 due to the influence of the potential difference, which may affect the detection value input to the output current control means 50. . For example, considering the case where a single power source is used as the operational amplifier of the output current control means 50, the ground of the control circuit is the primary side ground line (g), and the ground point FG is assumed to be the power source E of the input filter 6. If the output terminal (a) has a negative potential for the above reason, the potential generated at the connection point between the resistor R14 and the resistor R15 constituting the signal amplifier 51 is also negative. The input to the operational amplifier Amp2 becomes negative, the expected differential amplification operation cannot be obtained, and the output current cannot be controlled to a predetermined value.

  Therefore, in the present embodiment, the above-mentioned problem is prevented from occurring by setting the installation point of the grounding point FG to the housing as the connection point between the primary side of the DC-DC conversion circuit 1 and the resistor R1. Yes. By providing a grounding point FG to the casing on the grounding wire (g) on the primary side, even when the output terminal (a) is grounded to the heat sink of the LED load, there is a problem between the terminals of the resistor R1. Therefore, even when the ground fault occurs at the output terminal (a), the output current can be controlled to a predetermined value.

  Further, in the present embodiment, a timing circuit is newly provided by changing the configuration of the output abnormal state determination means 4 as compared with the fourth embodiment. Specifically, as shown in FIG. 6, the timing circuit includes a gate circuit AND4, a timer circuit 4c, and a latch circuit 4d, which are connected as shown. When either of the outputs of the comparators Comp1 and Comp2 becomes low level, the output of the gate circuit AND4 also becomes low level, and the timer circuit 4c starts timing accordingly, and deviates from the range that the output voltage detection signal can normally take. When the state continuously occurs for a predetermined time, the signal from the timer circuit 4c to the latch circuit 4d is switched, and the output of the latch circuit 4d becomes low level in response to the signal and is reset when the power is turned on again. , Hold this state.

  With this configuration, when an abnormality occurs in the output voltage detection signal and the abnormality is detected by the overvoltage detection circuit 4a or the low voltage detection circuit 4b, the gate circuit By holding the signal applied to AND1 in the latch circuit 4d and fixing it to the Low level, it becomes possible to maintain the output operation stop of the circuit when an abnormality occurs. Further, since the output of the comparator Comp1 is also directly input to the gate circuit AND1, when the increase of the output voltage is detected by the overvoltage detection circuit 4a when the load 2 is open, the output operation of the circuit is promptly performed. It is possible to temporarily stop and prevent the generation of an excessive output voltage.

  According to the above configuration, when a fault in the power supply or ground fault occurs in the output of the device, or when an abnormal condition such as a short circuit or open circuit or an abnormal element voltage occurs in the load, the abnormal condition is continuously recognized. In this case, the output operation of the circuit can be stopped and the stopped state can be maintained, so that it is possible to reliably determine an abnormality without being affected by noise, etc., and an abnormality has occurred. In some cases, it is possible to provide a safer device by maintaining the stoppage of the output operation.

  In the present embodiment, the timing circuit is assumed to be one, and the case where the same time is measured for both the overvoltage abnormality and the low voltage abnormality is shown, but considering the abnormal state and the stress caused by the current flowing in the circuit at that time, For example, each time may be set independently.

  Further, by inputting the output from the overvoltage detection circuit 4a to the gate circuit AND1, the configuration is also used to temporarily stop the circuit operation. However, the second overvoltage detection is used for detecting the no-load (load release) state. Unlike the reference voltage Vref1, a circuit may be provided separately to detect at a higher voltage value and stop the circuit operation quickly.

(Embodiment 7)
A circuit diagram of the seventh embodiment of the present invention is shown in FIG. 7, and an operation explanatory diagram of the microcomputer 40 is shown in FIG. In the present embodiment, the determination of the abnormal output state is performed using the microcomputer 40, and the point that the external output for notifying the user of the abnormality when the output is determined abnormal is provided. This is a very different point from the embodiment. In addition, the difference between the present embodiment and the sixth embodiment is that the power supply reverse connection protection circuit 8 is illustrated in the input section instead of the input filter 6 and the secondary side rectification / smoothing circuit is in the subsequent stage. The point which connected the filter which consists of the coil L4 and the capacitor | condenser C7, and the point which used the PWM signal generation part 53 as current mode control are mentioned.

  The power supply reverse connection protection circuit 8 is for protecting the circuit by cutting off the current flowing through the circuit when the power supply is connected to the input with reverse polarity. However, since the switching element Q1 has impedance, For the same reason as above, even when such a circuit is provided in the input section, the ground point FG is connected to the ground line (the connection point between the primary side of the DC-DC conversion circuit 1 and the resistor R1 as shown in the figure). It is good to provide in g).

  Since the filter circuit including the coil L4 and the capacitor C7 provided at the subsequent stage of the secondary side rectification / smoothing circuit can smooth the output voltage from the DC-DC conversion circuit 1, an LED which is a low impedance load This is effective for reducing the ripple of the current flowing through the load. At this time, the output voltage detection signal may be detected between the output terminal (c) and the output terminal (a) of the apparatus, but as shown in the figure, the connection point between the capacitor C1 and the diode D1 and the output terminal ( You may detect between a).

  In the present embodiment, an example is shown in which the PWM signal generator 53 is configured by current mode control. An oscillation signal for driving the DC-DC conversion circuit 1 is given from the TIMER port HF of the microcomputer 40, and the one-shot circuit Oneshot2 receives the rising edge to the set terminal S of the set / reset flip-flop SR-FF. A pulse signal for setting is applied, the output Q of the set / reset flip-flop SR-FF becomes High level, and the switching element SW1 is driven on.

  The comparator Comp3 compares the output from the error calculator 52 with the value detected by the voltage generated in the resistor Rs and the instantaneous value of the current flowing through the primary side of the transformer T1, and gives the result to the one-shot circuit Oneshot1. . In response to the fall, the one-shot circuit Oneshot1 gives a reset pulse signal to the reset terminal R of the set / reset flip-flop RS-FF, and the output Q of the set / reset flip-flop SR-FF becomes a low level. The switching element SW1 is driven off.

In addition to the output Q of the set / reset flip-flop SR-FF, an oscillation signal is input to the gate circuit AND1 from the TIMER port HF of the microcomputer 40. When the oscillation signal becomes low level, the gate circuit AND1 The output becomes a low level, and the switching element SW1 is driven off. This defines the maximum on-time of the switching element SW1.
As described above, the current mode control is realized in the present embodiment.

  In the present embodiment, the output abnormal state is determined using the microcomputer 40. However, including an external output that notifies the user of the abnormality when the output is determined to be abnormal, This will be described with reference to FIGS.

  FIG. 8 is an explanatory diagram of the operation of the microcomputer 40 relating to output state monitoring. The flow of output state monitoring after step # 1 will be described. In step # 2, the output voltage detection signal is acquired as Vout by A / D conversion. In step # 3, it is determined whether or not the acquired value of Vout is greater than a predetermined value VHI. If the value of Vout is not greater than the predetermined value VHI, the process proceeds to step # 4, where the output of the high frequency signal is permitted. As a result, a high-frequency signal is output from the TIMER port HF of the microcomputer 40 or, if it has already been output, the high-frequency signal is continuously output. As a result, the output operation of the DC-DC conversion circuit 1 is performed. Done.

  In step # 5, it is determined whether or not the value of Vout is smaller than a predetermined value VLO. If the value of Vout is not smaller than the predetermined value VLO, the process proceeds to step # 6, where the value of the Vout abnormality counter that counts (measures) the abnormal state of Vout is cleared, and then the process is repeated from step # 2.

  When the value of Vout is larger than the predetermined value VHI in step # 3, the process proceeds to step # 7, where the output of the high frequency signal is stopped, and as a result, the output operation of the DC-DC conversion circuit 1 is stopped.

  In step # 8, the value of the Vout abnormality counter is counted up and the occurrence time of the abnormal state is counted. If it is determined in step # 5 that the value of Vout is smaller than the predetermined value VLO, the process proceeds to step # 8, and the value of the Vout abnormality counter is counted up.

  In step # 9, it is determined whether or not the value of the Vout abnormality counter is equal to or greater than the threshold value. If the threshold value has not been reached, the operation is continued. The output of the signal is stopped, and as a result, the output operation of the DC-DC conversion circuit 1 is stopped.

  In step # 11, an error signal ERR for notifying the user that the circuit operation has been stopped due to an output abnormality is output from the output port ERR of the microcomputer 40. At this time, the transistor Q2 in FIG. 7 is turned on, and a current flows through an error display LED provided outside, so that the user can be notified of the abnormality. Here, Vb in FIG. 7 is a power source supplied from the outside. This state is maintained until the device power is reset.

  With the above operation, the microcomputer 40 can be used to determine the abnormal output state and notify the user when the abnormality is determined.

  In the present embodiment, since it is possible to notify the user that an abnormality has occurred, there is an effect that the user can surely know the occurrence of the abnormality. Further, since the output abnormal state is determined using the microcomputer 40, a desired abnormality determination threshold (the above-mentioned predetermined values VHI, VLO) and timekeeping can be easily determined according to the load or the like by simply rewriting the software. The time (threshold value of step # 9) can be set.

  In the present embodiment, the output abnormality is all determined by the microcomputer 40. For example, an overvoltage detection circuit at no load (load release) may be configured to perform a protective operation promptly with a separately provided circuit. .

  An example of another abnormality notification circuit of the present embodiment is shown in FIG. The circuit shown in FIG. 9 is effective when used in combination with the following microcomputer operation, for example. The operation of the error signal ERR for notifying the user that the circuit operation has been stopped due to an output abnormality is, for example, normally output High / Low at a low frequency at a normal time, and is fixed to Low at the time of abnormality determination. Thus, the output of the warning signal WNG provided outside is changed between the normal time and the time of occurrence of an abnormality.

  In this way, the change in the warning signal WNG can be received by another external device (not shown) to determine the occurrence of an abnormality and notify the user. Further, the microcomputer 40 is operated so as to be able to determine which abnormality is determined to stop the operation, and the specification of the signal generated in response to the result is changed (for example, Low when the operation is stopped by the overvoltage state continuation determination) It may be possible to determine which abnormality has occurred based on the warning signal WNG by, for example, fixing to High and fixing to High when the low voltage state continuation determination is stopped.

  By the way, the configurations of the DC-DC conversion circuit 1 and the control circuit including the above-described embodiments are not limited to the configurations exemplified in the embodiments. For example, the error calculation unit 52 is shown as an example of a proportional integration circuit, but may be another proportional circuit. Further, the operation flow of the microcomputer 40 is not limited to that shown in the drawing, and any configuration that can obtain the same operation may be used.

(Embodiment 8)
FIG. 10 shows a cross-sectional view of a lamp according to an eighth embodiment of the present invention. The illustrated lamp shows an outline of the configuration of a headlamp 90 for a vehicle. A power supply device 95 having the above-described configuration and casing in a metal casing is mounted and mounted on the lower surface portion of the casing of the headlamp 90. An LED module 20 composed of a plurality of LED elements is attached to a heat radiating plate 92 and constitutes a light source unit together with an optical unit 91 composed of a lens and a reflecting plate. The light source unit is fixed to the housing of the headlamp 90 with a light source unit fixing jig 93. An input power line 96 of the power supply device 95 is connected to a battery (not shown), and an abnormality notification signal line 97 is connected to a vehicle-side unit (not shown). An output line 94 of the power supply device 95 is connected to the LED module 20.

  As described above, according to the present invention, when an abnormal state such as a power fault occurs in the output line 94 of the power supply device 95 and protection is required, the lighting operation is quickly stopped, and the output line 94 is for the LED module 20. When an abnormal current such as a ground fault does not flow to the heat sink 92, it is possible to provide a safe lamp that can ensure the driver's night vision by maintaining the lighting.

(Embodiment 9)
FIG. 11 is a perspective view of a vehicle according to the ninth embodiment of the present invention. This is an example in which the above-described lamp is used as the headlamp 101 of the vehicle 100. Even if a wiring failure or some kind of accident causes disconnection of the wiring or peeling of the wiring coating, and the power supply output has a power or ground fault, the driver's night vision can be secured. It is possible to provide a vehicle that can ensure the safety of the user.

  In addition, here, the lighting device of the present invention is used for the headlamp 101 of the vehicle 100, but the same effect can be obtained with respect to application to the direction indicator 102, the taillight 103, and the like.

  In addition, in each embodiment, the circuit for directly controlling the current to a predetermined value has been described as the power supply device for lighting the LED load. However, the power supply device for controlling the output voltage described in the first to third embodiments to a predetermined value. The present invention is also effective when the LED load is turned on.

It is a circuit diagram of a 1st embodiment of the present invention. It is a circuit diagram of a 2nd embodiment of the present invention. It is a circuit diagram of a 3rd embodiment of the present invention. It is a circuit diagram of a 4th embodiment of the present invention. It is a circuit diagram of a 5th embodiment of the present invention. It is a circuit diagram of a 6th embodiment of the present invention. It is a circuit diagram of a 7th embodiment of the present invention. It is operation | movement explanatory drawing of the microcomputer of the 7th Embodiment of this invention. It is a circuit diagram of the other abnormality alerting circuit of the 7th Embodiment of this invention. It is sectional drawing of the lamp of the 8th Embodiment of this invention. It is a perspective view of the vehicle of the 9th Embodiment of this invention.

Explanation of symbols

R1 Current limiting resistor T1 Transformer 1 DC-DC conversion circuit 2 Load 3 Output voltage detection unit 4 Output abnormal state determination means 5 Output adjustment unit

Claims (10)

In a power supply device having a DC-DC conversion circuit in which a primary current path and a secondary current path are separated by a transformer,
The abnormal current that flows when an abnormality occurs in the output terminal of the power supply device between one of the two output terminals of the DC-DC conversion circuit and the primary-side ground line or an equivalent reference potential line is limited. Connect a current limiting resistor to
An output voltage detector for detecting the state of the output terminal of the power supply device;
Receiving an output voltage detection signal from the output voltage detection unit, comprising an output abnormal state determination means for determining an output abnormality when the signal is out of a predetermined range;
A power supply device characterized in that when the output terminal of the power supply device has a power fault, the output operation is stopped in response to the determination result of the output abnormal state determination means. 2. The power supply device according to claim 1, wherein the output operation is continued when the output terminal of the power supply device connected to the current limiting resistor has a ground fault. The value of the current limiting resistor is set to be equal to or less than the allowable loss of the resistor and the power supply device even if at least the power supply voltage supplied to the power supply device is applied directly across the current limiting resistor. The power supply device according to claim 1, wherein the power supply device is a power supply device. The power supply device according to claim 1, wherein a capacitor is connected in parallel with the current limiting resistor. The power supply device has a metal casing, and is grounded to the casing at a connection point between the primary side of the DC-DC conversion circuit and the current limiting resistor. The power supply device in any one of -4. 6. The power supply according to claim 1, wherein the output abnormality determination by the output abnormal state determination means determines that the output is abnormal when a state that is abnormal occurs continuously for a predetermined time or more. apparatus. The power supply apparatus according to any one of claims 1 to 6, further comprising means for outputting a signal for notifying a user of an output abnormality when it is determined that the output is abnormal. 8. The DC-DC conversion circuit is controlled so that an output current becomes a predetermined value, and a connected load is a low impedance load such as a light emitting diode. The power supply apparatus in any one. A lamp having the power supply device according to claim 8 mounted thereon. A vehicle comprising the lamp according to claim 9.

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