CN103124456B - LED lamp device - Google Patents

Abstract

The present invention provides an LED lighting device capable of stably operating a phase control dimmer to suppress flicker and having high efficiency. This LED lighting device includes a rectifier circuit that converts a phase-controlled AC power supply voltage into a rectified voltage; a capacitor that is connected to a DC output of the rectifier circuit through a diode and smoothes the rectified voltage to generate a DC voltage; converts the A DC-DC conversion circuit for supplying power to a light-emitting diode load hereinafter referred to as LED; and a current setting circuit for outputting a current setting value of the DC-DC conversion circuit based on the rectified voltage, constituted to have the same a variable resistance circuit connected to the DC output of the rectification circuit; and a resistance value setting circuit that changes the resistance value of the variable resistance circuit according to the rectification voltage, and the resistance value setting circuit operates at a ratio of the rectification voltage to When the required reference voltage is high, the resistance value of the variable resistance circuit is increased.

Description

LED lighting device

technical field

The present invention relates to an LED lighting device.

Background technique

LEDs are attracting attention as light sources with excellent environmental performance, and are used as LED lighting for general lighting in houses and offices. Among LED lighting, there are lightbulb-shaped LED lightings that have the same connectors as incandescent bulbs and are mounted on appliances for incandescent bulbs. There are also dimmers that use a phase control method as a dimming unit for incandescent bulbs (hereinafter Abbreviated as dimmer) corresponding products.

In many dimmers, the AC power supply and the load are turned on and off by turning on and off a bidirectional thyristor (TRIAC: Triode AC Semiconductor Switch), which is a semiconductor element. After the TRIAC is turned on (arcing), if a current greater than a predetermined current value called holding current continues to flow, it will be turned off again (arc extinguishing). Most dimmers are designed on the premise that the load is an incandescent light bulb. If the load is an incandescent light bulb, a sufficient current exceeding the holding current flows from the time the triac is turned on to the time near the zero-crossing point of the AC power supply, and the triac maintains the on state. However, in LED lighting where the load is an LED, the current is smaller than that of an incandescent bulb, so a sufficient current exceeding the holding current cannot flow from the moment the triac is turned on to the moment near the zero cross point of the AC power supply, and an AC The phenomenon that the triac turns off before the power supply zero crossing point. Hereinafter, this phenomenon is referred to as false arc extinction. In particular, in a situation where false arc extinguishing occurs randomly or when the timing of false arc extinguishing is irregular, the operation of the LED lighting device becomes unstable, and flicker occurs during lighting.

As one means of solving the above-mentioned problems, an LED lighting device having a function of continuously flowing a current equal to or greater than a holding current to the triac to prevent false arc extinguishing is conceivable. Such an LED lighting device is disclosed in Patent Document 1, for example. In this device, an equivalent load (DummyLoad) such as a constant current circuit is connected in parallel with a DC-DC converter that supplies power to the LED, and by passing a current through the equivalent load, the current flowing through the triac exceeds the holding current. In addition, the current flowing in the equivalent load also plays the role of resetting the timer circuit of the dimmer and making the disconnected bidirectional thyristor conduct again.

Patent Document 1: Japanese Patent Laid-Open No. 2010-140824

Contents of the invention

In the technique described in Patent Document 1, an equivalent load is provided so that a current equal to or greater than the hold current continues to flow. This can solve the above-mentioned problems, but the holding current varies from dimmer to dimmer, and there are many dimmers that require a current of 30 mA or more to maintain the on state of the triac. In particular, when an LED lighting device is constituted by a capacitive input circuit, the input current is substantially zero during the discharge period of the smoothing capacitor, so all current larger than the holding current must flow through the equivalent load. Here, when the effective value of the voltage applied to the equivalent load is 100V and the current flowing through the equivalent load is 30mA, the loss of the equivalent load is 3W. Considering commercialized lightbulb-shaped LED lighting, most of the power consumption is less than 10W, and the loss of 3W due to the equivalent load is not preferable in terms of efficiency.

An object of the present invention is to realize an efficient LED lighting device capable of stably operating a dimmer and suppressing flicker.

In order to solve the above-mentioned problems, the LED lighting device of the present invention includes: a rectification circuit that converts the phase-controlled AC power supply voltage into a rectified voltage; and connecting the DC output of the rectification circuit through a diode to smooth the rectified voltage and generate a DC voltage. a capacitor; a DC-DC conversion circuit that converts the above-mentioned DC voltage and supplies power to a light-emitting diode (hereinafter referred to as LED) load; and a current setting circuit that outputs the current setting value of the above-mentioned DC-DC conversion circuit based on the above-mentioned rectified voltage, the The LED lighting device is characterized in that: it is configured to include a variable resistance circuit connected to the DC output of the above-mentioned rectification circuit; The fixed circuit increases the resistance value of the variable resistance circuit when the rectified voltage is higher than the required reference voltage.

According to the LED lighting device of the present invention, it is possible to realize a highly efficient LED lighting device capable of stably operating a dimmer and suppressing flicker.

Description of drawings

Fig. 1 is a block diagram of the LED lighting device of the present invention.

Fig. 2 is an internal circuit diagram of a phase control dimmer.

Fig. 3 is an operation waveform when an incandescent bulb is connected to a phase control dimmer.

4 is a configuration example of a variable resistance circuit and a resistance value setting circuit in the LED lighting device of the present invention.

Fig. 5 is an example of an operation waveform of the LED lighting device of the present invention.

6 is a configuration example of a variable resistance circuit and a resistance value setting circuit in the LED lighting device of the present invention.

Figure 7 is the output voltage waveform of the regulator circuit.

Fig. 8 is an example of a specific circuit configuration of the LED lighting device of the present invention.

Fig. 9 is a power supply circuit for a control circuit in the LED lighting device of the present invention.

Symbol Description

100 AC power

101 dimmer

102 rectifier circuit

103, 134 diodes

104, 113, 137 capacitors

105DC-DC conversion circuit

106LED load

107 variable resistance circuit

108 resistor value setting circuit

109 current setting circuit

110 bidirectional thyristor

111, 116, 117, 120, 121, 123, 129, 130, 132, 138, 141 resistors

112 variable resistor

114 bidirectional trigger diode (DIAC: DiodeACSwitch)

115 load

118, 127 comparators

119, 128 DC voltage source

122, 125, 131, 135, 143 MOSFETs

124, 142 Zener diodes

126 regulator (Regulator) circuit

133 diode bridge

136 choke coil

139 control circuit

140 power supply circuit for control circuit

detailed description

Embodiments of the present invention will be described with reference to the drawings.

Fig. 1 is a block diagram of the LED lighting device of the present invention. In FIG. 1 , the right side from the rectifier circuit 102 is the LED lighting device of the present invention. The rectification circuit 102 rectifies the AC power supply voltage phase-controlled by the dimmer 101 to generate a rectified voltage. The DC output of the rectification circuit 102 is connected to a capacitor 104 via a diode 103 . The capacitor 104 smoothes the rectified voltage to generate a DC voltage. That is, the LED lighting device in this embodiment is a capacitive input type circuit. Thereby, the pulsation of the DC voltage is reduced, and it is easy to suppress the pulsation of the current flowing through the LED for the DC-DC conversion circuit 105 at the rear end. The DC-DC conversion circuit 105 converts the DC voltage and supplies power to the LED load 106 . The LED load 106 is not limited to the number of LEDs and the connection method, and may include an LED module incorporating a protective element or the like.

The DC output of the rectification circuit 102 is connected to the variable resistance circuit 107 . The resistance value setting circuit 108 outputs a resistance value setting signal for changing the resistance value of the variable resistance circuit 107 based on the rectified voltage. The variable resistance circuit 107 and the resistance value setting circuit 108 are used to control the ON and OFF states of the bidirectional thyristor in the dimmer 101 according to the rectified voltage, and to reset the timer circuit of the dimmer 101 to make the bidirectional thyristor Thyristor is turned on again. The current setting circuit 109 outputs a current setting value of the DC-DC conversion circuit 105 based on the rectified voltage. Control of the LED current corresponding to the operation of the dimmer 101 , that is, dimming, can be performed by the current setting circuit 109 .

Before describing specific operations, the dimmer 101 will be described. FIG. 2 is a diagram showing an outline of an internal circuit for a dimmer 101 of a phase control method using a triac. As shown in FIG. 2 , the triac 110 is connected between the AC power source 100 and a load 115 . In addition, a timer circuit that is a series body of a resistor 111 , a variable resistor 112 , and a capacitor 113 is connected in parallel with the triac 110 . A connection point between the variable resistor 112 and the capacitor 113 is connected to the gate of the bidirectional thyristor 110 via the triac 114 .

FIG. 3 shows the on and off states of the triac 110 and the waveforms of the load voltage and load current when an incandescent bulb is connected as the load 115 . During the ON period of the triac 110 , the load voltage is substantially the same as the voltage of the AC power source 100 . Because an incandescent bulb is almost purely resistive, the load current has a waveform similar to the voltage. Near the zero-crossing point of the AC power supply 100 , when the load current is less than the holding current of the triac 110 , the triac 110 is turned off. While the triac 110 is off, a minute current flows through the paths from the AC power source 100 to the resistor 111 , the varistor 112 , the capacitor 113 , and the load 115 , and charges are accumulated in the capacitor 113 . Compared to an incandescent bulb, the impedance of the dimmer 101 is sufficiently large that the load voltage is approximately zero. When the voltage of the capacitor 113 rises and the triac 114 is turned on, the triac 110 is turned on again. When the resistance value of the variable resistor 112 is increased by the operation of the dimmer 101 , the time until the triac 110 is turned on again becomes longer. As a result, the load power decreases, and in the case of an incandescent bulb, the light output decreases.

In the present invention, the load 115 in FIG. 2 is the LED lighting device in FIG. 1 , which has different characteristics from the incandescent bulb. Specifically, the impedance is high compared to an incandescent bulb, and is not necessarily purely resistive like an incandescent bulb. Therefore, the operation waveform does not necessarily have to be the same as in FIG. 3 .

FIG. 4 is a configuration example of the variable resistance circuit 107 and the resistance value setting circuit 108 in the LED lighting device of the present invention. The resistance value setting circuit 108 is composed of resistors 116 and 117, a comparator 118, and a DC voltage source 119, and outputs a resistance value setting signal at L level when the rectified voltage is higher than the required reference voltage.

The variable resistance circuit 107 is composed of a series body of a resistor 120 and a MOSFET 122 as a switching element, and a resistor 121 connected in parallel to the series body, and the resistance value is set to two types by turning the MOSFET 122 on and off. Instead of MOSFET 122 , other types of switching elements such as bipolar transistors and IGBTs may be used.

If the rectified voltage is higher than the reference voltage, the MOSFET 122 is turned off, the resistor 120 is cut off, and the resistance value of the variable resistance circuit 107 increases accordingly. Here, the resistance value of the variable resistance circuit 107 does not necessarily have to be two types, and may be configured to continuously change according to the rectified voltage. In addition, the specific configurations of the variable resistance circuit 107 and the resistance value setting circuit 108 are not limited as long as the operations described below can be realized.

5 is an operation waveform of the LED lighting device of the present invention, showing the waveforms of rectified voltage, DC voltage, and rectified current, and the resistance value of the variable resistance circuit 107 . Here, the DC voltage is the voltage of the capacitor 104 as described above. The rectified current is the DC output current of the rectifying circuit 102 and has substantially the same waveform as the rectified current flowing through the dimmer 101 .

When the triac 110 is turned on, the rectified voltage rises to approximately the same voltage level as the AC power supply 100 . At this time, the rectified voltage becomes higher than the reference voltage, and the resistance value of the variable resistance circuit 107 increases. In addition, since the current to charge the capacitor 104 starts to flow from the AC power supply 100 via the dimmer 101 , the rectifier circuit 102 , and the diode 103 , the rectified current also increases rapidly. The current charging the capacitor 104 decreases as the capacitor 104 is charged and the DC voltage rises, so the rectified current also gradually decreases.

The rectified current substantially coincides with the current flowing through the variable resistance circuit 107 around the time when the DC voltage reaches the maximum value and the charging of the capacitor 104 is completed (hereinafter simply referred to as charging completion time). At this point in time, the resistance value of the variable resistance circuit 107 is set in advance so that the rectified current is smaller than the required reference current. Furthermore, if the reference current is set in advance to be smaller than the holding current of the triac 110, the triac 110 is turned off. Holding current varies by dimmer, but is also 5mA minimum. Therefore, if the reference current is set to be less than 5 mA, almost all dimmers can reliably turn off the triac when charging is completed.

The resistance value of the variable resistance circuit 107 at this time is set based on the above-mentioned reference current and the maximum value of the expected rectified voltage. For example, considering the case of use with an AC power supply voltage of 100Vac, the rectified voltage at the completion of charging is about 141V at maximum. Therefore, when the rectified voltage is 141V, in order to make the rectified current smaller than 5mA of the reference current, the resistance value is set to be larger than 28.2kΩ (=141V÷5mA).

Of course, if the resistor 121 is not connected to the variable resistor circuit 107 of FIG. 4, and the variable resistor circuit 107 is opened when the rectified voltage is higher than the reference voltage, then almost all dimmers can be turned on after the charging is completed. Reliably turn off the bidirectional thyristor at the same time. Strictly speaking, however, the resistors 116 and 117 of the elements of the resistance value setting circuit 108 in FIG. 4 can also be considered as part of the variable resistance circuit 107. For these reasons, it is difficult to completely open the variable resistance circuit 107. Therefore, even when the resistor 121 is not connected, it is necessary to set the resistance values of the resistors 116 and 117 as described above.

After the triac 110 is turned off, the rectified voltage drops as shown in FIG. 5 . When the rectified voltage is lower than the reference voltage, the resistance value of the variable resistance circuit 107 decreases. A current flows from the AC power supply 100 to the variable resistance circuit 107 via the timer circuit of the dimmer 101 and the rectification circuit 102 to reset the timer circuit and turn on the triac 110 again. However, while the triac 110 is off, the energy stored in the capacitor 104 is used to stably operate the DC-DC converter circuit 105 .

The problem with conventional LED lighting devices is that, in each cycle of the AC power supply, when the triac erroneously extinguishes the arc and does not erroneously extinguish the arc, or when the timing of the erroneous arc extinction occurs irregularly, the operation of the dimmer changes. Get unstable. In this way, when the operation of the dimmer is unstable, flickering occurs in the LED load.

Conventional countermeasures include connecting an equivalent load to the DC output of the rectifier circuit to prevent erroneous arc extinguishing of the triac, thereby stably operating the dimmer. In this method, the larger the current flowing through the equivalent load, the wider the applicability to dimmers can be expected. However, it is unrealistic to consider the reduction in efficiency due to the increase in loss of the equivalent load.

In contrast, in the present invention, the triac 110 is deliberately turned off at the same timing when the charging of the capacitor 104 is completed. Also in such a form, the dimmer 101 and the DC-DC conversion circuit 105 can be operated stably, and flicker can be prevented. In addition, the method of the present invention is more efficient than the method of flowing a current larger than the holding current with an equivalent load.

FIG. 6 shows another example of the variable resistance circuit 107 and the resistance value setting circuit 108 . In the circuit of FIG. 6 , a resistor 123 , a Zener diode 124 , and a MOSFET 125 constitute a regulator circuit 126 . Instead of MOSFET 125 , other types of semiconductor elements such as bipolar transistors may be used. This regulator circuit 126 is a constituent element for both the variable resistance circuit 107 and the resistance value setting circuit 108 in FIG. 4 . Therefore, instead of distinguishing the variable resistance circuit 107 and the resistance value setting circuit 108 with dotted lines as shown in FIG. 4 .

As shown in FIG. 7, the regulator circuit 126 clamps the rectified voltage at a desired voltage value. The clamp voltage can be set to the Zener voltage of the Zener diode 124 . The comparator 127 indirectly determines whether the rectified voltage is higher than the reference voltage by comparing the output voltage of the regulator circuit 126 with a required threshold. The threshold can be set according to the voltage value of the DC voltage source 128 . In addition, the comparator 127 outputs a resistance value setting signal at L level when the rectified voltage is higher than the reference voltage. By lowering the level of the rectified voltage by the rectifier circuit 126 , even when the reference voltage is as low as several V to several tens of V, the comparison accuracy of the comparator 127 is not affected.

To the output of the regulator circuit 126 , a series body of a resistor 129 and a MOSFET 131 as a switching element and a resistor 130 are connected in parallel. Instead of MOSFET 131 , other types of switching elements such as bipolar transistors and IGBTs may be used. When the rectified voltage is higher than the reference voltage, the resistance value setting signal becomes L level, and MOSFET 131 is turned off. The resistance 130 is cut off, and the resistance value of the variable resistance circuit 107 increases accordingly.

As shown in FIG. 7 , when the rectified voltage is higher than the Zener voltage of the Zener diode 124 , the output voltage of the regulator circuit 126 is substantially equal to the Zener voltage. Furthermore, when the MOSFET 131 is turned off, the current flowing in the variable resistance circuit 107 is a value determined by the Zener voltage and the resistance 130 . Here, when the capacitor 104 is fully charged, the Zener voltage and the resistance value of the resistor 130 may be determined such that the current value determined by the Zener voltage and the resistor 130 is smaller than the reference current in order to make the rectified current smaller than the reference current. Assuming that the reference current is 5mA and the Zener voltage is 10V, the resistance value of the resistor 130 may be set to be greater than 2kΩ (=10V÷5mA).

FIG. 8 specifically shows the structures of the rectifying circuit 102 and the DC-DC converting circuit 105 in the LED lighting device shown in FIG. 1 . In FIG. 8 , the full-wave rectification circuit constituted by the diode bridge 133 is equivalent to the rectification circuit 102 in FIG. 1 . In addition, a step-down chopper circuit composed of a diode 134, a MOSFET 135 as a switching element, a choke coil 136, a capacitor 137, a resistor 138 for current detection, a control circuit 139, and a power supply circuit 140 for a control circuit corresponds to the circuit shown in FIG. DC-DC conversion circuit 105. In addition, a resistor 132 for preventing inrush current is added as a component not shown in FIG. 1 . In addition, fuses, filter capacitors, and the like may be added. Depending on the voltage of the LED load 106, a buck-boost chopper or a boost chopper can be used instead of a buck chopper, and a flyback converter can also be used if isolation is required. Instead of MOSFET 135 , other types of switching elements such as bipolar transistors and IGBTs may be used.

In FIG. 8 , the control circuit 139 controls the current output by the DC-DC conversion circuit 105 to the LED load 106 according to the current setting value. Specifically, control to turn on MOSFET 135 before the current flowing in MOSFET 135 reaches a current setting value may be considered. By controlling the current flowing through MOSFET 135 , the current flowing through LED load 106 can be indirectly controlled. Such a control circuit 139 can be easily configured using a commercially available control IC for LEDs. Of course, instead of using a control IC, it may be configured by combining discrete components such as a comparator, or may be configured by software using a microcomputer or a digital signal processor.

The control circuit power supply circuit 140 is connected to the cathode of the diode 103 and converts the DC voltage of the capacitor 104 to generate a power supply voltage for the control circuit 139 . Specifically, operating voltages of control ICs, comparators, operational amplifiers, and the like in the control circuit 139 are generated. Note that wiring (connection) is omitted in FIG. 8 , but the control circuit power supply circuit 140 may generate power supply voltages for the resistance value setting circuit 108 and the current setting circuit 109 as needed.

As a specific configuration of the control circuit power supply circuit 140, as shown in FIG. 9, a regulator circuit using a resistor 141, a Zener diode 142, and a MOSFET 143 can be considered. Instead of MOSFET 143 , other types of elements such as bipolar transistors may be used. In addition to FIG. 9, other types of regulator circuits such as a three-terminal regulator may be configured.

Here, a configuration in which the control circuit power supply circuit 140 is connected to the anode of the diode 103 to convert the rectified voltage before being smoothed by the AND capacitor 104 to generate a power supply voltage for the control circuit is conceivable. For example, when the variable resistor circuit 107 and the resistance value setting circuit 108 of FIG. 6 are configured, the output voltage of the regulator circuit 126 can be smoothed to generate the power supply voltage of the control circuit. However, in this case, when the charging of the capacitor 104 is completed, the rectified current is increased according to the current flowing in the control circuit power supply circuit 140 , which defeats the purpose of making the rectifier circuit smaller than the reference current. In other words, it is equivalent to reducing the resistance value of the variable resistance circuit 107 according to the resistance value of the control circuit power supply circuit 140 . Therefore, such a structure is not suitable for the LED lighting device of this invention.

On the other hand, if the control circuit power supply circuit 140 is connected as shown in FIG. A state in which the AC power supply 100 is cut off. That is, when the charging of the capacitor 104 is completed, the current flowing through the control circuit power supply circuit 140 is not made to be larger than the rectified current. Therefore, it is an effective connection method to make the rectified current smaller than the reference current.

Instead of providing the power supply circuit 140 for the control circuit as shown in FIG. 8 , the power supply voltage for the control circuit may be generated using the voltage generated in the DC-DC conversion circuit 105 . For example, a method of providing an auxiliary coil in the choke coil 136 may be considered. This method is the same as the method of FIG. 8 in converting the DC voltage of the capacitor 104 to generate the power supply voltage of the control circuit, and can also achieve the same effect.

Claims (3)

1. a LED lamp device, it possesses the rectification circuit by being converted to commutating voltage by the AC supply voltage of phase control; To export with the direct current of described rectification circuit via diode and be connected, make described commutating voltage smoothly and generate the capacitor of direct voltage; Change described direct voltage and the DC-DC change-over circuit that LED load is powered; With the current setting circuit of current setting value exporting described DC-DC change-over circuit according to described commutating voltage, the feature of this LED lamp device is:

Possess and export with the direct current of described rectification circuit the variable resistance circuit be connected; With the resistance value initialization circuit of resistance value changing described variable resistance circuit according to described commutating voltage,

Described variable resistance circuit possesses the concatermer of resistance and switch element,

Described resistance value initialization circuit, when described commutating voltage is than required reference voltage height, disconnects described switch element, increases the resistance value of described variable resistance circuit,

Near the moment of described capacitor charging complete, the average anode current of described rectification circuit is less than required reference current,

Described resistance value initialization circuit possesses: commutating voltage is clamped down on the voltage stabilizing circuit in required magnitude of voltage; With by comparing the output voltage of this voltage stabilizing circuit and required threshold value, indirectly judge the comparator whether described commutating voltage higher than described reference voltage,

Described concatermer is connected with the output of described voltage stabilizing circuit.

2. LED lamp device as claimed in claim 1, is characterized in that:

Described voltage stabilizing circuit, possesses resistance, semiconductor element and Zener diode, and described commutating voltage is clamped down on the Zener voltage in described Zener diode.

3. LED lamp device as claimed in claim 1 or 2, is characterized in that:

Described DC-DC change-over circuit possesses: control the control circuit to the electric current that described LED load exports according to described current setting value; Voltage with the cathode side of the described diode of conversion generates, generates the control circuit power circuit of the supply voltage of described control circuit, described resistance value initialization circuit and described current setting circuit.