KR100784439B1 - Inrush Current Suppression Circuit of Power Supply - Google Patents

Abstract

The present invention relates to an inrush current suppression circuit of a power supply device capable of suppressing inrush current generated at the time of initial startup and immediately after a power short circuit in a general DC power supply and a ballast for a discharge lamp.

The inrush current suppression circuit of the power supply device of the present invention for this purpose is a commercial power supply unit, a bridge diode rectifier configured to convert the commercial AC power supplied by the commercial power supply unit into a DC power supply, and a DC power supply by the bridge diode rectifier. In the inrush current suppression circuit of a power supply device comprising a smoothing capacitor (C0) to charge the output voltage to output a smoothing voltage, and a switching regulator for switching a smooth power supply by the smoothing capacitor (C0), the bridge diode rectifier and the smoothing A resistor R0 connected between the capacitors to suppress initial inrush current, a MOSFET Q1 connected to a source and a drain at both ends of the resistor R0, and a driving voltage is input to a gate, and the MOSFET Q1. It includes a driving circuit for outputting a driving voltage in proportion to the voltage of the smoothing capacitor (C0) When the voltage of the smoothing capacitor C0 is sufficient when the power supply is turned off and on, the secondary inrush current is limited. When the voltage of the smoothing capacitor C0 is low, the current flows only through the resistor R0. The secondary inrush current is suppressed.

Description

Inrush current suppression circuit of power supply unit {INRUSH CURRENT SUPPRESSING CIRCUIT FOR POWER SUPPLY}

1 is a circuit diagram showing a device for supplying a typical commercial AC power supply to the DC power supply.

2 is an inrush current limiting circuit using a conventional NTC thermistor.

3 is an inrush current limiting circuit using a conventional thyristor.

Figure 4 is a circuit diagram showing one embodiment of the inrush current suppression circuit of the power supply apparatus of the present invention.

5 is a circuit diagram showing another embodiment of the inrush current suppression circuit of the power supply apparatus of the present invention.

<Description of the symbols for the main parts of the drawings>

1: commercial power supply

2: bridge diode rectifier

3: switching regulator

4: driving circuit

5: gate

6: source

7: drain

The present invention relates to an inrush current suppression circuit of a power supply device, and more particularly, to suppress an inrush current generated when a power is supplied immediately at initial startup and shortly after a power supply short circuit in a general DC power supply device and a discharge lamp ballast. It relates to an inrush current suppression circuit of a power supply device.

In general, electric and electronic devices require a DC power supply, which is a device that converts commercial AC power into a predetermined DC power so as to operate the device.

1 is a circuit diagram illustrating a device for supplying a general commercial AC power supply to a DC power supply. The commercial power supply unit 100 includes a commercial power supply unit 100, a bridge diode rectifier 200, a smoothing capacitor C0, and a resistor R0. I'm using the method.

Referring to FIG. 1, since the charge charge of the smoothing capacitor C0 is "0" in the initial state, since the same as the short state when the input power is applied, it is as large as several tens A to 100A or more depending on the line impedance. Inrush current is generated.

Inrush current refers to a large current value that temporarily occurs in a circuit when an electric product is turned on. A large inrush current exceeds or exceeds the current limit value of a semiconductor device including a diode used in a power supply. Since the spike voltage generated causes damage to the semiconductor device, the inrush current value should be lowered properly.

As a method of reducing the inrush current value, a method using a negative temperature coefficient (NTC) thermistor has been proposed.

FIG. 2 illustrates an inrush current limiting circuit using a conventional NTC thermistor, which includes a commercial power supply unit 100, a bridge diode rectifier 200, an NTC thermistor (NTH), a smoothing capacitor (C0), and a switching regulator (300). ), Which inserts an NTC thermistor (NTH) into the path through which current flows in the circuit.

NTC thermistors have a large resistance value at low temperatures and at the same time limit the flow of less current because of the large overall line impedance.When the temperature rises due to the heat generated by the NTC thermistor's own resistance as the current flows, the NTC thermistor resists at a constant rate as the temperature changes. This lowers, thereby limiting the initial inrush current without losing itself during normal operation.

Referring to FIG. 2, when commercial power is applied by the operation of the commercial power supply, the bridge diode rectifier 200 converts the commercial power into direct current, and the direct current voltage becomes a smooth voltage through the smoothing capacitor C0.

On the other hand, when the initial power is applied, the NTC thermistor (NTH), which has high resistance at low temperature, controls the initial inrush current, and the temperature gradually increases due to the heat loss generated by the current flowing after the power is turned on, thereby reducing the resistance. It is possible to reduce the loss by the resistance during operation.

However, the method of preventing the inrush current by using the NTC thermistor (NTH) is that when the momentary power failure occurs during operation or when the operation is resumed immediately after the power supply is stopped, the NTC thermistor is completely cooled and the initial high Since the power is supplied before returning to the resistance value, there is no sufficient suppression of the inrush current.

In other words, it usually takes tens to hundreds of seconds for the NTC thermistor to recover from the high temperature state to the initial resistance value of the low temperature state. If the power on / off is repeated before this time, the inrush current suppression capability is lost. As a result, the semiconductor device may be damaged.

To compensate for this, a resistor is used instead of an NTC thermistor, and after the inrush current is suppressed, a current is flowed into the thyristor using a thyristor to prevent a loss in the resistance.

3 shows an inrush current limiting circuit using a conventional thyristor, which includes a commercial power supply unit 100, a bridge diode rectifier 200, a thyristor THY, a resistor R0, and a smoothing capacitor C0. And a switching regulator 300, the thyristor THY should be supplied with a driving signal generated at the switching regulator 300 side for driving.

However, in the method using the thyristor, a voltage drop occurs in the conduction state, so that there is a disconnection which causes self-loss. In the case of using the power factor control circuit, a malfunction occurs because the switching frequency is higher than 50 Hz. There were disadvantages that could be.

An object of the present invention for solving the problems according to the prior art is to further comprise a resistor (MOSFET) and a gate drive circuit in the rectifier circuit consisting of a commercial power supply, a bridge diode, a smoothing capacitor, bridge the MOSFET device It is used as a diode switching element and the MOSFET is driven in proportion to the charge charge of the smoothing capacitor, so that the voltage of the smoothing capacitor is initially supplied and when the power supply is turned off and on again during operation. The present invention provides an inrush current suppression circuit of a power supply device that allows the inrush current to be suppressed by a resistor when sufficiently present.

In addition, another object of the present invention is to form an NTC thermistor at the input terminal of the bridge rectifier consisting of a commercial power supply, a bridge diode, and a smoothing capacitor, and to further configure a PTC thermistor, MOSFET, and gate driving circuit at the output terminal, thereby forming a MOSFET device as a bridge diode. It is used as a switching element, and the MOSFET is driven in proportion to the charge charge of the smoothing capacitor, the initial inrush current is suppressed through the NTC thermistor, and the power supply is turned off by the resistance of the PTC thermistor whose resistance rises as the temperature rises. The inrush current suppression circuit of the power supply is provided so that the secondary inrush current is limited by the resistance of the PTC thermistor.

An inrush current suppression circuit of a power supply device according to an aspect of the present invention for solving the technical problem is a commercial power supply and a bridge diode rectifier configured to convert a commercial AC power supplied by the commercial power supply to a DC power supply; And a smoothing capacitor (C0) charged with a DC power supply by the bridge diode rectifier to output a smoothing voltage, and a switching regulator for switching the smoothing power by the smoothing capacitor (C0). A resistor Q0 connected between the bridge diode rectifier and the smoothing capacitor to suppress an initial inrush current and a source and a drain connected to both ends of the resistor R0 and a driving voltage is input to a gate. ) And a driving voltage to the MOSFET Q1 in proportion to the voltage of the smoothing capacitor C0. And a driving circuit for outputting the second inrush current when the voltage of the smoothing capacitor C0 is sufficient when the power supply is turned off and on, and the resistance when the voltage of the smoothing capacitor C0 is low. The secondary inrush current is suppressed by allowing the current to flow only at R0.

An inrush current suppression circuit of a power supply according to another aspect of the present invention for solving the above technical problem is a commercial power supply and a bridge diode rectifier configured to convert the commercial AC power supplied by the commercial power supply to a DC power supply; And a smoothing capacitor (C0) for charging a DC power supply by the bridge diode rectifier to output a smoothing voltage, and a switching regulator for switching the smoothing power by the smoothing capacitor (C0). The NTC thermistor (NTH) connected between the commercial power supply and the bridge diode rectifier to suppress initial inrush current, and the bridge diode rectifier and the smoothing capacitor (C0) are connected to suppress secondary inrush current. The PTC thermistor (PTH) and both ends of the PTC thermistor (PTH) Bus and a drain connection is made to the MOSFET that is the driving voltage input to the gate (Q1) and the MOSFET (Q1) and a drive circuit for outputting a driving voltage in proportion to the voltage of the smoothing capacitor (C0).

The invention will become more apparent through the preferred embodiments described below with reference to the accompanying drawings. Hereinafter will be described in detail to enable those skilled in the art to easily understand and reproduce through embodiments of the present invention.

4 is a circuit diagram showing an embodiment of the inrush current suppression circuit of the power supply apparatus of the present invention, to convert the commercial power supply 1 and the commercial AC power supplied by the commercial power supply 1 into DC power. Switching for switching the smoothing power supply by the bridge diode rectifier 2, the smoothing capacitor C0 which charges with the DC power supply by the bridge diode rectifier 2, and outputs the smoothing voltage, and the smoothing capacitor C0. It relates to an inrush current suppression circuit of a power supply device including a regulator (3).

According to a characteristic aspect of the present invention, an inrush current suppression circuit of a power supply is connected between the bridge diode rectifier 2 and the smoothing capacitor C0 to suppress an initial inrush current and a resistor R0; The source 6 and the drain 7 are connected to both ends of R0, and the driving voltage is input to the gate 5, and the MOSFET Q1 is proportional to the voltage of the smoothing capacitor C0 at the MOSFET Q1. It includes a driving circuit (4) for outputting a driving voltage to the secondary inrush current is limited if the voltage of the smoothing capacitor (C0) is sufficient when the power supply is turned off and on and the voltage of the smoothing capacitor (C0) In this case, the secondary inrush current is suppressed by allowing the current to flow only through the resistor R0.

The driving circuit 4 is electrically connected to the first resistor R1, the first capacitor C1, and the first capacitor C1, which are connected to the smoothing capacitor C0 in turn, so that the MOSFET Q1 is turned on. The first zener diode (D1) for applying a driving voltage to the gate of the (), the second resistor (R2) connected between the first capacitor (C1) and the first zener diode (D1), and the first The third resistor R3 and the fourth resistor R4 for distributing the voltage of the capacitor C1 and the driving voltage between the gate 5 and the source 6 of the MOSFET Q1 are protected from a threshold value or more. And a second zener diode D2.

According to the inrush current suppression circuit of the power supply apparatus according to the embodiment of the present invention, first, when the initial power is supplied, the inrush current is limited by the resistor R0, and the supplied current charges the smoothing capacitor C0. Done.

As the smoothing capacitor C0 is charged, the voltage of the smoothing capacitor C0 gradually increases by increasing the charge charge, and when the voltage rises above the reference value, the driving circuit 4 operates.

That is, a current flows from the smoothing capacitor C0 to the first resistor R1 to charge the first capacitor C1, and the voltage of the first capacitor C1 increases, so that the threshold value of the first zener diode D1 is increased. If it rises above, the 1st zener diode D1 will become conductive.

As a result, the conduction of the first zener diode D1 causes the drive circuit 4 to apply a drive voltage to the gate 5 of the MOSFET Q1 to short-circuit the drain 7 and the source 6 so as to short-circuit the current. No longer flows to resistor R0, only to MOSFET Q1.

Subsequently, if the voltage is smoothly present in the smoothing capacitor C0 when the power is turned off and then turned on again during the operation of the power supply device, the inrush current is small, and when the voltage is low, the second discharge resistor is a discharge resistor. The charge charged in the first capacitor C1 is discharged by the resistor R2, thereby reducing the voltage of the first capacitor C1.

When the voltage of the first capacitor C1 decreases below the threshold of the first zener diode D1, the first zener diode D1 is turned off, and no driving voltage is applied to the MOSFET Q1 anymore. As the MOSFET Q1 is turned off, the current flows only through the resistor R0, so that the secondary inrush current is suppressed.

In one embodiment of the present invention, the voltage of the smoothing capacitor C0 at which the driving circuit 4 starts to operate may have a magnitude of the secondary inrush current generated by conduction of the MOSFET Q1, which is less than the limit value of the standard. It is desirable to set so that it can be.

As such, when the MOSFET is used in place of the thyristor according to the exemplary embodiment of the present invention, since the internal resistance of the MOSFET is very small, self conduction loss may be reduced than when the thyristor is used.

Fig. 5 is a circuit diagram showing another embodiment of the inrush current suppression circuit of the power supply apparatus of the present invention, to convert the commercial power supply 1 and the commercial AC power supplied by the commercial power supply 1 into DC power. Switching for switching the smoothing power supply by the bridge diode rectifier 2 which is comprised, the smoothing capacitor C0 which charges with DC power supply by the said bridge diode rectifier 2, and outputs a smoothing voltage, and the smoothing capacitor C0. An inrush current suppression circuit of a power supply device including a regulator (3), comprising: an NTC thermistor (NTH) connected between the commercial power supply unit (1) and the bridge diode rectifier (2) to suppress an initial inrush current; A PTC thermistor (PTH) connected between the bridge diode rectifier (2) and the smoothing capacitor (C0) to suppress secondary inrush current, and the PTC thermistor (PTH) The source 6 and the drain 7 are connected to the MOSFET Q1 to which the driving voltage is input to the gate 5, and the driving voltage is proportional to the voltage of the smoothing capacitor C0 to the MOSFET Q1. It comprises a drive circuit 4 for outputting.

In addition, the driving circuit 4 is electrically connected to the first resistor R1, the first capacitor C1, and the voltage of the first capacitor C1, which are sequentially connected to the smoothing capacitor C0. A first zener diode D1 for applying a driving voltage to the gate of Q1, a second resistor R2 connected between the first capacitor C1 and the first zener diode D1, and the first zener diode D1; A third resistor (R3) and a fourth resistor (R4) for distributing the voltage of one capacitor, and a protective agent for protecting the driving voltage between the gate (5) and the source (6) of the MOSFET (Q1) from being above a threshold value. It consists of two zener diodes D2.

According to the inrush current suppression circuit of the power supply apparatus according to another embodiment of the present invention, when the initial power is first supplied, the inrush current is limited by the NTC thermistor (NTH) having a high resistance characteristic when the temperature is low, and the supply is limited. The current to be charged is a smoothing capacitor C0.

As the smoothing capacitor C0 is charged, the voltage of the smoothing capacitor C0 gradually increases by increasing the charge charge, and when the voltage rises above the reference value, the driving circuit 4 operates.

That is, a current flows from the smoothing capacitor C0 to the first resistor R1 to charge the first capacitor C1, and the voltage of the first capacitor C1 increases, so that the threshold value of the first zener diode D1 is increased. If it rises above, the 1st zener diode D1 will become conductive.

As a result, the conduction of the first zener diode D1 causes the drive circuit 4 to apply a drive voltage to the gate 5 of the MOSFET Q1 to short-circuit the drain 7 and the source 6 so as to short-circuit the current. Flows only into MOSFET (Q1).

Subsequently, if the voltage is smoothly present in the smoothing capacitor C0 when the power is turned off and then turned on again during the operation of the power supply device, the inrush current is small, and when the voltage is low, the second discharge resistor is a discharge resistor. The charge charged in the first capacitor C1 is discharged by the resistor R2, thereby reducing the voltage of the first capacitor C1.

When the voltage of the first capacitor C1 decreases below the threshold of the first zener diode D1, the first zener diode D1 is turned off, and no driving voltage is applied to the MOSFET Q1 anymore. MOSFET Q1 is turned off.

At this time, the NTC thermistor (NTH) not only suppresses the inrush current to a minimum, but also the resistance of the PTC thermistor (PTH) because the PTC thermistor (PTH) having a higher resistance at higher temperatures has a resistance characteristic by a predetermined temperature. Secondary inrush current is suppressed.

In another embodiment of the present invention, the voltage of the smoothing capacitor C0 at which the driving circuit 4 starts to operate is such that the magnitude of the secondary inrush current generated by the conduction of the MOSFET Q1 is equal to or less than the limit value of the specification. It is desirable to set so that it can be.

As described above, in another embodiment of the present invention, the NTC thermistor is used to suppress the initial inrush current, and when the power supply of the power supply is turned off and then on, the PTC thermistor having a resistance due to a predetermined temperature is configured to suppress the secondary inrush current. It is.

When the resistance of the PTC thermistor (PTH) is used, the voltage drop of the MOSFET occurs. To reduce the resistance loss caused by the PTC thermistor, the resistance increases as the temperature rises, thereby reducing the continuous self-resistance loss. It can be done.

As described above, the present invention uses the MOSFET element as a bridge diode switching element and causes the MOSFET to be driven in proportion to the charging charge of the smoothing capacitor, so that the power supply is initially turned off and in operation. When the voltage of the smoothing capacitor is sufficiently present when it is turned on again, the inrush current is suppressed by the resistance, thereby effectively suppressing not only the initial inrush current but also the secondary inrush current generated when the power supply is turned off and on. I have to.

In addition, the present invention configures the NTC thermistor at the input of the bridge diode rectifier, and further configures the PTC thermistor, MOSFET, and gate driving circuit at the output, so that the MOSFET device is used as the bridge diode switching device and the MOSFET is proportional to the charge charge of the smoothing capacitor. PTC thermistor's resistance when the power supply is turned off and back on by the PTC thermistor's resistance, which suppresses the initial inrush current through the NTC thermistor and increases the resistance as the temperature rises. By limiting the secondary inrush current by this, there is an advantage that can effectively suppress the initial inrush current and the secondary inrush current.

Although the present invention has been described with reference to the accompanying drawings, it will be apparent to those skilled in the art that many different and obvious modifications are possible without departing from the scope of the invention from this description. Therefore, the scope of the invention should be construed by the claims described to include many such variations.

Claims (6)

Commercial power supply (1), A bridge diode rectifier 2 configured to convert commercial AC power supplied by the commercial power supply unit 1 into DC power; A smoothing capacitor C0 that charges with a DC power supply by the bridge diode rectifier 2 and outputs a smoothing voltage; In the inrush current suppression circuit of a power supply device including a switching regulator (3) for switching a smooth power supply by the smoothing capacitor (C0), A resistor R0 connected between the bridge diode rectifier 2 and the smoothing capacitor C0 to suppress an initial inrush current; A MOSFET Q1 having a source 6 and a drain 7 connected to both ends of the resistor R0 and a driving voltage input to the gate 5; It comprises a drive circuit (4) for outputting a drive voltage in proportion to the voltage of the smoothing capacitor (C0) to the MOSFET (Q1), When the power supply device is turned off and on, the secondary inrush current is limited when the voltage of the smoothing capacitor C0 is sufficient. When the voltage of the smoothing capacitor C0 is low, the current flows only through the resistor R0. To suppress the secondary inrush current. The method of claim 1, The driving circuit (4); A first resistor R1 and a first capacitor C1 that are sequentially connected to the smoothing capacitor C0, A first zener diode (D1) electrically connected to the voltage rising of the first capacitor (C1) to apply a driving voltage to the gate of the MOSFET (Q1); And a second resistor (R2), which is an inverting resistor connected between the first capacitor (C1) and the first zener diode (D1). The method of claim 2, The driving circuit (4); A third resistor R3 and a fourth resistor R4 for distributing the voltage of the first capacitor C1; And a second zener diode (D2) for protecting the driving voltage between the gate (5) of the MOSFET (Q1) and the source (6) above a threshold value. . Commercial power supply (1), A bridge diode rectifier 2 configured to convert commercial AC power supplied by the commercial power supply unit 1 into DC power; A smoothing capacitor C0 that charges with a DC power supply by the bridge diode rectifier 2 and outputs a smoothing voltage; In the inrush current suppression circuit of a power supply device comprising a switching regulator (3) for switching a smooth power supply by the smoothing capacitor (C0), An NTC thermistor (NTH) connected between the commercial power supply unit 1 and the bridge diode rectifier 2 to suppress an initial inrush current, A PTC thermistor (PTH) connected between the bridge diode rectifier (2) and the smoothing capacitor (C0) to suppress secondary inrush current; A MOSFET Q1 connected to a source 6 and a drain 7 across the PTC thermistor PTH and having a driving voltage input to the gate 5; And a driving circuit (4) for outputting a driving voltage in proportion to the voltage of the smoothing capacitor (C0) to the MOSFET (Q1). The method of claim 4, wherein The driving circuit (4); A first resistor R1 and a first capacitor C1 that are sequentially connected to the smoothing capacitor C0, A first zener diode (D1) conducting as the voltage of the first capacitor (C1) increases and applying a driving voltage to the gate of the MOSFET (Q1); And a second resistor (R2), which is an inverting resistor connected between the first capacitor (C1) and the first zener diode (D1). The method of claim 5, The driving circuit (4); A third resistor R3 and a fourth resistor R4 for distributing the voltage of the first capacitor C1; And a second zener diode (D2) for protecting the driving voltage between the gate (5) of the MOSFET (Q1) and the source (6) above a threshold value. .

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