TWI644506B - Power supply device - Google Patents

Abstract

The present invention provides a power supply device that rapidly discharges a capacitor included in a smooth portion at an abnormal time and can reduce the usual loss. The power supply device includes: a smoothing unit 3; a smoothing unit 4; an inverse transform unit 5; a housing 7 that houses the above three; and detects at least one of the forward conversion unit 3, the inverse conversion unit 5, and the housing 7. The abnormal abnormality detecting unit; the smoothing unit 4 includes a capacitor 10 connected in parallel with the output of the forward converting unit 3, a first discharging resistor 12 that discharges the capacitor 10, and a switching element 14 connected in series with the first discharging resistor 12. When the abnormality detecting unit detects an abnormality, the abnormal detecting portion closes the switching element 14, and when the switching element 14 is closed, the capacitor 10 is discharged by the first discharge resistor 12.

Description

Power supply unit

The present invention relates to a power supply device.

The inverter described in Patent Document 1 (inverter: in accordance with the National Institute of Education Electronic Computer Noun Tool is called an inverter, and there is also a case called a reverse inverter or an inverter), A DC power source is generated from an AC power source, and a DC output through an output of a smoothing circuit composed of a reactor and a smoothing capacitor is used to control the ON of the switching element of the inverter circuit. The AC output is obtained by means of OFF (OFF), and the AC output of the high frequency is supplied to a heating coil for induction heating. In this inverter device, a discharge resistor that discharges a smoothing capacitor with a predetermined discharge time constant is connected in parallel with a smoothing capacitor.

[Previous Technical Literature] [Patent Literature]

Patent Document 1: Japanese Patent No. 3419641

In the inverter device described in Patent Document 1, when the discharge resistor is connected in parallel with the smoothing capacitor, the discharge resistor always consumes electric power. In order to reduce the electric power consumed by the discharge resistor, the resistance value of the discharge resistor is increased, the discharge time constant is increased, and the time required for the smoothing capacitor to discharge is increased. If the electric charge remains in the smoothing capacitor, the inspection and maintenance of the circuit are hindered. Therefore, when an abnormality occurs in the device, the smoothing capacitor is required to be quickly discharged (for example, within 10 seconds).

The inverter device described in Patent Document 1 is used for induction heating of a conditioning tool such as a pot, and the output thereof is small, and the electrostatic capacity of the smoothing capacitor is also small. Therefore, even if the resistance value of the resistor for discharge is increased, the discharge time constant becomes large, and the influence is slight. The capacitance of the smoothing capacitor described in one example of Patent Document 1 is 9 μF, and the resistance value of the discharge resistor is 240 KΩ, and the discharge time constant is about 2 seconds.

However, in a power supply device having a large output such as heat treatment of steel materials and welding of electric welded steel pipes, the electrostatic capacitance of the smoothing capacitor is also large. In particular, a power supply device for welding welded electric steel pipes requires a low-ripple power supply device, and the electrostatic capacitance of the smoothing capacitor used for such a power supply device is a maximum value of several tens of μF. When the electrostatic capacitance of the smoothing capacitor is so large, an increase in the resistance value of the discharge resistor causes a significant increase in the discharge time constant. On the other hand, if the resistance value of the discharge resistor is decreased, the amount of electric power consumed by the discharge resistor increases, and since the relationship between the power consumption and the rated value of the resistor requires a large number of resistors, there is a power source. Increase in manufacturing cost and operating cost of the device, and power supply The device will be large-scale concerns.

The present invention has been made in view of the above-described problems, and an object of the invention is to provide a power supply device that can quickly discharge a capacitor included in a smooth portion during an abnormality and can reduce the loss in normal times.

A power supply device according to an aspect of the present invention includes: a conversion unit that converts AC power supplied from an AC power source into DC power; and smoothes DC power including ripple generated from the forward conversion unit a smoothing unit that converts the DC power smoothed by the smoothing unit into an AC power; an apparatus that stores the forward transform unit, the smoothing unit, and the inverse transform unit; and detects the forward transform The abnormality detecting unit of the abnormality of at least one of the inverse transform unit and the housing; the smoothing unit includes at least one capacitor connected in parallel with the output of the forward converting unit, and discharging the capacitor a first discharge resistor and a switching element connected in series with the first discharge resistor; when the abnormality detecting unit detects an abnormality, the abnormality detecting unit closes the switching element, and when the switching element is closed The capacitor is discharged by the first discharge resistor; the capacitor of the smoothing portion includes a first capacitor, the first capacitor System is connected via a diode connected in forward bias mode to the forward transform unit to output, and the first discharge resistor and the first capacitor in parallel lines.

According to the present invention, it is possible to provide a power supply device which can rapidly discharge a capacitor included in a smooth portion at the time of abnormality and can reduce the loss in normal times.

1‧‧‧Power supply unit

2‧‧‧AC power supply

3‧‧‧Shunchang Department

4‧‧‧Smooth Department

5‧‧‧ inverse transformation

6‧‧‧Circuit breaker

7‧‧‧ frame

8‧‧‧Control Department

9‧‧‧load

10‧‧‧ capacitor

11‧‧‧Reactor

12‧‧‧First discharge resistance

13‧‧‧Second discharge resistor

14‧‧‧Switching elements

20‧‧‧ diode

21‧‧‧First capacitor

22‧‧‧second capacitor

23‧‧‧First discharge resistance

24‧‧‧second discharge resistor

25‧‧‧ Third discharge resistor

26‧‧‧Switching elements

30‧‧‧ PLL circuit

31‧‧‧Abnormal detection circuit

32‧‧‧Converter

33‧‧‧Transformers

40‧‧‧ phase comparison circuit

41‧‧‧ analog addition and subtraction

42‧‧‧Voltage Controlled Oscillator

43‧‧‧Signal Control Circuit

50‧‧‧ waveform shaper

50A‧‧‧Resistors

50B‧‧‧ capacitor

51‧‧‧ waveform shaper

51A‧‧‧Resistors

51B‧‧‧ capacitor

52‧‧‧Information flip-flop

53‧‧‧Factor

54‧‧‧ comparator

55‧‧‧Reversal

56‧‧‧Variable Resistor

57‧‧‧Shielding means

CL‧‧‧clock input埠

D‧‧‧Data input埠

G1 to g4‧‧‧ control terminals

I1‧‧‧ Current

M1 to M4‧‧‧ power semiconductor components

Q‧‧‧Set signal 埠

R‧‧‧Reset input埠

S‧‧‧Setting input埠

V1‧‧‧ voltage

Fig. 1 is a block diagram for explaining an example of a power supply device according to an embodiment of the present invention.

Fig. 2 is a circuit diagram of a smoothing portion of the power supply device of Fig. 1.

Fig. 3 is a circuit diagram showing a modification of the smoothing portion of the power supply device of Fig. 1.

Fig. 4 is a block diagram for explaining another example of the power supply device according to the embodiment of the present invention.

Fig. 5 is a circuit diagram of a control unit of the power supply device of Fig. 4.

Fig. 6 is a circuit diagram of a control unit of the power supply device of Fig. 4.

Fig. 1 shows an example of a power supply device for explaining an embodiment of the present invention, and Fig. 2 shows an example of a smoothing unit.

The power supply device 1 includes a forward conversion unit 3 that converts AC power supplied from the AC power supply 2 into DC power, and a smoothing unit 4 that smoothes DC power including chopping output from the forward conversion unit 3. The inverse transform unit 5 converts the DC power smoothed by the smoothing unit 4 into AC power. In the present example, the power supply device 1 further includes a breaker 6 that cuts off the power supply to the forward conversion unit 3 when the AC power supply 2 passes the overcurrent in the forward conversion unit 3, and the conversion unit 3 The smoothing unit 4, the inverse conversion unit 5, and the circuit breaker 6 are housed in the casing 7.

The forward conversion unit 3 may be rectified by, for example, a diode bridge, or may be variably rectified and smoothed using a semiconductor element such as a thyristor that can be turned on according to an external signal. After the DC voltage. In the case of using a semiconductor element, the conduction of the semiconductor element is controlled by the control unit 8.

The inverse transform unit 5 is composed of, for example, a full-bridge circuit mainly composed of four power semiconductor elements capable of switching operations, and is generated by a predetermined switching operation of four power semiconductor elements. Frequency AC power. In addition, six power semiconductor elements can also be used to make the high frequency output a three-phase output. The switching operation of the power semiconductor element is controlled by the control unit 8.

As the power semiconductor element, a switchable action such as an IGBT (Insulated Gate Bipolar Transistor) and a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) can be used. For various types of power semiconductor elements, for semiconductor materials, for example, those using germanium (Si) or using tantalum carbide (SiC).

The output of the inverse conversion unit 5 is connected to the load 9 including the heating coil, and the high-frequency AC power generated by the inverse conversion unit 5 is supplied to the heating coil. Further, the object to be heated is induction-heated by the heating coil. The object to be heated and the purpose of heating are not particularly limited, and examples thereof include heat treatment of steel materials (such as quenching) and welding of electric steel pipes.

In the example shown in FIG. 2, the smoothing unit 4 includes a capacitor 10, a reactor 11, a first discharge resistor 12, a second discharge resistor 13, and a switching element 14.

The capacitor 10 is connected in parallel with the output of the forward converting unit 3 to cancel or reduce the chopping contained in the DC output of the forward converting unit 3. Electricity The electrostatic capacity of the container 10 is appropriately set in accordance with the output of the power supply device 1. For example, when the output of the power supply device 1 is about 300 kW, the electrostatic capacity of the capacitor 10 can be set to about 20,000 μF (however, the electrostatic capacity is In the value of a very low chopping power supply unit). The capacitor 10 is, for example, an electrolytic capacitor that is relatively easy to increase in capacity, but is not limited to an electrolytic capacitor.

Further, in this example, the reactor 11 is interposed between the positive electrode of the output of the forward conversion unit 3 and the terminal of the capacitor 10 connected to the positive electrode side. The reactor 11 operates in conjunction with the capacitor 10 and forms a low-pass filter to improve the ability to remove chopping.

The first discharge resistor 12 is connected in series with the switching element 14, and the first discharge resistor 12 and the switching element 14 connected in series are connected in parallel with the output of the forward conversion unit 3. The switching element 14 can be opened and closed according to an external signal, and is closed and closed by the control unit 8. Further, when the switching element 14 is closed (conducted), the capacitor 10 is discharged by the first discharge resistor 12 and the switching element 14.

The switching element 14 can be, for example, a mechanical contact element such as a magnetic switch that is switched by a movable iron piece attracted by an electromagnet, or a semiconductor element such as a thyristor, but has mechanical properties. In comparison with the components of the contacts, it is preferable to use semiconductor components having a long life of the components.

The second discharge resistor 13 is connected in parallel with the first discharge resistor 12, and the capacitor 10 is constantly discharged by the second discharge resistor 13. The resistance value of the second discharge resistor 13 is greater than the resistance value of the first discharge resistor 12 Large, for example, the resistance value of the first discharge resistor 12 is several hundred Ω, and the resistance value of the second discharge resistor 13 is several tens of kΩ to several hundreds kΩ.

When the AC power supply 2 has an overcurrent flowing to the forward conversion unit 3, the circuit breaker 6 cuts off the power supply to the forward conversion unit 3, and when the power supply to the forward conversion unit 3 is cut off, the display conversion unit 3 is displayed. The abnormal abnormal signal is sent to the control unit 8.

The control unit 8 is configured mainly by a processor, and controls the switching operation of the power semiconductor element of the inverse conversion unit 5, and controls the conduction of the semiconductor element when the forward conversion unit 3 uses a semiconductor element such as a thyristor. Further, the control unit 8 closes the switching element 14 when an abnormal signal is input from the circuit breaker 6.

By the closing of the switching element 14, the capacitor 10 is discharged through the second discharge resistor 13 and through the first discharge resistor 12. The resistance value of the first discharge resistor 12 (for example, several hundred Ω) is smaller than the resistance value of the second discharge resistor 13 (for example, several tens of kΩ to several hundreds of kΩ), and the charge accumulated in the capacitor 10 is almost always distributed in the first. Discharge resistor 12. The smaller the resistance value of the discharge resistor is, the larger the current flowing through the discharge resistor is with respect to the voltage between the terminals of the capacitor 10, and when the circuit breaker 6 and the control unit 8 detect that there is an abnormality in the forward conversion portion 3, the resistance value can be obtained. The smaller first discharge resistor 12 causes the capacitor 10 to discharge rapidly. For example, when the electrostatic capacity of the capacitor 10 is 20,000 μF and the resistance value of the first discharge resistor 12 is 300 Ω, the discharge time constant is about 6 seconds.

Furthermore, from the viewpoint of the safety of heat generation, a resistor that is normally energized is generally used with a rated power of about 1/4, but The charge accumulated in the capacitor 10 during the abnormality flows only to the first discharge resistor 12 at the timing when the switching element 14 is closed, and the heat generation due to the energization of the first discharge resistor 12 is instantaneous, so that the first discharge resistor 12 can be used in Near or above the upper limit of rated power. Thereby, the number of resistors constituting the first discharge resistor 12 can be reduced, and the manufacturing cost of the power supply device 1 can be reduced and the power supply device 1 can be downsized. For example, when the output voltage of the AC power supply 2 is 440 V and the forward conversion unit 3 is rectified by a diode bridge, the output voltage of the forward conversion unit 3 is about 600V. Further, when the resistance value of the first discharge resistor 12 is 300 Ω, the current flowing through the first discharge resistor 12 is at most 2 A, and the power consumption of the first discharge resistor 12 is at most 1200 W. In this case, for example, a resistor having a large rated power such as an enamelled resistor is used, and the first discharge resistor 12 is constituted by one resistor. This is because the first discharge resistor 12 is used only for discharge, and is used at a very low usage rate.

Further, in the normal state, that is, when an abnormality is not detected, and the power supply device 1 is normally operated or stopped, the first discharge resistor 12 is not energized, and no electric power is consumed by the first discharge resistor 12. Therefore, the running cost of the power supply device 1 can be reduced.

The second discharge resistor 13 may be omitted from the viewpoint of rapidly discharging the capacitor 10 in an abnormal state, but it is preferable to provide the second discharge resistor 13 so that the capacitor 10 passes normally when the power supply device 1 is normally operated or stopped. The second discharge resistor 13 is discharged. For example, in a transient state in which the charging of the capacitor 10 is started or the like, there is a case where the voltage between the terminals of the capacitor 10 instantaneously becomes high, but the capacitor 10 is placed through the second discharge resistor 13 By this, it is possible to suppress an excessive voltage from being applied to the inverse conversion unit 5, and the power semiconductor element of the inverse conversion unit 5 can be protected.

Further, since the resistance value of the second discharge resistor 13 is much larger than the resistance value of the first discharge resistor 12 (for example, several tens of kΩ to several hundreds of kΩ), the current flowing through the second discharge resistor 13 is extremely small (for example, several mA). Up to several tens of mA), so even if the second discharge resistor 13 constantly consumes power, the amount of power consumed is negligible.

Fig. 3 shows a modification of the smoothing portion 4.

In the example shown in FIG. 3, the smoothing unit 4 includes a first capacitor 21, a capacitor connected in parallel with the output of the forward converting unit 3, and a second capacitor directly connected to each other via the diode 20. The smoothing portion 4 further includes a first discharge resistor 23, a second discharge resistor 24, a third discharge resistor 25, and a switching element 26.

The first discharge resistor 23 is connected in series with the switching element 26, and the first discharge resistor 23 and the switching element 26 connected in series are connected in parallel with the first capacitor 21. The switching element 26 can be opened and closed according to an external signal, and is closed and closed by the control unit 8.

The second discharge resistor 24 is connected in parallel with the first discharge resistor 23, and the first capacitor 21 is constantly discharged by the second discharge resistor 24. From the viewpoint of reducing the amount of electric power consumed by the second discharge resistor 24, the resistance value of the second discharge resistor 24 is larger than the resistance value of the first discharge resistor 23, for example, the resistance value of the first discharge resistor 23 is several hundred. Ω, and the resistance value of the second discharge resistor 24 is several tens of kΩ to several hundred kΩ.

The third discharge resistor 25 is coupled to the second capacitor 22 The second capacitor 22 is constantly discharged by the third discharge resistor 25. The resistance value of the third discharge resistor 25 is larger than the resistance value of the first discharge resistor 23 from the viewpoint of reducing the amount of electric power consumed by the third discharge resistor 25, for example, the resistance value of the first discharge resistor 23 is several hundred. Ω, and the resistance value of the third discharge resistor 25 is several tens of kΩ to several hundred kΩ.

The first capacitor 21 connected in parallel with the output of the forward conversion unit 3 via the diode 20 is charged when the voltage between the terminals of the first capacitor 21 is lower than the voltage between the terminals of the second capacitor 22. Therefore, the chopping contained in the output of the forward converting portion 3 is substantially eliminated or reduced by the second capacitor 22. Similarly to the capacitor 10 of the smoothing unit 4 shown in Fig. 2, the second capacitor 22 is constantly discharged by the third discharge resistor 25, thereby suppressing the rise of the voltage between the terminals of the second capacitor 22 in the transient state. The power semiconductor element of the inverse transform unit 5 is protected. The first capacitor 21 operates in conjunction with the diode 20 and the second discharge resistor 24 to form a transient voltage suppression circuit to further suppress an increase in the voltage between the terminals of the second capacitor 22 in the transient state. Since the rise of the voltage between the terminals of the second capacitor 22 in the transient state is suppressed by the above-described transient voltage suppression circuit, the third discharge resistor 25 can be omitted.

Preferably, the electrostatic capacity of the first capacitor 21 is smaller than the electrostatic capacity of the second capacitor 22. For the first capacitor 21 having a relatively small electrostatic capacitance, for example, a film capacitor having a longer life than the electrolytic capacitor is suitable. .

Similarly, in the example shown in Fig. 3, when the AC power supply 2 flows to the forward conversion unit 3, an overcurrent flows, and the circuit breaker 6 cuts off. The power supply to the forward conversion unit 3 is sent from the circuit breaker 6 to the control unit 8, and the control unit 8 closes the switching element 26. By the closing of the switching element 26, the first capacitor 21 is first discharged in addition to the second discharge resistor 24 and through the first discharge resistor 23. The resistance value of the first discharge resistor 23 (for example, several hundred Ω) is smaller than the resistance value of the second discharge resistor 24 (for example, several tens of kΩ to several hundreds of kΩ), and the charge accumulated in the first capacitor 21 is almost always distributed. The first discharge resistor 23, the first capacitor 21 is rapidly discharged by the first discharge resistor 23. Then, the first capacitor 21 is discharged and the voltage between the terminals of the first capacitor 21 becomes lower than the voltage between the terminals of the second capacitor 22, whereby the second capacitor 22 is again rapidly discharged through the first discharge resistor 23. . For example, when the electrostatic capacity of the first capacitor 21 is 7000 μF, the electrostatic capacity of the second capacitor 22 is 20,000 μF, and the resistance value of the first discharge resistor 23 is 300 Ω, the discharge time constant is about 8 seconds.

The abnormality of the power supply device 1 is an example in which an overcurrent flows from the AC power supply 2 to the forward conversion unit 3, and the abnormality of the forward conversion unit 3 is detected by the circuit breaker 6 and the control unit 8. For example, the abnormality of the power supply device 1 may be that the opening of the casing 7 is detected. For example, an opening detecting portion composed of a switch or a sensor is appropriately provided in the door or the door frame of the casing 7, and the opening detecting portion is turned on (ON) or turned off (OFF) in response to the opening of the casing 7. The control unit 8 detects the opening of the casing 7 in accordance with the ON state and the OFF state of the opening detection unit. When the opening of the casing 7 is detected, in the smoothing portion 4 shown in Fig. 2, the switching element 14 is closed by the control portion 8, so that the capacitor 10 is provided. The first discharge resistor 12 is rapidly discharged. Further, in the smoothing portion 4 shown in Fig. 3, the switching element 26 is closed by the control unit 8, and the first capacitor 21 and the second capacitor 22 are passed through the first discharge. The resistor 23 is rapidly discharged.

In addition, in the abnormality of the power supply device 1, the abnormality of the inverse conversion unit 5 may be detected, and an example of the abnormality of the inverse conversion unit 5 and the detection method thereof will be described with reference to FIGS. 4 to 6. The components common to the power supply device 1 described above are denoted by the same reference numerals, and the description thereof will be omitted or simplified.

The control unit 8 has a phase synchronization loop circuit (hereinafter simply referred to as "PLL circuit") 30 that controls the frequency of the AC power output by the inverse conversion unit 5 to be the same as the resonance frequency of the load 9 connected to the inverse conversion unit 5. And the abnormality detecting circuit 31. The inverse conversion unit 5 is provided with a current transformer 32 that detects the current I1 supplied to the load 9, and a transformer 33 that detects the voltage V1 applied to the load 9.

As shown in FIG. 5, the PLL circuit 30 is provided with a phase comparison circuit 40 for detecting the current I1 detected by the converter 32 and the phase of the voltage V1 detected by the transformer 33; analogy addition and subtraction The controller 41 adds or subtracts a preset frequency setting value in response to the phase detected by the phase comparison circuit 40. The voltage controlled oscillator 42 outputs a signal having a frequency corresponding to the voltage output from the analog subtractor 41. And the control signal circuit 43 sends the control signals to the control terminals g1 to g4 of the power semiconductor elements M1 to M4 of the inverse conversion unit 5 in response to the frequency of the signal output from the voltage controlled oscillator 42.

The PLL circuit 30 controls the operation frequency control of the inverse conversion unit 5 so as to cancel the phase difference between the current I1 supplied to the load 9 and the voltage V1 applied to the load 9, and the AC power output from the inverse conversion unit 5 is output. The frequency coincides with the resonant frequency of the load 9 including the inductance component L and the capacitance component C. Thereby, the efficiency of the power supply device 101 can be improved.

However, when a part of the circuit on the load 9 side is short-circuited or an abnormality in the open circuit occurs, the impedance of the load 9 changes rapidly, and the resonance frequency greatly fluctuates. In this manner, the PLL circuit 30 adjusts the operating frequency of the inverse conversion unit 5 so as to follow the resonance frequency of the load 9. In the transient state, a large current and/or voltage instantaneously occurs in the inverse conversion unit 5, and the power is destroyed. Concerns about the semiconductor elements M1 to M4. Specifically, due to the change in the impedance of the load 9, when the phase of the current I1 leads the phase of the voltage V1, a large surge voltage occurs, and the power semiconductor is destroyed by the surge voltage. Concerns of components M1 to M4. Therefore, the abnormality detecting circuit 31 forms a phase shift detecting unit such that the current transformer 32 and the transformer 33 operate together to detect the current I1 detected by the converter 32 and the detected by the transformer 33. The phase shift of the voltage V1.

The abnormality detecting circuit 31 receives the current I1 detected by the current transformer 32 and the voltage V1 detected by the transformer 33, and as shown in Fig. 6, the abnormality detecting circuit 31 is provided with The waveform shaper 50 integrates the waveform of the input voltage V1 into a predetermined square wave; the waveform shaper 51 forms a predetermined square wave of the input current I1; the data flip-flop 52 is a phase offset detecting means for detecting the phase shift of the voltage V1 and the current I1; The device 53 serves as a latch for holding the output of the data flip-flop 52; the comparator 54 detects whether the magnitude of the current I1 reaches a reference value; and the inverter 55 reverses the comparator 54 Output signal.

The waveform shaper 50 is provided with a resistor 50A having a DC resistance value corresponding to the voltage input to the data flip-flop 52 for blocking the unnecessary harmonic components included in the waveform of the voltage V1. Broken capacitor 50B and so on. Similarly to the waveform shaper 50, the waveform shaper 51 includes a resistor 51A having a DC resistance value corresponding to the voltage input to the data flip-flop 52, and a non-essential included in the waveform of the current I1. The capacitor 51B that blocks the high harmonic component and the like.

The data flip-flop 52 has: clock input 埠 CL, input clock signal; data input 埠 D, input data signal; set input 埠 S, input setting signal; reset input 埠 R, input reset The signal and the setting signal 埠Q are sent to the setting signal if the setting state is entered; and if the clock signal is simultaneously input with the data signal, the setting state is entered and the setting signal is sent from the setting signal 埠Q.

The comparator 54 compares the comparators respectively input to the magnitudes of the alternating signals of the two input ports. An input signal of the comparator 54 is input with an alternating current signal indicating the value of the current I1 supplied to the load 9. The other input of the comparator 54 is input with an alternating current signal obtained by dividing the predetermined alternating voltage V2 by the variable resistor 56 as a predetermined reference value. If the current I1 is larger than the reference value, the comparator 54 outputs a stable operation signal. This stable operation signal is inverted in the inverter 55 and transmitted to the data positive The reset input of the counter 52 is 埠R. By means of the comparator 54, the inverter 55 and the variable resistor 56, a mask means 57 for continuously outputting a reset signal to the data flip-flop 52 before the current I1 value becomes greater than the reference value is formed.

In the above configuration, before the operation of the power supply device 1 reaches the steady state after the power supply device 1 is started, specifically, the operating frequency of the inverse conversion unit 5 coincides with the resonance frequency of the load 9, and the current I1 supplied to the load 9 Before the reference value is larger, the masking means 57 continues to output a reset signal to the data flip-flop 52 to stop the phase shift detecting operation by the abnormality detecting circuit 31. Thereby, it is eliminated that the current I1 supplied to the load 9 is unstable, and the power supply device 1 whose phase does not coincide with the voltage is forced to stop immediately after starting. Further, when the operation of the power supply device 1 reaches a steady state, the phase shift detecting operation by the abnormality detecting circuit 31 is started.

When the resonance frequency of the load 9 matches the operation frequency of the inverse conversion unit 5 and the phase of the voltage V1 and the phase of the current I1 coincide with each other, the data flip-flop 52 is maintained in the reset state and does not migrate to the setting. In the state, and the setting signal is not sent from the setting signal 埠Q, the power supply device 1 continues the original operation.

On the other hand, when the load 9 is abnormal, when the resonance frequency of the load 9 is shifted from the operating frequency of the inverse transform unit 5, the phase of the voltage V1 and the phase of the current I1 do not coincide with each other, causing an abnormality of the inverse transform unit 5. When the state as described above is formed, the data flip-flop 52 shifts to the set state, and the set signal is sent from the set signal 埠Q, and the set signal is input to the abnormal signal indicating the abnormality of the inverse transform unit 5 via the flip-flop 53. PLL circuit 30.

The PLL circuit 30 after the abnormal signal input appropriately sets the power semiconductor elements M1 to M4 to the off state to stop the power supply to the load 9 to protect the power semiconductor elements M1 to M4. The abnormal signal is continuously output until the flip-flop 53 is reset. Further, the control unit 8 between the internal PLL circuit 30 and the abnormality detecting circuit 31 by the abnormal signal contacts the switching element 14 in the smoothing portion 4 shown in Fig. 2, and causes the capacitor 10 to pass the first discharge. The resistor 12 is rapidly discharged. Further, in the smoothing portion 4 shown in FIG. 3, the switching element 26 is closed, and the first capacitor 21 and the second capacitor 22 are quickly discharged by the first discharge resistor 23.

According to the abnormality detecting method of the inverse transform unit 5 described above, the abnormality of the inverse transform unit 5 can be quickly detected from the phase shift of the current I1 and the voltage V1 due to the fluctuation of the resonant frequency of the load 9. Before the operation frequency of the inverse transform unit 5 follows the operation of the PLL circuit 30 of the resonance frequency of the load 9, the abnormality of the inverse transform unit 5 is surely detected. When the abnormality of the inverse transform unit 5 is detected, the power semiconductor elements M1 to M4 of the inverse transform unit 5 are appropriately turned off, whereby the destruction of the power semiconductor elements M1 to M4 can be prevented in advance.

Further, the abnormality detecting circuit 31 for detecting the phase shift of the current I1 and the voltage V1 includes a data flip-flop 52 which is formed by the data signal input simultaneously with the clock signal. a state, and a setting output of a signal belonging to the set state is sent; and when the phase of the current I1 and the voltage V1 is shifted, the setting signal (abnormal signal) is output from the data flip-flop 52, whereby a simple circuit can be utilized. Composition test The phase of the output current I1 and the voltage V1 is shifted.

Further, the abnormality detecting circuit 31 includes a shielding means 57 for comparing the current value of the current I1 supplied to the load 9 with a predetermined reference value, and until the value of the current I1 becomes larger than The reset signal is continuously outputted to the data flip-flop 52 until the reference value is reached; when the current I1 is unstable, and the phase of the current I1 and the phase of the voltage V1 do not coincide with each other, the abnormality detecting circuit 31 is temporarily stopped. Since the phase shift detecting operation is performed, it is possible to eliminate the adverse effect of forcibly stopping the power supply device 1 after starting.

As described above, the abnormality detecting unit that detects the abnormality of the forward converting unit 3 by the circuit breaker 6 and the control unit 8 and the abnormality detecting unit that detects the abnormality of the detecting frame 7 by the opening detecting unit and the control unit 8 are described. The abnormality detecting unit that detects the abnormality of the inverse transform unit 5 by the control unit 8 including the abnormality detecting circuit 31, the converter 32, and the transformer 33 may be used alone or in combination of a plurality of phases.

Claims (9)

A power supply device includes: a forward conversion unit that converts AC power supplied from an AC power source into DC power; and a smoothing unit that smoothes DC power including chopping output from the forward conversion unit; The unit converts the DC power smoothed by the smoothing unit into AC power, and the housing includes the forward conversion unit, the smoothing unit, and the inverse conversion unit, and an abnormality detecting unit that detects the forward An abnormality of at least one of the conversion unit, the inverse conversion unit, and the frame; the smoothing unit includes at least one capacitor connected in parallel with an output of the forward conversion unit; and the first discharge resistor is a capacitor Discharging; and the switching element is connected in series with the first discharge resistor; and when the abnormality detecting unit detects an abnormality, the switching element is closed by the abnormality detecting unit, and when the switching element is closed, The capacitor is discharged by the first discharge resistor, and the capacitor of the smoothing portion includes a first capacitor, the first capacitor System is connected via a diode connected in forward bias mode to the conversion of cis to the output portion, the first discharge resistor and the first capacitor in parallel lines. The power supply device according to claim 1, wherein the smoothing portion further includes a second discharge resistor connected in parallel with the first discharge resistor, and causing the capacitor to be constantly discharged; The resistance value of the second discharge resistor is larger than the resistance value of the first discharge resistor. The power supply device according to claim 1, wherein the capacitor of the smoothing portion includes a second capacitor directly connected to an output of the forward converting portion and having a capacitance larger than the first capacitor Still big. The power supply device of claim 3, wherein the smoothing portion further includes a third discharge resistor connected in parallel with the second capacitor, and causing the second capacitor to be constantly discharged. The resistance value of the third discharge resistor is larger than the resistance value of the first discharge resistor. The power supply device of claim 1, wherein the switching element has a mechanical contact. The power supply device according to claim 1, wherein the switching element is a semiconductor element. The power supply device according to any one of claims 1 to 6, wherein the abnormality detecting unit includes a circuit breaker that is configured to pass an overcurrent when the alternating current power source flows to the forward conversion unit. Cut off The power supply device supplies the power supply to the forward conversion unit; and the power supply device closes the switching element when the power supply to the forward conversion unit is cut off by the circuit breaker. The power supply device according to any one of claims 1 to 6, wherein the abnormality detecting portion includes an opening detecting portion that detects when the frame is opened. When the power supply device detects the opening by the opening detecting portion, the switching element is closed. The power supply device according to any one of claims 1 to 6, wherein the inverse conversion unit controls the output frequency of the inverse conversion unit to coincide with a resonance frequency of a load connected to the power supply device, the abnormality The detection unit includes a phase shift detecting unit that detects a phase shift between an output voltage of the inverse transform unit and an output current; and the power supply device is detected by the phase shift When the output detects a phase shift, the aforementioned switching element is closed.