JP2000115998A - Power supply - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to protect a power supply provided with a boosting active filter against any anomaly through a simple, inexpensive, small- sized and light-weight constitution. SOLUTION: A power supply comprises an active filter AF of a boosting converter connected with the input side of a DC-to-DC converter CONV which supplies a load with power. The power supply is provided with an anomaly detection circuit HB4 which takes the status of the operation of the switching element Q1 of the active filter AF as voltage information out of auxiliary winding N2 for monitoring the current passed through the choke coil L1 of the active filter AF, and judges any anomaly in the switching element Q1 from its voltage level. According to output from the anomaly detection circuit HB4, the inrush current limiting circuit Pr between an alternating-current power supply and the active filter AF is controlled, thereby performing circuit protecting operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an abnormal protection device for monitoring the operating state of a switching element in a circuit constituting a boost type active filter used for improving a power factor of a power supply device and performing a protective operation when an abnormality occurs. .

[0002]

2. Description of the Related Art One of the measures for improving the input power factor of a switching power supply apparatus which receives power supply from an AC power supply line is to connect an active filter as a smoothing filter to the input side of a main converter. It has been known.

This active filter has a circuit configuration generally known as a chopper type converter. By appropriately controlling the on / off operation of the switching element, the input voltage and the input current (average value) are made proportional to each other, so that The ratio is to be improved to approximately 1.0.

When such an active filter is provided in the power supply device, two independent control circuits for the active filter and the main converter are required in the power supply device.
Naturally, drive power must be supplied to each control circuit.

In general, drive power is supplied to each control circuit by different means during startup and during normal operation in order to stabilize the voltage value and reduce loss.

FIG. 3 shows an example of a circuit of a conventional power supply device employing an active filter. In FIG. 3, an AC input is connected to an AC input terminal of a diode bridge DB for rectifying to DC through a double-throw switch S1 capable of intermittently connecting each line, and a rush current limiting circuit is provided on the hot side of the AC input. Pr is inserted in series.

The inrush current limiting circuit Pr has a triac TR connected in parallel with a resistor Rt with a built-in thermal fuse. ) -A gate resistor Rg and a capacitor Cg are connected in parallel between the gates. The photodiode side of the phototriac PTR1 is connected to the output terminal on the secondary side.

One end of the choke coil L1 is connected to the "+" terminal of the diode bridge DB, and the other end of the choke coil L1 is connected to the anode of the diode D1 and the drain of the MOS-FET Q1 as a switching element. ing.

The source of the switching element Q1 is connected to the "-" terminal of the diode bridge DB via a current detection resistor Rs, and the cathode of the diode D1 is connected to the "-" terminal of the diode bridge DB via a smoothing capacitor Cin and the current detection resistor Rs. Form a loop toward the terminal.

The PWM output terminal of the active filter control circuit HB1 is connected to the gate of the switching element Q1.

The above-mentioned choke coil L1, switching element Q1, diode D1, smoothing capacitor Cin, current detection resistor Rs and active filter control circuit HB1
Constitutes a main circuit of the active filter AF.

The current detection terminals Isen1 and Isen2 of the active filter control circuit HB1 are connected to both ends of the current detection resistor Rs, and the current value of the line is input as voltage information. The pulsating output voltage that has been full-wave rectified by the diode bridge DB is input to the input terminal Iac of the active filter control circuit HB1, and the output voltage of the “+” terminal of the smoothing capacitor Cin is input to the input terminal Vsens.

The active filter control circuit HB1 has P
A PWM control circuit for controlling the switching element Q1 based on the current and voltage detection inputs (AC input voltage, DC current and voltage) to perform proportional control of the input voltage and the input current. This improves the power factor.

One end of a primary winding P1 of a transformer T is connected to the cathode of the diode D1.
The other end of 1 is connected to the drain of Q2 of a MOS-FET as a switching element.

The source of the switching element Q2 is connected to the "-" terminal of the smoothing capacitor Cin, and the gate is connected to the PWM output terminal of the converter control circuit HB2. The secondary winding S of the transformer T has one end connected to the anode of the diode Ds1 and the other end connected to the output terminal GND.
Connected to the side.

On the secondary side of the transformer T, the cathode of the diode Ds1 is connected to the cathode of the diode Ds2 and one end of the choke coil Lo.
The other end of o is connected to the output terminal Vo and one end of the smoothing capacitor Co.

The anode of the diode Ds2 and the other end of the smoothing capacitor Co are connected to the output terminal GND. The transformer T, the switching element Q2, the diodes Ds1 and Ds2, the choke coil Lo, the smoothing capacitor Co, and the converter control. The circuit HB2 constitutes a main part of a DC-DC converter which is a main converter of the illustrated power supply device.

The transformer T has an auxiliary power supply winding P2
The auxiliary power supply winding P2 has one end connected to the anode of the diode D2 and the other end connected to the "-" terminal of a relatively large-capacity smoothing capacitor C1.

The cathode of the diode D2 is connected to the "+" terminal of the smoothing capacitor C1 and then to the anode of the diode D3. The cathode of the diode D3 is
Connected to the power supply terminal (Vcc) of converter control circuit HB2, the cathode of diode D2 and auxiliary power supply winding P
A capacitor C2 (C2 << C1) is connected to the other end of the capacitor C2.

One end of a resistor Rst is further connected to a power supply terminal (Vcc) of the converter control circuit HB2.
The other end of the resistor Rst is connected to one end of a primary winding P1 (diode D1).
1). These diodes D2, D3,
Capacitors C1 and C2 constitute an auxiliary power supply circuit Pc that supplies drive power to converter control circuit HB2 during the (normal) operation of the illustrated DC-DC converter, while resistance R
st constitutes a start-up circuit that supplies drive power to the converter control circuit HB2 when the DC-DC converter is started.

The anode of a diode D4 is connected to the "+" terminal of the smoothing capacitor C1.
4 is connected to the power supply terminal Vcc of the active filter control circuit HB1 together with the "+" terminal of the smoothing capacitor C3, and the "-" terminal of the capacitor C3 is connected to the GND line on the "-" terminal side of the smoothing capacitor Cin. Is done. These diodes D2, D4 and capacitor C
1, C3 constitutes the auxiliary power supply circuit Pa of the active filter control circuit.

Further, the output voltage of the output terminal Vo is input to the voltage detection terminal Vosens of the error amplifier circuit HB3. The error amplifier circuit HB3 is composed of an error amplifier or the like, and forms an error signal between the output voltage of the output terminal Vo and a predetermined reference voltage. The error signal is output to the converter control circuit HB2 via an insulating photocoupler PC1. The signal is input to the feedback input terminal FB.

Converter control circuit HB2 performs constant voltage control based on a detection signal of output voltage Vo input from error amplifier circuit HB3 such that output voltage Vo has a desired value.

In the power supply device shown in FIG. 3, supply of drive power to each control circuit is performed as follows.

First, when an AC power supply is connected by the switch S1, the AC voltage rectified by the diode bridge DB via the resistor Rt of the rush current limiting circuit Pr is smoothed via the choke coil L1 and the diode D1. The voltage applied to the capacitor Cin is charged while the peak of the charging current is suppressed by the resistor Rt, and the voltage between the terminals increases.

Power is supplied to the auxiliary power supply circuit Pc via the starting resistor Rst. When the voltage between the terminals of the smoothing capacitor Cin rises and reaches the starting voltage of the converter control circuit HB2, the converter control circuit HB2 switches the switching element. A PWM drive signal is output to Q2, and the DC-DC converter starts operating.

When the DC-DC converter CONV starts operating, a voltage is generated in the auxiliary power supply winding P2, and the voltage is applied to the auxiliary power supply circuit Pa on the active filter side and the auxiliary power supply circuit Pc on the DC-DC converter side. The driving power is supplied to the active filter control circuit HB1 or the converter control circuit HB2.

After that, instead of supplying power from the starting resistor Rst, the active filter control circuit HB1 and the converter control circuit HB2 use the active filter and the DC-D
The operation of the C converter CONV is continued. When the converter control circuit HB2 is activated and supplies power to the secondary side and reaches a predetermined voltage level, the rush current limiting circuit PB
The triac TR constituting r starts driving, the current limiting resistor Rt is short-circuited, and power supply from the AC power supply line to the power supply device starts.

In synchronization with this, the supply of drive power to the active filter control circuit HB1 via the auxiliary power supply circuit Pa starts, so that the active filter control circuit HB1
Outputs a PWM drive signal to the switching element Q1, starts the operation of the active filter AF, and performs control such that the voltage between the terminals of the smoothing capacitor Cin becomes a predetermined voltage. The operation of the control circuit HB1 of the active filter is roughly as follows.

That is, the control circuit HB1 of the active filter includes a capacitor C which is the output of the active filter.
The voltage level of "in" is detected, and the pulse width of the switching element Q1 is adjusted by PWM control so as to have a predetermined voltage level. At this time, the input current is controlled to be a sine wave proportional to the AC input voltage waveform. , Thereby improving the power factor.

Therefore, the control circuit HB1 of the active filter compares the voltage level of the capacitor Cin taken from the input terminal Vsens with a predetermined voltage level by an internal (not shown) voltage error amplifier to obtain an error amplification value. At this time, a reference current level to be referred to in current control is calculated by a multiplier (not shown) in the circuit based on the AC voltage waveform input to the Iac terminal. On the other hand,
The control circuit HB1 of the active filter includes a current detection resistor R
s is detected by the Isen1 and Isen2 terminals and compared with the reference current level obtained as described above by an internal current error amplifier (not shown) to obtain an error amplification value. By generating a PWM signal that eliminates the error value and outputting the PWM signal from the output terminal OUT to the switching element Q1, the pulse width of the switching element Q1 is determined.

The active filter control circuit HB1
Supply of drive power to the DC-DC converter CONV
Is applied to the auxiliary power supply circuit Pa by applying a voltage generated in the auxiliary power supply winding P2 of the transformer T which constitutes a part of the transformer T.

Further, since the voltage supplied to the DC-DC converter CONV is stabilized by the active filter AF, the amount of energy that can be extracted from the auxiliary power supply winding P2 does not change drastically. Sufficient drive power can be supplied from the circuit Pa to the active filter control circuit HB1.

[0034]

The voltage and current ratings required for the switching element (Q1 in FIG. 3) of the active filter in the switching power supply as described above are as follows.
It is determined by the output power of the entire power supply device.

For example, when designing a switching power supply such as an active filter, a transient resistanceless ratio is obtained from a pulse current value and a duty ratio, and the withstand voltage of the element, the pulse current rating, etc. are determined based on the temperature rise due to loss in the element. However, since the DC current rating of the element is generally less than about half of the pulse current rating, in the case of an active filter incorporated in the power supply unit of equipment that handles high power, the abnormalities provided in the AC input stage If the DC current rating of the switching element is smaller than the rating of the fuse for time protection, the fuse blows when the switching element continues to be turned on due to an abnormality in the control circuit etc. in the active filter circuit. Previously, the switching element sometimes failed.

If the switching element of the active filter shifts to the open state in such a manner, the input voltage range of the subsequent DC / DC converter is wide, and the operation of the boost type active filter is stopped, and the output voltage If the operation is stable even when Vo becomes ケ ー ス 2 times the input voltage, since the output of the DC / DC converter is normal, the device using this power supply device operates normally. May not be noticed at all.

However, the boost type active filter is a choke input chopper circuit, and when the operation of this circuit, that is, the operation of the switching element is stopped, it simply becomes a choke input rectifier circuit. 100μ ~ 1mH
With such an inductance, the harmonic current cannot be sufficiently suppressed, and if the load is constant, the effective input current increases.

The outlet capacity of a general household is 15
In the case of large-capacity devices that have a capacity of about A and have no margin, the increased current may cause troubles such as overheating of outlets.

In particular, in high power applications, switching elements are often connected in parallel for the purpose of reducing the loss due to the on-resistance of the FET or the like used for the switching element of the active filter and the problem of current rating. If an abnormality occurs in one of the drive circuits and one of the switching elements fails due to a short circuit, the other normal elements fail in a chain reaction, or conversely, the abnormality occurs. Even if it occurs, it will operate without incident, and if the operation continues with the load on each element increased, it may cause another failure. Was.

An object of the present invention is to solve the above-mentioned problems and to provide a simple, inexpensive, small, and light-weight structure capable of protecting a power supply device having a boost type active filter from abnormalities.

[0041]

According to the present invention, there is provided a power supply apparatus having an active filter including a boost converter connected to an input side of a main converter for supplying power to a load. An abnormality detection circuit that extracts an operation state of the semiconductor switch element of the active filter as voltage information from an auxiliary winding that monitors a current flowing through a choke coil of the active filter, and determines an abnormality of the semiconductor switch element based on the voltage level. And a protection switch circuit that performs a circuit protection operation by controlling intermittent power supply between the AC power supply and the active filter according to the output of the abnormality detection circuit.

According to the present invention, when an abnormality occurs in the control circuit and the switching element in the active filter, the current flowing through the element is suppressed to reduce stress on the element and prevent a chain failure. AC input to the active filter circuit can be reliably cut off.

[0043]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the following, members that are the same as or correspond to those of the above-described conventional configuration are denoted by the same reference numerals, and detailed description thereof is omitted.

[Embodiment 1] FIG. 1 shows a circuit configuration of a first embodiment of the present invention. In the configuration of FIG. 1, a phototriac PTRa as an on / off control element is added in order to use a rush current prevention circuit (corresponding to Pr in FIG. 3) as the protection switch circuit HB5, and further, a choke coil L1 (primary winding N1) is used. ) Is provided with an auxiliary winding N2, and the auxiliary winding N2 and the protection switch circuit HB5
The configuration is the same as that of FIG. 3 except that an abnormality detection circuit HB4 is added so as to be connected between.

The abnormality detection circuit HB4 has a choke coil L1.
, A diode Da and a capacitor Ca,
It comprises resistors Rz and Ra and a Zener diode ZD, and has the following connection configuration.

That is, one end of the auxiliary winding N2 of the choke coil L1 (on the side opposite to the main winding N1) is connected to the diode Da.
The cathode of this diode Da is connected to one end of a capacitor Ca and the cathode of a Zener diode ZD via a resistor Rz, and a phototriac PTRa which is a drive control element of the protection switch circuit HB5 via a resistor Ra. Is connected to the anode of the photodiode. The other end of the auxiliary winding N2 is connected to a capacitor C
a, the anode of the Zener diode ZD, and the cathode of the phototriac PTRa.

The protection switch circuit HB5 includes a triac TR, a resistor Rt (with a built-in temperature fuse), a capacitor Cg, a gate resistor Rg, and a phototriac PTR1, which constitute an inrush current prevention circuit, and a phototriac controlled by an abnormality detection circuit output. It is configured by adding a PTRa, and has the following connection configuration.

A resistance Rt with a built-in thermal fuse and a triac TR are connected in parallel, and a phototriac PT is connected between the anode (T2) and the gate of the triac TR.
The triacs of R1 and PTRa are connected in series, and a gate resistor Rg and a capacitor Cg are connected in parallel between the cathode (T1) and the gate. The photodiode side of the phototriac is connected to the output terminal on the secondary side.

The basic configuration of the active filter AF and the DC-DC converter CONV is as shown in FIG. 3, and a duplicate description is omitted here.

Next, the operation of each section in the above configuration will be described. First, the operation of the protection switch circuit HB5 including the function as the inrush current limiting circuit Pr will be described. The operations of the active filter AF and the DC-DC converter CONV are basically the same as those shown in the related art. After the start operation (switch S1 is turned on), when the main converter is started, the photo triac PTR1 is turned on, and the triac TR, which is the main drive control element, is turned on for each cycle of AC input, so that the normal operation state is established. Transition.

However, in this embodiment, since the phototriac PTRa is added, the drive of the active filter is normally started after the main converter is started, and the pulse current starts flowing through the choke coil L1. Active filter AF via detection circuit HB4
The conduction of the triac TR is turned on only after it is confirmed that the entire circuit including the above is operating normally.

The abnormality detection circuit HB4 detects an abnormality in the circuit as follows.

That is, in the case of the abnormality detection circuit HB4 of FIG. 1, since the auxiliary winding N2 of the choke coil L1 has a phase opposite to that of the main winding N1, the current depends on the current flowing when the switching element Q1 is turned on. Energy is stored in the coil, and when the switching element Q1 is turned off, it is supplied from the auxiliary winding side to the capacitor Ca via the diode Da, and is converted to a voltage corresponding to the amount of charging current. When the voltage exceeds a certain level, the voltage is made constant by the Zener diode ZD and the protection switch circuit HB
The drive of the protection switch circuit HB5 is controlled by outputting to the phototriac PTRa, which is the drive control element of No. 5.

That is, by setting the auxiliary winding N2 to the opposite phase, the voltage corresponding to the amount of current supplied to the load is output from the abnormality detection circuit HB4 only when the switching element Q1 is normally pulse-driven. When the switching element Q1 remains on due to a control circuit abnormality or the like, no voltage is generated in the auxiliary winding N2, and the output of the abnormality detection circuit HB4 also drops to 0 level, and the protection switch The triac TR as a main drive element of the circuit HB5 is cut off via the phototriac PTRa, and enters a protection operation mode.

When the protection operation is started, the photo triac PTRa and the triac TR are turned off, and
As a result, the resistance R with a built-in thermal fuse, which is a current limiting resistor, connected in parallel to the triacs PTRa and TR
Through t, the input current flows while the current is limited. When the temperature of the resistor itself rises due to the loss in the resistor according to the amount of input current and reaches the fusing temperature of the built-in thermal fuse, power supply to the subsequent-stage circuit is cut off.

As described above, an abnormality occurs in the control circuit or the switching element in the active filter circuit,
In the case of a continuous conduction state, the load on the element can be reduced by promptly suppressing the input current, and the above-mentioned secondary adverse effects due to the continuous operation of only the converter circuit are suppressed. If this continues, the circuit can be reliably shut off, preventing the failure from expanding,
It is possible to operate the power supply device safely and reliably.

Further, in the present embodiment, it is not necessary to provide a large margin for the withstand voltage of the switching element as in the prior art, and as is clear from the comparison with FIG. 3, the protection is performed by using the rush current limiting circuit Pr. Since the switch circuit HB5 is configured, the addition of components is minimal, and the device can be configured simply, inexpensively, and small and light.

As for a choke coil of a smoothing filter, a configuration in which an auxiliary winding is provided for use as a power supply of a control circuit or the like is known in the related art, and such a kind can be used. There is no significant increase in cost.

[Second Embodiment] In the above embodiment, the protection circuit is configured by using the inrush current limiting circuit.
The present embodiment exemplifies a configuration in which a protection switch circuit using a c-contact (or a b-contact, a so-called normally closed type in which a circuit is opened at the time of driving) type relay is provided on the secondary side of the diode bridge DB.

Also in this embodiment, the same or corresponding members as those in FIGS. 1 and 3 are denoted by the same reference numerals, and detailed description thereof will be omitted.

FIG. 2 shows a circuit configuration of the present embodiment. In the configuration of FIG. 2, the choke coil L1 (primary winding N
3 is different from the circuit of FIG. 3 in that an auxiliary winding N2 is provided in 1) and a protection switch circuit HB6 including a relay and the like is provided on the rectified "+" line side via an abnormality detection circuit HB4. The other circuit configuration is the same as that of FIG.

The abnormality detection circuit HB4 includes a choke coil L
The auxiliary coil N2 has a diode Da and a capacitor C
a, a Zener diode ZD, resistors R1 and R2, and a transistor Qa, and has the following connection configuration.

That is, one end of the auxiliary winding N2 of the choke coil L1 (on the side opposite to the main winding N1) is connected to the diode Da.
The cathode of the diode Da is connected to the “+” end of the capacitor Ca and the Zener diode Z.
D is connected to the cathode. The anode of the Zener diode ZD is connected to a capacitor Ca via resistors R1 and R2.
"-" Terminal and the other end of the auxiliary winding N2. The base of the transistor Qa is connected to the connection end of the resistors R1 and R2, the emitter is connected to the other end of the resistor R2, and also to the "-" terminal of the capacitor Ca.

The collector of the transistor Qa is connected to the anode of the photodiode of the photothyristor PTH, which is the relay driving element of the protection switch circuit HB6, and the auxiliary power supply of the active filter supplied from the main converter via the resistor Rsd. Vc of circuit Pa
Connected to c side.

The protection switch circuit HB6 includes a relay RELAY for separating the rectified “+” line of the AC input from a subsequent circuit, and a resistor Rr used as a power supply for driving the relay.
Capacitor Cr and relay drive element photothyristor P
It is composed of TH, gate resistance Rgt, and capacitor Cgt, and has the following connection configuration.

That is, the relay RELAY is connected between the "+" terminal of the diode bridge DB and the choke coil L1, and one end of the relay driving circuit side is connected to the resistor Rr connected to the "+" terminal of the diode bridge DB. , And also to the “+” side of the smoothing capacitor Cr. The other end of the relay on the drive circuit side is connected to the thyristor-side anode of the photothyristor PTH.
The cathode on the thyristor side of the photothyristor PTH is
The resistor R is connected to the "-" terminal of the capacitor Cr and also connected to the "-" terminal of the smoothing capacitor Cin.
gt and the capacitor Cgt are each a photo thyristor P
It is connected in parallel between the anode and cathode on the thyristor side of TH.

Next, the operation of each section in the above configuration will be described. The operations of the active filter AF and the DC-DC converter CONV are basically the same as those shown in the related art.
After the start operation (switch S1 is turned on), when the main converter is started, the photo triac PTR1 is turned on, and the triac TR, which is the main drive control element, is turned on for each cycle of AC input, so that the normal operation state is established. Transition.

Since the auxiliary winding N2 of the choke coil L1 connected to the input side of the abnormality detection circuit HB4 has a phase opposite to that of the main winding N1, the auxiliary winding N2 corresponds to the current flowing when the switching element Q1 is turned on. Energy is stored in the coil, and when the switching element Q1 is turned off, it is supplied from the auxiliary winding side to the capacitor Ca via the diode Da, and is converted into a voltage corresponding to the amount of charging current.
Slicing is performed at a certain level or more by the Zener diode ZD, and the voltage is further divided by the resistors R1 and R2.

That is, when the voltage smoothed from the auxiliary winding N2 falls below a certain level, the transistor Qa is turned off and its collector terminal is opened. In this state, power is supplied from the auxiliary power supply circuit Pa to the photodiode of the photothyristor PTH of the protection switch circuit HB6, the thyristor shifts to the ON state, the relay switches to the open terminal side, and the AC input stage (diode bridge) The “+” output terminal of DB) and the circuits after the active filter AF are disconnected.

In this state, as long as the AC input is not cut off, a current larger than the holding current continues to flow through the thyristor, so that the relay is also held open and held.

In this embodiment, the principle of operation for detecting the abnormality of the switching element of the active filter AF is the same as that of this embodiment, and the auxiliary winding N2 is replaced with the primary winding N.
By setting the phase opposite to 1, a voltage corresponding to the amount of current supplied to the load is obtained as the output of the abnormality detection circuit HB4 only when the switching element Q1 is normally pulsed, and the control circuit abnormality When the switching element Q1 remains ON, no voltage is generated in the auxiliary winding N2, so that the collector output of the transistor Qa, which is the output of the abnormality detection circuit HB4, is in the open state, and the above-described protection operation is performed. Is performed.

As described above, the abnormality occurs in the control circuit or the switching element in the active filter circuit.
In the case of a continuous conduction state, the load on the element can be reduced by quickly suppressing the input current, and if the state continues, the circuit can be reliably shut off, and the faulty part is It is possible to prevent the power supply from being expanded and to operate the power supply device safely and reliably.

In this embodiment, the configuration is somewhat complicated due to the use of a relay or the like. However, in the protection mode equivalent to that of the first embodiment, since the thermal fuse is not blown, the work location at the time of repair is In the case where a very temporary abnormality occurs for some reason, it is possible to return to normal operation without repair work.

[0074]

As described above, according to the present invention, in a power supply device having an active filter of a boost converter connected to an input side of a main converter unit for supplying power to a load, a choke coil of the active filter is used. An operation state of the semiconductor switch element of the active filter is extracted as voltage information from an auxiliary winding that monitors a flowing current, and an abnormality detection circuit that determines an abnormality of the semiconductor switch element based on the voltage level, and an output of the abnormality detection circuit. , A protection switch circuit for performing a circuit protection operation by controlling the intermittent connection between the AC power supply and the active filter is provided. Or the switching element has an abnormality and is constantly conducting In case, can reduce the load to the element by suppressing the rapid input current, suppressing a secondary harmful effects described above due to the only converter circuit continues to operate,
Further, if the state continues, the circuit can be reliably shut off, preventing the failure portion from expanding, and the power supply device can be operated safely and reliably. is there.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a first embodiment of a power supply device employing the present invention.

FIG. 2 is a block diagram showing a configuration of a second embodiment of a power supply device employing the present invention.

FIG. 3 is a block diagram showing a configuration of a conventional power supply device.

[Explanation of symbols]

 AF Active filter CONV DC-DC converter DB Diode bridge Da diode HB1 Active filter control circuit HB2 Converter control circuit HB4 Abnormality detection circuit HB5 Protection switch circuit HB6 Protection switch circuit L1 Choke coil N2 Auxiliary winding PC1 Photocoupler PTH Photothyristor PTR1 Phototriac PTRa Phototriac Q1 Switching element RELAY Contact relay Rs Current detection resistor S1 Switch

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) EA20 EA37 EA45 EB04 EB39 EB40 FF03 FF04 FF25 FF26 LL05 LL10 5H730 AA12 AA14 AA20 BB23 BB52 CC03 CC04 DD04 EE08 EE59 FD01 FD41 FG05 XC09 XX02 XX15 XX22 XX35

Claims (6)

[Claims] 1. A power supply device having an active filter formed by a boost converter connected to an input side of a main converter unit for supplying power to a load, comprising: an auxiliary winding for monitoring a current flowing through a choke coil of the active filter; The operation status of the semiconductor switch element of the active filter is extracted as voltage information,
An abnormality detection circuit for judging abnormality of the semiconductor switch element based on the voltage level; and protection for performing a circuit protection operation by controlling intermittent connection between an AC power supply and the active filter in accordance with an output of the abnormality detection circuit. A power supply device having a switch circuit. 2. The power supply device according to claim 1, wherein an output from an auxiliary winding of the choke coil is taken out so as to have a phase opposite to that of a main winding side of the choke coil. 3. The protection switch circuit also serves as an inrush current limiting circuit for suppressing a current flowing to an electrolytic capacitor in the active filter at the time of startup, and a switching element in the protection switch circuit and the inrush current limiting circuit. The power supply device according to claim 1, wherein the circuit protection operation is performed by controlling on / off of driving according to an output of the abnormality detection circuit. 4. A temperature fuse is provided in a main power supply line according to an output of the abnormality detection circuit in the inrush current limiting circuit, and when the abnormality detection circuit detects an abnormality, the active filter is connected via the temperature fuse. 4. The power supply device according to claim 3, wherein switching is performed by the switch element so that power is supplied to the power supply side. 5. The switch element of the protection switch circuit is constituted by a normally closed type relay, which is in an on state during normal operation, and the relay is opened only when an abnormality is detected by the abnormality detection circuit. The power supply device according to claim 1, wherein: 6. The power supply device according to claim 1, wherein the protection switch circuit is driven by an auxiliary power supplied from a transformer in the main converter.