JPH07274580A - Anomaly detecting apparatus and protective apparatus for inverter and air conditioner - Google Patents

Abstract

PURPOSE:To swiftly detect short-circuit failure in the switching elements in a switching circuit for an inverter and thus protect a motor. CONSTITUTION:A position signal circuit 17 compares the terminal voltages Vv-Vw of the windings 15u-15w of a brushless motor 15 with the reference voltage Vo of a reference voltage generating circuit 16. The position signal circuit 17 then produces fundamental wave signal Vu'-Vw' output as a result of the comparison. A waveform synthesizing circuit 21 obtains exciting signals Up-Wn for turning on/off the transistors in a three-phase bridge circuit 40 based on the fundamental wave signals Vu'-Vw'. A short-circuit failure detecting circuit 47 compares the exciting signals Up-Wn with the fundamental wave signals Vu'-Vw', and thereby detects a short-circuit failure in the transistors in the three-phase bridge circuit 40. If the short-circuit failure detecting circuit 47 detects a short-circuit failure, the transistors in the three-phase bridge circuit 40 are turned off, and a free wheel diode connected with these transistors in parallel is defeated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an abnormality detection of an inverter device having a switching circuit for sequentially energizing each winding of a motor having a plurality of windings at commutation timing corresponding to a predetermined rotational position of a rotor. The present invention relates to a device and a protection device, and an air conditioner equipped with any of these.

[0002]

2. Description of the Related Art In recent years, in air conditioners, a brushless motor, which is a kind of DC motor, has been adopted in order to vary the capacity of the compressor and save power consumption, and it is driven by an inverter device. .
In the case of a brushless motor, the rotation position signal of the permanent magnet type rotor is usually required to determine the energized phase of the winding, but it may be difficult to arrange the position sensor depending on the usage environment of the motor. is there. For this reason, the inventors of the present application have developed a technique for obtaining a rotational position signal by detecting an induced voltage in a winding of a motor and electrically processing the induced voltage.
This was filed as Japanese Patent Application No. 62-162654.

Hereinafter, the case where the invention of this application is implemented by a pulse width modulation (hereinafter, simply referred to as PWM) system will be described as an example, and this will be described as a prior art with reference to FIGS. In the inverter device shown in FIG. 12, the DC power supply circuit 2 connected to the AC power supply 1 comprises a full-wave rectifier circuit 3, a reactor 4a and a smoothing capacitor 4b, the positive and negative terminals of which are the negative terminal side. Current detection resistor 31
Via the positive side DC power supply line 5 and the negative side DC power supply line 6. Between the positive side DC power supply line 5 and the negative side DC power supply line 6, a switching element, for example, a three-phase bridge circuit 13 including switching elements 7 to 12 is connected, and its output terminal 14 is connected.
Brushless motor 15 which is a motor for u, 14v, 14w
Windings 15u, 15v, 15w of a plurality of phases, for example, three phases are connected.

In this three-phase bridge circuit 13, the three transistors 7, 9, 11 connected between the positive side DC power supply line 5 and the output terminals 14u, 14v, 14w correspond to the positive side switching elements, The three transistors 8, 10, 12 connected between the negative side DC power supply line 6 and the output terminals 14u, 14v, 14w correspond to the negative side switching element, and these respective transistors 7 to 12 are arranged in a predetermined order. When the brushless motor 15 is on / off controlled, each of the windings 15u to 15w of the brushless motor 15 is 120 degrees (electrical angle, the same applies hereinafter).
It is rotationally driven by successively energizing with a phase difference of. In this case, one transistor has 12
Since the duty is controlled by the PWM signal P1 shown in FIG. 14 in the ON / OFF cycle of 0 degree ON and 240 degree OFF, the terminal voltage of each winding 15u, 15v, 15w of the brushless motor 15 is controlled. Vu,
Vv and Vw have the waveforms shown in FIG.

FIG. 13 shows the waveforms of the terminal voltage Vu and the winding current Iu of the winding 15u when the PWM control is not performed. In this waveform, the sloped portion over a section of about 60 degrees (period Ta) is the induced voltage of the winding, and the elongated positive and negative pulses are the respective transistors 7 to 12 of the three-phase bridge circuit 13.
The reference voltage generating circuit 1 is a pulse voltage generated by the free-wheel diodes D1 to D6 connected in parallel with the reference voltage Vo, and Vo is a resistance voltage dividing circuit connected between the DC power supply lines 5 and 6.
6 is the reference voltage formed by From FIG. 13, it is understood that the commutation timing is delayed by about 30 degrees from the time when the induced voltage crosses the reference voltage Vo.

The terminal voltages Vu, Vv, Vw are compared with each other by a comparator 18 provided in a position signal circuit 17 as a comparison means.
20 to 20 are compared with the reference voltage Vo to obtain the terminal voltages Vu, Vv, V as shown in FIG.
fundamental wave signals Vu ′, Vv ′, for recognizing a 180-degree section of w,
Converted to Vw '. Further, these fundamental wave signals Vu
′, Vv ′, and Vw ′ are given to the waveform synthesizing circuit 21 which is the energization signal forming means, and here, by comparison with the PWM signal P1, only a positive pulse component is formed and a continuous square wave with a time width of 180 degrees is formed. The rotational position signals Ua, Va, Wa having a phase difference of 120 degrees from each other are converted. That is, the waveform synthesizing circuit 21 also has a function as position signal means for obtaining the rotational position signals Ua, Va, Wa which are rotational position information, together with the position signal circuit 17.

Further, in the waveform synthesizing circuit 21, of the first to third timer functions held therein, the first
With the timer function of, the three rotational position signals U
Six first phase division patterns X1 to X6 each having a time width Tx of 60 degrees are formed from a, Va, and Wa.
With the timer function of, the first phase division pattern X
The time width starting from the end point of 1 to X6 is 30 degrees (T
x6), and six second phase division patterns Y1 to Y6 are formed. Further, the third timer function causes the time widths starting from the end points of the second phase division patterns Y1 to Y6 to be different from each other. Six third phase division patterns Z1 to Z6 having 15 degrees (Tx / 4) are formed. Then, the waveform synthesizing circuit 21 finally uses the energizing signals Up, Un, Vp, Vn, as shown in FIG. 14 from the first and second phase division patterns X1 to X6 and Y1 to Y6 as described above.
Wp and Wn are combined. These energization signals Up, Un,
The phase patterns of Vp, Vn, Wp, and Wn match the commutation timing patterns required for the transistors 7 to 12 of the three-phase bridge circuit 13.

On the other hand, the speed control circuit 22 determines the speed deviation from the speed command signal Sc and the energization signal Wn given as the rotation speed detection signal of the brushless motor 15 from the waveform synthesizing circuit 21, and responds to the speed deviation. The velocity deviation signal Sd is output and given to the pulse width modulation circuit 23. The pulse width modulation circuit 23 controls the duty of the PWM signal P1 according to the magnitude of the speed deviation signal Sd.

PWM from the pulse width modulation circuit 23
The signal P1 is supplied to the waveform synthesizing circuit 21 and acts as an enable signal at the time of waveform synthesizing.

Further, the current detection signal S1 of the current detection resistor 31
Are applied to the overcurrent protection circuit 32. The overcurrent protection circuit 32 always sets the output signal E1 to the high level H, and sets the output signal E1 at which the current detection signal S1 is equal to or more than the protection current value to the low level L. Then, the output signal E1 from the overcurrent protection circuit 32 and the energization signals Up and U from the waveform synthesis circuit 21.
n, Vp, Vn, Wp, and Wn are given to the input terminals of AND circuits 34, 35, 36, 37, 38, 39 forming the gate circuit 33, and the PWM signal P1 from the pulse width modulation circuit 23 is ANDed. Circuits 34, 35, 36, 37,
It is adapted to be applied to the input terminals of 38 and 39.
Therefore, when the overcurrent protection circuit 32 detects the overcurrent, the output signal E1 becomes the low level L and the energization signal Up.
Through Wn are shut off (stopped) by AND circuits 34 through 39.

Now, the output signal E1 of the overcurrent protection circuit 32
Is high level H, the duty-controlled PW
The M signal P1 is supplied to the AND circuits 34, 36, 38 and 35,
Energization signals Up, Vp, Wp and U depending on 37 and 39
After combining with n, Vn, and Wn, that is, the logical product is taken,
Drive units 25, 27, 2 such as photocouplers of the drive circuit 24
Three-phase bridge circuit 13 via 9 and 26, 28, 30
Are supplied as base signals as input signals to the bases of the positive side transistors 7, 9, 11 and the negative side transistors 8, 10, 12, and these are on / off controlled in the PWM mode, whereby the brushless motor 15 continues to be driven. At the same time, the rotation speed is controlled by the duty control.

[0012]

In the above conventional structure, when a metal piece enters the three-phase bridge circuit 13,
When one or more transistors are short-circuited in an abnormal state such as when any of the transistors 7 to 12 is thermally destroyed or when any of the drive units 25 to 30 of the drive circuit 24 is abnormal, overcurrent protection is performed. There is a risk that the circuit 32 does not work effectively and the permanent magnet rotor of the brushless motor 15 is demagnetized.

Now, in the case where the transistor 8 of the three-phase bridge circuit 13 has a short circuit abnormality, FIG. 15 to FIG.
Will be described with reference to. In FIG. 15, in a normal state, the transistor 8 is given an ON signal (base signal) from the end point of the second phase division pattern Y4 to the end point of the second phase division pattern Y6 by the second timer function, so that the terminal voltage Vu Is low level (0 volt) during this period. In the latter half of this period, the transistor 11 is turned on, and therefore, as shown in FIG.
1, the winding currents Iu and Iw flow through the paths of the windings 15w and 15u and the transistor 8, and accordingly, the direct current Idc flows through the current detection resistor 31. This transistor 8
It is assumed that the transistor 8 has a short circuit abnormality due to, for example, thermal breakdown during the ON period of.

The transistor 8 is at the end point of the second phase division pattern Y6 (since the OFF signal is given at the time point A in FIG. 15, the transistor 8 is normally turned off (instead, the transistor 10 is turned on), and the terminal is The voltage Vu changes to the high level (+) direction, but in the event of a short circuit abnormality, the terminal voltage Vu
u remains low level. Therefore, the winding current Iu continues to flow and increases as the induced voltage between the W and U phases decreases. Normally, the zero cross of the terminal voltage Vu is detected at the timing of time B in FIG. 15 and the rotational position of the rotor of the brushless motor 15 is determined, but this is because the U phase does not become open. No determination can be made, and the on-states of the transistors 11 and 8, 10 continue. And
The DC current Idc also increases in accordance with the increase of the winding current, and when it reaches the protection current value (time C in FIG. 15), the output signal E1 of the overcurrent protection circuit 32 becomes the low level L,
Therefore, the energization signal is not applied to the transistors 7 to 12, and the transistors 7, 9 and 10 to 12 are turned off except the transistor 12 in the short-circuited state.

However, since the transistor 8 is in a short-circuited state (on state), as shown in FIG. 17, the induced voltage of the winding is used as a power source, the winding 15u, the transistor 8, the freewheel diode D4, and the winding 15v. Winding currents Iu, Iv, and Iw flow in the paths of 15 and 15u, the winding 15u, the transistor 8, the freewheel diode D6, and the windings 15w and 15u. Then, this current becomes larger as the induced voltage becomes higher at high speed rotation, and there is a risk that the permanent magnet type rotor used in the brushless motor 15 may be demagnetized.

As described above, when a short circuit abnormality occurs in the transistor of the three-phase bridge circuit 13 of the inverter device, the brushless motor 15 may deteriorate in performance and may be unusable.

In particular, when the brushless motor 15 is used to drive a compressor of an air conditioner,
It is necessary to replace the entire compressor containing the brushless motor 15.

The present invention has been made in view of the above circumstances, and a first object thereof is to provide an abnormality detecting device for an inverter device capable of promptly detecting a short circuit abnormality of a switching element of a switching circuit. .

A second object of the present invention is to provide a protection device for an inverter device capable of interrupting a current flowing through a winding of a motor when a short circuit abnormality of a switching element of a switching circuit is detected.

A third object of the present invention is to promptly detect the short-circuit abnormality of the switching element of the switching circuit in the inverter device or to shut off the current flowing to the motor, thus requiring replacement of the compressor. And not to provide an air conditioner.

[0021]

According to a first aspect of the present invention, there is provided an abnormality detecting device for an inverter device, wherein a switching circuit having a plurality of switching elements for sequentially energizing windings of a plurality of phases of a motor, and a rotor of the motor. From the energization signal forming means for obtaining the energization signal corresponding to the commutation timing by determining the commutation timing from the rotation position information of the position signal means. In the inverter device having a drive circuit for ON / OFF controlling the switching element based on the energization signal of, the comparison means for comparing the terminal voltage of the windings of the plurality of phases and the reference voltage is provided, and the comparison result of the comparison means Short circuit abnormality detection for detecting a short circuit abnormality of the switching element of the switching circuit based on the current signal of the current signal forming means Characterized by the configuration of providing the means.

According to a second aspect of the present invention, there is provided an abnormality detecting device for an inverter device, the inverter device having the same switching circuit, position signal means, energization signal forming means and drive circuit as those of the first aspect, wherein terminals of the windings of a plurality of phases are provided. Comparing means for comparing the voltage with the reference voltage is provided, and short-circuit abnormality detecting means for detecting a short-circuit abnormality of the switching element of the switching circuit based on the comparison result of the comparing means and the rotational position information of the position signal means. It is characterized by its structure.

According to another aspect of the present invention, there is provided an abnormality detecting device for an inverter device, wherein the position signal means has a comparing means for comparing the terminal voltages of windings of a plurality of phases with a reference voltage, and the rotational position is determined based on the comparison result. It is characterized in that it is configured to obtain information.

According to another aspect of the present invention, there is provided an abnormality detecting device for an inverter device, wherein the position signal means has an integrating means for integrating terminal voltages of windings of a plurality of phases, and rotational position information is obtained based on the integrated value. There is a feature in that.

A protection device for an inverter device according to a fifth aspect includes the abnormality detection device for an inverter device according to any one of the first to fourth aspects, wherein the switching circuit includes a plurality of forward switching elements and If the short-circuit abnormality detecting means is determined to be normal, the reverse switching element is turned on and the forward switching element is turned on / off to turn on / off the winding. When the energization control is performed and the short-circuit abnormality detecting means determines that there is an abnormality,
The present invention is characterized in that a protection means for turning off all of the reverse switching element and the forward switching element is provided.

A protection device for an inverter device according to a sixth aspect comprises the abnormality detection device for the inverter device according to any one of the first to fourth aspects, wherein the switching circuit sequentially energizes the windings of the plurality of phases. Therefore, a plurality of positive side switching elements having free-wheel diodes are connected in parallel between the positive side DC power supply line and the output terminal, and are connected in parallel between the negative side DC power supply line and the output terminal. A configuration including a plurality of negative side switching elements having a freewheel diode, a plurality of overcurrent fusing elements connected between the output terminal of the switching circuit and the windings of the plurality of phases, and further a plurality of these Positive side conduction means is connected between the winding side terminal of the overcurrent fusing element and the positive side DC power supply line, and the winding side terminals of the plurality of overcurrent fusing elements and the negative side DC power supply are connected. If a negative side conduction means is connected between the positive side and the negative side conduction means, and the short circuit abnormality detection means is determined to be normal, the positive side and negative side conduction means are turned off, and the short circuit abnormality detection means is the positive side switching element. If the abnormality is determined to be abnormal, the negative side conduction means is turned on, and if the short-circuit abnormality detection means determines that the negative side switching element is abnormal, the positive side conduction means is turned on. The feature is that the structure is provided.

The air conditioner according to claim 7 is equipped with the abnormality detection device for an inverter device according to any one of claims 1 to 4 or the protection device for an inverter device according to claim 5 or 6. Is characterized by.

[0028]

According to the failure detecting device of the inverter device of the first aspect, the energizing signal of the energizing signal forming unit and the comparison result of the comparing unit are collated to determine a predetermined high level of the energizing signal,
Normal in the low level state, depending on whether the comparison result is in the predetermined high level or low level state.
Since the short-circuit abnormality is determined, the short-circuit abnormality of the switching element of the switching circuit can be promptly detected.

According to another aspect of the present invention, there is provided a failure detection device for an inverter device in which the rotational position information of the position signal means and the comparison result of the comparison means are collated to determine whether the rotational position information is at a predetermined high level or low level. Since it is determined whether the comparison result is in a predetermined high level or low level state, it is possible to quickly detect a short circuit abnormality of the switching element of the switching circuit.

According to the abnormality detecting device of the inverter device of the third aspect, since the position signal means is provided with the comparing means for obtaining the rotational position information, the hall signal is used to obtain the rotational position information of the motor rotor. It is not necessary to provide a position sensor such as an element or a Hall IC, and this comparing means can be used for short circuit abnormality detection of the switching element by the short circuit abnormality detecting means.

According to the abnormality detecting device of the inverter device of the fourth aspect, since the position signal means is provided with the integrating means for obtaining the rotational position information, the Hall element, There is no need to provide a position sensor such as a Hall IC.

According to another aspect of the present invention, there is provided a protection device for an inverter device, wherein when the short-circuit abnormality detecting means of the abnormality detecting device detects a short-circuit abnormality, the protection means causes the forward switching element of the switching circuit and the reverse switching element in parallel therewith. Since all the directional switching elements are turned off, the current flowing in the winding of the motor can be cut off.

According to a sixth aspect of the present invention, in the protection device for an inverter device, when the short-circuit abnormality detecting means of the abnormality detection device detects the short-circuit abnormality, when the short-circuit abnormality is determined to be the positive side switching element of the switching circuit, When the negative side conduction means is turned on and the overcurrent fusing element is blown by the power supply short-circuit current, and when it is judged that the short circuit abnormality is the negative side switching element of the switching circuit, the positive side conduction means is turned on and the power supply short-circuit current causes the overcurrent fusing. Since the element is fused, the current flowing through the winding of the motor can be cut off.

According to the air conditioner of the seventh aspect, the abnormality detection device or the protection device detects the short circuit abnormality of the switching element of the switching circuit in the inverter device or shuts off the current flowing through the winding of the motor of the compressor. , It is possible to prevent the performance of the motor from being deteriorated or becoming unusable.

[0035]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIG.
As described with reference to FIG. 5, in this embodiment,
The same parts as those of the conventional example shown in FIGS. 12 to 17 are designated by the same reference numerals, and the description thereof will be omitted. Different parts will be described.
In FIG. 1, a DC power supply circuit 2 and a position signal circuit 1
7, waveform synthesis circuit 21, gate circuit 33 and drive circuit 2
4 is shown as a block diagram for simplification of the drawing, but its internal configuration is the same as that of FIG.

First, in FIGS. 1 and 2, a three-phase bridge circuit 40, which is a switching circuit replacing the three-phase bridge circuit 13, is provided in parallel with the transistors 7 to 12, which are forward switching elements, in parallel with the free-wheel diodes D1 to D6. The reverse switching elements 41 to 46, each of which is composed of a series circuit of the elements 41a to 46a, are connected to each other. In this case, the switching elements 41a to 46a are configured so that they can be turned on and off by control signals such as relay contacts and transistors.

The short-circuit abnormality detection circuit 47 as short-circuit abnormality detection means receives the fundamental wave signals Vu 'to Vw' from the position signal circuit 17 and the energization signals Up to Wn from the waveform synthesizing circuit 21 at its input terminals. As will be described later, the short circuit abnormality of the transistors 7 to 12 is detected by the comparison of the above. When the short circuit abnormality is detected, the stop signal ST is output from the output terminal and the gate circuit 3 is detected.
3 and an abnormality notification signal S from another output terminal
An alarm 4 such as a buzzer or a lamp that outputs A and is a notification means.
It is designed to operate by giving it to 8. When the stop signal ST is given from the short circuit abnormality detection circuit 47, the gate circuit 33 performs the energization signals Up to Wn and the PWM signal in the same manner as when the output signal E1 of the overcurrent protection circuit 32 becomes the low level L. It is designed to shut off P1.

Further, when the short circuit abnormality detection circuit 47 detects a short circuit abnormality, it outputs an abnormality detection signal SS from the output terminal and supplies it to the input terminal of the protection circuit 49 as a protection means. When the abnormality detection signal SS is not given from the short-circuit abnormality detection circuit 47, the protection circuit 49 outputs an ON signal from the output terminal and gives it to the switching elements 41a to 46a of the three-phase bridge circuit 40 to turn them on. However, when the abnormality detection signal SS is given, an OFF signal is output from the output terminal and given to the switching elements 41a to 46a to turn them all off.

The relationship between the operation of the air conditioner and the control of the brushless motor 15 will be described with reference to FIG. First, the compressor 50 is configured such that the compression unit 51 and the brushless motor 15 are housed in the same iron hermetic container 52, and the compression unit 51 and the plasticless motor 15 are directly connected by a main shaft. Compressor 50, four-way valve 53,
Indoor heat exchanger 54, pressure reducing device 55, outdoor heat exchanger 5
6 is connected by a refrigerant pipe, and the high temperature refrigerant compressed in the compression section 51 of the compressor 50 is passed through the four-way valve 53 to the indoor heat exchanger 54 during heating and the four-way valve 5 during cooling.
3 is switched to the state shown by the broken line in the figure, and the outdoor heat exchanger 5
It is designed to run to 6. During heating, the refrigerant condensed in the indoor heat exchanger 54 is decompressed by the decompression device 55, becomes a low temperature, and flows to the outdoor heat exchanger 56. The refrigerant evaporates in the outdoor heat exchanger 56 and returns to the compressor 50. On the contrary, during cooling, the refrigerant condensed in the outdoor heat exchanger 56 is decompressed by the decompression device 55,
It becomes a low temperature and flows into the indoor heat exchanger 54. The refrigerant evaporates in the indoor heat exchanger 54 and returns to the compressor 50. Air is passed through the heat exchangers 54, 56 on the indoor side and the outdoor side by the air blowing action of the fans 57, 58, respectively, and the air blowing causes indoor air and outdoor air in the heat exchangers 54, 56, respectively. It is configured so that heat exchange with air is efficiently performed.

During operation, the room temperature is detected by the temperature sensor 59 provided on the air intake side of the indoor heat exchanger 54, and the detection signal is input to the control unit (not shown). Then, the control unit sets the speed command signal Sc of the brushless motor 15 based on the difference between the detected temperature of the temperature sensor 61 and the set temperature, and the speed control of the brushless motor 15 is performed by the duty control by the PWM signal P1 as described above. Is done.

Next, the operation of this embodiment will be described with reference to FIGS. 4 and 5 as well. In FIG. 4, the terminal voltages Vu, Vv, Vw and the fundamental wave signal (comparison result) Vu are shown.
′, Vv ′, and Vw ′ are shown by omitting changes due to PWM control. Thus, the short-circuit abnormality detection circuit 47 has the energization signals Up, Un, Vp, Vn, from the waveform synthesis circuit 21.
The comparison between Wp and Wn and the fundamental wave signals (comparison results) Vu ′, Vv ′ and Vw ′ from the position signal circuit 17 is compared with the switching timing of the energization signals Up to Wn of the waveform synthesis circuit 21, that is, the commutation timing. Is performed every time immediately after, and when the result of the collation has the relationship shown in FIG. 5, it is determined to be normal.

For example, as shown in FIG. 4, immediately after the commutation of the end point of the second phase division pattern Y6 by the second timer function, the transistor 8 is normally turned on and then the transistor 10 is normally turned off and then turned on. If you switch to
Terminal voltage Vv is low level (0 volt), terminal voltage Vw
Is high level (+), and the terminal voltage Vu temporarily changes from low level to high level. This temporary change in the terminal voltage Vu is caused by the winding 15u, the freewheel diode D1, the switching element 41a, the transistor 11, while the electrical energy stored in the winding 15u is being discharged.
This is because current flows through the paths of the windings 15w and 15u, and the output terminal 14u and the positive side DC power supply line 5 have the same potential due to the freewheel diode D1 and the switching element 41a. Therefore, the energization signals Up, Un, Vp, Vn,
Immediately after the Wp and Wn are in the predetermined state of “L, L, L, H, L”, the fundamental wave signal (comparison result) Vu ′,
Vv ′ and Vw ′ are in the predetermined state of “H, L, H”, and it can be determined that the state is normal. In this case, when the fundamental wave signal Vu ′ is “L”, a short circuit between the collector and the emitter of the transistor 8 is abnormal, and when the fundamental wave signal Vv ′ is “H”, the collector and the emitter of the transistor 9 are short circuited. When it is abnormal and the fundamental wave signal Vw ′ is “L”, it can be determined that there is a short circuit abnormality between the collector and the emitter of the transistor 12.

When the transistors 7 to 12 of the three-phase bridge circuit 40 are normal, the short circuit abnormality detection circuit 47 does not give the abnormality detection signal SS to the protection circuit 49, so that the protection circuit 49 turns on the switching elements 41a to 46a. To turn them on, and the brushless motor 15 is driven by the same action as in the conventional case. On the other hand, for example, in the period D of FIG. 4, that is, when the transistor 8 is turned on by the energization signal Un, a short circuit abnormality occurs in the transistor 8 due to thermal breakdown.
At the time of verification at time point E in FIG. 4, energization signals Up, Un, V
Immediately after p, Vn, Wp, and Wn reach the predetermined state of “L, L, L, H, H, L”, the fundamental wave signal (comparison result) V
Since u ′, Vv ′, and Vw ′ are not in a predetermined state like “L, L, H” and the fundamental wave signal Vu ′ is “L”, it can be determined that the transistor 8 has a short circuit abnormality. it can. The short-circuit abnormality detection circuit 47 then detects the abnormality detection signal S
Since S is output and given to the protection circuit 49, the protection circuit 49
Applies an OFF signal to the switching elements 41a to 46a to turn them OFF, and outputs a stop signal ST to the gate circuit 33, so that the gate circuit 33 outputs the signal U
The outputs of p ′ to Wn ′ are stopped, and the drive circuit 24 turns off the transistors 7 to 12.

As a result, the current described in FIG. 17 of the related art has its current path changed to the switching elements 41a and 46a.
It does not occur because it is blocked by. When the short-circuit abnormality detection circuit 47 detects a short-circuit abnormality, the short-circuit abnormality detection circuit 47 outputs the abnormality release notification signal SA to operate the alarm device 48. Therefore, the operator performs the alarm operation of the alarm device 48 to cause the three-phase bridge circuit 4 to operate.
It is possible to know that a short circuit abnormality has occurred in the 0 transistor.

The above is a description of the case where the short circuit abnormality occurs in the transistor 8 of the three-phase bridge circuit 40. However, even when the short circuit abnormality occurs in any of the other transistors 7, 9 to 12, FIG. It can be detected by collating the high level H and low level L states of the energization signals Up to Wn with the high level H and low level L states of the fundamental wave signals Vu ′, Vv ′, Vw ′.

As described above, according to this embodiment, the short-circuit abnormality detection circuit 47 has the high-level H and low-level L states of the energizing signals Up to Wn of the waveform synthesizing circuit 21 and the fundamental wave signal of the position signal circuit 17 ( (Comparison result) The high level H and low level L states of Vu ′ to Vw ′ are collated, and if the collation result is in the state of FIG. 5, it is determined to be normal, and the collation result is not in the state of FIG. Sometimes transistors 7 to 1
Since the short circuit abnormality of any one of No. 2 is determined, the short circuit abnormality of the transistors 7 to 12 can be promptly detected.

When the short-circuit abnormality detection circuit 47 detects a short-circuit abnormality, the gate circuit 33 and the drive circuit 24.
Through the transistors 7 to 1 of the three-phase bridge circuit 40
2 is turned off, and the switching elements 41a to 46a in parallel with the freewheel diodes D1 to D6 are turned off via the protection circuit 49. Therefore, the current flowing through the windings 15u to 15W of the brushless motor 15 is reduced. Can be shut off. Therefore, there is no risk of demagnetizing the permanent magnet type rotor of the brushless motor 15, and it is possible to prevent the performance of the brushless motor 15 from deteriorating or becoming unusable, and to protect the brushless motor 15. be able to.

From this fact, it is possible to avoid a situation in which the entire compressor 50 of the air conditioner is replaced due to deterioration in the performance of the brushless motor 15 or inability to use it, which is economically advantageous.

Further, the position signal circuit 17 has terminal voltages Vu and V.
The fundamental wave signals (comparison results) Vu ′, Vv ′, Vw ′ are obtained by comparing v, Vw and the reference voltage Vo, and the waveform synthesis circuit 2
Since the rotational position signals Ua, Va, and WA, which are rotational position information, are obtained from the fundamental wave signals Vu ′, Vv ′, Vw ′, the hall element 1 detects the rotational position of the rotor of the brushless motor 15. , It is not necessary to provide a position sensor such as a Hall IC, and the position signal circuit 17 forming a part of the position signal means can also be used as a comparison means for giving a comparison result to the short circuit abnormality detection circuit 47. Will be easier.

FIG. 6 shows a second embodiment of the present invention. The same parts as those in FIG. 2 are designated by the same reference numerals and the description thereof will be omitted. Only different parts will be described below. That is, in the three-phase bridge circuit 60, which is a switching circuit instead of the three-phase bridge circuit 40, the cathodes of the diodes D1, D3, and D5 are commonly connected, and the common connection point is a switching element composed of a relay contact, a transistor, or the like. 61
The reverse switching element 61 is configured by being connected to the positive side DC power supply line 5 via a, and the anodes of the diodes D2, D4 and D6 are commonly connected, and the common connection point is the contact point of the relay. , The reverse direction switching element 62 is configured by being connected to the negative side DC power supply line 6 via a switching element 62a composed of a transistor or the like.

In this case, the short circuit abnormality detection circuit 4 shown in FIG.
When 7 does not output the abnormality detection signal SS, the switching elements 61a and 62a are turned on by the ON signal given by the protection circuit 49. When the short circuit abnormality detection circuit 47 outputs the abnormality detection signal SS, the switching elements 61a and 62a are switched. The elements 61a and 62a are turned off by receiving an off signal from the protection circuit 49.

Therefore, the second embodiment can also obtain the same effects as the first embodiment, and in particular, in the second embodiment, the switching elements 61a and 62a are the same as those of the first embodiment.
There is an advantage that it can be done individually.

7 to 10 show a third embodiment of the present invention. The same parts as those of the first embodiment shown in FIGS. 1 to 5 are designated by the same reference numerals and their description is omitted. The different parts will be described. First, in FIGS. 7 and 8, a three-phase bridge circuit 63, which is a switching circuit that replaces the three-phase bridge circuit 13, has three-phase bridge connections of thyristors 64 to 69 between the positive and negative side DC power supply lines 5 and 6. And the output terminal 14u of the three-phase auxiliary bridge circuit 70
One terminal of each of the windings 15u, 15v and 15w of the brushless motor 15 is connected to ', 14v' and 14w '. Further, current fuses 71, 72 and 73 as overcurrent fusing elements are connected between the output terminals 14u, 14v and 14w and the output terminals 14u ', 14v' and 14w '.

In this case, the thyristors 64, 66 and 68
Is a positive side conduction means connected between the common connection point of the current fuses 71, 72 and 73 and the windings 15u, 15v and 15w of the brushless motor 15 and the positive side DC power supply line 5, and is a thyristor. Reference numerals 65, 67 and 69 constitute a negative side conducting means connected between a common connection point of the current fuses 70, 71 and 72 and the windings 15u, 15v and 15w and the negative side DC power supply line 6. .

In FIG. 7, a position signal detecting circuit 74, which is a position signal detecting means, includes position sensors 75 to 77 such as Hall elements and Hall ICs arranged to detect the rotational position of the rotor of the brushless motor 15. The detection signals from these position sensors 75 to 77 are subjected to waveform shaping, and rotational position signals Hu, Hv, and Hw (rotational position signal U of the first embodiment) that are rotational position information of the rotor of the brushless motor 15 are obtained.
It corresponds to a, Va and Wa. Waveform shaping circuit 7 for obtaining
8 and. Then, the rotational position signals Hu, Hv and Hw from the waveform shaping circuit 78 are given to an energization signal forming circuit 79 which is an energization signal forming means, and the energization signal forming circuit 79 is based on the rotation position signals Hu, Hv and Hw. The energizing signal Up is performed in the same manner as the waveform synthesizing circuit 21.
To Wn are formed, and these are given to the gate circuit 33.
The energization signal Wn of the energization signal forming circuit 79 is supplied to the speed control circuit 22 as a rotation speed detection signal.

The comparison circuit 80 as a comparison means is composed of three comparators like the position signal circuit 17, and compares the terminal voltages Vu, Vv and Vw with the reference voltage Vo, and the comparison result. Barrel comparison signals Cu, Cv and Cw (fundamental wave signals Vu ′, Vv ′ and V of the first embodiment)
(corresponding to w ') is output and these are applied to the input terminal of the short-circuit abnormality detection circuit 81 which is short-circuit abnormality detection means.

The rotational position signals Hu, Hv and Hw from the position signal circuit 74 are connected to the input terminals of the short circuit abnormality detecting circuit 81.
The short-circuit abnormality detection circuit 81 is provided with the rotation position signals Hu, Hv, Hw and the comparison signal C.
By comparing with u, Cv, and Cw, normality and short circuit abnormality are determined as described later. When the short-circuit abnormality detection circuit 81 detects a short-circuit abnormality, it outputs a stop signal ST from the output terminal to give it to the gate circuit 33, and also outputs an abnormality notification signal SA from the output terminal.
Is output to the alarm device 48.

Further, when the short circuit abnormality detection circuit 81 detects a short circuit abnormality in any of the transistors 7 to 12 of the three-phase bridge circuit 63, the abnormality detection signal SSM (M =
1 to 6) are output from the output terminals and applied to the input terminals of the protection circuit 82 as a protection means. in this case,
The abnormality detection signal SSM, that is, SS1 to SS6 is a signal corresponding to the thyristors 64 to 69, and is the protection circuit 82.
When the abnormality detection signals SS1 to SS6 are applied, the thyristors 64 to 69 corresponding thereto are turned on by turning on signals. Then, the short-circuit abnormality detection circuit 81 uses the negative side transistors 8, 10 or 1
2 when a short circuit abnormality occurs, the thyristors 64, 6
The abnormality detection signal SS1, SS3 or SS5 corresponding to 6 or 68 is output, and the positive side transistor 7, 9 or 1 is output.
When 1 has a short circuit abnormality, thyristors 65, 6
The abnormality detection signal SS2, SS4 or SS6 corresponding to 7 or 69 is output.

Next, the operation of the third embodiment will be described with reference to FIGS. 9 and 10 as well. In FIG. 9, the terminal voltages Vu, Vv, Vw and the comparison signals Cu, Cv,
Cw is shown by omitting the change due to PWM control.
The short circuit abnormality detection circuit 81 compares the rotational position signals Hu, Hv, Hw from the position signal circuit 74 with the comparison signals Cu, Cv, Cw from the comparison circuit 80, and compares the energization signals Up to Wn.
The switching timing, that is, immediately after the commutation timing, is determined to be normal when the comparison result has the relationship of FIG. In this case, the short-circuit abnormality detection circuit 81 does not output the abnormality detection signal SSM when it determines that the circuit is normal, and the protection circuit 82 puts the thyristors 64 to 69 into the off state without giving an on signal. .

Thus, similar to the first embodiment, for example,
Immediately after the rotational position signals Hu, Hv, Hw are in the predetermined state of "L, L, H", the comparison signals Cu, Cv, Cw are in the predetermined state of "H, L, H" and are normal. Can be determined. In this case, when the comparison signal Cu is "L", a short circuit between the collector and emitter of the transistor 8 is abnormal, and when the comparison signal Cv is "H", a short circuit between the collector and emitter of the transistor 9 is abnormal. When the signal Cw is “L”, it can be determined that there is a short circuit between the collector and the emitter of the transistor 12.

When the transistors 7 to 12 of the three-phase bridge circuit 63 are normal, the abnormality detection signal SSM is not supplied from the short circuit abnormality detection circuit 81 to the protection circuit 82, so that the thyristors 64 to 69 are in the off state. The brushless motor 15 is driven by the same operation as the example.
For example, in the range A of FIG. 10, that is, in the ON period of the transistor 8 by the energization signal Un, the transistor 8
If a short circuit abnormality occurs due to thermal destruction, the comparison signals Cu, Cv, Cw are “L, L, H” immediately after the position signals Hu, Hv, Hw are in the state of “L, L, H”. Therefore, the short-circuit abnormality detection circuit 81 determines that the transistor 8 has a short-circuit abnormality as the comparison result at the time point E in the figure.
Then, the short-circuit abnormality detection circuit 81 outputs the stop signal ST and gives it to the gate circuit 33, so that the three-phase bridge circuit 6
All 3 transistors 7 to 12 are turned off,
Further, since the abnormality detection signal SS1 is output and given to the protection circuit 82, the protection circuit 82 gives an ON signal to the thyristor 64 to turn it on.

As described above, when the thyristor 64 is turned on, the DC power supply is short-circuited through the path of the thyristor 64, the current fuse 71 and the transistor 8 having the short circuit abnormality.
The short circuit current causes the current fuse 71 to blow in a short time. Therefore, the current described in FIG. 17 of the conventional example is
Since the current path is cut off by the current fuse 71, it does not occur.

The above is a description of the case of the short circuit abnormality of the transistor 8 of the three-phase bridge circuit 63. However, even when the other transistors 7, 9 to 12 and the freewheel diodes D1 to D6 have the short circuit abnormality. Similarly, any of the current fuses 71 to 73 is blown. Therefore, according to the third embodiment, the same effect as the above embodiment can be obtained.

FIG. 11 shows a fourth embodiment of the present invention. The same parts as those in FIG. 8 are designated by the same reference numerals and the description thereof will be omitted. Only different parts will be described below. That is, the three-phase bridge circuit 83, which is a switching circuit that replaces the three-phase bridge circuit 63, includes a three-phase auxiliary bridge circuit 90 in which diodes 84 to 89 are connected in a three-phase bridge.
The common connection points of the diodes 84 and 85, 86 and 87, 88 and 89 are connected to the output terminals 14u ', 14v', 1 respectively.
4w '. And the diodes 84, 86 and 8
The anode of 8 is connected to the positive side DC power supply line 5 via a relay contact, a switching element 91 such as a transistor,
As a result, the positive-side conducting means 92 is constituted, and the diode 8
The cathodes of 5, 87 and 89 are connected to the negative side DC power supply line 6 via the contacts of the relay, the switching element 93 such as a transistor, thus constituting the negative side conducting means 94.

The short circuit abnormality detection circuit and protection circuit (not shown) corresponding to the three-phase bridge seaway 83 are basically the same as the short circuit abnormality detection circuit 81 and protection circuit 82 shown in FIG. Although the configuration is different, the short-circuit abnormality detection circuit outputs a positive-side abnormality detection signal to the protection circuit when the positive-side transistor 7, 9 or 11 has a short-circuit abnormality, and the protection circuit uses the switching element. 93
Is turned on, and the negative side transistor 8, 10 or 12
Is a short circuit abnormality, a negative side abnormality detection signal is output to the protection circuit, and the protection circuit turns on the switching element 91. Therefore, also in this embodiment, the same effect as the third embodiment can be obtained.

In the first embodiment, the windings 15u, 15
The terminal voltages Vu, Vv and Vw of v and 15 W are compared with the reference voltage Vo of the reference voltage generating circuit 16, and the rotational position signal Ua which is the rotational position information is obtained from the fundamental wave signals Vu ′, Vv ′ and Vw ′ which are the comparison results. , Va and Wa are provided with position signal means (position signal circuit 17 and waveform synthesizing circuit 21), but instead, Japanese Patent Application No. 6-8
Windings 15u, 15v and 15w, as shown at 510
Integrating means (low-pass filter) for integrating the terminal voltages Vu, Vv, and Vw of (1) and integrating means (smoothing circuit) for integrating the neutral point voltages of the windings 15u, 15v, and 15w are provided, and the comparison results of these integrating means are used. A position signal means configured to obtain a rotational position signal which is rotational position information may be provided, and in this case, it is suitable for the brushless motor 15 which is PWM-controlled.

Besides, the present invention is not limited to the above-mentioned embodiment, but the following modifications or expansions are possible. It can be independently implemented as an abnormality detection device that operates the alarm 48 by the abnormality notification signal SA of the short circuit abnormality detection circuit 47 or 81. In this case, the output terminals 14u, 14v and 1 of the three-phase bridge circuit 13 (see FIG. 12)
4w and the windings 15u, 15v and 15w may be provided with a manual switch so that the operator can manually turn off the switch when he / she knows a short circuit abnormality due to the alarm operation of the alarm 48. Also, it is possible to prevent the brushless motor 15 from becoming unusable due to performance degradation. Not limited to the air conditioner, it can be applied to all devices including a motor controlled by an inverter device.

[0068]

Since the present invention is as described above, it has the following effects. According to the abnormality detecting device of the inverter device of claim 1, comparison of the energizing signal of the switching circuit from the energizing signal forming device and the comparing device for comparing the terminal voltage of the windings of the plurality of phases of the motor and the reference voltage. Since the short circuit abnormality of the switching element of the switching circuit is determined based on the relationship with the result, the short circuit abnormality of the switching element can be promptly detected.

According to the abnormality detecting device of the inverter device of the second aspect, the rotational position information from the position signal means for detecting the rotational position of the rotor of the motor is compared with the comparison result of the comparing means similar to the first aspect. Since the short circuit abnormality of the switching element of the switching circuit is determined based on the relationship, the same effect as that of claim 1 can be obtained.

According to the abnormality detecting device of the inverter device of the third aspect, since the position signal means has the comparing means for comparing the terminal voltage of the windings of a plurality of phases with the reference voltage, the position sensor is not provided. Information on the rotational position of the rotor of the motor can be obtained, and the comparison result of the comparison means can be given to the short-circuit abnormality detection means, which simplifies the circuit configuration.

According to the abnormality detecting device of the inverter device of the fourth aspect, the integrating means for integrating the terminal voltages of the windings of a plurality of phases is provided, and the rotational position information is obtained based on the integrated value. This is suitable when there is no need to provide a position sensor and the motor is PWM-controlled.

According to another aspect of the present invention, when the short-circuit abnormality detecting means detects the short-circuit abnormality, the forward switching element of the switching circuit and the reverse switching element in parallel with the switching element are all turned off. As a result, the current flowing in the winding can be cut off, and therefore, the permanent magnet type rotor of the motor is not demagnetized, and the performance of the motor is prevented from being deteriorated or rendered unusable. be able to.

According to the sixth aspect of the present invention, when the short-circuit abnormality detecting means detects the short-circuit abnormality, the overcurrent fusing element connected between the output terminal of the switching circuit and the winding of the motor. Since the power supply is short-circuited by the power supply short-circuit current, the same effect as that of the fifth aspect can be obtained.

According to the air conditioner of the seventh aspect, a short circuit abnormality of the switching element of the switching circuit in the inverter device for controlling the motor of the compressor can be detected promptly, or the motor is detected by detecting the short circuit abnormality. It protects and eliminates the need to replace the entire compressor.

[Brief description of drawings]

FIG. 1 is a block diagram of an electrical configuration showing a first embodiment of the present invention.

[Fig. 2] Connection diagram of three-phase bridge circuit

[Figure 3] Air conditioner piping diagram

[Figure 4] Waveform diagram of each part

FIG. 5 is a diagram for collating signals when determining a short circuit abnormality.

FIG. 6 is a view corresponding to FIG. 2 showing a second embodiment of the present invention.

FIG. 7 is a diagram corresponding to FIG. 1 showing a third embodiment of the present invention.

FIG. 8 is a view corresponding to FIG.

FIG. 9 is a view corresponding to FIG.

FIG. 10 is a view corresponding to FIG.

FIG. 11 is a view corresponding to FIG. 8 showing a fourth embodiment of the present invention.

FIG. 12 is an electrical configuration diagram showing a conventional example.

FIG. 13 is a waveform diagram of the terminal voltage and winding current of one winding of the brushless motor.

14 is a waveform diagram of each part of FIG.

FIG. 15 is a waveform chart of each part for explaining the occurrence of a short circuit abnormality.

FIG. 16 is a wiring diagram of a three-phase bridge circuit showing a current flow when a short circuit abnormality occurs.

FIG. 17 is a diagram corresponding to FIG. 16 showing the flow of overcurrent.

[Explanation of symbols]

2 is a DC power supply circuit, 5 is a positive side DC power supply line, 6 is a negative side DC power supply line, 7, 9 and 11 are positive side transistors (positive side switching elements, forward switching elements), 8, 10 and 1
2 is a negative side transistor (negative side switching element, forward direction switching element), 13 is a three-phase bridge circuit, 14u
Through 14w and 14u 'through 14w' are output terminals, 15
Is a brushless motor (motor), 15u to 15w are windings, 17 is a position signal circuit (comparing means, position signal means),
21 is a waveform synthesis circuit (position signal means, energization signal forming means), 22 is a speed control circuit, 23 is a pulse width modulation circuit,
24 is a drive circuit, 32 is an overcurrent protection circuit, 33 is a gate circuit, 40 is a three-phase bridge circuit (switching circuit),
D1 to D6 are freewheel diodes, 41 to 4
6 is a reverse switching element, 41a to 46a are switching elements, 47 is a short circuit abnormality detection circuit (short circuit abnormality detection means), 49 is a protection circuit (protection means), 50 is a compressor, 60 is a three-phase bridge circuit (switching circuit) ,
61 and 62 are reverse switching elements, 61a and 6
2a is a switching element, 63 is a three-phase bridge circuit (switching element), 64, 66 and 68 are thyristors (positive side conducting means), 65, 67 and 69 are thyristors (negative side conducting means), and 71 to 73 are current fuses. (Overcurrent fusing element), 74 is a position signal circuit (position signal means),
75 to 77 are position sensors, 79 is an energization signal forming circuit (energization signal forming means), 81 is a short circuit abnormality detection circuit (short circuit abnormality detection means), 82 is a protection circuit (protection means), and 83 is a three-phase bridge circuit (switching). Circuit), 84 to 89
Is a diode, 91 is a switching element, 92 is a positive side conducting means, 93 is a switching element, and 94 is a negative side conducting means.

Claims (7)

[Claims] 1. A switching circuit having a plurality of switching elements for sequentially energizing windings of a plurality of phases of a motor, position signal means for obtaining rotational position information of a rotor of the motor, and rotation of the position signal means. An energization signal forming means for determining the commutation timing from the position information and obtaining an energization signal corresponding to the commutation timing, and a drive circuit for on / off controlling the switching element based on the energization signal from the energization signal forming means. In the inverter device having, comparison means for comparing the terminal voltage of the windings of the plurality of phases with a reference voltage is provided, and the switching element is short-circuited based on the comparison result of the comparison means and the conduction signal of the conduction signal forming means. An abnormality detection device for an inverter device, which is provided with short-circuit abnormality detection means for detecting an abnormality. 2. A switching circuit having a plurality of switching elements for sequentially energizing windings of a plurality of phases included in a motor, position signal means for obtaining rotational position information of a rotor of the motor, and rotation of the position signal means. An energization signal forming means for determining the commutation timing from the position information and obtaining an energization signal corresponding to the commutation timing, and a drive circuit for on / off controlling the switching element based on the energization signal from the energization signal forming means. In the inverter device having, comparison means for comparing the terminal voltage of the windings of the plurality of phases with a reference voltage is provided, and the switching element is short-circuited based on the comparison result of the comparison means and the rotational position information of the position signal means. An abnormality detection device for an inverter device, which is provided with short-circuit abnormality detection means for detecting an abnormality. 3. The position signal means has a comparison means for comparing the terminal voltages of the windings of a plurality of phases with a reference voltage, and the rotation position information is obtained based on the comparison result. The abnormality detection device for an inverter device according to claim 1 or 2. 4. The position signal means has an integrating means for integrating the terminal voltages of the windings of a plurality of phases, and the rotational position information is obtained based on the integrated value. An inverter device abnormality detection device according to item 1 or 2. 5. The abnormality detection device for an inverter device according to claim 1, wherein the switching circuit includes a plurality of forward switching elements and a reverse switching element connected in parallel therewith. When the short circuit abnormality detecting means determines that the short circuiting abnormality is detected, the reverse direction switching element is turned on to control the energization of the winding by turning on and off the forward direction switching element. A protection device for an inverter device, which is provided with protection means for turning off all of the reverse direction switching element and the forward direction switching element when the means is determined to be abnormal. 6. An abnormality detection device for an inverter device according to claim 1, further comprising a positive side DC power supply line and an output for sequentially energizing the plurality of phase windings in the switching circuit. A plurality of positive side switching elements connected between the terminals and having freewheel diodes in parallel, and a plurality of negative side switching elements connected between the negative side DC power supply line and the output terminal and having freewheel diodes in parallel A plurality of overcurrent fusing elements are connected between the output terminal of the switching circuit and the windings of the plurality of phases, and the winding side terminals of the plurality of overcurrent fusing elements are connected to each other. While connecting the positive side conduction means between the positive side DC power supply line, the negative side conduction means is connected between the winding side terminal of the plurality of overcurrent fusing elements and the negative side DC power supply line, The short circuit When the abnormality detecting means determines that the positive side and the negative side conducting means are turned off, when the short circuit abnormality detecting means determines that there is a short circuit abnormality in the positive side switching element, the negative side conducting means Means for turning on the means, and when the short-circuit abnormality detecting means determines that there is a short-circuit abnormality in the negative side switching element, protection means for turning on the positive side conducting means is provided. apparatus. 7. An air conditioner comprising the abnormality detection device for an inverter device according to claim 1 or the protection device for an inverter device according to claim 5 or 6.