JPH06209581A - Protection device for inverter device - Google Patents

Abstract

PURPOSE:To detect a failure where only one of a positive-side switching element or a negative-side switching element is turned on in the switching circuit of an inverter device for protection. CONSTITUTION:Terminal voltages Vu-Vw of a brushless motor 15 are compared with a reference voltage V0 to obtain fundamental wave signals Vu'-Vw' and a conduction signal circuit 17 for outputting conduction signals Up-Wn for turning on or off transistors 7-12 of a three-phase bridge circuit 13 based on the fundamental wave signals Vu'-Vw' is provided. Then, a means 50' for detecting that only one of positive-side transistors 7, 9, and 11 and negative-side transistors 8, 10, and 12 is turned on by monitoring the fundamental wave signals Vu'-Vw' is provided and a means 51 for stopping the ON/OFF control of the transistors 7-12 based on the conduction signals Up-Wn when the detection state continues for a set amount of time is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a switching circuit for sequentially energizing each winding of a motor having a plurality of windings such as a brushless motor at commutation timing corresponding to a predetermined rotation position of a rotor. The present invention relates to a protection device for an inverter device.

[0002]

2. Description of the Related Art In recent years, in air conditioners and refrigerators, brushless motors, which are a kind of DC motors, have been adopted to drive compressors in order to vary the capacity of the compressors and save power consumption. .
In the case of a brushless motor, usually, the rotational position signal of the rotor is required to determine the energized phase of the winding, but it may be difficult to arrange the position detection sensor depending on the usage environment of the motor. Therefore, the inventors of the present application developed a technique for obtaining a rotational position signal by detecting an induced voltage in a motor winding and electrically processing the induced voltage, and applied for this 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 of the prior art with reference to FIGS. ◎ In the inverter device shown in FIG. 7, the DC power supply circuit 2 connected to the AC power supply 1 is a full-wave rectifier circuit 3,
It consists of a reactor 4a and a smoothing capacitor 4b, and its positive and negative terminals are connected to the positive side DC power supply line 5 and the negative side DC power supply line 6 via a current detection resistor 31 on the negative terminal side. Between the positive side DC power source line 5 and the negative side DC power source line 6, a switching element, for example, a three-phase bridge circuit 13 including switching transistors 7 to 12 is connected as a switching circuit, and its output terminals 14u and 14 are provided.
Each winding 15u, 1 of the brushless motor 15 on v, 14w
5v and 15w 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 negative side switching elements, and these transistors 7 to 12 are arranged in a predetermined order. When the on / off control is performed, the brushless motor 15 is rotationally driven by sequentially and continuously energizing the windings 15u to 15w with a phase difference of 120 degrees (electrical angle, the same applies below). In this case, one transistor is 120
Control is performed with an ON / OFF cycle of 1 degree ON and 240 degrees OFF, and the duty is controlled by the PWM signal P1 shown in FIG.
5 terminal voltages Vu, Vv, Vw of each winding 15u to 15w
Has the waveform shown in FIG.

FIG. 8 shows the waveforms of the terminal voltage Vu and the current Iu of the winding 15u when the PWM control is not involved. 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 free wheel diodes D1 to D6 connected in parallel with the respective transistors of the three-phase bridge circuit 13. Pulse voltage,
V0 is a reference voltage formed by the resistance voltage dividing circuit 16 connected between the DC power supply lines 5 and 6. From FIG. 8, it is understood that the commutation timing is delayed by about 30 degrees from the time when the induced voltage crosses the reference voltage V0.

The terminal voltages Vu, Vv, and Vw are compared with the reference voltage V0 by comparators 18 to 20 provided in the energization signal circuit 17, so that the terminal voltages Vu to Vw as shown in FIG. It is converted into fundamental wave signals Vu ′, Vv ′, Vw ′ for 180 ° section recognition. Further, these fundamental wave signals Vu ′, Vv ′, Vw ′ are given to the waveform synthesizing circuit 21 provided in the energization signal circuit 17, and the time width 180 is obtained from only the positive pulse component by collation with the PWM signal P1. Consists of a continuous square wave of degrees, and
Recognition waveform signals Ua, V having a phase difference of 120 degrees from each other
a, Wa.

Further, in the waveform synthesizing circuit 21, of the first and second timer functions held therein, the first
Of the three recognition waveform signals U by the timer function of
Six first phase division patterns X1 to X6 each having 60 degrees are formed from a, Va, and Wa, and the end point of each of the first phase division patterns X1 to X6 is set as a starting point by the second timer function. 6 with a time width of 30 degrees (Ta / 2) each
The second phase division patterns Y1 to Y6 are formed. Then, the waveform synthesizing circuit 21 finally determines the first
And from the second phase division pattern, as shown in FIG.
The energization signals Up, Un, Vp, Vn, Wp, Wn are combined. These energization signals Up, Un, Vp, Vn, Wp,
The phase pattern of Wn matches the commutation timing pattern required for the transistors 7 to 12 of the three-phase bridge circuit 13.

On the other hand, the speed judgment circuit 22 judges 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 corresponds to the speed difference. Speed deviation signal Sd
Is output 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.

The PWM signal P1 from the pulse width modulation circuit 23 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 SI 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, and sets the output signal E1 to the low level when the current detection signal SI exceeds a set value. Then, the output signal E1 from the overcurrent protection circuit 32
And energization signals Up, Un, V from the waveform synthesis circuit 21
p, Vn, Wp, and Wn are AND circuits 34, 35, 36, 37, 38, 3 forming the gate circuit 33 as a drive circuit.
9 to the input terminal of the pulse width modulation circuit 23
The PWM signal P1 from is supplied to the input terminals of the AND circuits 34, 36 and 38. Therefore, when the overcurrent protection circuit 32 detects an overcurrent, the output signal E
1 becomes low level, and the energizing signals Up to Wn are cut off (stopped) by the AND circuits 34 to 39.

Now, the output signal E1 of the overcurrent protection circuit 32
Is high level, duty controlled PWM
The signal P1 is combined with the energization signals Up, Vp, Wp by the AND circuits 34, 36, 38, that is, ANDed, and then the three-phase bridge circuit 13 is generated via the gate portions 25, 27, 29 of the gate circuit 24. Positive side transistors 7, 9, 11
Is supplied as a base control signal which is an input signal to the base of, and these are on / off controlled in the PWM mode.
Only the energizing signals Un, Vn, Wn are applied to the bases of the negative side transistors 8, 10, 12 by the gate portions 26, 28, 3 respectively.
0 is supplied via 0, and on / off control is performed without PWM mode, whereby the brushless motor 15 continues to be driven and its rotation speed is controlled by duty control.

[0012]

In the above conventional structure, when the energization signal circuit 17 is composed of a microcomputer, if the microcomputer runs away due to noise or the like, the energization signal circuit 17 has an oscillator. Occasionally, when an abnormality occurs in the energization signal circuit 17, such as when the oscillation abnormality occurs or stops, and when there is a defective component or wiring defect in the energization signal circuit 17, the energization signals Up, Un, Vp,
There is a problem that abnormalities occur in Vn, Wp, and Wn.

By the way, the energizing signals Up, Un, Vp, V
The states of the three-phase bridge circuit 13 when n, Wp, and Wn become abnormal and continue, are the transistors 7 to.
Since there are two types, 12 is on or off respectively,
2 6 or 64 states are possible. This can be classified into three types as follows.

(A) First pattern When the positive and negative side transistors sharing the output terminal among the positive side transistors 7, 9, 11 and the negative side transistors 8, 10, 12 are in the ON state.

(B) Second pattern When at least one of the positive side transistors 7, 9 and 11 is in the on state and at least one of the negative side transistors 8, 10 and 12 is in the on state. If both the negative-side transistor and the positive-side transistor that share the output terminal are both off.

(C-1) No. 1 of the third pattern When all the positive side transistors 7, 9 and 11 are in the off state and at least one of the negative side transistors 8, 10 and 12 is in the on state. .

(C-2) Part 2 of the third pattern In the case where at least one of the positive side transistors 7, 9 and 11 is in the ON state and all the negative side transistors 8, 10 and 12 are in the OFF state. .

10 to 13 show a three-phase bridge circuit 13
It is a partial circuit diagram which takes out and shows the brushless motor 15 part. FIG. 10 shows an example of the first pattern, in which the transistors 7, 8, 9, 12 are turned on and the remaining transistors 10, 11 are turned on. In this state, the transistors 7 sharing the output terminal 14u,
Since the switch 8 is turned on, a current flows through the path of the positive side DC power supply line 5, the transistors 7, 8 and the current detection resistor 31 and the negative side DC power supply line 6, as indicated by the dotted arrow. The amount of this current becomes excessive because the DC power supply lines 5 and 6 are short-circuited.

FIG. 11 shows an example of the second pattern, in which the transistors 7, 9 and 12 are turned on and the remaining transistors 8, 10, and 11 are turned off. In this state, as shown by the dotted arrow, the path of the positive side DC power supply line 5, the transistor 7, the windings 15u and 15w, the transistor 12, the current detection resistor 31 and the negative side DC power supply line 6, and the positive side DC power supply line. 5, transistor 9, winding 15v,
A current flows through the path of 15w, the transistor 12, the current detection resistor 31, and the negative side DC power supply line 6. The amount of this current is determined by the relationship between the DC power supply voltage, the inductance and resistance of the windings, and the induced voltage in the windings 15u, 15v, 15w. In this state, the rotation speed of the brushless motor 15 decreases. Then, the induced voltage also decreases, and the current increases.

FIG. 12 shows one example of the third pattern, in which the transistor 12 is on and the remaining transistors 7 to 11 are off. In this state, the induced voltage induced in the windings 15u, 15v, 15w is used as a power source, as shown by the dotted arrow,
15w, transistor 12, diode D2 and winding 1
5u path, windings 15v, 15w, transistor 1
2, a current flows through the path of the diode D4 and the winding 15v. The amount of this current is determined by the induced voltage induced in the windings 15u, 15v, 15w and the inductance and resistance of the windings 15u, 15v, 15w. The current waveform of each winding 15u, 15v, 15w in this case is as shown in FIG. As is clear from FIG. 14, each winding 15
The current waveforms of u, 15v, and 15w are normal before the time of occurrence of the abnormality (indicated by an arrow), but after the time of occurrence of the abnormality in which only the transistor 12 is in the ON state, the current waveforms are changed to a greater extent than in the normal state. Since the induced voltage decreases as the rotation speed of the brushless motor 21 decreases, the current also gradually decreases.

FIG. 13 shows an example of the second part of the third pattern, in which the transistor 11 is on and the remaining transistors 7 to 10 and 12 are off. In this state, the induced voltages of the windings 15u, 15v, and 15w are used as a power source, and the windings 15w and 15w are
u, diode D1, transistor 11 and winding 15w
A current flows through the path of (1) and the paths of the windings 15w and 15v, the diode D3, the transistor 11 and the winding 15w, and the same state as in FIG. 12 is obtained.

As described above, in the case of the first and second patterns shown in FIGS. 10 and 11, since the current detection resistor 31 is included in the current path, the overcurrent protection circuit 32 operates. Since the energization signals Up to Wn for the transistors 7 to 12 are cut off, even if an abnormality occurs in the energization signal circuit 17, it can be protected. However, FIG.
2 and No. 1 and No. 2 of the third pattern shown in FIG. 13, since the current detection resistor 31 does not exist in the current path, the overcurrent protection circuit 32 does not operate and the three-phase bridge circuit 13 is damaged. Or brushless motor 2
There is a problem that demagnetization occurs in the permanent magnet of the first rotor.

The present invention has been made in view of the above circumstances. An object of the present invention is to provide an energization signal circuit even when a failure occurs in which only one of a positive side switching element and a negative side switching element of a switch circuit is turned on. It is an object of the present invention to provide a protection device for an inverter device capable of reliably protecting the switching circuit and the motor.

[0024]

SUMMARY OF THE INVENTION The present invention is a positive side switching having a diode connected in parallel between a positive side DC power supply line and an output terminal for sequentially energizing windings of a plurality of phases included in a motor. A switching circuit including an element and a negative side switching element having a diode connected in parallel between the negative side DC power supply line and the output terminal; and a predetermined value based on a comparison result between the terminal voltage of the winding and a reference voltage. In the inverter device including an energization signal circuit that obtains an energization signal corresponding to the commutation timing and a drive circuit that controls on / off of the switching element according to the energization signal, a comparison result of the terminal voltage of the winding and the reference voltage is displayed. By monitoring, only one of the positive-side switching element and the negative-side switching element is in the ON state, and a detecting means, Detection state due to having a characteristic wherein the on-off control according to energization signal to stop formed by and a stop means constituted of a switching element when a continued set time.

In this case, in the inverter device according to claim 1, it is detected that only one of the positive side switching element and the negative side switching element is in an ON state by monitoring an input signal to the switching element of the drive circuit. It may be configured to include a detection unit that performs the above, and a stop unit that stops the on / off control according to the energization signal of the switching element when the detection state of the detection unit continues for a set time.

[0026]

According to the inverter protection device of the first aspect, only one of the positive side switching element and the negative side switching element is turned on by the detection means for monitoring the result of comparison between the terminal voltage of the winding and the reference voltage. It is detected that it is in a state, and the stop means stops the on / off control according to the energization signal of the energization signal circuit of the switching element when the detection state of the detection means continues for the set time. Even if the failure cannot be protected by the current protection circuit, it can be protected.

According to another aspect of the present invention, the detecting device monitors the input signal to the switching element of the drive circuit so that only one of the positive side switching element and the negative side switching element is in the ON state. Since the presence is detected, the same effect as in claim 1 can be obtained.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS.
As described with reference to FIG. 3, in this first embodiment, FIG.
The same parts as those of the conventional example shown in FIG. 14 are denoted by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 1, the improper energization protection circuit 49, which is a protection device, comprises a detection means 50 and a stop means 51. The detection means 50 outputs an AND circuit 40 and a NOR circuit 41 to which the fundamental wave signals Vu ′, Vv ′, and Vw ′ are given to the respective input terminals, and output signals S1 and S2 from the AND circuit 40 and the NOR circuit 41. An OR circuit 42 provided to the input terminal. Also, the stopping means 5
Reference numeral 1 denotes a charging / discharging circuit 48, which is composed of a resistor 44, a capacitor 45, and a diode 43, to which the output signal S3 from the OR circuit 42 is input, and an output signal S4 from the charging / discharging circuit 48 is given to one input terminal. An output from the NOR circuit 47 is constituted by a NOR circuit 46 and a NOR circuit 47 to which the output signal from the NOR circuit 46 is applied to one input terminal and the high level reset signal R is applied to the other input terminal. The signal is applied to the other input terminal of the NOR circuit 46.

Further, the output signal E1 from the overcurrent protection circuit 32 and the output signal E2 from the NOR circuit 46 are adapted to be applied to both input terminals of the AND circuit 56, and the output from the AND circuit 56 is provided. The signal E3 is applied to the input terminals of the AND circuits 34 to 39. That is, the output signal E3 is supplied to the input terminals of the AND circuits 34 to 39 instead of the conventional output signal E1.

Next, the operation of this embodiment will be described with reference to FIGS. 2 and 3. As shown in FIGS. 2 and 3, in the normal state prior to the time of occurrence of the abnormality (indicated by the arrow), the fundamental wave signals Vu ′, Vv ′. Vw 'is also output normally, and these fundamental wave signals Vu', Vv ', Vw'
The output signal S1 of the AND circuit 40 which receives the input is low level, and the output signal S2 of the NOR circuit 41 repeats the high level and the low level periodically (the high level and the low level are inverted from the PWM signal P1).

As a result, the output signal S3 of the OR circuit 42
Becomes the same as the output signal S2, the capacitor 45 of the charging / discharging circuit 48 is charged when the output signal S3 is at the high level, and is discharged when the output signal S3 is at the low level, and the output signal S4 is shown in FIG. 2 and FIG. It becomes the state of 3. Therefore, both input terminals of the NOR circuit 46 become low level, the output signal E2 thereof becomes high level, and if the overcurrent protection circuit 32 does not detect the overcurrent at this time, the output signal E1
Will also be at a high level. As a result, the output signal E3 of the AND circuit 56 also becomes high level, and the three-phase bridge circuit 13 operates normally as in the conventional case.

At the time of occurrence of an abnormality shown in FIG. 2, the energization signal Wn
Only the current is output and the remaining energization signals Up to Wp are not output. Therefore, the negative transistor 1
Only 2 is turned on (No. 1 of the third pattern shown in FIG. 12). In this state, the terminal voltages Vu, Vv, V
Since w is all at zero level, the fundamental wave signals Vu ′, Vu
Both v ′ and Vw ′ also become low level, the output signal S2 of the NOR circuit 41, that is, the output signal S3 of the OR circuit 42 continues to be high level, and the capacitor 45 of the charge / discharge circuit 48 is continuously charged, The output signal S4 is shown in FIG.
It gradually rises as shown in.

After that, when the high level of the output signal S3 continues for a set time T, for example, four times the period of the pulse width modulation signal P1 or more, the output signal S4 changes from the low level to the high level with respect to the NOR circuit 46. Since the output signal E2 of the NOR circuit 46 is inverted from the high level to the low level, the output signal E3 of the AND circuit 56 also becomes the low level. Therefore, the energization signals Up to Wn are cut off by the AND circuits 34 to 39, and the transistors 7 to 12 of the three-phase bridge circuit 13 are all turned off.

At the time of occurrence of an abnormality shown in FIG. 3, the energizing signal Wp
FIG. 13 shows a case where only the current-supplying signals Up to Vn, Wn are not output, and thus only the positive-side transistor 11 is turned on (No. 2 of the third pattern shown in FIG. 13). . In this state, the terminal voltage Vu,
Vv and Vw are all substantially equal to the potential of the positive side DC power supply line 5, and the fundamental wave signals Vu ′, Vv ′ and Vw ′ are all at high level, and the output signal S 2 of the AND circuit 40, that is, the OR circuit 4
As the output signal S3 of No. 2 continues to be at the high level, the capacitor 45 of the charging / discharging circuit 48 continues to be charged / discharged, and the output signal S4 thereof gradually rises as shown in FIG.

After that, when the high level of the output signal S3 continues for the set time T, the output signal S4 changes from the low level to the high level of the NOR circuit 46, so that the output signal E2 of the NOR circuit 46 is inverted from the high level to the low level. Then, the output signal E3 of the AND circuit 56 also becomes low level. Therefore, the energization signals Up to Wn are the AND circuits 34 to 3
The transistors 7 to 12 of the three-phase bridge circuit 13 are all turned off by being cut off by 9.

Although the above description has been made with respect to the occurrence of an abnormality due to the failure of the energization signal circuit 17, the protection operation can be similarly performed with respect to the occurrence of an abnormality due to the failure of the pulse width modulation circuit 23.

As described above, according to the present embodiment, the detecting means 50 causes the terminal voltages Vu, Vv, Vs and the reference voltage Vs.
Fundamental wave signals Vu ′, Vv ′, Ww ′ that are comparison results with 0
By monitoring the positive side transistors 7, 9, 11
When the ON state of only one side of the negative side transistors 8, 10 and 12 is detected and the detected state by the detecting means 50 continues for the set time T, the stopping means 51 changes the energizing signals Up to Wn. Based transistors 7-12
The on / off control of was stopped. Therefore, even when an abnormality that cannot be protected by the overcurrent protection circuit 32 occurs, the abnormal current can be interrupted in a short time, and the three-phase bridge circuit 13 or the brushless motor 15 can be protected from damage.

FIGS. 3 to 6 show a second embodiment of the present invention. The same parts as those of the first embodiment shown in FIGS. 1 to 3 are designated by the same reference numerals and their description is omitted. Only different parts will be described below.

That is, in the second embodiment, the detecting means 52 is provided in place of the detecting means 50, and the detecting means 52 supplies the base control signal to the positive side transistors 7, 9 and 11. AND circuits 33, 35 and 3
OR circuit 53 to which the output signal of 7 is given to each input terminal
And an OR circuit 54 to which the output signals of the AND circuits 34, 36 and 38 for supplying the base control signals to the negative side transistors 8, 10 and 2 are applied to the respective input terminals, and the OR circuits 54 and 54. Exclusive OR circuit 55 to which output signals S1 and S2 are applied to both input terminals
The output signal S3 from the exclusive OR circuit 55 is supplied to the charging / discharging circuit 48.

As shown in FIGS. 5 and 6, in the normal state before the occurrence of the abnormality, the output signal S1 of the OR circuit 53 repeats the high level and the low level in synchronization with the PWM signal P1, and the OR signal Output signal S1 of circuit 54
Will continue high level. Therefore, the output signal of the exclusive OR circuit 55 is the high level and low level inverted from the PWM signal P1.
Therefore, the subsequent operation in the normal state is similar to that of the first embodiment.

FIG. 5 shows a case where an abnormality similar to that of FIG. 2 (No. 1 of the third pattern) occurs at the time of occurrence of the abnormality. In this case, since the energization signal Wn is output, only the output signal of the AND circuit 39 becomes high level. As a result, the output signal S1 of the AND circuit 53 becomes low level, and the output signal S2 of the OR circuit 54 remains high level. Therefore, the exclusive OR circuit 5
The output signal S3 of 5 becomes high level continuously. The subsequent operation is similar to that of the first embodiment.

FIG. 6 shows a case where an abnormality similar to that of FIG. 3 (No. 2 of the third pattern) occurs at the time of occurrence of the abnormality. In this case, since the energization signal Wp is output, only the output signal of the AND circuit 38 becomes high level. As a result, the output signal S1 of the OR circuit 53 becomes high level and the output signal S2 of the OR circuit 54 becomes low level. Therefore, the output signal S3 of the exclusive OR circuit 55 continuously becomes high level. The subsequent operation is similar to that of the first embodiment.

Further, in the second embodiment, even if a failure occurs in the pulse modulation circuit 23, the protection can be performed in the same manner. Therefore, the second embodiment also provides the protection. The same effect as that of the first embodiment can be obtained.

In each of the above embodiments, the pulse modulation circuit 3
Is provided to perform the PWM control, but this may be provided as needed.

[0046]

The protective device for the inverter device according to the present invention comprises:
As described above, when an abnormality occurs in which only one of the positive-side switching element and the negative-side switching element of the drive circuit is turned on, the abnormality is detected and the protection operation is performed. It has an excellent effect of not causing breakage.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention.

FIG. 2 is a waveform diagram of each part in FIG.

FIG. 3 is a waveform diagram of each part in a state different from that in FIG.

FIG. 4 is a circuit diagram showing a second embodiment of the present invention.

5 is a waveform diagram of each part of FIG.

FIG. 6 is a waveform diagram of each part in a state different from that of FIG.

FIG. 7 is a circuit diagram showing a conventional example.

8 is a voltage and current waveform diagram of one winding of the brushless motor shown in FIG.

9 is a waveform diagram of each part of FIG.

FIG. 10 is a partial circuit diagram showing an abnormal state 1

FIG. 11 is a partial circuit diagram showing an abnormal state (part 2)

FIG. 12 is a partial circuit diagram showing an abnormal state 3

FIG. 13 is a partial circuit diagram showing an abnormal state 4

14 is a current waveform diagram of each winding in FIG.

[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, 14u to 14w are output terminals, 7, 9 and 11 are positive side transistors (positive side switching elements) 8, 10, 1
2 is a negative side transistor (negative side switching element), 13
Is a three-phase bridge circuit (switching circuit), 15 is a brushless motor, 15u to 15w are windings, 17 is an energization signal circuit, 22 is a speed determination circuit, 23 is a pulse width modulation circuit,
Reference numeral 31 is a waveform synthesis circuit, 32 is an overcurrent protection circuit, 33 is a gate circuit (driving circuit), 49 is an erroneous conduction protection circuit (protection device), 50 and 52 are detection means, and 51 is a stop means.

Claims (2)

[Claims] 1. A positive side switching element and a negative side DC power supply line having a diode connected in parallel between a positive side DC power supply line and an output terminal for sequentially energizing windings of a plurality of phases included in a motor. A switching circuit composed of a negative side switching element having a diode connected in parallel with an output terminal, and energization corresponding to a predetermined commutation timing based on a comparison result between the terminal voltage of the winding and a reference voltage. In an inverter device including an energization signal circuit that obtains a signal and a drive circuit that controls on / off of the switching element according to the energization signal, the positive side switching is performed by monitoring a comparison result between a terminal voltage of the winding and a reference voltage. The detection means for detecting that only one of the element and the negative side switching element is in the ON state, and the detection state by this detection means Protection device time continued the inverter formed by and a stopping means for stopping the on-off control according to the energizing signal of the switching element when. 2. A positive side switching element having a diode in parallel and a negative side DC power source line connected between a positive side DC power source line and an output terminal for sequentially energizing windings of a plurality of phases included in a motor. A switching circuit composed of a negative side switching element having a diode connected in parallel with an output terminal, and energization corresponding to a predetermined commutation timing based on a comparison result between the terminal voltage of the winding and a reference voltage. An inverter device comprising an energization signal circuit for obtaining a signal and a drive circuit for on / off controlling the switching element according to the energization signal, wherein the positive side switching element and the negative side are monitored by monitoring an input signal to the switching element of the drive circuit. The detection means for detecting that only one of the switching elements is in the ON state and the detection state by this detection means. There set time continued protection device of the inverter device comprising; and a stopping means for stopping the on-off control according to the energizing signal of the switching element when.