JP2001016898A - Controller of ac motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a controller of an AC motor which can drive a plurality of AC motors, either simultaneously or separately by means of a single inverter device. SOLUTION: An inverter section for three phases for an induction motor 1 is constituted of IGBTs 21, 26, IGBTs 22, 27, 23, 28 of an IGBT module 16, and an inverter section for three phases for an induction motor 2 is constituted of both the IGBTs 21, 26, 24, 29, 25, 30 of the IGBT module 16. The IGBTs 21, 26 are used jointly by the induction motors 1 and 2. Each of P/Cs 51, 52 controls the switching of the IGBTs 27, 28, 29, 30 via switching transistors 37, 38, 39, 40, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an AC motor control device suitable for controlling a plurality of AC motors such as a running AC motor mounted on an electric vehicle and an AC motor of an air conditioning electric compressor.

[0002]

2. Description of the Related Art Conventionally, for example, as an air conditioner for an electric vehicle, there is an air conditioner which drives an electric compressor to perform air conditioning.

In this air conditioner, DC power input from a battery mounted on an electric vehicle is taken into an inverter only for air conditioning and intermittently formed to form three-phase AC power to drive and control an AC motor of an electric compressor exclusively for air conditioning. By doing so, air conditioning is performed.

[0004]

Incidentally, the above-mentioned electric vehicle has an inverter device which has almost the same circuit configuration as that of the above-mentioned air conditioner, not only for the air conditioner but also for the drive control of a running AC motor. Is installed. Therefore, when mounted on an electric vehicle, both inverter devices must be housed in separate casings, and the internal power element cooling system must be separated, which is disadvantageous in terms of mounting space, weight and cost. There is a problem that becomes.

SUMMARY OF THE INVENTION In view of the above, an object of the present invention is to provide an AC motor control device that can drive a plurality of AC motors simultaneously or independently by using a single inverter device. I do.

[0006]

In order to achieve the above object, an AC motor control device according to the first aspect of the present invention provides a multi-phase AC motor control device comprising two semiconductor switching elements (21 to 30) connected in series. A switching circuit for generating a multi-phase AC output based on power supply from a DC power supply (4) by a switching operation of each of the switching circuits to form a multi-phase AC motor (1, 2) for each phase winding (1a); , 1b, 1c), and an inverter device (3) having a plurality of inverters respectively applied to each of the switching circuits, and a control means (5) for switching each switching circuit of the plurality of inverters so as to form a multiphase AC output. , 1
7, 51, 52, 37 to 40, 17A).

In the AC motor control device,
Each of the plurality of inverters includes a switching circuit (21, 26) having the same phase among the multi-phase switching circuits.
Are mutually a single shared switching circuit,
The common switching circuit is connected to each of the in-phase windings (1a, 2a) of the plurality of AC motors at a common terminal of the two semiconductor switching elements. Prohibiting means (51, prohibiting the switching operation of each switching circuit other than the common switching circuit in each inverter unit other than the inverter unit that drives this AC motor when driving a part of the AC motors among the motors. 52, 37 to 40, 17, 1
7A).

According to this, by sharing each inverter section for a plurality of AC motors with a single common switching circuit, a single inverter apparatus can be manufactured while reducing weight and space while saving weight. It can be configured at a cost, and it is possible to secure simultaneous driving of a plurality of AC motors or driving of only one of them.

Here, according to the invention described in claim 2,
2. The AC motor control device according to claim 1, wherein the plurality of inverters are used as a single other shared switching circuit in each of the multi-phase switching circuits having the same phase except for the shared switching circuit. The other common switching circuit is connected at a common terminal of the two semiconductor switching elements to each of the common-mode windings (1a, 2a) different from the common-mode windings (1a, 2a) among the phase windings of the plurality of AC motors. Have been.

According to this, substantially the same operation and effect as the first aspect of the invention can be achieved while ensuring the reduction in the number of switching circuits.

According to the third aspect of the present invention, in the AC motor control device according to the first or second aspect, each of the switching circuits (22 to 2) other than the common switching circuit is provided.
5, 27 to 30), the driving circuits (d, f) for driving these semiconductor switching elements in the semiconductor switching elements (27 to 30) connected to the lower end of the DC power supply.
And at least one of them drives a plurality of semiconductor switching elements, and when the prohibition means outputs a signal indicating prohibition, one or more of the plurality of drive outputs are selectively prohibited.

Thus, the operation and effect of the invention described in claim 1 or 2 can be achieved while simplifying the drive circuit.

According to a fourth aspect of the present invention, there is provided an AC motor control device comprising three-phase switching circuits each comprising two semiconductor switching elements (21, 26, 22, 27, 23, 28) connected in series. The three-phase AC output of the first three-phase AC motor (1) is formed by the switching operation of these switching circuits to form a three-phase AC output based on the power supply from the DC power supply (4). ) And the two semiconductor switching elements (21, 26, 24, 29, 25, 3) connected in series.
0), and the switching operation of these switching circuits forms a three-phase AC output based on power supply from a DC power supply, thereby forming each of the second three-phase AC motors (2). Phase windings (2a, 2a
(b), an inverter device (3) having a second inverter applied to the second inverter, and control means for switching the switching circuits of the first and second inverters so as to form a three-phase AC output. (5, 17, 51, 5
2, 37 to 40, 17A).

In the AC motor control device, the first and second inverters each include a switching circuit (21, 26) having the same phase as each other among the three-phase switching circuits. This shared switching circuit is connected to both in-phase windings (1a, 2a) of the respective phase windings of the first and second AC motors at a common terminal of both conductor switching elements. The control means inhibits the switching operation of both switching circuits other than the common switching circuit of the second inverter when driving only the first AC motor, and controls the first inverter when driving only the second AC motor. Prohibiting means (51, 52, prohibiting the switching operation of both switching circuits other than the common switching circuit of
37 to 40, 17, 17A).

According to this, each inverter section for both AC motors shares a single common switching circuit, so that a single inverter device can be reduced in weight and space while reducing cost. In addition, simultaneous driving of both AC motors or driving of only one of them can be ensured.

Here, according to the invention described in claim 5,
5. The AC motor control device according to claim 4, wherein each of the switching circuits other than the shared switching circuit (22 to 2).
5, 27 to 30), the driving circuits (d, f) for driving these semiconductor switching elements in the semiconductor switching elements (27 to 30) connected to the lower end of the DC power supply.
At least one of the plurality of semiconductor switching elements drives a plurality of semiconductor switching elements, and when the prohibiting means outputs an output indicating prohibition, any one of the plurality of driving outputs is selectively prohibited.

Thus, the operation and effect of the invention described in claim 4 can be achieved while simplifying the drive circuit.

According to a sixth aspect of the present invention, in the AC motor control device according to the first or second aspect, the DC power supply of each of the switching circuits (22 to 25, 27 to 30) other than the common switching circuit. Of the semiconductor switching elements (27 to 30) connected to the lower end of the driving circuit (d,
At least one of f) drives a plurality of semiconductor switching elements, and when the prohibiting means outputs an output indicating prohibition, one or more of the plurality of driving outputs are selectively prohibited.

Thus, the operation and effect of the invention described in claim 1 or 2 can be achieved while simplifying the drive circuit.

Note that the reference numerals in parentheses of the above means indicate the correspondence with specific means described in the embodiments described later.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 shows an embodiment of an AC motor control device according to the present invention. This AC motor control device is used for drive control of both induction motors 1 and 2 of a three-phase type including a U-phase, a V-phase and a W-phase.

The induction motor 1 has a U-phase winding 1a, a V-phase winding 1b, and a W-phase winding 1c. , 1c are rotated by applying three-phase AC voltages Vu, Vv, Vw (see FIG. 3). On the other hand, the induction motor 2 has a U-phase winding 2a, a V-phase winding 2b, and a W-phase winding 2c. The induction motor 2 has the respective phase windings 2a, 2b, The three-phase AC voltages Vu, Vv, Vw are applied to 2c to rotate.

The AC motor control device comprises a main power supply 4, the main power supply 4, both induction motors 1, 2 and an AC motor control E.
An inverter device 3 connected to the CU 5 (hereinafter, referred to as a motor control ECU 5).

The main power supply 4 is connected to a high voltage (for example, 28
8V). Further, the motor control ECU 5 determines the control target values of the two induction motors 1 and 2 and outputs the control target values to the inverter device 3. In this case, the control target value is determined according to the frequency proportional to the input to the motor control ECU 5.

The inverter device 3 includes a smoothing capacitor 1
5, an IGBT module 16, a gate circuit 17, and two photocouplers 51 and 52. Capacitor 1
Reference numeral 5 is connected in series to the main power supply 4, and the capacitor 15 smoothes the output voltage of the main power supply 4 and outputs it to the IGBT module 16.

The IGBT module 16 constitutes each inverter section for both induction motors 1 and 2, and the IGBT module 16
The BT module 16 includes IGBTs 2 corresponding to the respective phase windings 1a to 1c and 2a to 2c of the induction motors 1 and 2.
1 to 30 and flywheel diodes 21a to 30a connected in parallel to the IGBTs 21 to 30, respectively.
And

Here, both IGBTs 21 and 26, both IGBs
T22,27, both IGBT23,28, both IGBT2
The IGBTs 4 and 29 and the IGBTs 25 and 30 each constitute a series switching circuit.

The IGBT module 16 includes switching transistors 37 to 40. Each of the switching transistors 37 to 40 includes an IGBT.
A circuit for bypassing a gate signal to the BTs 27 to 30 is configured.

The switching transistor 37 has its collector connected to the gate of the IGBT 27 via a resistor 27b, and the emitter of the switching transistor 37 is connected to the emitter of the IGBT 27.

The switching transistor 38 has its collector connected to the gate of the IGBT 28 via a resistor 28b. The emitter of the switching transistor 38 is connected to the emitter of the IGBT 28.

The switching transistor 39 has its collector connected to the gate of the IGBT 29 via a resistor 29b. The emitter of the switching transistor 39 is connected to the emitter of the IGBT 29.

The switching transistor 40 is
At the collector, a resistor 30b is connected to the gate of the IGBT 30.
And the emitter of the switching transistor 40 is connected to the emitter of the IGBT 30.

In the first embodiment, the IGBT 21
Are connected at their emitters to the respective phase windings 1a, 2a of the induction motors 1, 2 together with the collector of the IGBT 26. The IGBT 22 uses an IGB
Together with the collector of T27, it is connected to the phase winding 1b of the induction motor 1.

The IGBT 23 is connected at its emitter to the phase winding 1c of the induction motor 1 together with the collector of the IGBT 28. The IGBT 24 is connected at its emitter to the phase winding 2b of the induction motor 2 together with the collector of the IGBT 29. In addition, IGBT25
Is connected at its emitter to the phase winding 2c of the induction motor 2 together with the collector of the IGBT 30.

The gate drive circuit 17 includes eight gate drive units a to h. The gate drive units a and b input gate signals to the gates of the IGBTs 21 and 26, respectively.

The gate driver d outputs the gate signal to the IGB
Input to the gate of T27 through both resistors 27c and 27b, and to the gate of IGBT29 both resistors 29c and 29b.
Input through b. Further, the gate driving unit f transmits a gate signal to the gate of the IGBT 28 by using the two resistors 28c and 28b.
And input to the gate of the IGBT 30 through both resistors 30c and 30b.

In the gate drive circuit 17, with the above configuration, each of the gate drive units a to h controls the switching of the corresponding IGBT 21 to 30 by the gate signal (see FIGS. 3 and 4).

Each of the photocouplers 51 and 52 (hereinafter referred to as P / C
51, 52) are controlled by the motor control ECU 5, and each of the switching transistors 37 to 40
Is switched while electrically insulating the.

Here, the P / C 51 inputs the drive signal to the base of the switching transistor 37 through the resistor 37a and also to the base of the switching transistor 38 through the resistor 38a.

The P / C 52 inputs the drive signal to the base of the switching transistor 39 through the resistor 39a and to the base of the switching transistor 40 through the resistor 40a.

Here, each of the P / Cs is controlled by the motor control ECU 5 by its light emitting diode, and the drive signal is received by receiving the light of the light emitting diode by a phototransistor facing the light emitting diode. Occurs and switches the corresponding switching transistor.

In the first embodiment, the inverter device 3 has an arrangement structure having a sectional shape as shown in FIG. Here, reference numeral 61 indicates a connector for the main power supply 4 and reference numeral 62 indicates a connector for both induction motors 1 and 2. Reference numerals 64 and 65 indicate a printed circuit board,
Reference numeral 66 indicates a casing. Reference numeral 66a indicates a cooling fin provided on the casing 66.

The operation of the first embodiment configured as described above will be described. (1) In the case of simultaneous drive of both induction motors 1 and 2 When each of the gate drive units a to h of the gate drive circuit 17 generates a gate signal in accordance with the rotation speed signal output from the motor control ECU 5, Gate drive units a, b
Outputs a gate signal to each of the IGBTs 21 and 26, and the gate driver c outputs the gate signal to the IGBT 22
Output to Further, the gate driving unit d outputs the gate signal
The gate driver e outputs the gate signal to the IGBT 23, and outputs the gate signal to the IGBT 23.
Outputs a gate signal to both IGBTs 28 and 30, the gate driver g outputs a gate signal to the IGBT 24, and the gate driver h outputs a gate signal to the IGBT 25.

Further, the motor control ECU 5 controls each P / C
If control is performed so that no drive signal is generated at 51 and 52,
The drive signal of each of these P / Cs 51 and 52 is low level Lo.
(See FIG. 3). Therefore, each of the switching transistors 37 to 40 is maintained in the off state.

Therefore, the switching of all the IGBTs 21 to 30 is directly controlled by the respective gate signals from the gate drive circuit 17.

As a result, each of the IGBTs 21 to 30
The smoothed voltage of the capacitor 15 is formed into three-phase AC voltages V _U , V _V , and V _W at frequencies corresponding to the required number of revolutions, and is simultaneously output to the induction motors 1 and 2. For this reason, the two induction motors 1 and 2 simultaneously induce three-phase alternating magnetic fields in their three-phase windings and rotate.

As described above, since the gate drive circuit 17 is composed of six separate gate drive units a to h, the gate signals from the gate drive units a to h are separately provided from each other. Generated. In addition, as described above, the phase windings 1a of the U-phases of the induction motors 1 and 2,
2a is connected to the emitter of the IGBT 21 and the collector of the IGBT 26. Further, each IGB connected to each V-phase winding 1b, 2b of both induction motors 1, 2 respectively.
The gate signals of the gate drive unit d are input to T27 and T29, and the gate signals of the gate drive unit f are input to the IGBTs 28 and 30 connected to the W-phase windings 1c and 2c, respectively.

Thus, in the inverter device 3, the switching circuit including the IGBTs 21 and 26, the switching circuit including the IGBTs 22 and 27, and the switching circuit including the IGBTs 23 and 28 constitute an inverter unit for the induction motor 1. And both I
A switching circuit composed of GBTs 21 and 26,
Switching circuit composed of BT24 and BT29 and both IGB
The switching circuit composed of T25 and T30 constitutes the inverter unit for the induction motor 2.

That is, according to the inverter device 3, the inverter units for the induction motors 1 and 2 are connected to the IGBTs 22 and 27.
Is shared by a single shared switching circuit, so that the same three-phase AC voltage is applied to each phase of the induction motors 1 and 2 during the energization time shown in FIG. , Both induction motors 1 and 2 can be driven at exactly the same rotational speed. (2) When Only Induction Motor 1 is Driven As described above, each of the gate drive units a to f of the gate drive circuit 17 generates a gate signal, and unlike the above, each of the gate drive units g and h generates a gate signal. When no power is generated, the motor control ECU 5 sets the P / C5 as shown in FIG.
P / C5 in a state where the drive signal of No. 1 is at the low level Lo.
2 so that the driving signal of each P / C is at a high level Hi.
When the switches 51 and 52 are controlled, each of the switching transistors 39 and 40 is turned on by a corresponding P / C 52 drive signal. Therefore, each IGBT 24, 25, 29, 30
Are both turned off. However, each of the IGBTs 21, 22, 2
Switching of the gates 3, 26, 27 and 28 is controlled based on gate signals from the gate driving units a to f of the gate driving circuit 17.

Therefore, each IGBT 2 is connected to the induction motor 1.
A three-phase AC voltage is applied by 1, 22, 23, 26, 27, and 28 (see FIG. 4). Therefore, the induction motor 1
Rotates. On the other hand, since only the U-phase induced voltage Vu is applied to the induction motor 2, the induction motor 2 is stopped without rotating. (3) When Only the Induction Motor 2 is Driven Each of the gate drive units a, b, d, and f to h of the gate drive circuit 17 generates a gate signal, and each of the gate drive units c and e generates a gate signal. When there is no motor control ECU
5 controls the P / Cs 51 and 52 such that the drive signal of the P / C 51 is set to the high level Hi and the drive signal of the P / C 52 is set to the low level Lo. Of the switching transistors 39, 4
0 is turned off by the drive signal of the corresponding P / C 52.
Therefore, each of the IGBTs 22, 23, 27 and 28 is turned off, while each of the IGBTs 24, 25, 29 and 30 and each of the IGBTs 21 and 22 are connected to each of the gate drivers a, b, d, f,
Switching is controlled by g and h gate signals.

Accordingly, each IGBT 2 is connected to the induction motor 2.
1, 22, 23, 26, 27, 28 apply a three-phase AC voltage. Therefore, the induction motor 2 rotates.
On the other hand, since only the U-phase induced voltage is applied to the induction motor 1, the induction motor 1 is stopped.

As described above, according to the configuration of the AC motor control device as in the first embodiment, both the IGBTs 21 and 26 of the IGBT module 16 are common, and both the IGBTs 21 and 26 and both the IGBTs 22 , 27,
23, 28 constitute a three-phase inverter unit for the induction motor 1, and the two IGBTs 21, 26 and the two IGBTs 24, 29, 25, 30 constitute the induction motor 2.
For the three-phase inverter unit.

Thus, the single inverter device 3 having ten IGBTs can simultaneously drive the induction motors 1 and 2 or drive only one of them.

This means that a single inverter device 3 replaces the inverter devices conventionally used independently for both induction motors. As a result, the AC motor control device can be provided at low cost, low weight, and space saving without separately employing a cooling system or a casing of each IGBT or the like.

Here, for example, a brushless DC motor, which is an AC motor for driving an electric vehicle, is used instead of the induction motor 1, and the induction motor 2 is used as a drive source of an air-conditioning electric compressor of the electric vehicle. For example, even when the electric vehicle is stopped, by driving only the induction motor 2, an AC motor control device capable of cooling and heating can be provided at low cost, low weight, and space saving. (Second Embodiment) FIG. 5 shows a second embodiment of the present invention.

In the second embodiment, the gate drive circuit 17A is different from the AC motor control device described in the first embodiment in that each of the switching transistors 37 to 40, each of the resistors 37a to 40a,
And each of the P / Cs 51 and 52 is employed.

The gate drive circuit 17A includes a gate drive section a
To j. The gate drive unit d has a configuration shown in FIG. 6 unlike the gate drive unit d of the gate drive circuit 17 described in the first embodiment.

The gate drive section d includes a P / C 70 and a transistor circuit 80. P / C70
Is the motor control ECU 5 described in the first embodiment.
To drive the transistor circuit 80 for switching. The transistor circuit 80 switches the IGBT 27 described in the first embodiment.

The gate drive unit f is also different from the gate drive unit f of the gate drive circuit 17 described in the first embodiment.
It has the same configuration as the gate drive section d of the gate drive circuit 17A. The remaining gate drivers a to c, e, g to j
Also has the same configuration as the gate drive section d of the gate drive circuit 17A.

Thus, each of the gate drive units a to j is controlled by its transistor circuit 80 so that each of the corresponding I
GBTs 21, 26, 22, 27, 23, 28, 24, 2
9, 25 and 30 are switching-driven. Other configurations are the same as those of the first embodiment.

In the second embodiment configured as described above, the gate drive circuit 17 is controlled by the motor control ECU 5.
By controlling the gate drive circuit 17A to generate gate signals from all the gate drive units a to j of A,
The BTs 21 to 30 are both switched and driven.

Thus, the two induction motors 1 and 2 are simultaneously rotated, as described in the first embodiment. The gate drive circuit 17A is controlled by the motor control ECU 5.
Of the gate drive units a to j of the gate drive units g, h,
By stopping the output of the gate signals i and j and controlling the gate drive circuit 17A so as to generate the gate signals from the gate drive units a to f, only the induction motor 1 is rotated in the same manner as in the first embodiment. Let it.

Further, the motor control ECU 5 stops the output of the gate signals of the gate drive units a to f among all the gate drive units a to j of the gate drive circuit 17A, and outputs the gate signals from the gate drive units g, h, i, j. If the gate drive circuit 17A is controlled to generate a gate signal, the induction motor 2
Only the same is rotated as in the first embodiment. As a result, according to the second embodiment, the same operation and effect as those of the first embodiment can be achieved.

In practicing the present invention, the present invention may be applied to an AC motor for traveling and an AC motor for air conditioning mounted on a hybrid vehicle, in addition to an electric vehicle. The present invention may be applied to a double AC motor such as a double induction motor adopted as a motor.

In practicing the present invention, the two induction motors are not limited to three-phase motors, but may be four-phase or more multi-phase motors. For example, the present invention may be applied to control of both induction motors of six phases. In this case, the logarithm of the IGBT and the number of gate drive units of the gate drive circuit may be increased by the increase in the number of phases of each induction motor.

In implementing the present invention, the number of induction motors controlled according to the present invention is not limited to two, but may be generally plural.

In implementing the present invention, unlike the above embodiments, the V-phase or W-phase windings of both induction motors 1 and 2 are connected to the common terminal of both IGBTs 23 and 28 or both IGBTs 24 and 29. Connected to the common terminal of both IG
The functions and effects substantially the same as those of the above embodiments can be achieved while eliminating the BTs 25 and 30.

Further, in implementing the present invention, each IGBT described in each of the above embodiments may be various semiconductor switching elements such as a bipolar transistor, a field effect transistor, and a thyristor.

[Brief description of the drawings]

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

FIG. 2 is a cross-sectional view showing a mechanical configuration of the inverter device of FIG.

FIG. 3 is a timing chart in the case where both induction motors are simultaneously driven in the first embodiment.

FIG. 4 is a timing chart when only the induction motor 1 is driven in the first embodiment.

FIG. 5 is a circuit configuration diagram showing a second embodiment of the present invention.

FIG. 6 is a detailed circuit diagram of a gate drive unit of the gate drive circuit of FIG.

[Explanation of symbols]

1, 2 ... induction motor, 1a to 1c, 2a to 2c ... phase winding, 3 ... inverter device, 4 ... main power supply, 5 ... motor control ECU, 15 ... capacitor, 16 ... IGBT module, 17, 17A ... gate Drive circuits, 21 to 30 ...
IGBTs, 32 to 35, 37 to 40: switching transistors, 51, 52: photocouplers.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Kunio Iriya, Inventor Denso, 1-1-1, Showa-cho, Kariya-shi, Aichi Prefecture (72) Inventor Koji Nonoyama 1-1-1, Showa-cho, Kariya-shi, Aichi, Japan (72) Inventor Yuji Takeo 1-1-1, Showa-cho, Kariya-shi, Aichi Prefecture Inside DENSO Corporation (72) Inventor Yasuta Kitamine 1-1-1, Showa-cho, Kariya-shi, Aichi F term (Reference) 5H572 AA02 AA11 BB10 CC02 DD03 EE04 EE05 FF06 HA01 HA10 HB07 HC01 HC04 HC08 JJ03 JJ26 KK05 LL01 PP03

Claims (6)

[Claims] 1. A multi-phase switching circuit comprising two semiconductor switching elements (21 to 30) connected in series. The switching operation of these switching circuits causes a multi-phase AC based on power supply from a DC power supply (4). An inverter device (3) having a plurality of inverter units for forming outputs and applying the outputs to the respective phase windings (1a, 1b, 1c) of the plurality of polyphase AC motors (1, 2); Control means (5, 17, 51, 52, 37 to 40, 17) for performing switching operation of each switching circuit of the section so as to form a polyphase AC output.
A), wherein the plurality of inverter units each includes a switching circuit (21, 2
6) are formed as a single common switching circuit, and the common switching circuit has a common terminal of both semiconductor switching elements, and each of the common-mode windings (1a) among the phase windings of the plurality of AC motors. 2a), wherein the control means, when driving a part of the plurality of AC motors, drives the AC motor in each of the inverter units other than the inverter unit driving the part of the AC motors. An AC motor control device including prohibiting means (51, 52, 37 to 40, 17, 17A) for prohibiting the switching operation of each switching circuit other than the common switching circuit. 2. The plurality of inverter sections are each used as a single other common switching circuit in each of the multi-phase switching circuits having the same phase except for the common switching circuit. The common switching circuit is connected, at a common terminal of the two semiconductor switching elements, to respective common-phase windings different from the respective common-phase windings (1a, 2a) among the respective phase windings of the plurality of AC motors. 2. The method according to claim 1, wherein
2. The AC motor control device according to 1. 3. A semiconductor switching element (2) connected to the lower end of the DC power supply of each of the switching circuits (22 to 25, 27 to 30) other than the common switching circuit.
7 to 30), at least one of the driving circuits (d, f) for driving the semiconductor switching elements drives a plurality of semiconductor switching elements, and when the prohibiting means outputs an output indicating prohibition, the plurality of driving circuits are driven. 3. The AC motor control device according to claim 1, wherein at least one of the outputs is prohibited. 4. A three-phase switching circuit comprising two semiconductor switching elements (21, 26, 22, 27, 23, 28) connected in series, and a switching operation of these switching circuits causes the switching operation of the DC power supply (4). A first inverter unit for forming a three-phase AC output based on the power supply and applying the three-phase AC output to each phase winding (1a, 1b, 1c) of the first three-phase AC motor (1); Switching element (21, 26, 24, 29, 25, 30)
The three-phase switching circuits of the second three-phase type AC motor (2) are formed by switching operation of these switching circuits to form a three-phase AC output based on power supply from the DC power supply. Windings (2a, 2b,
2c) an inverter device (3) having a second inverter section, and a control means (3) for switching each switching circuit of the first and second inverter sections so as to form a three-phase AC output. 5, 17, 51, 52, 37 to 4
0, 17A), wherein the first and second inverter units each include a pair of switching circuits (21, 26) having the same phase among the three-phase switching circuits. The common switching circuit is connected to both of the in-phase windings (1a, 2a) of the phase windings of the first and second AC motors at a common terminal of the two conductor switching elements. Being connected, when the control means drives only the first AC motor, the control means inhibits switching operations of both switching circuits other than the shared switching circuit of the second inverter section, and further comprises the second AC motor Prohibiting means (51, 5) for prohibiting the switching operation of both switching circuits other than the common switching circuit of the first inverter unit when only the first inverter unit is driven. , The AC motor control device comprising a 37 to 40,17,17A). 5. A semiconductor switching element (2) connected to the lower end of the DC power supply of each of the switching circuits (22 to 25, 27 to 30) other than the common switching circuit.
7 to 30), at least one of the driving circuits (d, f) for driving the semiconductor switching elements drives a plurality of semiconductor switching elements, and when the prohibiting means outputs an output indicating prohibition, the plurality of semiconductor switching elements are output. 5. The AC motor control device according to claim 4, wherein any one of the drive outputs is prohibited. 6. A semiconductor switching element (2) connected to a lower end of the DC power supply of each of the switching circuits (22 to 25, 27 to 30) other than the common switching circuit.
7 to 30), at least one of the driving circuits (d, f) for driving the semiconductor switching elements drives a plurality of semiconductor switching elements, and when the prohibiting means outputs an output indicating prohibition, the plurality of semiconductor switching elements are output. 2. The method according to claim 1, wherein one or more of the drive outputs are prohibited.
Or the AC motor control device according to 2.