JP2003174790A - Synchronous motor device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a synchronous motor device for a vehicle driven by a three-phase inverter which materializes the rise of reliability, the reduction of magnetic noise, the reduction of loss, and the reduction of switching noise. <P>SOLUTION: A pair of three-phase armature windings 31 and 32 of a synchronous motor 3 for a vehicle are controlled individually for their drive by a pair of three-phase inverter circuits 10 and 20. Consequently, even if the action of one three-phase inverter circuit fails, this device can stop it and operate the synchronous motor for a vehicle without any problem with a remaining three- phase inverter circuit. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle synchronous motor device or a vehicle synchronous generator / motor device.

[0002]

2. Description of the Related Art A three-phase synchronous motor having a simple structure and high efficiency is used as a rotary electric machine for generating power for running a vehicle and power for driving an auxiliary machine.

Since a battery is used as a power source in a three-phase synchronous motor for a vehicle, it is usual that the three-phase AC power supplied to the three-phase synchronous motor (three-phase brushless motor) is formed by PWM control of a three-phase inverter circuit. is there.

In a conventional three-phase synchronous motor device driven by a three-phase inverter circuit, a distributed winding armature winding wound by a wave winding method or the like is generally adopted. In this case, the armature core (stator core ) In the case where the teeth facing the same field magnetic pole are set to different magnetic poles by allowing different phase armature currents to flow in the adjacent slots (1 armature magnetic pole per phase) Alternatively, in the case where the two slots adjacent to each other face the same field magnetic pole so that the two slots adjacent to each other have the same phase magnetic pole by allowing the armature currents of the same phase to flow in the two adjacent slots (1 phase 1 There is an armature magnetic pole 2) per pole.

However, in the conventional three-phase inverter circuit driven synchronous motor device for a vehicle, the reliability is further improved and the magnetic noise, loss, and switching noise voltage are further reduced without significantly increasing the manufacturing cost. Was strongly requested.

It is an object of the present invention to provide a vehicular synchronous motor device that satisfies some or all of the above requirements.

[0007]

According to the present invention, there is provided a synchronous motor device for a vehicle, wherein a pair of stator cores, in which slots and teeth are alternately formed at a predetermined circumferential pitch, are separately wound around the slots adjacent to each other. One of the vehicle synchronous motors having the three-phase armature windings, and the two-phase armature windings are individually energized with a rotation vector current synchronized with the rotation of the rotor of the vehicle synchronous motor. By PWM controlling the pair of three-phase inverter circuits that drive the vehicle synchronous motor and the switching elements of the three-phase inverter circuits, the rotation vector currents generated by the three-phase inverter circuits are individually controlled. And a control unit for generating a desired torque in the vehicle synchronous motor.

That is, according to this configuration, since the pair of three-phase inverter circuits individually feeds power to the pair of three-phase armature windings of the same vehicle synchronous motor,
The following effects can be achieved.

First, even if the operation of one of the three-phase inverter circuits becomes unsuccessful for some reason, the remaining three-phase inverter circuits can be stopped to operate the vehicle synchronous motor without any problems. It can greatly improve the sex. For example, a vehicle synchronous motor (also simply referred to as a traveling motor) that generates traveling power for a vehicle is naturally required to have extremely excellent reliability. If the travel motor suddenly becomes unable to drive due to a failure of the three-phase inverter circuit or a break in the three-phase armature winding, a serious accident may occur. On the other hand, in the present invention, since two sets of three-phase armature windings and three-phase inverter circuits for driving the windings are provided, even if one of the sets is malfunctioning, traveling without any problem occurs. Driving is possible, and vehicle driving safety is significantly improved. In addition,
As a matter of course, when the vehicle synchronous motor is driven by one of the three-phase inverter circuits, the maximum output of the vehicle synchronous motor decreases. However, in various types of vehicular synchronous motors including traveling motors, it is rare to operate at full load, and normally, partial load operation is performed. During this partial load operation, even if the energization to one of the three-phase armature windings becomes unsuccessful, the duty ratio of the remaining three-phase inverter circuit, the average output current, or the PWM control is performed. The same torque can be generated in the vehicular synchronous motor by increasing the time during which the switching element is substantially energized.

Further, in this configuration, the switching surge noise voltage generated in the three-phase inverter circuit can be reduced by shifting the on / off timings of the switching elements of the two three-phase inverter circuits.

Further, with this configuration, a three-phase inverter circuit for a large output motor can be realized at low cost. More specifically, each switching element of the three-phase inverter circuit is composed of a semiconductor chip. However, the area of one semiconductor chip has a certain limit mainly due to yield reasons, and an increase in chip area leads to a decrease in yield. This causes a large increase in manufacturing cost. It is possible to reduce the total cost by using two semiconductor chips having a half area in parallel. However, when two semiconductor chips are used in parallel, there is a difference in characteristics between the two semiconductor chips, especially a difference in ON resistance value. Then, the current is not evenly divided between the two semiconductor chips, and the current concentrates on the semiconductor chip on the side with the smaller on-resistance. As is well known, heat generation of a semiconductor chip, that is, power loss, is proportional to this on-resistance × square of current, so that heat generation between both semiconductor chips varies, resulting in a difference in temperature between the two semiconductor chips. For this reason,
When two semiconductor chips are used in parallel, the ON resistances of the two semiconductor chips connected in parallel need to be sufficiently aligned, and the wiring resistances must be similarly aligned, which makes designing and manufacturing troublesome. Become. On the other hand, in the present invention, the use of two semiconductor chips is similar to the above, but since each semiconductor chip drives the phase windings different from each other, the concentration of current due to the variation of the ON resistance is It does not occur, and the above-mentioned trouble does not occur.

In a preferred aspect 1, the both three-phase armature windings are star-shaped windings, and the neutral points of the both three-phase armature windings are not connected.

That is, when both of the neutral points are short-circuited, if the two three-phase inverter circuits operate in the same phase, the two switching elements described above operate in parallel, and the electrical angle of 3
6-phase operation is performed when the operation is shifted by 0 degree, but it is difficult to normally operate the synchronous motor for vehicle if one of the switching elements has an ON failure (failure in which it is always on) in the neutral point short-circuit driving. Becomes On the other hand, if these neutral points are separated, even if one switching element of one of the three-phase inverter circuits fails to turn on, this one of the three-phase inverter circuits will be stopped and the remaining one of the three-phase By operating the inverter circuit normally, the vehicular synchronous motor can be driven without any problems. At this time, one of the three-phase inverter circuits is stopped and the armature current is reduced.
It suffices to increase the WM duty ratio and the time during which the switching element that is PWM-controlled is substantially energized, and no problem occurs except in high-power operation.

In an aspect 2 which is an aspect of the preferred aspect 1, the both three-phase inverter circuits are synchronized with the both three-phase armature windings by the rotation of the rotor of the vehicle synchronous motor, and the adjacent slots. The vehicle synchronous motor is driven by individually supplying the rotation vector currents that are deviated by an electrical angle corresponding to the slot pitch between them.

That is, in this configuration, for example, U, X, -V, -Y
Slots can be arranged in the order of W, Z, -U, -X, V, Y, -W, -Z. U, V, W are the phase windings of the first three-phase armature winding, and X, Y, Z are the phase windings of the second three-phase armature winding. U and X are applied with a voltage shifted by an electrical angle of 30 degrees (π ÷ 6), and are individually wound around two slots adjacent to each other with an electrical angle shifted by 30 degrees on the armature core. The voltages V and Y are applied with a voltage shifted by an electrical angle of 30 degrees, and are individually wound on two adjacent slots with an electrical angle shifted by 30 degrees (π ÷ 6) to the armature core. W, Z
Is applied with a voltage shifted by an electrical angle of 30 degrees (π ÷ 6), and is individually wound around two slots adjacent to each other with an electrical angle shifted by 30 degrees on the armature core.

To further explain, in the above-described winding structure of the armature magnetic pole 2 per one phase and one pole, the same phase winding is wound in two adjacent slots. This structure is essentially the same as halving the number of slots and winding twice the number of phase windings in one slot, but the number of teeth is also halved, resulting in a large distortion of the spatial magnetic flux flow. Therefore, the magnetic noise increases accordingly. This is improved by the winding structure of the armature pole 2 per pole per phase. However, in this configuration, since the phase of the current passed through each phase winding of the three-phase armature winding and the spatial arrangement of each phase winding further match, the harmonic components of the current magnetic field are reduced. The magnetic noise can be further reduced as compared with the above-mentioned winding structure of the armature magnetic pole 2 per one phase.

Further, since the switching current interrupted by one switching of each switching element of the three-phase inverter circuit is halved, the switching surge voltage generated in the DC power supply line of the three-phase inverter circuit can be greatly reduced. It is possible to reduce the size of the smoothing capacitor and reduce its loss and heat generation.

In a preferred mode 3, the control unit cuts off the rotation vector current output from one of the three-phase inverter circuits during a low output operation below a predetermined level.

With this configuration, in a small load operation in which the absolute value of the PWM duty ratio or the average output current of the three-phase inverter circuit is small, the loss of the three-phase inverter circuit can be further reduced and the device efficiency can be improved. . This point will be described in more detail below.

The power loss of the three-phase inverter circuit includes the resistance loss a in the completely on state of each switching element constituting the three-phase inverter circuit, the transition period from the on state to the off state of each switching element, and the on state from the off state. It is the sum of the resistance loss b during the transition to the state.

In a small load operation, the case where two three-phase inverter circuits are operated and the duty ratio of one three-phase inverter circuit (or the substantial energization time of its switching element) is increased to obtain an equivalent armature current. Compare with when you get. In the latter case, the number of switching elements that are turned on is halved, but since the actual energizing time per switching element is extended by that amount, the above resistance loss a
Are almost the same. However, in the latter case, the number of times the switching element is turned on and off is halved, so that the resistance loss b can be halved. Note that this resistance loss b occurs because the channel resistance (internal resistance of the pair of main electrodes) becomes extremely large during the above-mentioned transition period although the current becomes small.

In a preferred aspect 4, the control unit controls the PWM duty ratio of the other switching element of the both three-phase inverter circuits when the switching element of one predetermined phase of the both three-phase inverter circuits has an off failure. To increase the substantial energization time, and suppress an increase in the asymmetry of the armature current due to the OFF failure of one of the switching elements of the three-phase inverter circuit.

In other words, according to this configuration, even if one of the switching elements of one of the three-phase inverter circuits has an OFF failure (failure in which it is always in an OFF state) for some reason, the operation can be performed without problems by the following two methods. Can continue.

One method is to increase the duty ratio of the sound three-phase inverter circuit by stopping the three-phase inverter circuit of the off-failed one (to prevent current from flowing through each switching element). As a result, the operation can be continued without any trouble. This method is particularly effective during partial load operation.

Another method is to increase the duty ratio or the substantial energization time of the switching elements of the predetermined two phases which are not off-failed, so that the vector due to the turning-on of the equivalently off-failed switching element is increased. A vector current equal to the current is generated.

In this way, the effect of the off failure of the switching element of the three-phase inverter circuit can be minimized.

In a preferred aspect 5, the control unit controls one of the three-phase inverter circuits to control one of the three-phase inverter circuits when the switching element of a predetermined phase of the three-phase inverter circuits has an on-failure. To prevent the undesired current from flowing in the three-phase armature winding, and continue the operation of the other remaining three-phase inverter circuit.

In other words, according to this configuration, even if one of the switching elements of one of the three-phase inverter circuits is on-failed (a failure of always being in the on-state) for some reason, only the other three-phase inverter circuit is duty-fed. Operating by increasing the ratio or the switching element's substantial energization time and stopping the three-phase inverter circuit with the ON failure (to prevent current from flowing through each switching element) You can continue.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of a vehicular synchronous motor device of the present invention will be described with reference to the following embodiments.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the circuit configuration of an inverter device for a three-phase brushless DC motor according to the present invention.

(Structure) 1 is a battery, 10 is a first three-phase inverter circuit, 20 is a second three-phase inverter circuit, 3
Reference numeral 0 is a field winding type three-phase synchronous generator-motor that constitutes a vehicle running motor, 40 is a controller (control section), and 50 is a field current control circuit. Although the field winding type three-phase synchronous generator motor is used in this embodiment, a field magnet type three-phase synchronous generator motor or a reluctance torque type three-phase synchronous generator motor may be used. The drive may be dedicated to the electric motor.

The three-phase inverter circuits 10 and 20 are MOS
This is a normal three-phase inverter circuit using the transistor T as a switching element, and has a well-known configuration, so a detailed description thereof will be omitted. D is a flywheel diode. The three-phase inverter circuits 10 and 20 are supplied with DC power from the battery 1.

Reference numeral 30 has a first three-phase armature winding 31, a second three-phase armature winding 32, and a field winding 33. The three-phase armature winding 31 is It is driven by the three-phase inverter circuit 10, and the three-phase armature winding 32 is driven by the three-phase inverter circuit 20. The three-phase armature winding 31 is configured by connecting the U-phase winding U, the V-phase winding V, and the W-phase winding W in a star shape, and the three-phase armature winding 32 is the X-phase winding X, The Y-phase winding Y and the Z-phase winding Z are connected in a star shape. As will be described later, in normal control, the U-phase winding U is applied with a three-phase AC voltage that leads the X-phase winding X by an electrical angle θ (= π ÷ 6), and the V-phase winding V is Y-phase. Electrical angle θ (= π ÷
6) The three-phase AC voltage advanced by 6) is applied, and the W-phase winding W is applied with the three-phase AC voltage advanced by an electrical angle θ (= π ÷ 6) from the Z-phase winding Z. The U-phase winding U, the V-phase winding V, the W-phase winding W, the X-phase winding X, the Y-phase winding Y, and the Z-phase winding Z are provided on the inner circumference of an armature (stator) core not shown. The formed even number of slots are wound in the order of U, X, -V, -Y, W, Z, -U, -X, V, Y, -W, -Z. That is, in this embodiment, a total of 1 adjacent to each other
Two slots occupy an electrical angle of 2π, and one slot pitch is set to θ (= π ÷ 6). The pitch of the field poles of the rotor of the three-phase synchronous motor 30 (not shown) is π
It is said that. (Operation) The field current control circuit 50 has a built-in switching element (not shown) which is controlled by the controller 40 and PWM-controls the magnitude of the field current passing through the field winding 30. Since the details of this type of field current control are essentially the same as those of a normal automobile generator, detailed description thereof will be omitted.

The controller 40 detects the currents of the respective phase windings U, V, W, X, Y and Z (hereinafter also referred to as phase currents) iu, iv, iw, ix detected by a current sensor (not shown).
Three-phase two-phase conversion of yy and iz into q-axis current iq and d-axis current id is performed, and the q-axis current iq and d-axis current id are converted into phase windings U, V, and W based on the external torque command value. The PWM duty ratio of the phase voltage applied to X, Y, and Z is controlled. Preferably, the q-axis current iq is feedback-controlled on the basis of the difference between the target value of the q-axis current iq and the measured value so as to converge to the target value of the q-axis current iq which is proportional to the external torque command value, and d
The d-axis current id is feedback-controlled so that the axis current id becomes zero. Since this type of control is well known, detailed description thereof will be omitted. As the current sensor, a method of measuring the voltage drop of the current detection resistance element of each of the lower arms of the three-phase inverter circuits 10 and 20 may be adopted in addition to the Hall element or the like.

The control operation which characterizes this embodiment will be described below with reference to the flow chart shown in FIG.
This control operation is executed by the controller 40. In the normal state, the phase currents iu, iv, iw, i
The waveforms of x, iy, and iz are the same except that the phases are different, and the frequencies thereof are detected by a rotation angle sensor (not shown) and are controlled so as to be synchronized with the rotation angle of the rotor.

First, it is determined whether or not the output current (which may be torque) of the three-phase inverter circuits 10 and 20 is below a predetermined value (S100), and if it exceeds the predetermined value, step S10.
If it is equal to or less than the predetermined value, one of the three-phase inverter circuits is stopped (all switching elements are turned off), and the average output current of the remaining other three-phase inverter circuit is almost doubled. The maximum value of the PWM duty ratio is increased (S102).

In the next step S104, it is determined whether or not there is an OFF failure or an ON failure in each switching element (MOS transistor) of both the three-phase inverter circuits 10 and 20. This determination is made by monitoring the abnormalities of the respective phase currents of the three-phase armature windings 31 and 32 detected by the Hall element.
Alternatively, it can be easily detected by monitoring the lower arm current of each phase of both the three-phase inverter circuits 10 and 20. For example, each three-phase inverter circuit 10, 20
When PWM is controlled, if any of the switching elements has an OFF failure, the current that should flow through the switching element having the OFF failure does not flow. Therefore, this OFF failure can be detected by detecting it. . Further, in the case where each of the three-phase inverter circuits 10 and 20 is PWM-controlled with a predetermined duty ratio that is not 0, if any switching element has an ON failure, a current that should not flow through this ON failure switching element flows. Therefore, by detecting it, this ON failure can be detected.

Next, it is judged whether or not there is an OFF failure or ON failure (S106), and if there is no OFF failure or ON failure, the process returns to the main routine (not shown). If there is, there is an OFF failure or ON failure. The three-phase inverter circuit is stopped (all switching elements are turned off), and the maximum value of the PWM duty ratio is increased so that the average output current of the other remaining three-phase inverter circuit is almost doubled (S102).

In the above description, the field current control circuit 4 is used.
Although the operation of 0 has not been described, the field current control circuit 40 can be used for field current control for keeping the battery voltage constant during power generation, like an ordinary alternator regulator. (Operation and Effect) According to the vehicular synchronous motor device of this embodiment described above, the following effects can be obtained.

First, even if the operation of one of the three-phase inverter circuits fails for some reason (control is impossible, the switching element fails), it is stopped and the remaining three-phase inverter circuit operates the vehicle synchronous motor without any problems. Therefore, the reliability of the device can be significantly improved.

Further, the switching surge noise voltage generated by the three-phase inverter circuit can be reduced by shifting the on / off timings of the switching elements of the two PWM-controlled three-phase inverter circuits.

Further, since it is driven substantially in six phases, magnetic noise can be reduced. Of course, the phase angle between the respective phase voltages output from both the three-phase inverter circuits 10 and 20 may be set to 0, if necessary.

Further, since the switching current per switching element of the three-phase inverter circuit is halved, the switching surge voltage generated in the DC power supply line of the three-phase inverter circuit can be greatly reduced, and the smoothing capacitor can be downsized. The loss and heat generation can be reduced.

In addition, since the operation is performed by only one of the three-phase inverter circuits during the low output operation below the predetermined level, the resistance loss during the switching transition period can be reduced.

In the present invention, MO is used as the switching element.
S-FET was adopted, but bipolar transistor and I
Of course, GBT may be used. (Additional Description) Various methods are known as the PWM control method used in the three-phase inverter circuits 10 and 20 of FIG. The two examples will be supplemented below with reference to FIGS. 4 and 5.

FIG. 4 shows a gate voltage waveform of each switching element T of the three-phase inverter circuits 10 and 20 in the first PWM control. The three switching elements on the lower arm side of the three-phase inverter circuit 10 are sequentially switched for each electrical angle of 2π / 3, and are always on during the 2π / 3 period in which the self should be on. The three switching elements on the upper arm side of the three-phase inverter circuit 10 are PWM-controlled. The three switching elements on the lower arm side of the three-phase inverter circuit 20 are sequentially switched for each electrical angle of 2π / 3, and are always on during the 2π / 3 period in which the self should be on.
The three switching elements on the upper arm side of the three-phase inverter circuit 20 are PWM-controlled.

In such PWM control, when the PWM control of one of the three-phase inverter circuits is stopped, a substantially equivalent output can be obtained by doubling the PWM duty ratio of the other three-phase inverter circuit.

FIG. 5 shows a gate voltage waveform (for one PWM cycle) of each switching element T of the three-phase inverter circuits 10 and 20 in the second PWM control. In this aspect,
A PWM duty ratio of 100% indicates a positive maximum value of the phase voltage amplitude, a PWM duty ratio of 0% indicates a negative maximum value of the phase voltage amplitude, and a PWM duty ratio of 50% indicates a phase voltage amplitude of 0.
Indicates. In FIG. 5, the amplitude of the U and X phase voltages is about 80%,
The amplitude of the V and Y phase voltages is about 40%, and the amplitude of the W and Z phase voltages is about 20%. One PWM cycle is 100 μs if the PWM carrier frequency is 10 kHz.

In this mode, one PWM cycle can have seven periods T1 to T7 as shown in FIG. That is, T1 and T7 are periods in which all the upper arm side switching elements are off and all the lower arm side switching elements are on. T2 and T6 are periods in which the upper arm side switching element of the phase with the largest duty ratio is turned on and the lower arm side switching elements of the remaining two phases are turned on. At T3 and T5, the lower arm side switching element in the phase with the smallest duty ratio is turned on and remains 2
It is a period in which the upper arm side switching element of the phase is turned on. T7 is a period in which all the upper arm side switching elements are turned on and all the lower arm side switching elements are turned off.

In such a PWM control, when the PWM control of one of the three-phase inverter circuits is stopped, the energization period during which the switching element substantially conducts the current in each PWM cycle of the other three-phase inverter circuit remains. In order to extend the switching element, if the PWM duty ratio exceeds 50%, the original duty ratio (the period when the gate voltage is at the high level / 1 PWM cycle) is doubled by the difference obtained by subtracting 50% from the original duty ratio. Good, P
For a switching element with a WM duty ratio of less than 50%, the absolute value of the difference obtained by subtracting 50% from the original duty ratio may be subtracted from the original duty ratio (period when the gate voltage is at high level / 1 PWM cycle). .

In addition, it corresponds to the above-mentioned torque command value.
When feedback control is performed so that the difference between the q-axis current command value iq and the q-axis current detection value iq 'is 0, the torque of the other three-phase inverter circuit remains when one of the three-phase inverter circuits is stopped. The command value may be doubled.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a vehicular synchronous motor device of the present invention.

FIG. 2 is a flowchart showing an example of control of the vehicle synchronous motor device shown in FIG.

3 is a flowchart showing an example of control of the vehicle synchronous motor device shown in FIG.

FIG. 4 is a timing chart showing an example of PWM control waveforms of the vehicle synchronous motor device shown in FIG. 1.

5 is a timing chart showing an example of control waveforms of the vehicle synchronous motor device shown in FIG.

[Explanation of symbols]

1 battery 10 First three-phase inverter circuit 20 Second three-phase inverter circuit 30 three-phase synchronous generator motor 40 controller (control unit) 50 field current control circuit

Claims (6)

[Claims] 1. A vehicle having a pair of the three-phase armature windings separately wound around the adjacent slots of a stator core in which slots and teeth are alternately formed at a predetermined circumferential pitch. A synchronous motor; and a pair of three-phase inverter circuits that individually drive a rotation vector current synchronized with the rotation of the rotor of the vehicle synchronous motor to the both three-phase armature windings to drive the vehicle synchronous motor. , PW each switching element of the both three-phase inverter circuit
A control unit for individually controlling the rotation vector currents respectively generated by the respective three-phase inverter circuits by M control to generate a desired torque in the vehicle synchronous motor. Synchronous motor device. 2. The synchronous motor device for a vehicle according to claim 1, wherein the three-phase armature windings are star-shaped windings, and the neutral points of the three-phase armature windings are unconnected. A synchronous motor device for a vehicle characterized by the above. 3. The vehicular synchronous motor device according to claim 2, wherein the two-phase three-phase inverter circuits are synchronized with the rotation of the rotor of the vehicular synchronous motor on both the three-phase armature windings, and are adjacent to each other. A vehicular synchronous motor device, wherein the vehicular synchronous motor is driven by individually energizing rotation vector currents that are shifted by an electrical angle corresponding to a slot pitch between slots. 4. The vehicular synchronous motor device according to any one of claims 1 to 3, wherein the control unit outputs the rotation vector current output from one of the three-phase inverter circuits during a low output operation below a predetermined level. A synchronous motor device for a vehicle, which is characterized in that: 5. The vehicular synchronous motor device according to any one of claims 1 to 3, wherein the control unit controls the two three-phase inverter circuits to operate when a switching element of one predetermined phase of the three-phase inverter circuits is turned off. A vehicle synchronization characterized by changing the PWM duty ratio of the other switching element of the three-phase inverter circuit to prevent an increase in the asymmetry of the armature current due to the off failure of one of the switching elements of the three-phase inverter circuit. Electric motor device. 6. The vehicular synchronous motor device according to any one of claims 1 to 3, wherein the control unit controls the switching operation of a switching element of one of the predetermined phases of the two three-phase inverter circuits when the switching failure occurs. One of the three-phase inverter circuits is controlled to prevent an undesired current due to the ON failure from flowing in the three-phase armature winding, and the remaining other three-phase inverter circuit is continued to operate. A synchronous motor device for a vehicle.