Drive device for rotary electric machine and drive system for rotary electric machine

Abstract

Provided is a drive device which is for a rotary electric machine and is capable of suppressing increases in size and cost.　The drive device (4) comprises: upper-arm-side switching elements (21, 22, 23) and lower-arm-side switching elements (24, 25, 26); upper switching elements (31, 32, 33) and lower switching elements (34, 35, 36) respectively connected in series between a connection point (a) between an upper capacitor (6) and a lower capacitor (7) and connection points (e, f, g); first AC output terminals (83, 84, 85) respectively connected to connection points (b, c, d); and second AC output terminals (86, 87, 88) respectively connected to the connection points (e, f, g).

Description

Rotating electric machine drive device and rotating electric machine drive system

[0001] The present disclosure relates to a drive device for a rotating electric machine and a drive system for a rotating electric machine.

[0002] Rotating electric machines used to drive automobiles are required to have high efficiency across the entire rotational range. One rotating electric machine that meets this requirement has two stators, each equipped with a three-phase winding, and two rotors coaxially arranged on the respective stators with a gap between them (see, for example, Patent Document 1). Another rotating electric machine has one stator with two sets of three-phase windings and one rotor arranged on the stator with a gap between them (see, for example, Patent Document 2).

[0003] JP 6-62597 A JP 2018-110481 A

[0004] Conventional drive devices for driving these rotating electric machines include two independent inverters for separately driving two sets of three-phase windings, which results in a large number of switching elements, which increases the size and cost of the drive device.

[0005] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a driving device for a rotating electric machine having two sets of three-phase windings, which can suppress increases in size and cost.

[0006] a first AC output terminal connected to the first connection point between the n sets of upper-arm switching elements and lower-arm switching elements; a second AC output terminal connected to the first connection point between the n sets of upper-arm switching elements and lower-arm switching elements; a third AC output terminal connected to the first connection point between the n sets of upper-arm switching elements and lower-arm switching elements; a fourth AC output terminal connected to the first connection point between the n sets of upper-arm switching elements and lower-arm switching elements; a fifth AC output terminal connected to the first connection point between the n sets of upper-arm switching elements and lower-arm switching elements;

[0007] In the drive device for a rotating electric machine disclosed herein, where n is a natural number equal to or greater than 3 and m is a natural number equal to or less than n, the drive device includes a positive input terminal and a negative input terminal connected to an external DC power supply, a positive electric circuit and a negative electric circuit connected to the positive input terminal and the negative input terminal, respectively, an upper capacitor and a lower capacitor connected in series between the positive electric circuit and the negative electric circuit, n sets of upper arm switching elements and lower arm switching elements connected in series between the positive electric circuit and the negative electric circuit, connection points between the n sets of upper arm switching elements and lower arm switching elements, n sets of upper switching elements and lower switching elements connected in series between the connection points between the upper capacitor and the lower capacitor, m first AC output terminals connected to the connection points between the n sets of upper switching elements and lower switching elements, and n second AC output terminals connected to the connection points between the n sets of upper arm switching elements and lower arm switching elements, thereby making it possible to suppress increases in size and cost.

[0008] It is a configuration diagram of a drive system for a rotating electric machine according to Embodiment 1. It is a diagram showing the relationship between the rotation speed and torque of a rotating electric machine in the drive system for a rotating electric machine according to Embodiment 1. It is a configuration diagram of a drive system for a rotating electric machine according to Embodiment 2.

[0009] Hereinafter, a driving device and a driving system for a rotating electric machine according to an embodiment of the present disclosure will be described in detail with reference to the drawings. Note that the same reference numerals in the various drawings indicate the same or corresponding parts.

[0010] Embodiment 1. Fig. 1 is a configuration diagram of a drive system for a rotating electric machine according to embodiment 1. Fig. 1 shows a drive system 1 that is configured with a first rotating electric machine 2, a second rotating electric machine 3, a drive device 4, and a DC power supply 5. In this embodiment, the rotors of the first rotating electric machine 2 and the second rotating electric machine 3 are fastened to the same rotating shaft.

[0011] The drive device 4 of this embodiment includes a positive input terminal 81 and a negative input terminal 82, and a positive electric circuit 91 and a negative electric circuit 92 connected to the positive input terminal 81 and the negative input terminal 82, respectively. A DC power supply 5 is connected between the positive input terminal 81 and the negative input terminal 82. The drive device 4 of this embodiment also includes an upper capacitor 6 and a lower capacitor 7 connected in series between the positive electric circuit 91 and the negative electric circuit 92, a first upper-arm switching element 21 and a first lower-arm switching element 24, a second upper-arm switching element 22 and a second lower-arm switching element 25, and a third upper-arm switching element 23 and a third lower-arm switching element 26.

[0012] Furthermore, the drive device 4 of this embodiment has a first upper switching element 31 and a first lower switching element 34 connected in series between a connection point a between the upper capacitor 6 and the lower capacitor 7 and a connection point e between the first upper-arm switching element 21 and the first lower-arm switching element 24, a second upper switching element 32 and a second lower-side switching element 35 connected in series between the connection point a and a connection point f between the second upper-arm switching element 22 and the second lower-arm switching element 25, and a third upper switching element 33 and a third lower-side switching element 36 connected in series between the connection point a and a connection point g between the third upper-arm switching element 23 and the third lower-arm switching element 26.

[0013] A connection point b between the first upper switching element 31 and the first lower switching element 34 is connected to the first AC output terminal 83 via the shutoff switching element 51, a connection point c between the second upper switching element 32 and the second lower switching element 35 is connected to the first AC output terminal 84 via the shutoff switching element 52, and a connection point d between the third upper switching element 33 and the third lower switching element 36 is connected to the first AC output terminal 85 via the shutoff switching element 53. A freewheeling diode 59 is connected in parallel to each of the shutoff switching elements 51, 52, and 53, which allows a current to flow in the opposite direction to that when the switching is on when the switching is off.

[0014] A connection point e between the first upper-arm switching element 21 and the first lower-arm switching element 24 is connected to a second AC output terminal 86 via a shutoff switching element 41, a connection point f between the second upper-arm switching element 22 and the second lower-arm switching element 25 is connected to a second AC output terminal 87 via a shutoff switching element 42, and a connection point g between the third upper-arm switching element 23 and the third lower-arm switching element 26 is connected to a second AC output terminal 88 via a shutoff switching element 43. A freewheel diode 49 that passes a current in the opposite direction to when the shutoff switching elements 41, 42, and 43 are connected in parallel to each other when the shutoff switching elements are switched off.

[0015] The first upper-arm switching element 21 and the first lower-arm switching element 24 are forward connected so that current flows in the same direction when switched on, and each switching element has a freewheeling diode 29 connected in parallel to it that flows current in the opposite direction to when switched off. The second upper-arm switching element 22 and the second lower-arm switching element 25 are forward connected so that current flows in the same direction when switched on, and each switching element has a freewheeling diode 29 connected in parallel to it that flows current in the opposite direction to when switched off. The third upper-arm switching element 23 and the third lower-arm switching element 26 are forward connected so that current flows in the same direction when switched on, and each switching element has a freewheeling diode 29 connected in parallel to it that flows current in the opposite direction to when switched off.

[0016] The first upper switching element 31 and the first lower switching element 34 are reverse-connected so that current flows in the opposite direction when switched on, and a freewheeling diode 39 that passes current in the opposite direction to when switched on is connected in parallel to each switching element when switched off. The second upper switching element 32 and the second lower switching element 35 are reverse-connected so that current flows in the opposite direction when switched on, and a freewheeling diode 39 that passes current in the opposite direction to when switched off is connected in parallel to each switching element. The third upper switching element 33 and the third lower switching element 36 are reverse-connected so that current flows in the opposite direction when switched on, and a freewheeling diode 39 that passes current in the opposite direction to when switched off is connected in parallel to each switching element.

[0017] The first rotating electric machine 2 is a three-phase rotating electric machine having windings U2, V2, and W2. The three-phase terminals of the first rotating electric machine 2 are connected to first AC output terminals 83, 84, and 85, respectively. The second rotating electric machine 3 is a three-phase rotating electric machine having windings U3, V3, and W3. The three-phase terminals of the second rotating electric machine 3 are connected to second AC output terminals 86, 87, and 88, respectively. The rotors of the first rotating electric machine 2 and the second rotating electric machine 3 are fastened to the same rotating shaft.

[0018] The switching elements used in the driving device 4 of the rotating electric machine of this embodiment are, for example, IGBTs (Insulated Gate Bipolar Transistors) and MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors). Note that each switching element of the driving device 4 of the rotating electric machine of this embodiment is controlled by a control unit (not shown). The driving device of the rotating electric machine configured in this manner is a three-level neutral point clamped power converter.

[0019] In the drive device 4 of this embodiment, the first rotating electric machine 2 can be drive-controlled by switching on and off the upper switching elements 31, 32, and 33 and the lower arm switching elements 24, 25, and 26. Furthermore, in the drive device 4 for this rotating electric machine, the second rotating electric machine 3 can be drive-controlled by switching on and off the upper arm switching elements 21, 22, and 23 and the lower arm switching elements 24, 25, and 26, and the second rotating electric machine 3 can be drive-controlled in three levels by switching on and off the upper switching elements 31, 32, and 33 and the lower switching elements 34, 35, and 36.

[0020] In this way, the driving device for a rotating electric machine according to this embodiment can control one of two rotating electric machines using two-level driving and the other using three-level driving. Therefore, the driving device for a rotating electric machine according to this embodiment can individually drive and control two rotating electric machines using a single three-level neutral point clamped power converter while expanding the high efficiency range, thereby avoiding increases in size and cost.

[0021] Next, the operation of the drive system for rotating electric machines of this embodiment will be described. The rotors of the first rotating electric machine 2 and the second rotating electric machine 3 are fastened to the same rotating shaft. The torque capacity and output capacity of the first rotating electric machine 2 are assumed to be smaller than the torque capacity and output capacity of the second rotating electric machine 3. The current capacities of the upper switching elements 31, 32, 33 and the lower switching elements 34, 35, 36 are assumed to be smaller than the current capacities of the upper arm switching elements 21, 22, 23 and the lower arm switching elements 24, 25, 26.

[0022] 2 is a diagram showing the relationship between the rotation speed and torque of the rotating electric machine in the drive system for the rotating electric machine of this embodiment. In FIG. 2, the horizontal axis represents the rotation speed, and the vertical axis represents the torque. On the vertical axis, torque A < torque B < torque C < maximum torque.

[0023] As shown in Fig. 2, the driving device for a rotating electric machine according to this embodiment drives only the first rotating electric machine 2, which has a small torque capacity, in a region where the torque is smaller than A. Then, in a region where the torque is equal to or greater than A but less than B, the driving device drives the second rotating electric machine 3 at three levels. Furthermore, in a region where the torque is equal to or greater than B but less than C, the driving device drives the second rotating electric machine 3 at two levels. Then, in a region where the torque is equal to or greater than C but less than the maximum torque, the driving device drives the first rotating electric machine 2 and the second rotating electric machine 3 simultaneously.

[0024] The switching of operation as described above in the drive device for a rotating electric machine of this embodiment is determined so as to achieve the most efficient operation based on the allowable torque, efficiency, operable time, etc. of each rotating electric machine. In the description of the operation of the drive device for a rotating electric machine of this embodiment, it is assumed that the torque capacity and output capacity of the first rotating electric machine 2 are smaller than the torque capacity and output capacity of the second rotating electric machine 3, but the torque capacity and output capacity of the first rotating electric machine 2 and the torque capacity and output capacity of the second rotating electric machine 3 may be the same.

[0025] If the torque capacity and output capacity of the first rotating electric machine 2 are greater than the torque capacity and output capacity of the second rotating electric machine 3, the current capacity of the upper switching elements 31, 32, 33 and the lower switching elements 34, 35, 36 can be made greater than the current capacity of the upper arm switching elements 21, 22, 23 and the lower arm switching elements 24, 25, 26. In a driving device for a rotating electric machine configured in this manner, a similar effect can be obtained by determining the switching of operation so as to achieve the most efficient operation based on the allowable torque, efficiency, and operable time of each rotating electric machine.

[0026] In the drive device 4 of the present embodiment, connection points b, c, d between the first upper switching elements 31, 32, 33 and the first lower switching elements 34, 35, 36 are connected to the first AC output terminals 83, 84, 85 via the shutoff switching elements 51, 52, 53, respectively, but the shutoff switching elements 51, 52, 53 are not necessary. Without the shutoff switching elements 51, 52, 53, the drive device 4 cannot reliably put the first rotating electric machine 2 into a state where it is not driven, but the number of switching elements can be reduced, thereby further suppressing increases in size and cost.

[0027] Furthermore, in the drive device 4 of the present embodiment, connection points e, f, g between the first upper-arm switching elements 21, 22, 23 and the first lower-arm switching elements 24, 25, 26 are connected to the second AC output terminals 86, 87, 88 via the shutoff switching elements 41, 42, 43, respectively, but the shutoff switching elements 41, 42, 43 may be omitted. Without the shutoff switching elements 41, 42, 43, the drive device cannot reliably put the second rotating electric machine 3 into a state where it is not driven, but the number of switching elements can be reduced, thereby further suppressing increases in size and cost.

[0028] The drive device of this embodiment has the advantage of suppressing increases in size and cost. For example, when two rotating electric machines are driven by separate drive devices, six switching elements are required to drive the first rotating electric machine at two levels, and 12 switching elements are required to drive the second rotating electric machine at three levels. Therefore, when two rotating electric machines are driven by separate drive devices, a total of 18 switching elements are required. In contrast, when two rotating electric machines are driven by a single drive device, as in the drive device of this embodiment, the six interrupting switching elements are removed as described above, allowing for a configuration with only 12 switching elements.

[0029] Furthermore, the drive device of this embodiment is configured with a total of 18 switching elements, including the six shutoff switching elements. However, because the shutoff switching elements do not require switching operation for power conversion associated with driving the rotating electric machines, they can be configured with small, inexpensive switching elements with smaller capacities than the upper arm switching elements and the lower arm switching elements. Therefore, even when the drive device of this embodiment is configured with 18 switching elements, it is still smaller and less expensive than a drive device that drives two rotating electric machines individually. In this way, the drive device of this embodiment can be prevented from becoming larger and more expensive than a drive device that drives two rotating electric machines individually.

[0030] In this embodiment, the first and second rotating electric machines are three-phase rotating electric machines. However, they may be rotating electric machines with any number of phases other than three, such as four, five, or six. In this case, the number of combinations of upper-side switching elements and lower-side switching elements and the number of combinations of upper-arm switching elements and lower-arm switching elements may be determined according to the number of phases of the first and second rotating electric machines. Furthermore, the number of phases of the first rotating electric machine and the second rotating electric machine may be different, as long as the number of phases of the first rotating electric machine is the same as or smaller than the number of phases of the second rotating electric machine. Driving a rotating electric machine with four or more phases can achieve low pulsation and low noise.

[0031] For example, if the first rotating electric machine is a three-phase rotating electric machine and the second rotating electric machine is a four-phase rotating electric machine, the drive device may include four sets of upper-arm switching elements and lower-arm switching elements connected in series between the positive electrode current path and the negative electrode current path, and four sets of upper-side switching elements and lower-side switching elements connected in series between three of the connection points between the four sets of upper-side switching elements and the lower-arm switching elements and a connection point between the upper-side capacitor and the lower-side capacitor.

[0032] As described above, the driving device for a rotating electric machine according to this embodiment includes a positive input terminal and a negative input terminal connected to an external DC power supply, a positive electric circuit and a negative electric circuit connected to the positive input terminal and the negative input terminal, an upper capacitor and a lower capacitor connected in series between the positive electric circuit and the negative electric circuit, n sets of upper-arm switching elements and lower-arm switching elements connected in series between the positive electric circuit and the negative electric circuit, junctions between the n sets of upper-arm switching elements and lower-arm switching elements, n sets of upper-arm switching elements and lower-arm switching elements connected in series between the junctions between the upper capacitor and the lower capacitor, m first AC output terminals connected to the junctions between the n sets of upper-arm switching elements and lower-arm switching elements, and n second AC output terminals connected to the junctions between the n sets of upper-arm switching elements and lower-arm switching elements, where n is a natural number equal to or greater than 3 and m is a natural number equal to or less than n. A driving device for a rotating electric machine configured in this manner can be prevented from becoming large and expensive.

[0033] Second Embodiment Fig. 3 is a configuration diagram of a drive system for a rotating electric machine according to a second embodiment. Fig. 3 shows a drive system 1 including a third rotating electric machine 9, a drive device 4, and a DC power supply 5. In this embodiment, the third rotating electric machine 9 is a dual three-phase rotating electric machine having one rotor and one stator, with one stator equipped with two sets of three-phase windings. One of the two sets of three-phase windings is a first winding having windings U2, V2, and W2, and the other is a second winding having windings U3, V3, and W3.

[0034] The configuration of the drive unit 4 of this embodiment is the same as that of the drive unit of embodiment 1. In this embodiment, the torque capacity and output capacity of the rotational drive by the first winding are equal to the torque capacity and output capacity of the rotational drive by the second winding.

[0035] The three phase terminals of the first winding are connected to first AC output terminals 83, 84, and 85, respectively. The three phase terminals of the second winding are connected to second AC output terminals 86, 87, and 88, respectively.

[0036] In the rotating electric machine drive device 4 of this embodiment, the third rotating electric machine 9 can be driven and controlled using the first winding by switching on and off the upper switching elements 31, 32, 33 and the lower arm switching elements 24, 25, 26. Furthermore, in this rotating electric machine drive device 4, the third rotating electric machine 9 can be driven and controlled using the second winding by switching on and off the upper arm switching elements 21, 22, 23 and the lower arm switching elements 24, 25, 26, and the third rotating electric machine 9 can be controlled in three levels using the second winding by switching on and off the upper switching elements 31, 32, 33 and the lower switching elements 34, 35, 36.

[0037] In this way, the driving device for a rotating electric machine according to this embodiment can control one of two sets of three-phase windings using two-level driving and the other using three-level driving. Therefore, the driving device for a rotating electric machine according to this embodiment can individually drive and control two sets of three-phase windings using a single three-level neutral point clamped power converter while expanding the high efficiency range, thereby avoiding increases in size and cost.

[0038] In the driving device for a rotating electric machine according to this embodiment, switching between the two sets of three-phase windings is determined so as to achieve the most efficient operation based on the allowable torque, efficiency, and available operating time when each three-phase winding is used for rotational driving. In this embodiment, the torque capacity and output capacity of the first winding for rotational driving are equal to the torque capacity and output capacity of the second winding for rotational driving, so the allowable torque, efficiency, and available operating time when each three-phase winding is used for driving are equal. In this case, the winding with the lower temperature can be operated preferentially. If the winding temperatures are the same, the winding to be operated can be selected randomly from the two sets of three-phase windings.

[0039] In the description of the operation of the rotating electric machine drive device of this embodiment, the torque capacity and output capacity of the rotational drive by the first winding are equal to those of the rotational drive by the second winding. However, the torque capacity and output capacity of the rotational drive by the first winding may be different from those of the rotational drive by the second winding. For example, if the torque capacity and output capacity of the rotational drive by the first winding are greater than those of the rotational drive by the second winding, the current capacity of the upper switching elements 31, 32, 33 and the lower switching elements 34, 35, 36 can be made greater than the current capacity of the upper arm switching elements 21, 22, 23 and the lower arm switching elements 24, 25, 26. Even in a rotating electric machine drive device configured in this manner, it is possible to determine which windings are to be operated under the most efficient conditions based on the allowable torque, efficiency, and available operating time of the rotational drive by each of the three-phase windings.

[0040] In the drive device 4 of this embodiment, connection points b, c, d between the first upper switching elements 31, 32, 33 and the first lower switching elements 34, 35, 36 are connected to the first AC output terminals 83, 84, 85 via the shutoff switching elements 51, 52, 53, respectively, but the shutoff switching elements 51, 52, 53 are not necessary. Without the shutoff switching elements 51, 52, 53, the drive device 4 cannot reliably put the third rotating electric machine 9 into a state where it is not driven by the first winding, but the number of switching elements can be reduced, thereby further suppressing increases in size and cost.

[0041] Furthermore, in the drive device 4 of this embodiment, connection points e, f, g between the first upper-arm switching elements 21, 22, 23 and the first lower-arm switching elements 24, 25, 26 are connected to the second AC output terminals 86, 87, 88 via the shutoff switching elements 41, 42, 43, respectively, but the shutoff switching elements 41, 42, 43 may be omitted. Without the shutoff switching elements 41, 42, 43, the drive device 4 would not be able to reliably put the third rotating electric machine 9 into a state where it is not driven by the second winding, but the number of switching elements can be reduced, thereby further suppressing increases in size and cost.

[0042] In this embodiment, the first winding and the second winding are three-phase windings, but they may be any number of phases other than three, such as four, five, or six. In this case, the number of combinations of upper-side switching elements and lower-side switching elements and the number of combinations of upper-arm switching elements and lower-arm switching elements can be determined according to the number of phases of the first winding and the second winding. Furthermore, the number of phases of the first winding and the second winding may be different, as long as the number of phases of the first winding is the same as or smaller than the number of phases of the second winding. Driving a rotating electric machine with four or more phases can achieve low pulsation and low noise.

[0043] As described above, the driving device for a rotating electric machine according to this embodiment includes a positive input terminal and a negative input terminal connected to an external DC power supply, a positive electric circuit and a negative electric circuit connected to the positive input terminal and the negative input terminal, an upper capacitor and a lower capacitor connected in series between the positive electric circuit and the negative electric circuit, n sets of upper-arm switching elements and lower-arm switching elements connected in series between the positive electric circuit and the negative electric circuit, junctions between the n sets of upper-arm switching elements and lower-arm switching elements, n sets of upper-arm switching elements and lower-arm switching elements connected in series between the junctions between the upper capacitor and the lower capacitor, m first AC output terminals connected to the junctions between the n sets of upper-arm switching elements and lower-arm switching elements, and n second AC output terminals connected to the junctions between the n sets of upper-arm switching elements and lower-arm switching elements, where n is a natural number equal to or greater than 3 and m is a natural number equal to or less than n. A driving device for a rotating electric machine configured in this manner can be prevented from becoming large and expensive.

[0044] The first and second rotating electric machines of the first embodiment and the third rotating electric machine of the second embodiment are permanent magnet synchronous rotating electric machines, induction machines, wound-field synchronous rotating electric machines, reluctance synchronous rotating electric machines, etc. The rotating electric machines of the first and second embodiments may be any type of rotating electric machine. Furthermore, in the first embodiment, the first and second rotating electric machines may be the same type of rotating electric machine or different types of rotating electric machines.

[0045] Although various exemplary embodiments are described in this disclosure, the various features, aspects, and functions described in one or more embodiments are not limited to the application of a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless variations not illustrated are contemplated within the scope of the technology disclosed in this specification. For example, this includes cases where at least one component is modified, added, or omitted, or where at least one component is extracted and combined with components of another embodiment.

[0046] REFERENCE SIGNS LIST 1 Drive system, 2 First rotating electric machine, 3 Second rotating electric machine, 4 Drive device, 5 DC power supply, 6 Upper capacitor, 7 Lower capacitor, 9 Third rotating electric machine, 21 First upper arm switching element, 22 Second upper arm switching element, 23 Third upper arm switching element, 24 First lower arm switching element, 25 Second lower arm switching element, 26 Third lower arm switching element, 29, 39, 49, 59 Freewheeling diode, 31 First upper switching element, 32 Second upper switching element, 33 Third upper switching element, 34 First lower switching element, 35 Second lower switching element, 36 Third lower switching element, 41, 42, 43, 51, 52, 53 Shutoff switching element, 81 Positive input terminal, 82 Negative input terminal, 83, 84, 85 First AC output terminal, 86, 87, 88 2nd AC output terminal, 91 positive electrode circuit, 92 negative electrode circuit.

Claims

1. A driving device for a rotating electric machine comprising: a positive input terminal and a negative input terminal connected to an external DC power source; a positive electric circuit and a negative electric circuit connected to the positive input terminal and the negative input terminal, respectively; an upper capacitor and a lower capacitor connected in series between the positive electric circuit and the negative electric circuit; n sets of upper arm switching elements and lower arm switching elements connected in series between the positive electric circuit and the negative electric circuit; n sets of upper side switching elements and lower side switching elements connected in series between connection points between the n sets of upper arm switching elements and the lower arm switching elements and connection points between the upper side capacitor and the lower side capacitor, m sets of first AC output terminals connected to the connection points between the n sets of upper side switching elements and the lower side switching elements, respectively; and n sets of second AC output terminals connected to the connection points between the n sets of upper side switching elements and the lower arm switching elements, respectively.

2. A driving device for a rotating electric machine as described in claim 1, characterized in that n sets of the upper arm side switching elements and the lower arm side switching elements are connected in forward direction, n sets of the upper side switching elements and the lower side switching elements are connected in reverse direction, and a free wheel diode is connected in parallel to each of the upper arm side switching elements, the lower arm side switching elements, the upper side switching elements and the lower side switching elements.

3. A driving device for a rotating electric machine as described in claim 1 or 2, characterized in that a cut-off switching element with a freewheeling diode connected in parallel is connected between a connection point between the n sets of upper switching elements and the lower switching elements and the m first AC output terminals, and between a connection point between the n sets of upper arm switching elements and the lower arm switching elements and the n second AC output terminals.

4. A rotary electric machine drive system comprising: a rotary electric machine drive device according to any one of claims 1 to 3; a DC power supply connected between the positive input terminal and the negative input terminal; a first rotary electric machine having m-phase windings connected to m of the first AC output terminals; and a second rotary electric machine having n-phase windings connected to n of the second AC output terminals, wherein the rotor of the first rotary electric machine and the rotor of the second rotary electric machine are fastened to the same rotating shaft.

5. A driving system for a rotating electric machine comprising: a driving device for a rotating electric machine as defined in any one of claims 1 to 3; a DC power supply connected between the positive input terminal and the negative input terminal; and a rotating electric machine having one stator equipped with m-phase first windings connected to m of the first AC output terminals and n-phase second windings connected to n of the second AC output terminals.

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