WO2021117630A1 - Drive device of rotary electric machine - Google Patents

Abstract

This drive device (10) of a rotary electric machine having a plurality of windings corresponding to a plurality of phases is provided with: a first inverter (INV1) which is connected to a DC power supply and includes upper and lower arm switches connected to one end of the windings for each phase; a second inverter (INV2) having upper and lower arm switches connected to the other end of the windings for each phase; a high-potential connection line (La); a low-potential connection line (Lb); a drive circuit (11) capable of H-driving the rotary electric machine; and a control unit (12) capable of executing asymmetric switching control for alternately operating the first inverter and the second inverter. One switch among the paired upper and lower arm switches is a high-loss switch that has a high conduction loss during asymmetric switching control, and the other switch is a low-loss switch that has a low conduction loss during asymmetric switching control. In at least a pair of upper and lower arm switches, the high-loss switch has lower on-resistance than the low-loss switch.

Description

Drive device for rotary electric machine Cross-reference of related applications

This application is based on Japanese Application No. 2019-222183, which was filed on December 9, 2019, and the contents of the description are incorporated herein by reference.

The present disclosure relates to a drive device for a rotary electric machine, which is applied to a rotary electric machine having a plurality of windings corresponding to a plurality of phases.

A drive device for a rotary electric machine is known, which includes two inverters and has a drive circuit configured to enable H drive of the rotary electric machine. Patent Document 1 describes a drive circuit for driving a winding of each phase with two inverters (H-bridge inverters) in a rotary electric machine having three-phase windings.

JP-A-2017-93077

In a drive circuit configured to enable H drive of a rotary electric machine, alternate PWM drive is known in which two inverters are alternately PWM-controlled. In the alternate PWM drive, one of the two inverters executes PWM control and the other does not execute PWM control. Of the two inverters, the inverter on the side that is not executing PWM control has a higher conduction loss in one of the paired upper arm switch and lower arm switch than in the other switch. Become. Due to the imbalance of loss between the upper arm switch and the lower arm switch that are paired with each other, there is a concern that the amount of heat generated will be higher in the switch on the side with the higher loss, and the deterioration of the element and the temperature destruction will proceed unbalanced. Will be done.

In Patent Document 1, in order to improve the above-mentioned loss imbalance, PD-PWM (Phase Disposition PWM) control, which similarly PWM-controls the upper arm switch and the lower arm switch of two inverters under predetermined conditions, is performed. Execute. However, in the PD-PWM control of Patent Document 1, there is a concern that the system loss may increase while the above-mentioned imbalance of conduction loss is improved. Further, complicated phase control is required, and if the phase control is deviated, there is a concern that torque ripple may occur.

In view of the above, it is an object of the present disclosure to provide a technique for improving the loss imbalance between the upper arm switch and the lower arm switch constituting the inverter without increasing the system loss by simple control.

The present disclosure provides a drive device for a rotary electric machine, which is applied to a rotary electric machine having a plurality of windings corresponding to a plurality of phases. This drive device was connected to a DC power supply, and was connected to a first inverter including an upper arm switch and a lower arm switch, which were connected to one end of the winding for each phase, and to the other end of the winding for each phase. A second inverter including an upper arm switch and a lower arm switch, a high potential connection line connecting the DC high potential side of the first inverter and the DC high potential side of the second inverter, and a DC low of the first inverter. A drive circuit capable of H-driving the rotary electric machine, including a low-potential connection line connecting the potential side and the DC low-potential side of the second inverter, and opening / closing of the upper arm switch and the lower arm switch. A control unit capable of executing asymmetric switching control for alternately operating the first inverter and the second inverter by controlling the inverter is provided. One of the paired upper arm switch and the lower arm switch is a high-loss switch on the side where the conduction loss increases during the asymmetric switching control, and the other switch has a conduction loss during the asymmetric switching control. It is a low loss switch on the lower side. In at least a pair of the upper arm switch and the lower arm switch, the high loss switch is a switching element having a lower on-resistance than the low loss switch.

In the drive device according to the present disclosure, a pair of upper arm switches is used when executing asymmetric switching control in which the first inverter and the second inverter are alternately operated by controlling the opening and closing of the upper arm switch and the lower arm switch. One of the lower arm switch and the lower arm switch can be a high loss switch on the side where the conduction loss is high when not operating in the asymmetric switching control, and the other can be a low loss switch on the side where the conduction loss is low. In the drive device according to the present disclosure, in at least one pair of upper arm switch and lower arm switch, the high loss switch is a switching element used as each switch so that a switching element having a lower on-resistance than the low loss switch is used. Has been selected. Since a switching element having a low on-resistance is used as the high-loss switch having a high conduction loss, the conduction loss is reduced and the loss in the high-loss switch is reduced. This improves the loss imbalance between the high loss switch and the low loss switch. In other words, the loss imbalance between the upper arm switch and the lower arm switch is improved. As a result, it is possible to improve the loss imbalance between the upper arm switch and the lower arm switch constituting the inverter without increasing the system loss by simple control.

The above objectives and other objectives, features and advantages of the present disclosure will be clarified by the following detailed description with reference to the accompanying drawings. The drawing is
FIG. 1 shows a drive device for a rotary electric machine according to an embodiment. FIG. 2 is a diagram showing a drive pattern of alternating PWM drive as an example of asymmetric switching control when driving a rotary electric machine to H. FIG. 3 is a diagram showing a current path during the alternate PWM drive shown in FIG. FIG. 4 is a diagram showing the on-resistance of the semiconductor element used as a switch in the drive device of FIG. FIG. 5 is a diagram showing the loss of the switch in the drive device of FIG. FIG. 6 is a diagram showing a drive pattern of alternating PWM drive according to a modified example. FIG. 7 is a diagram showing a control example of each switch when driving the rotary electric machine in Y.

(First Embodiment)
FIG. 1 shows a drive device 10 that executes drive control of a rotary electric machine. The rotary electric machine includes a U-phase winding U, a V-phase winding V, and a W-phase winding W. The drive device 10 includes a drive circuit 11, a control unit 12, and a DC power supply VDC. The drive circuit 11 includes a first inverter INV1, a second inverter INV2, a high potential connection line La, a low potential connection line Lb, and a connection line switch SC.

The first inverter INV1 is connected to the DC power supply VDC, and is connected to the upper arm switch SU1a and the lower arm switch SU1b connected to one end of the U-phase winding U of the rotary electric machine, and to one end of the V-phase winding V. It also includes an upper arm switch SV1a and a lower arm switch SV1b, and an upper arm switch SW1a and a lower arm switch SW1b connected to one end of the W-phase winding W.

The second inverter INV2 is connected to the DC power supply VDC, and is connected to the upper arm switch SU2a and the lower arm switch SU2b connected to the other end of the U-phase winding U of the rotary electric machine, and to the other end of the V-phase winding V. It includes a connected upper arm switch SV2a and a lower arm switch SV2b, and an upper arm switch SW2a and a lower arm switch SW2b connected to the other end of the W-phase winding W.

The high potential connection line La is a wiring that connects the DC high potential side of the first inverter INV1 and the DC high potential side of the second inverter INV2. The low potential connection line Lb connects the DC low potential side of the first inverter INV1 and the DC low potential side of the second inverter.

In the first inverter INV1, the high potential side terminals of the upper arm switches SU1a, SV1a, SW1a of each phase are connected to the positive electrode terminals of the DC power supply VDC, and the low potential side terminals of the lower arm switches SU1b, SV1b, SW1b of each phase are It is connected to the negative electrode terminal of the DC power supply VDC. The upper arm switches SU1a, SV1a, SW1a and the lower arm switches SU1b, SV1b, SW1b are semiconductor switching elements, respectively. More specifically, the upper arm switches SU1a, SV1a, and SW1a are MOSFETs (Metal-Oxide-Semiconductor Field-Effective Transistors) made of silicon carbide (SiC) as a material. The lower arm switches SU1b, SV1b, and SW1b are IGBTs (Insulated Gate Bipolar Transistors) made of silicon and having freewheeling diodes connected in antiparallel.

In the second inverter INV2, the high potential side terminals of the upper arm switches SU2a, SV2a, SW2a of each phase are connected to the high potential connection line La, and the low potential side terminals of the lower arm switches SU2b, SV2b, SW2b of each phase are low. It is connected to the potential connection line Lb. The upper arm switches SU2a, SV2a, SW2a and the lower arm switches SU2b, SV2b, SW2b are semiconductor switching elements, respectively. More specifically, the upper arm switches SU2a, SV2a, and SW2a are MOSFETs made of SiC as a material. The lower arm switches SU2b, SV2b, and SW2b are IGBTs made of silicon and having a freewheeling diode connected in antiparallel.

In the first inverter INV1, one ends of windings U, V, and W (second inverter) are located at intermediate points between the upper arm switches SU1a, SV1a, and SW1a of each phase and the lower arm switches SU1b, SV1b, and SW1b, respectively. One end that is not connected to INV2) is connected. In the second inverter INV2, one ends of windings U, V, and W (first inverter) are located at intermediate points between the upper arm switches SU2a, SV2a, SW2a and the lower arm switches SU2b, SV2b, SW2b of each phase, respectively. One end that is not connected to INV1) is connected.

The connection line switch SC is provided on the high-potential connection line La, and conducts or cuts off the first inverter INV1 and the second inverter INV2 by conducting or cutting off the high-potential connection line La. When the connection line switch SC is in the closed state (on state), the drive circuit 11 can be used as an H-bridge circuit, and the rotary electric machine can be driven by H.

When the connection line switch SC is in the open state (off state), the drive circuit 11 enables Y drive of the rotary electric machine. For example, by closing all the upper arm switches SU2a, SV2a, SW2a of the second inverter INV2 and opening all the lower arm switches SU2b, SV2b, SW2b, Y drive of the rotary electric machine becomes possible. .. That is, the U-phase winding U of the rotary electric machine, the V-phase winding V, and the W-phase winding W can be connected by a Y connection. In this case, the upper arm switches SU2a, SV2a, and SW2a correspond to the neutral point configuration switch that constitutes the neutral point of the Y connection (star-shaped connection).

The control unit 12 includes a microcomputer composed of a CPU and various memories, and opens and closes each switch in the first inverter INV1 and the second inverter INV2 based on various detection information in the rotary electric machine and requests for power running and power generation. Energization control is performed by (on / off). The detection information of the rotating electric machine includes, for example, the rotation angle of the rotor (electric angle information) detected by an angle detector such as a resolver, the power supply voltage (inverter input voltage) detected by the voltage sensor, and the current sensor. The energizing current of each phase is included. The control unit 12 further controls the opening and closing of the connection line switch SC. The control unit 12 generates and outputs an operation signal for operating each switch of the first inverter INV1 and the second inverter INV2 and the connection line switch SC.

FIG. 2 is a diagram showing an example of switch control of the first inverter INV1 and the second inverter INV2 by the control unit 12. More specifically, as a drive example when the connection line switch SC is controlled to the closed state to drive the rotary electric machine in H, a drive pattern when alternating PWM drive is executed is shown. The alternate PWM drive is an example of asymmetric switching control in which the first inverter INV1 and the second inverter INV2 are operated alternately.

In the alternate PWM drive shown in FIG. 2, one cycle of the U-phase voltage UV waveform is configured by the period T1 and the period T2. The phase of the U-phase current UI is 90 ° behind the U-phase voltage UV. During the period T1, PWM control is executed on the first inverter INV1 side, and the upper arm switches SU2a, SV2a, SW2a are fixed in the closed state and the lower arm switches SU2b, SV2b, SW2b are fixed in the open state on the second inverter INV2 side. During the period T2, the second inverter INV2 side executes PWM control, and the first inverter INV1 side fixes the upper arm switches SU1a, SV1a, SW1a in the closed state and the lower arm switches SU1b, SV1b, SW1b in the open state. The control of the period T1 and the period T2 is executed alternately.

In FIG. 3, the current path flowing through the drive circuit 11 during the period T1 is shown by a thick line. When the U-phase current is a negative current in the period T1, the current flows in the direction indicated by the arrow in FIG. 3, and the current flows through the MOSFETs of the upper arm switches SU2a, SV2a, and SW2a. When the U-phase current is a positive current, the current flows in the direction opposite to the direction indicated by the arrow in FIG. 3, and the current flows through the diodes of the upper arm switches SU2a, SV2a, and SW2a. While a current flows through the upper arm switches SU2a, SV2a, and SW2a periodically for each period T1, a state in which no current flows through the lower arm switches SU2b, SV2b, and SW2b is repeated during the period T1. Therefore, the amount of heat generated by the upper arm switches SU2a, SV2a, and SW2a is larger than the amount of heat generated by the lower arm switches SU2b, SV2b, and SW2b.

As shown in FIGS. 2 and 3, when the alternate PWM control is executed, the upper arm of the first inverter INV1 and the second inverter INV2 on the side not controlled by the PWM control (for example, the second inverter INV2). The switches (for example, upper arm switches SU2a, SV2a, SW2a) are controlled to be in the closed state and current flows, and the lower arm switches (for example, lower arm switches SU2b, SV2b, SW2b) are controlled to be in the open state and no current flows. .. Therefore, a conduction loss occurs in the upper arm switch, and no conduction loss occurs in the lower arm switch. Due to the conduction loss, the amount of heat generated by the upper arm switch becomes larger than the amount of heat generated by the lower arm switch.

FIG. 4 is a diagram showing the on-resistance of the IGBT or MOSFET. The vertical axis shows the collector current Ic or the drain current Id, and the horizontal axis shows the collector-emitter voltage Vce or the drain-source voltage Vds. Reference numbers 21, 22, and 23 indicate a MOSFET made of silicon carbide (SiC), a MOSFET made of silicon (Si), and an IGBT made of silicon, respectively. As shown in reference numbers 21 and 22, MOSFETs have linear on-resistance characteristics from a low potential region of about 0 volt, and have higher on-resistance than IGBTs (reference number 23) that include a pn junction in the forward current-carrying layer. It gets lower. Further, as shown in Reference Nos. 21 and 22, the on-resistance of the MOSFET made of SiC is lower than that of the MOSFET made of silicon.

FIG. 5 is a diagram showing the result of calculating the change in loss when the IGBT is replaced with a MOSFET having a lower on-resistance by simulation. Reference numerals 31 to 34 indicate a forward conduction loss, a reverse conduction loss, a switching loss, and a recovery loss, respectively. From the left side of FIG. 5, (1) an IGBT is used as the upper arm switch SU1a, (2) a MOSFET is used as the upper arm switch SU1a, and (3) an IGBT is used as the lower arm switch SU1b. There is. The IGBT used in (1) and (3) is the same semiconductor element, and corresponds to the semiconductor element of reference number 23 shown in FIG. The MOSFET used in (2) corresponds to the semiconductor element of reference number 21 shown in FIG. 4, and has a lower on-resistance than the IGBTs of (1) and (3).

As shown in FIG. 5, when the IGBT is used as the upper arm switch SU1a (1), the order shown mainly in reference numbers 31 and 32 is higher than that when the IGBT is also used as the lower arm switch SU1b (3). Due to the high conduction loss in the directional and reverse directions, the overall loss is high. When both IGBTs are used, the total loss in the upper arm switch SU1a is higher than the total loss in the lower arm switch SU1b.

On the other hand, when the MOSFET is used as the upper arm switch SU1a, the conduction loss in the forward direction and the reverse direction shown in reference numbers 31 and 32 is reduced as compared with the case shown in (1). ing. By replacing the IGBT with a MOSFET having a lower on-resistance by replacing the upper arm switch SU1a with a MOSFET having a lower on-resistance, about 1/4 of the conduction loss can be reduced, and the total loss in the upper arm switch SU1a can be reduced to the total loss in the lower arm switch SU1b. It was found that it can be reduced to the same extent as. As a result, it was found that the imbalance between the total loss in the upper arm switch SU1a and the total loss in the lower arm switch SU1b can be improved.

As described above, according to the first embodiment, as the asymmetric switching control in which the first inverter INV1 and the second inverter INV2 are operated alternately, when the alternate PWM control is executed, the inverter on the side not controlled by the PWM is used. , Upper arm switches SU1a, SV1a, SW1a, SU2a, SV2a, SW2a are high loss switches on the side where the conduction loss is high, and lower arm switches SU1b, SV1b, SW1b, SU2b, SV2b, SW2b are on the side where the conduction loss is low. It becomes a low loss switch. In the drive device 10, MOSFETs are used as the upper arm switches SU1a, SV1a, SW1a, SU2a, SV2a, and SW2a, while IGBTs are used as the lower arm switches SU1b, SV1b, SW1b, SU2b, SV2b, and SW2b. , The on-resistance is lower than that of the IGBT used for the lower arm switches SU1b, SV1b, SW1b, SU2b, SV2b, and SW2b. By using MOSFETs with lower on-resistance as the upper arm switches SU1a, SV1a, SW1a, SU2a, SV2a, and SW2a, which are high-loss switches with high conduction loss, the conduction loss can be reduced as compared with the case of using IGBTs. Can be done. As a result, as shown in FIG. 5, the imbalance between the total loss in the paired upper arm switch and the total loss in the lower arm switch can be improved.

In the first embodiment, MOSFET is exemplified as a switching element having a relatively low on-resistance used in a high-loss switch, and IGBT is exemplified as a switching element having a relatively high on-resistance used in a low-loss switch. However, it is not limited to this. The switching element used in the high-loss switch may have a lower on-resistance than the switching element used in the low-loss switch. When a semiconductor element is used as a switching element, the high-loss switch can have a lower on-resistance than the low-loss switch by appropriately selecting the element structure, material, element size, and the like of the semiconductor element.

For example, as the element structure, a unipolar semiconductor element may be used as the high loss switch, and a bipolar semiconductor element may be used as the low loss switch. Since the unipolar semiconductor element is composed of only conductive semiconductor layers (for example, n layers) having the same forward conduction layer, it has a linear on-resistance characteristic from a low potential region of about 0 volt as shown in FIG. , The on-resistance is lower than that of a bipolar semiconductor device having a pn junction in the forward conductive layer. Further, as the high loss switch, it is preferable to use a unipolar semiconductor element capable of synchronous rectification when conducting in the reverse direction. Since such a unipolar element can be energized in the reverse direction without passing through a body diode by inputting an on signal to the gate terminal when conducting in the reverse direction, it has a linear on-resistance characteristic from a low potential region of about 0 volt. , Furthermore, the on-resistance becomes lower. As a unipolar semiconductor element capable of synchronous rectification when conducting in the reverse direction, a MOSFET can be exemplified.

For example, as a material of a semiconductor element, a semiconductor element made of a semiconductor having a wider bandgap than silicon may be used as a high-loss switch, and a semiconductor element made of silicon as a low-loss switch may be used. By using a semiconductor having a wider bandgap as a material, the on-resistance can be reduced. Examples of semiconductors having a wider bandgap than silicon include silicon carbide (SiC) and gallium nitride (GaN). A semiconductor having a wide bandgap has a high dielectric breakdown strength, and the element thickness (thickness in the conduction direction) of the semiconductor element can be reduced, so that the on-resistance can be reduced.

Further, the high-loss switch may be a semiconductor element having a larger element size than the low-loss switch. A large element size means that a surface substantially perpendicular to the conduction direction of the semiconductor element is large. By increasing the element size of the semiconductor element, the current density becomes low, so that the on-resistance can be reduced.

Further, the high-loss switch may be a semiconductor element having a thinner element thickness in the conduction direction than the low-loss switch. In a vertical MOSFET or IGBT, if the element thickness in the conduction direction is reduced, the conduction distance is shortened, so that the on-resistance can be reduced.

(Modification example)
As shown in FIG. 6, in the alternate PWM control, the waveform of the U-phase voltage VU and the U-phase current IU are the same even if the order of executing the PWM control is reversed for the first inverter INV1 and the second inverter INV2. A waveform can be obtained. In the alternate PWM control shown in FIG. 6, the waveforms of the U-phase voltage VU and the U-phase current IU are the same as those in FIG. 2, but the order of the period T1 and the period T2 is changed.

In the alternate PWM drive shown in FIG. 6, PWM control is executed on the first inverter INV1 side and the upper arm switches SU2a, SV2a on the second inverter INV2 side during the period T1 as in FIG. The SW2a is fixed in the open state and the lower arm switches SU2b, SV2b, and SW2b are fixed in the closed state. In the period T2, PWM control is executed on the second inverter INV2 side, and the upper arm switches SU1a, SV1a, SW1a are fixed in the open state and the lower arm switches SU1b, SV1b, SW1b are fixed in the closed state on the first inverter INV1 side. To do. The control of the period T1 and the period T2 is executed alternately.

When the alternate PWM control shown in FIG. 6 is executed, the upper arm switch is controlled to be in the open state and a current flows in the inverter of the first inverter INV1 and the second inverter INV2 that is not PWM controlled. Instead, the lower arm switch is controlled to the closed state and current flows. Therefore, a conduction loss occurs in the lower arm switch, and no conduction loss occurs in the upper arm switch.

Therefore, when executing the alternate PWM control shown in FIG. 6, it is preferable to use a semiconductor element having a lower on-resistance than the upper arm switch as the lower arm switch in the drive device 10 shown in FIG. Specifically, for example, contrary to the first embodiment, as the upper arm switches SU1a, SV1a, SW1a, an IGBT made of silicon and having a freewheeling diode connected in antiparallel is used, and the lower arm switch SU1b is used. , SV1b, SW1b may be MOSFETs made of SiC as a material.

In other words, in the first inverter INV1 and the second inverter INV2 of the drive circuit 11, semiconductor elements having high on-resistance are used for the upper arm switches SU1a, SV1a, SW1a, SU2a, SV2a, SW2a, and the lower arm switches SU1b, SV1b, When a semiconductor element having a low on-resistance is used for SW1b, SU2b, SV2b, and SW2b, the control unit 12 raises the upper arm when PWM control is executed by the other inverter, as shown in FIG. It is preferable that the alternating PWM control is executed so as to control the switch in the open state and control the lower arm switch in the closed state.

Further, in the first inverter INV1 and the second inverter INV2 of the drive circuit 11, semiconductor elements having high on-resistance are used for the lower arm switches SU1b, SV1b, SW1b, SU2b, SV2b, and SW2b, and the upper arm switches SU1a, SV1a, and SW1a are used. When a semiconductor element having a low on-resistance is used for SU2a, SV2a, and SW2a, the control unit 12 switches the upper arm switch when PWM control is executed by the other inverter, as shown in FIG. It is preferable that the alternating PWM control is executed so as to control the closed state and control the lower arm switch to the open state.

(Second Embodiment)
FIG. 7 is a diagram showing an example of a state in which the drive circuit 11 is controlled so as to be usable for Y drive of the rotary electric machine by the control unit 12. As shown in FIG. 7, the connection line switch SC is controlled to be in the open state, the upper arm switches SU2a, SV2a, SW2a of the second inverter INV2 are controlled to be in the closed state, and the lower arm switches SU2b, SV2b, of the second inverter INV2 are controlled. By controlling the SW2b to the open state, the U-phase winding U, the V-phase winding V, and the W-phase winding W of the rotary electric machine are in a Y-connected state. More specifically, the Y connection is realized by connecting the winding terminals of the windings U, V, and W on the second inverter INV2 side via the upper arm switches SU2a, SV2a, and SW2a, respectively. The rotary electric machine can be driven in Y by forming a Y connection using the second inverter INV2 and executing PWM control or the like on the first inverter INV1. The upper arm switches SU2a, SV2a, and SW2a correspond to the neutral point configuration switch that constitutes the neutral point of the Y connection. Since the lower arm switches SU2b, SV2b, and SW2b do not form a neutral point, they correspond to non-neutral point configuration switches.

As shown in FIG. 7, when the Y drive of the rotary electric machine is executed, the upper arm switches SU2a, SV2a, and SW2a are controlled to be in the closed state and a current flows, and the lower arm switches SU2b, SV2b, and SW2b are controlled to be in the open state. The current does not flow. Therefore, conduction loss occurs in the upper arm switches SU2a, SV2a, and SW2a, and no conduction loss occurs in the lower arm switches SU2b, SV2b, and SW2b. That is, the upper arm switches SU2a, SV2a, and SW2a, which are neutral point configuration switches, have a relatively high conduction loss, and the lower arm switches SU2b, SV2b, and SW2b, which are non-neutral point configuration switches, have a relatively low conduction loss. ..

In the drive device 10, MOSFETs are used as the upper arm switches SU2a, SV2a, SW2a, while IGBTs are used as the lower arm switches SU2b, SV2b, SW2b, and these MOSFETs are used for the lower arm switches SU2b, SV2b, SW2b. On resistance is lower than that of IGBT. By using MOSFETs with lower on-resistance as the upper arm switches SU2a, SV2a, and SW2a, which are neutral point configuration switches with high conduction loss, conduction loss can be reduced as compared with the case of using IGBTs. As a result, the imbalance between the total loss of the upper arm switches SU2a, SV2a, and SW2a and the total loss of the lower arm switches SU2b, SV2b, and SW2b can be improved.

In the above embodiment, the connection line switch SC provided on the high-potential connection line La and capable of switching between conduction and interruption of the high-potential connection line La has been described as an example, but the present invention is not limited to this. The connection line switch SC may be provided on either the high potential connection line La or the low potential connection line Lb.

As the switching element used in the neutral point configuration switch, a switching element having a low on-resistance similar to that of a high-loss switch can be used. When a semiconductor element is used as a switching element, the neutral point configuration switch can have a lower on-resistance than the non-neutral point configuration switch by appropriately selecting the element structure, material, element size, etc. of the semiconductor element. it can. Regarding the element structure of the semiconductor element, for example, the neutral point configuration switch may be a unipolar semiconductor element. Further, the neutral point configuration switch may be a unipolar semiconductor element capable of synchronous rectification when conducting in the reverse direction.

Regarding the material of the semiconductor element, the neutral point configuration switch may be a semiconductor element made of a semiconductor (for example, SiC, GaN) having a bandgap wider than that of silicon. Further, the neutral point configuration switch may be a semiconductor element having a larger element size than the non-neutral point configuration switch. Further, the neutral point configuration switch may be a semiconductor element having a thinner element thickness than the non-neutral point configuration switch.

In the pair of upper arm switch and lower arm switch, the installation position of the connection line switch SC so that the switch that becomes the neutral point configuration switch during Y drive matches the switch that becomes the high loss switch during H drive ( It is preferable to select the high-potential connection line La or the low-potential connection line Lb) and the pattern of alternating PWM control (the pattern shown in FIG. 2 or FIG. 6). In both the H drive and the Y drive patterns, the imbalance between the total loss in the upper arm switch and the total loss in the lower arm switch can be improved.

Specifically, when executing the alternate PWM control shown in FIG. 2, it is preferable to install the connection line switch SC on the high potential connection line La. By using a switching element with low on-resistance as the upper arm switch, which increases the conduction loss in both H drive and Y drive, the total loss in the lower arm switch and the total loss in the upper arm switch are inconsistent. The balance can be improved.

Further, when executing the alternate PWM control shown in FIG. 6, it is preferable to install the connection line switch SC on the low potential connection line Lb. By using a switching element with low on-resistance as the lower arm switch, which increases the conduction loss in both H drive and Y drive, the total loss in the upper arm switch and the total loss in the lower arm switch are inconsistent. The balance can be improved.

Of the switches, only the switch that is a high-loss switch and the neutral point configuration switch may be used as the switching element with low on-resistance, and the same switching element may be used for the other switches. For example, when the alternate PWM control shown in FIG. 2 is executed during H drive and the control shown in FIG. 7 is executed during Y drive, the upper arm switches SU2a, SV2a, and SW2a, which are high-loss switches and neutral point configuration switches, are executed. As the upper arm switches SU1a, SV1a, SW1a, which are high-loss switches and non-neutral point configuration switches, the lower arm switches SU1b, SV1b, SW1b, which are low-loss switches, are used. Similar to SU2b, SV2b, and SW2b, a switching element having a relatively high on-resistance may be used. For example, when a switching element with low on-resistance is relatively expensive, a switching element with low on-resistance is used only for the upper arm switches SU2a, SV2a, and SW2a, which have high conduction loss during both H drive and Y drive. By applying it, it is possible to improve the imbalance between the loss in the upper arm switch and the loss in the lower arm switch at each drive while suppressing the cost.

According to each of the above embodiments, the following effects can be obtained.

The drive device 10 of a rotary electric machine is applied to a rotary electric machine having a plurality of windings (for example, U-phase winding U, V-phase winding V, W-phase winding W) corresponding to a plurality of phases, and is applied to a drive circuit 11 and a drive circuit 11. , The control unit 12 is provided. The drive circuit 11 is configured to be capable of executing H drive of the rotary electric machine, and is connected to the DC power supply VDC and is connected to one end of the winding for each phase of the upper arm switches SU1a, SV1a, SW1a and the lower arm switch SU1b. , SV1b, first inverter INV1 including SW1b, second inverter INV2 including upper arm switches SU2a, SV2a, SW2a and lower arm switches SU2b, SV2b, SW2b provided for each phase at the other end of the winding. The high potential connection line La that connects the DC high potential side of the 1 inverter INV1 and the DC high potential side of the 2nd inverter INV2, and the DC low potential side of the 1st inverter INV1 and the DC low potential side of the 2nd inverter INV2. Includes a low potential connection line Lb to be connected.

The control unit 12 controls the opening and closing of the upper arm switches SU1a, SV1a, SW1a, SU2a, SV2a, SW2a and the lower arm switches SU1b, SV1b, SW1b, SU2b, SV2b, and SW2b to control the opening and closing of the first inverter INV1 and the second inverter INV2. Asymmetric switching control (for example, alternating PWM control) that alternately operates and is configured to be feasible.

In the drive device 10, one of the paired upper arm switch and lower arm switch (for example, upper arm switch SU1a and lower arm switch SU1b) is a high loss switch (for example, the side where the conduction loss is high during asymmetric switching control). For example, the upper arm switch SU1a) and the other switch (for example, the lower arm switch SU1b) are low-loss switches on the side where the conduction loss is low during asymmetric switching control. In at least a pair of upper and lower arm switches, a high loss switch (eg, upper arm switch SU1a) has a lower on-resistance than a low loss switch (eg, lower arm switch SU1b) than a switching element (eg, an IGBT). Is also a MOSFET with low on-resistance). Since a switching element having a low on-resistance is used as the high-loss switch having a high conduction loss, the conduction loss is reduced and the loss in the high-loss switch is reduced. Therefore, the loss imbalance between the high loss switch and the low loss switch is improved, and the loss imbalance between the upper arm switch and the lower arm switch is improved.

The switching element used in the high-loss switch may have a lower on-resistance than the switching element used in the low-loss switch. When a semiconductor element is used as a switching element, the high-loss switch can have a lower on-resistance than the low-loss switch by appropriately selecting the element structure, material, element size, and the like of the semiconductor element. Regarding the element structure of the semiconductor element, for example, the high-loss switch may be a unipolar semiconductor element. Examples of the unipolar semiconductor element include a field effect transistor (FET) and a MOSFET. Further, the high-loss switch may be a unipolar semiconductor element (for example, MOSFET) capable of synchronous rectification at the time of reverse conduction.

Regarding the material of the semiconductor element, the high-loss switch may be a semiconductor element made of a semiconductor (for example, SiC, GaN) having a bandgap wider than that of silicon. Further, the high-loss switch may be a semiconductor element having a larger element size than the low-loss switch. Further, the high-loss switch may be a semiconductor element having a thinner element thickness than the low-loss switch.

The drive circuit 11 further includes a connection line switch SC provided on at least one of the high-potential connection line La and the low-potential connection line Lb to open and close the continuity between the first inverter INV1 and the second inverter INV2. , It is possible to switch between H drive and Y drive of the rotary electric machine. Further, the control unit 12 can switch between H drive control and Y drive control of the rotary electric machine by controlling the opening and closing of the connection line switch SC, the upper arm switch, and the lower arm switch.

In the drive circuit 11, at the time of Y drive control, at least one of the first inverter INV1 and the second inverter INV2 has a neutrality in which one of the upper arm switch and the lower arm switch constitutes a neutral point. It is a point configuration switch, and the other is a non-neutral point configuration switch that does not constitute a neutral point. In this case, the neutral point configuration switch preferably has a lower on-resistance than the non-neutral point configuration switch. Since a switching element having a low on-resistance is used as the neutral point configuration switch having a high conduction loss, the conduction loss is reduced and the loss in the neutral point configuration switch is reduced. Therefore, the loss imbalance between the neutral point configuration switch and the non-neutral point configuration switch is improved, and the loss imbalance between the upper arm switch and the lower arm switch is improved.

Further, in the drive circuit 11 provided with the connection line switch SC and capable of switching between the H drive control and the Y drive control of the rotary electric machine, among the upper arm switch and the lower arm switch, it is a high loss switch and has a neutral point configuration. A switch, which is a switch, may be configured to have a lower on-resistance than other switches. For example, when a switching element with low on-resistance is relatively expensive, only a switch that is a high-loss switch and a neutral point configuration switch is used as a switching element with low on-resistance, and other switches are relatively inexpensive. It may be a switching element whose on-resistance is not low. As a result, it is possible to achieve both cost reduction and improvement of the imbalance between the loss in the upper arm switch and the loss in the lower arm switch.

The controls and methods thereof described in the present disclosure are realized by a dedicated computer provided by configuring a processor and memory programmed to perform one or more functions embodied by a computer program. May be done. Alternatively, the controls and methods thereof described in the present disclosure may be implemented by a dedicated computer provided by configuring the processor with one or more dedicated hardware logic circuits. Alternatively, the control unit and method thereof described in the present disclosure may be a combination of a processor and memory programmed to perform one or more functions and a processor composed of one or more hardware logic circuits. It may be realized by one or more dedicated computers configured. Further, the computer program may be stored in a computer-readable non-transitional tangible recording medium as an instruction executed by the computer.

Although this disclosure has been described in accordance with the examples, it is understood that the disclosure is not limited to the examples and structures. The present disclosure also includes various modifications and modifications within an equal range. In addition, various combinations and forms, as well as other combinations and forms that include only one element, more, or less, are also within the scope of the present disclosure.

Claims (8)

1. A rotary electric machine drive device (10) applied to a rotary electric machine having a plurality of windings corresponding to a plurality of phases.
   A first inverter (INV1) having an upper arm switch and a lower arm switch connected to a DC power supply and connected to one end of the winding for each phase.
   A second inverter (INV2) having an upper arm switch and a lower arm switch connected to the other end of the winding for each phase.
   A high potential connection line (La) connecting the DC high potential side of the first inverter and the DC high potential side of the second inverter, and
   A low potential connection line (Lb) connecting the DC low potential side of the first inverter and the DC low potential side of the second inverter, and
   (11), a drive circuit (11) capable of H-driving the rotary electric machine, and
   A control unit (12) capable of executing asymmetric switching control for alternately operating the first inverter and the second inverter by controlling the opening and closing of the upper arm switch and the lower arm switch is provided.
   One of the paired upper arm switch and the lower arm switch is a high-loss switch on the side where the conduction loss increases during the asymmetric switching control, and the other switch has a conduction loss during the asymmetric switching control. It is a low loss switch on the lower side,
   In at least a pair of the upper arm switch and the lower arm switch, the high-loss switch is a switching element having a lower on-resistance than the low-loss switch, which is a driving device for a rotary electric machine.
2. The drive device for a rotary electric machine according to claim 1, wherein the high-loss switch is a unipolar semiconductor element.
3. The drive device for a rotary electric machine according to claim 1 or 2, wherein the high-loss switch is a unipolar semiconductor element capable of synchronous rectification when conducting in the reverse direction.
4. The drive device for a rotary electric machine according to any one of claims 1 to 3, wherein the high-loss switch is a semiconductor element made of a semiconductor having a bandgap wider than that of silicon.
5. The drive device for a rotary electric machine according to any one of claims 1 to 4, wherein the high-loss switch is a semiconductor element having a larger element size than the low-loss switch.
6. The drive device for a rotary electric machine according to any one of claims 1 to 5, wherein the high-loss switch is a semiconductor element having a thinner element thickness than the low-loss switch.
7. The drive circuit is further provided with a connection line switch (SC) provided on at least one of the high-potential connection line and the low-potential connection line to conduct or cut off the first inverter and the second inverter. , The H drive and Y drive of the rotary electric machine can be switched.
   The control unit can switch between H drive control and Y drive control of the rotary electric machine by controlling the opening and closing of the connection line switch, the upper arm switch, and the lower arm switch.
   At the time of the Y drive control, at least one of the first inverter and the second inverter has a neutral point configuration in which one of the upper arm switch and the lower arm switch constitutes a neutral point. It is a non-neutral point configuration switch that is a switch and the other does not constitute a neutral point.
   The drive device for a rotary electric machine according to any one of claims 1 to 6, wherein the neutral point configuration switch is a switching element having a lower on-resistance than the non-neutral point configuration switch.
8. The drive of a rotary electric machine according to claim 7, wherein of the upper arm switch and the lower arm switch, the switch which is the high loss switch and the neutral point configuration switch has a lower on-resistance than the other switches. apparatus.

Images