JP2021125922A - Rotary electric machine system - Google Patents

Abstract

To provide a rotary electric machine system capable of suppressing the generation of an excessive surge voltage.SOLUTION: A rotary electric machine system comprises: a rotary electric machine 10 which has a power supply line CE, a ground line CG, a first inverter 20, a second inverter 30, and a winding 14, in which a first end of the winding 14 is connected to a first upper arm switch 22 and a first lower arm switch 23 of the first inverter 20, and a second end of the winding 14 is connected to a second upper arm switch 32 and a second lower arm switch 33 of the second inverter 30; an opening and closing switch 60 which is provided between a connection point with the first inverter 20 and a connection point with the second inverter 30 in at least one of the power supply line CE and the ground line CG; a first capacitor 25 which connects between the power supply line CE and the ground line CG on the first inverter 20 side from the opening and closing switch 60; and a second capacitor 35 which connects between the power supply line CE and the ground line CG on the second inverter 30 side from the opening and closing switch 60.SELECTED DRAWING: Figure 1

Description

The present invention relates to a rotary electric machine system.

Conventionally, there is known a system including an inverter which is connected to a battery, converts DC power supplied from the battery into AC power, and outputs the DC power to a rotary electric machine (for example, Patent Document 1). In this system, a snubber capacitor that absorbs surge energy generated when the switching element included in the inverter is switched off is provided. In this system, the temperature of the switching element is acquired, and when the acquired temperature of the switching element is equal to or less than the threshold value, the switching element and the snubber capacitor are electrically connected. As a result, the surge energy generated when the switching element is switched off is absorbed by the snubber capacitor, and the generation of an excessive surge voltage is suppressed. Further, when the temperature of the switching element exceeds the threshold value, the electrical connection between the switching element and the snubber capacitor is cut off. As a result, when the surge voltage is low, the circuit loss is reduced by not allowing the snubber capacitor to act.

JP-A-2018-7310

A first inverter and a second inverter are provided as inverters, and a system is known in which AC power is output to a rotating electric machine using the first and second inverters. This system includes a first electric path connected to the positive electrode side of a power storage device such as a battery, a second electric path connected to the negative electrode side of the power storage device, a first inverter, a second inverter, and a rotary electric machine. It is equipped with an open / close switch and a capacitor. The first inverter has a first upper arm switch and a first lower arm switch connected in series for each phase, and the high potential side terminal of the first upper arm switch is connected to the first electric path, and the first lower arm switch is connected. The low potential side terminal of the arm switch is connected to the second electric path. The second inverter has a second upper arm switch and a second lower arm switch connected in series for each phase, and the high potential side terminal of the second upper arm switch is connected to the first electric path and is second lower. The low potential side terminal of the arm switch is connected to the second electric path. The rotary electric machine has an armature winding, and the first end of the armature winding is connected to the low potential side terminal of the first upper arm switch and the high potential side terminal of the first lower arm switch, and the second upper arm. The second end of the armature winding is connected to the low potential side terminal of the switch and the high potential side terminal of the second lower arm switch. The open / close switch is provided between the connection point with the first inverter and the connection point with the second inverter in at least one of the first electric path and the second electric path. The capacitor is connected between the first electric path and the second electric path on the first inverter side of the open / close switch. In this system, the second inverter is connected to the power storage device via an open / close switch. Then, when the open / close switch is turned on, AC power is output to the rotating electric machine by the switching operation of each switch constituting the first inverter and the second inverter.

In this system, the electric path when the surge energy generated by the switching operation of the second inverter is absorbed by the capacitor includes a portion provided with an open / close switch. In this part, the inductance of the open / close switch itself and the shape of the electric path for providing the open / close switch increase the inductance. Therefore, an excessive surge voltage is generated due to the surge energy generated in the switching operation of the second inverter.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a rotary electric machine system capable of suppressing the generation of an excessive surge voltage.

The first means for solving the above-mentioned problems is a first electric path connected in series with a first electric path connected to the positive side of the power storage device and a second electric path connected to the negative side of the power storage device. The upper arm switch and the first lower arm switch are provided for each phase, the high potential side terminal of the first upper arm switch is connected to the first electric path, and the low potential side terminal of the first lower arm switch is connected. A first inverter connected to the second electric path, a second upper arm switch and a second lower arm switch connected in series are provided for each phase, and the high potential side terminal of the second upper arm switch is said. The low potential side terminal of the second lower arm switch connected to the first electric path has a second inverter connected to the second electric path and an armor winding, and the lower of the first upper arm switch. The first end of the armature winding is connected to the potential side terminal and the high potential side terminal of the first lower arm switch, and the low potential side terminal of the second upper arm switch and the high potential of the second lower arm switch. At least one of the rotary electric machine to which the second end of the armature winding is connected to the side terminal and the first electric path and the second electric path, the connection point with the first inverter and the second inverter. An open / close switch provided between the open / close switch, a first capacitor connecting between the first electric path and the second electric path on the first inverter side of the open / close switch, and the above. On the second inverter side of the open / close switch, a second capacitor for connecting between the first electric path and the second electric path is provided.

In the first means, a second capacitor is provided in addition to the first capacitor. The second capacitor is connected between the first electric path and the second electric path on the second inverter side of the open / close switch. Therefore, the surge energy generated by the switching operation of the second upper arm switch and the second lower arm switch is absorbed by the second capacitor. Therefore, it is possible to suppress the generation of an excessive surge voltage.

In the second means, the open / close switch is a first open / close switch, the second open / close switch connected in series to the second capacitor, and a control device for turning on / off the first open / close switch and the second open / close switch. The second capacitor and the series connection body of the second open / close switch are connected between the first electric path and the second electric path, and the control device is a control device of the first open / close switch. The second open / close switch is turned on during the on period, and the second open / close switch is turned off during the off period of the first open / close switch.

In the second means, a second open / close switch connected in series with the second capacitor is provided between the first electric path and the second electric path. Then, the second open / close switch is controlled so that the second open / close switch is turned on during the on period of the first open / close switch and the second open / close switch is turned off during the off period of the first open / close switch. By turning on the second open / close switch during the on period of the first open / close switch, the surge energy generated by the switching operation of the second upper arm switch and the second lower arm switch can be absorbed by the second capacitor. , The generation of excessive surge voltage can be suppressed. Further, by turning off the second open / close switch during the off period of the first open / close switch, the second upper arm switch and the second lower arm are provided in all phases of the second inverter even when the second capacitor is provided. Properly drive the rotary electric machine in which the one connected to the electric path provided with the first open / close switch is fixed on and the one not connected to the electric path provided with the first open / close switch is fixed off. can do.

The third means includes a current determination unit for determining whether or not the current flowing through the armature winding is larger than the threshold value, and the control device is determined by the current determination unit to be larger than the threshold value. On condition that, the second open / close switch is turned on.

When the current flowing through the armature winding is larger than the threshold value, the surge energy generated by the switching operation of the second upper arm switch and the second lower arm switch also becomes large. As a result, the generated surge voltage also increases, and it is necessary to turn on the second open / close switch.

On the other hand, when the current flowing through the armature winding is equal to or less than the threshold value, the surge voltage generated is also small, and it is not necessary to turn on the second open / close switch. In the third means, the second open / close switch is turned on only when it is determined that the value is larger than the threshold value, and the second open / close switch is turned off when it is determined that the value is equal to or less than the threshold value. Efficiency can be maintained.

In the fourth means, when the control device satisfies at least one of the first condition that the rotary electric machine is in the high rotation drive state and the second condition that the rotary electric machine is in the high torque drive state. The first open / close switch is turned on, and when both the first condition and the second condition are not satisfied, the first open / close switch is turned off.

When the rotary electric machine is in at least one of a high rotation drive state and a high torque drive state, the first open / close switch is turned on, and a relatively large current is often passed through the armature winding of the rotary electric machine. However, for example, in the case of high rotation and low torque, the current flowing through the armature winding may be less than the threshold value. In this case, when the second open / close switch is turned on, the system loss increases due to the action of the second capacitor. In the fourth means, even if the first open / close switch is on, the second open / close switch is turned off when it is determined that the current flowing through the armature winding is equal to or less than the threshold value. Therefore, for example, in a high rotation and low torque state, the loss of the rotating electric machine does not change depending on the presence or absence of the second capacitor, and high system efficiency can be maintained.

In the fifth means, the withstand voltage value of the second inverter is equal to or less than the withstand voltage value of the first inverter.

In a rotary electric system in which only the first capacitor is provided and the second capacitor is not provided, the second inverter is provided by the inductance of the portion where the open / close switch is provided in at least one of the first electric path and the second electric path. The surge voltage generated by the switching operation of the first inverter becomes larger than the surge voltage generated by the switching operation of the first inverter. Therefore, it is necessary to make the withstand voltage value of the second inverter larger than the withstand voltage value of the first inverter, and the increase in the withstand voltage value of the second inverter increases the manufacturing cost of the rotary electric machine system. In the fifth means, a second capacitor is provided in addition to the first capacitor, and the surge voltage generated by the switching operation of the second inverter is the same as or higher than the surge voltage generated by the switching operation of the first inverter. Is also configured to be smaller. Therefore, the withstand voltage value of the second inverter can be set to be equal to or lower than the withstand voltage value of the first inverter, and an increase in the manufacturing cost of the rotary electric machine system can be suppressed.

In the sixth means, the first upper arm switch and the second upper arm switch are switching elements having the same specifications, and the first lower arm switch and the second lower arm switch are switching having the same specifications. It is an element.

In the sixth means, the first upper arm switch and the second upper arm switch are switching elements having the same specifications. Here, switching elements having the same specifications mean that the electrical characteristics such as the withstand voltage value and the rated current are the same, and that, for example, the manufacturers and model numbers are the same. As a result, the manufacturing cost of the rotary electric machine system can be reduced. The same applies to the first lower arm switch and the second lower arm switch.

The whole block diagram of the rotary electric system of 1st Embodiment. The figure which shows the relationship between the electric angular velocity and the output torque of a rotary electric machine. The figure which shows the current path of a phase current in a predetermined state of a star connection drive. The figure which shows the current path of a phase current in a predetermined state of an open connection drive. The figure which shows the electric circuit which contributes to the surge voltage when the upper arm of the 1st inverter is switched from on to off. The figure which shows the electric path which contributes to a surge voltage when the upper arm of the 2nd inverter is switched from on to off in a comparative example. The figure which shows the electric circuit which contributes to the surge voltage when the upper arm of the 2nd inverter is switched from on to off in this embodiment. The figure which shows the combined inductance of a closed circuit including each inverter. The whole block diagram of the rotary electric machine system of the modification of 1st Embodiment. The whole block diagram of the rotary electric system of 2nd Embodiment. The flowchart which shows the procedure of the switching process of 2nd Embodiment. The flowchart which shows the procedure of the switching process of 3rd Embodiment.

(First Embodiment)
Hereinafter, a first embodiment in which the rotary electric machine system according to the present invention is embodied as an in-vehicle rotary electric machine system 100 will be described with reference to the drawings.

As shown in FIG. 1, the rotary electric machine system 100 according to the present embodiment controls the rotary electric machine 10, the first inverter 20, the second inverter 30, the battery 40 as a power storage device, and the rotary electric machine 10. The control device 50 and the like are provided.

The rotary electric machine 10 has functions of power running drive and regenerative drive. The rotary electric machine 10 inputs and outputs electric power to and from the battery 40. At the time of power running, the electric power supplied from the battery 40 gives a propulsive force to the vehicle, and at the time of regeneration, the deceleration energy of the vehicle is used. It generates electric power and outputs electric power to the battery 40.

The rotary electric machine 10 includes a rotor 11 and a stator 13. The rotor 11 is provided with a permanent magnet 12 that performs field magnetization. That is, the rotary electric machine 10 is a permanent magnet field type rotary electric machine. The permanent magnet 12 is, for example, a neodymium magnet or a ferrite magnet.

The stator 13 is provided with an open three-phase (U-phase, V-phase, W-phase) winding 14. The rotor 11 of the rotary electric machine 10 is connected to the drive wheels of the vehicle so as to be able to transmit power. In this embodiment, the winding 14 corresponds to the "armature winding".

The first end of the winding 14 of each phase is connected to the battery 40 via the first inverter 20. The battery 40 is a rechargeable and dischargeable storage battery, for example, an assembled battery in which a plurality of lithium ion storage batteries are connected in series. The battery 40 may be another type of storage battery.

The first inverter 20 includes a first upper arm switch 22 (22A, 22B, 22C) which is a switching element on the high potential side, and a first lower arm switch 23 (23A, 23B, 23C) which is a switching element on the low potential side. Is configured by connecting in parallel. In this embodiment, voltage-controlled semiconductor switching elements are used as switches 22 and 23, and more specifically, IGBTs are used. In each phase, the first end of the winding 14 is connected to the emitter terminal of the first upper arm switch 22 and the collector terminal of the first lower arm switch 23. A diode 24, which is a freewheel diode, is connected in antiparallel to the switches 22 and 23. In this embodiment, the collector terminal corresponds to the "high potential side terminal" and the emitter terminal corresponds to the "low potential side terminal".

The second inverter 30 includes a second upper arm switch 32 (32A, 32B, 32C) which is a switching element on the high potential side, and a second lower arm switch 33 (33A, 33B, 33C) which is a switching element on the low potential side. Is configured by connecting in parallel. In this embodiment, voltage-controlled semiconductor switching elements are used as the switches 32 and 33, and more specifically, IGBTs are used. In each phase, the second end of the winding 14 is connected to the emitter terminal of the second upper arm switch 32 and the collector terminal of the second lower arm switch 33. A diode 34, which is a freewheel diode, is connected in antiparallel to the switches 32 and 33.

The positive electrode side of the battery 40, the collector terminal of the first upper arm switch 22 and the collector terminal of the second upper arm switch 32 are connected by a power supply line CE as a first electric path. Further, the negative electrode side of the battery 40, the emitter terminal of the first lower arm switch 23, and the emitter terminal of the second lower arm switch 33 are connected by a ground wire CG as a second electric path. The power line CE and the ground line CG are composed of, for example, a bus bar.

Specifically, the positive electrode side of the battery 40, the collector terminal of the first upper arm switch 22 and the collector terminal of the second upper arm switch 32 are connected to the power supply line CE in this order. Therefore, the collector terminal of the second upper arm switch 32 is connected to the power supply line CE on the side opposite to the battery 40 from the connection point between the power supply line CE and the first inverter 20.

In the power supply line CE, an open / close switch 60 is provided between the connection point with the first inverter 20 and the connection point with the second inverter 30. In the present embodiment, a voltage-controlled semiconductor switching element is used as the open / close switch 60, and more specifically, an IGBT is used. A diode 62, which is a freewheel diode, is connected in antiparallel to the open / close switch 60. The diode 62 is connected to the power supply line CE so that the direction from the second inverter 30 to the first inverter 20 is in the forward direction.

Further, the power supply line CE and the ground line CG are connected by the first capacitor 25. The first capacitor 25 connects the power supply line CE and the ground line CG on the first inverter 20 side of the open / close switch 60, more specifically on the battery 40 side of the first inverter 20.

The control device 50 includes a well-known microcomputer including a CPU, ROM, RAM, flash memory, and the like. The control device 50 acquires various signals and executes various controls based on the acquired information.

Specifically, the control device 50 includes a voltage sensor 51 that detects the voltage VB of the first capacitor 25 when the rotary electric machine 10 is driven, a phase current sensor 53 that detects the phase current IM of the rotary electric machine 10, and the rotary electric machine 10. The detection value is acquired from the rotation angle sensor 54 or the like that detects the electric angle θ of. In the present embodiment, as the phase current sensor 53, a U-phase current sensor 53U that detects the phase current flowing through the U-phase winding 14 and a V-phase current sensor 53V that detects the phase current flowing through the V-phase winding 14 are used. It is provided. The control device 50 controls the first inverter 20 and the second inverter 30 in order to control the control amount of the rotary electric machine 10 to the command value based on the acquired detected value. In this embodiment, the control amount is the output torque TE.

Specifically, in the control of the first inverter 20, the control device 50 sets the first drive signal SG1 corresponding to each of the switches 22 and 23 in order to alternately turn on the switches 22 and 23 with a dead time in between. Output to switches 22 and 23. The first drive signal SG1 takes either an on command for turning on the switches 22 and 23 and an off command for turning off the switches 22 and 23. Similarly, in the control of the second inverter 30, the control device 50 sets the second drive signal SG2 corresponding to each of the switches 32 and 33 to the switch 32 in order to turn on the switches 32 and 33 alternately with a dead time in between. , 33 is output.

Further, the control device 50 generates a changeover signal SC in order to switch on / off of the open / close switch 60 based on the acquired detection value, and outputs the generated changeover signal SC to the open / close switch 60.

Then, the control device 50 controls the drive of the rotary electric machine 10 by using the first drive signal SG1, the second drive signal SG2, and the switching signal SC. The drive of the rotary electric machine 10 is, for example, a star connection drive or an open connection drive.

In FIG. 2, in the correlation diagram between the electric angular velocity ω as the time derivative value of the electric angle θ and the output torque TE, the first drive range HA in which the star connection drive can be performed and the second drive range HA in which the open connection drive can be performed can be performed. The drive range HB is shown. As shown by the broken line in FIG. 2, the first drive range HA is set in a range in which the electric angular velocity ω is lower than the threshold angular velocity ωth and the output torque TE is lower than the threshold torque Tth. Further, as shown by a solid line in FIG. 2, the second drive range HB is set to a range on the high electric angular velocity side or a high output torque side of the first drive range HA.

When the electric angular velocity ω and the output torque TE of the rotary electric machine 10 are included in the first drive range HA, the rotary electric machine 10 is driven by star connection. Specifically, as shown in FIG. 3, the open / close switch 60 is turned off. Further, the first inverter 20 is PWM controlled. In the PWM control, the on / off of the switches 22 and 23 included in the first inverter 20 is controlled based on the magnitude comparison between the voltage command value to the rotary electric machine 10 and the carrier signal such as the triangular wave signal. FIG. 3 shows a state in which the U-phase first upper arm switch 22A and the V and W-phase first lower arm switches 23B and 23C are turned on, and the other switches are turned off. The control method of the first inverter 20 in the star connection drive is not limited to PWM control, and may be overmodulation control, rectangular control, or the like.

Further, among the switches 32 and 33 included in the second inverter 30, the second upper arm switch 32 on the side where the open / close switch 60 is provided is kept on, and the second lower on the side where the open / close switch 60 is not provided. The arm switch 33 is kept off. As a result, the phase current IM flows through the first inverter 20 and the second inverter 30 along the path indicated by the arrow YA, and the power supply line CE connected to the collector terminal of the second upper arm switch 32 functions as a neutral point. do. In FIG. 3, the description of the first capacitor 25, the control device 50, and various sensors 51, 53, 54 is omitted. The same applies to FIG.

On the other hand, when the electric angular velocity ω and the output torque TE of the rotary electric machine 10 are included in the second drive range HB, the rotary electric machine 10 is driven by open wiring. Specifically, as shown in FIG. 4, the open / close switch 60 is turned on. Further, the first inverter 20 and the second inverter 30 are PWM controlled. In FIG. 4, the U-phase first upper arm switch 22A, V, W-phase first lower arm switch 23B, 23C, the U-phase second lower arm switch 33A, and the V, W-phase second upper arm switch 32B, 32C are turned on. It is shown that the other switches are off. As a result, the phase current IM flows through the first inverter 20 and the second inverter 30 along the path indicated by the arrow YB. The control method of the first inverter 20 and the second inverter 30 in the open connection drive is not limited to PWM control, and may be overmodulation control, rectangular control, or the like.

The rotary electric system 100 further includes a second capacitor 35. The second capacitor 35 connects the power supply line CE and the ground line CG on the second inverter 30 side of the open / close switch 60, and more specifically on the side of the second inverter 30 opposite to the open / close switch 60. .. In the present embodiment, the capacity of the second capacitor 35 is set to a capacity smaller than the capacity of the first capacitor 25. The reason why the second capacitor 35 is provided will be described later.

In the star connection drive and the open connection drive, surge energy is generated by the switching operation of the switches 22 and 23 of the first inverter 20. The surge voltage generated in the first upper arm switch 22 when the first upper arm switch 22 is switched from on to off will be described with reference to FIG. In FIG. 5, for ease of understanding, only the winding 14 for one phase and the switches 22, 23, 32, 33 are shown in the rotary electric machine 10, the first inverter 20, and the second inverter 30. There is. Further, in FIG. 5, the description of the control device 50 and various sensors 51, 53, 54 is omitted. The same applies to FIGS. 6 and 7.

5 to 7 show the inductances LA to LE of each part in the rotary electric machine system 100. Taking FIG. 5 as an example, the first inductance LA is the inductance of the portion of the power supply line CE on the side of the first capacitor 25 with respect to the first inverter 20 (more specifically, the first capacitor 25 of the power supply line CE). The inductance of the portion between the connection point with and the connection point with the first inverter 20). The second inductance LB is the inductance of the wiring connecting the first upper arm switch 22, the first lower arm switch 23, and the switches 22, 23. The third inductance LC is the inductance of the portion of the power supply line CE between the first inverter 20 and the second inverter 30. Therefore, the third inductance LC includes the inductance of the portion of the power supply line CE where the open / close switch 60 is provided. The fourth inductance LD is the inductance of the portion of the power supply line CE from the second inverter 30 to the second capacitor 35. The fifth inductance LE is the inductance of the wiring connecting the second upper arm switch 32, the second lower arm switch 33, and the switches 32, 33.

In FIG. 5, when the first upper arm switch 22 is switched from on to off and the first lower arm switch 23 is switched from off to on, that is, as shown by the arrow YC, the winding 14 is wound from the first upper arm switch 22. The surge voltage generated in the first upper arm switch 22 when the phase current IM flowing in the first upper arm switch 22 decreases will be described.

At this time, surge energy for increasing the phase current IM in the direction indicated by the arrow YC is generated in the first and second inductances LA and LB, and the surge energy is absorbed by the first capacitor 25. (See arrow YD in FIG. 5). Due to this surge energy, the first surge voltage VS1 is generated in the first closed circuit CA including the first upper arm switch 22, the first lower arm switch 23, and the first capacitor 25. The first surge voltage VS1 is set as in (Equation 1) by using the first combined inductance L1 of the first closed circuit CA and di / dt which is the time change rate of the current i flowing through the first upper arm switch 22. expressed.

VS1 = L1 · (di / dt) ... (Equation 1)
The first combined inductance L1 is the sum of the first and second inductances LA and LB. Further, as shown in FIG. 5, the first closed circuit CA does not include a portion of the power supply line CE provided with the open / close switch 60. Therefore, the first combined inductance L1 of the first closed circuit CA is smaller than the threshold inductance Lth (see FIG. 8), and the generation of an excessive first surge voltage VS1 is suppressed in the first closed circuit CA.

By the way, in the open connection drive, not only the switches 22 and 23 of the first inverter 20 but also the switches 32 and 33 of the second inverter 30 perform the switching operation. Therefore, surge energy is generated by the switching operation of the switches 32 and 33. The surge voltage generated in the second upper arm switch 32 when the second upper arm switch 32 is switched from on to off will be described with reference to FIG. 6 showing a comparative example. The comparative example shown in FIG. 6 is a rotary electric machine system in which only the first capacitor 25 is provided as a capacitor that absorbs surge energy.

In FIG. 6, when the second upper arm switch 32 is switched from on to off and the second lower arm switch 33 is switched from off to on, that is, as shown by the arrow YE, the winding 14 is wound from the second upper arm switch 32. The surge voltage generated in the second upper arm switch 32 when the phase current IM flowing in the second upper arm switch 32 decreases will be described.

At this time, surge energy for increasing the phase current IM in the direction indicated by the arrow YE is generated in the first, third, and fifth inductances LA, LC, and LE. As shown in FIG. 6, in the comparative example in which only the first capacitor 25 is provided in the rotary electric machine system 100, surge energy is absorbed by the first capacitor 25 (see arrow YF in FIG. 6). Due to this surge energy, a second surge voltage VS2 is generated in the second closed circuit CB including the first capacitor 25, the second upper arm switch 32, the second lower arm switch 33, and the open / close switch 60. The second surge voltage VS2 is expressed as in (Equation 2) by using the second combined inductance L2 of the second closed circuit CB and the time change rate di / dt of the current i flowing through the second upper arm switch 32. NS.

VS2 = L2 ・ (di / dt) ・ ・ ・ (Equation 2)
As shown in FIG. 6, the second closed circuit CB includes a portion of the open / close switch 60 and the power supply line CE provided with the open / close switch 60. The second combined inductance L2 in the comparative example is the sum of the first, third, and fifth inductances LA, LC, and LE, and is larger than the threshold inductance Lth (see FIG. 8). This is because, in the present embodiment, the second inductance LB and the fifth inductance LE are equivalent, and the second combined inductance L2 is larger than the first combined inductance L1 by the amount of the third inductance LC. The third inductance LC includes the inductance of the open / close switch 60 itself and the inductance of the path connecting the open / close switch 60 and the power supply line CE. Therefore, in the second closed circuit CB of the comparative example, an excessive second surge voltage VS2 is generated. Therefore, in the rotary electric machine system of the comparative example, the second withstand voltage value VB2 of the second inverter 30 is set higher than the first withstand voltage value VB1 of the first inverter 20 so that the second inverter 30 does not fail due to the second surge voltage VS2. It needs to be large, which increases the manufacturing cost of the rotary electric machine system.

Therefore, in the present embodiment, the rotary electric machine system 100 is provided with the second capacitor 35. The surge voltage generated in the second upper arm switch 32 when the second upper arm switch 32 is switched from on to off in the rotary electric machine system 100 of the present embodiment will be described with reference to FIG. 7. In FIG. 7, similarly to FIG. 6, when the second upper arm switch 32 is switched from on to off and the second lower arm switch 33 is switched from off to on, that is, as shown by the arrow YE, the second upper arm The surge voltage generated in the second upper arm switch 32 when the phase current IM flowing from the switch 32 to the winding 14 decreases will be described.

At this time, surge energy for increasing the phase current IM in the direction indicated by the arrow YE is generated in the fourth and fifth inductance LDs and LEs. As shown in FIG. 7, in the present embodiment in which the rotary electric machine system 100 is provided with the second capacitor 35, surge energy is absorbed by the second capacitor 35 (see arrow YG in FIG. 7). Due to this surge energy, a third surge voltage VS3 is generated in the third closed circuit CD including the second upper arm switch 32, the second lower arm switch 33, and the second capacitor 35. The third surge voltage VS3 is expressed as in (Equation 3) by using the third combined inductance L3 and the time change rate di / dt of the current i flowing through the second upper arm switch 32.

VS3 = L3 ・ (di / dt) ・ ・ ・ (Equation 3)
As shown in FIG. 7, the third closed circuit CD does not include the portion of the power supply line CE provided with the open / close switch 60. Specifically, the third combined inductance L3 of the third closed circuit CD is the sum of the fourth and fifth inductances LD and LE, which is smaller than the threshold inductance Lth (see FIG. 8) and has an excessive third surge voltage VS3. Is suppressed.

In this embodiment, the first inductance LA and the fourth inductance LD are equivalent. Therefore, as shown in FIG. 8, the third combined inductance L3 is equivalent to the first combined inductance L1. Therefore, in the rotary electric machine system 100 of the present embodiment, the second withstand voltage value VB2 of the second inverter 30 is set to the same value as the first withstand voltage value VB1 of the first inverter 20.

According to the present embodiment described in detail above, the following effects can be obtained.

In the present embodiment, in the power supply line CE, the open / close switch 60 is provided between the connection point with the first inverter 20 and the connection point with the second inverter 30. Further, the first capacitor 25 connects the power supply line CE and the ground line CG on the first inverter 20 side of the open / close switch 60. In the present embodiment, a second capacitor 35 is provided in addition to the first capacitor 25, and the second capacitor 35 is located between the power supply line CE and the ground line CG on the second inverter 30 side of the open / close switch 60. You are connected. Therefore, the surge energy generated by the switching operation of the switches 22 and 23 is absorbed by the first capacitor 25. Further, the surge energy generated by the switching operation of the switches 32 and 33 is absorbed by the second capacitor 35. Therefore, it is possible to suppress the generation of an excessive surge voltage.

In the rotary electric system of the comparative example in which only the first capacitor 25 is provided and the second capacitor 35 is not provided, the second inverter 30 is provided by the third inductance LC of the portion of the power supply line CE where the open / close switch 60 is provided. The second surge voltage VS2 generated by the switching operation of the first inverter 20 becomes larger than the first surge voltage VS1 generated by the switching operation of the first inverter 20. Therefore, it is necessary to make the second withstand voltage value VB2 of the second inverter 30 larger than the first withstand voltage value VB1 of the first inverter 20, and the increase of the second withstand voltage value VB2 increases the manufacturing cost of the rotary electric machine system.

On the other hand, in the present embodiment, the second capacitor 35 is provided in addition to the first capacitor 25, and the third surge voltage VS3 generated by the switching operation of the second inverter 30 is the switching operation of the first inverter 20. It is configured to be equivalent to the first surge voltage VS1 generated by the above. Therefore, the second withstand voltage value VB2 of the second inverter 30 can be set to the same value as the first withstand voltage value VB1 of the first inverter 20, and an increase in the manufacturing cost of the rotary electric machine system 100 can be suppressed.

When the second withstand voltage value VB2 of the second inverter 30 is set to the same value as the first withstand voltage value VB1 of the first inverter 20, the first inverter 20 and the second inverter 30 may be switching elements having the same specifications. can. Specifically, the first upper arm switch 22 and the second upper arm switch 32 can be switching elements having the same specifications, and the first lower arm switch 23 and the second lower arm switch 33 are the same. It can be a switching element of the specifications. As a result, the manufacturing cost of the rotary electric machine system 100 can be reduced.

(Modified example of the first embodiment)
As shown in FIG. 9, the second capacitor 35 may be provided individually for each of the switches 32 and 33 of the second inverter 30. In this case, the individually provided second capacitors 35 are connected in parallel to the switches 32 and 33 and the diodes 34 connected in antiparallel to the switches 32 and 33.

(Second Embodiment)
Hereinafter, the second embodiment will be described with reference to FIGS. 10 and 11, focusing on the differences from the first embodiment. In FIG. 10, the same configurations as those shown in FIG. 1 above are designated by the same reference numerals for convenience, and the description thereof will be omitted.

The present embodiment is different from the first embodiment in that an open / close switch 64 connected in series to the second capacitor 35 is provided. In the present embodiment, a voltage-controlled semiconductor switching element is used as the open / close switch 64, and more specifically, an IGBT is used. A diode 66, which is a freewheel diode, is connected in antiparallel to the open / close switch 64. Hereinafter, for the sake of distinction, the open / close switch 60 is referred to as a first open / close switch 60, and the open / close switch 64 is referred to as a second open / close switch 64.

The second capacitor 35 is connected between the power supply line CE and the ground line CG by the connection line CN, and the second open / close switch 64 is connected in series to the second capacitor 35 in the connection line CN. Specifically, the second open / close switch 64 is connected to the lower potential side of the second capacitor 35 in the connection line CN.

The control device 50 generates a changeover signal SC in order to switch the second open / close switch 64 on / off based on the electric angular velocity ω and the output torque TE of the rotary electric machine 10, and the generated changeover signal SC is used as the second open / close switch 64. Output. Hereinafter, for the sake of distinction, the changeover signal SC of the first open / close switch 60 is referred to as a first changeover signal SC1, and the changeover signal SC of the second open / close switch 64 is referred to as a second changeover signal SC2.

Then, the control device 50 controls the drive of the rotary electric machine 10 by using the first drive signal SG1, the second drive signal SG2, the first switching signal SC1 and the second switching signal SC2. At this time, the control device 50 performs a switching process for switching between the first switching signal SC1 and the second switching signal SC2.

FIG. 11 shows a flowchart of the switching process of the present embodiment. When the rotary electric machine 10 is driven, the control device 50 repeatedly executes the switching process at predetermined control cycles.

When the switching process is started, first, in step S10, it is determined whether or not the drive of the rotary electric machine 10 is an open connection drive. Information for specifying the first drive range HA and the second drive range HB shown in FIG. 2 is stored in the storage unit 55 (see FIG. 10) of the control device 50, and the control device 50 stores this information and rotation. Based on the electric angular velocity ω of the electric machine 10 and the output torque TE, it is determined whether or not the drive of the rotary electric machine 10 is an open connection drive.

When the drive of the rotary electric machine 10 is an open connection drive, an affirmative determination is made in step S10. In this case, in step S12, the first open / close switch 60 is turned on and the second open / close switch 64 is turned on to end the switching process. Therefore, the second open / close switch 64 is turned on during the on period when the first open / close switch 60 is turned on.

Further, when the drive of the rotary electric machine 10 is a star connection drive, a negative determination is made in step S10. In this case, in step S14, the first open / close switch 60 is turned off and the second open / close switch 64 is turned off to end the switching process. Therefore, the second open / close switch 64 is turned off during the off period when the first open / close switch 60 is turned off.

According to the present embodiment described in detail above, the following effects can be obtained.

When the drive of the rotary electric machine 10 is an open connection drive, the first open / close switch 60 is turned on. In the present embodiment, the second open / close switch 64 is turned on during the on period of the first open / close switch 60. As a result, the surge energy generated by the switching operation of the switches 32 and 33 can be absorbed by the second capacitor 35, and the generation of an excessive surge voltage can be suppressed.

Further, when the rotary electric machine 10 is driven by the star connection drive, the first open / close switch 60 is turned off. In the present embodiment, the second open / close switch 64 is turned off during the off period of the first open / close switch 60. When the drive of the rotary electric machine 10 is a star connection drive, the second upper arm switch 32 is fixed on and the second lower arm switch 33 is fixed off, so that surge energy is not generated and surge energy is absorbed. It is not necessary to turn on the second open / close switch 64 in order to make the switch 64. On the other hand, when the second open / close switch 64 is turned on in the star connection drive, the potential of the power supply line CE connected to the collector terminal of the second upper arm switch 32 that functions as a neutral point fluctuates, which causes the rotary electric machine 10 to change. Drive becomes unstable. In the present embodiment, when the drive of the rotary electric machine 10 is the star connection drive, the second open / close switch 64 is turned off, so that the star connection drive of the rotary electric machine 10 can be properly carried out.

(Third Embodiment)
Hereinafter, the third embodiment will be described with reference to FIG. 12, focusing on the differences from the second embodiment.

The present embodiment is different from the second embodiment in that in the switching process, it is determined whether or not the phase current IM is larger than the threshold current Is.

Subsequently, FIG. 12 shows a flowchart of the switching process of the present embodiment. In FIG. 12, the same processing as that shown in FIG. 11 above is given the same step number for convenience, and the description thereof will be omitted.

In the switching process of the present embodiment, if an affirmative determination is made in step S10, it is determined in step S20 whether or not the phase current IM acquired by using the phase current sensor 53 is larger than the threshold current Is. In this embodiment, the process of step S20 corresponds to the "current determination unit".

When a negative determination is made in step S20, that is, when it is determined that the phase current IM is equal to or less than the threshold current Is, the first open / close switch 60 is turned on and the second open / close switch 64 is turned off in step S22 to perform the switching process. To finish. On the other hand, if an affirmative determination is made in step S20, that is, if it is determined that the phase current IM is larger than the threshold current Is, the process proceeds to step S12 and the second open / close switch 64 is turned on. That is, in the switching process of the present embodiment, the second open / close switch 64 is turned on on the condition that the phase current IM is determined to be larger than the threshold current Is.

According to the present embodiment described in detail above, the following effects can be obtained.

In the present embodiment, the on / off of the second open / close switch 64 is switched based on the phase current IM flowing through the first open / close switch 60. As shown in (Equation 3), the surge voltage generated in the second inverter 30 is proportional to the time change rate di / dt of the current i flowing through the second upper arm switch 32 or the second lower arm switch 33. The time change rate di / dt varies depending on the phase current IM flowing through the first open / close switch 60, and the larger the phase current IM, the larger the time change rate di / dt. In the present embodiment, since the on / off of the second open / close switch 64 is switched based on the phase current IM flowing through the first open / close switch 60, the generation of an excessive surge voltage can be appropriately suppressed.

When the phase current IM is larger than the threshold current Is, the surge energy generated when the switching states of the switches 32 and 33 are switched also becomes large. Therefore, the generated surge voltage also increases, and it is necessary to turn on the second open / close switch 64.

When the phase current IM is equal to or less than the threshold current Is, the surge voltage generated also becomes small, and it is not necessary to turn on the second open / close switch 64. In this case, when the second open / close switch 64 is turned on, the second capacitor 35 acts to reduce the system efficiency. In the present embodiment, when it is determined that the threshold current Is or less, the second open / close switch 64 is turned off, so that the high system efficiency of the rotary electric machine system 100 can be maintained.

In the present embodiment, when the electric angular velocity ω and the output torque TE of the rotary electric machine 10 are included in the second drive range HB, that is, the first condition that the rotary electric machine 10 is in a high rotation drive state, and the rotary electric machine 10 has a high torque. When at least one of the second condition of being in the drive state is satisfied, the first open / close switch 60 is turned on, and open connection drive can be performed. However, even if the rotary electric machine 10 is driven by open wiring, for example, in a high rotation and low torque state, the phase current IM flowing through the first open / close switch 60 may be equal to or less than the threshold current Is. In this case, when the second open / close switch 64 is turned on, the second capacitor 35 acts to increase the loss and reduce the system efficiency of the rotary electric system 100.

In the present embodiment, even when the rotary electric machine 10 is driven by open connection, the second open / close switch 64 is turned off when it is determined that the threshold current Is or less. Therefore, the increase in loss when the second capacitor 35 operates can be suppressed to the minimum necessary, and the high system efficiency of the rotary electric system 100 can be maintained.

(Other embodiments)
The above embodiment may be modified as follows.

-The power storage device is not limited to the battery 40, and may be a capacitor.

-The rotary electric machine 10 is not limited to a three-phase one, but may be a two-phase one or a four-phase or more one.

The switch included in the first inverter 20 is not limited to the IGBT, and may be, for example, a MOSFET. In this case, the body diode of the MOSFET can be used as the diode 24 which is reversely connected to the switch, and it is not necessary to use the freewheel diode separately from the MOSFET. The same applies to the second inverter 30, the first open / close switch 60, and the second open / close switch 64.

The electric path provided with the open / close switch 60 is not limited to the power supply line CE, but may be the ground line CG. Further, the open / close switch 60 may be provided on both the power supply line CE and the ground line CG. When the open / close switch 60 is provided on the ground wire CG, the open / close switch 60 may be provided as follows. Specifically, the negative electrode side of the battery 40, the emitter terminal of the first lower arm switch 23, and the emitter terminal of the second lower arm switch 33 are connected to the ground wire CG in this order. That is, the emitter terminal of the second lower arm switch 33 is connected to the ground wire CG on the side opposite to the battery 40 from the connection point between the ground wire CG and the first inverter 20. In this case, in the ground wire CG, an open / close switch 60 may be provided between the connection point with the first inverter 20 and the connection point with the second inverter 30.

-For example, the third combined inductance L3 may be set smaller than the first combined inductance L1 by setting the fourth inductance LD smaller than the first inductance LA. In this case, the second withstand voltage value VB2 of the second inverter 30 can be set smaller than the first withstand voltage value VB1 of the first inverter 20, and the manufacturing cost of the rotary electric machine system 100 can be reduced.

-In the connection line CN, the second open / close switch 64 may be connected to the higher potential side than the second capacitor 35.

10 ... Rotating electric machine, 14 ... Winding, 20 ... 1st inverter, 22 ... 1st upper arm switch, 23 ... 1st lower arm switch, 25 ... 1st capacitor, 30 ... 2nd inverter, 32 ... 2nd upper arm Switch, 33 ... 2nd lower arm switch, 35 ... 2nd capacitor, 50 ... control device, 60 ... open / close switch, CE ... power supply line, CG ... ground wire.

Claims (6)

The first electric path (CE) connected to the positive electrode side of the power storage device (40) and
A second electric circuit (CG) connected to the negative electrode side of the power storage device, and
A first upper arm switch (22) and a first lower arm switch (23) connected in series are provided for each phase, and the high potential side terminal of the first upper arm switch is connected to the first electric path. The first inverter (20) in which the low potential side terminal of the first lower arm switch is connected to the second electric path, and
A second upper arm switch (32) and a second lower arm switch (33) connected in series are provided for each phase, and the high potential side terminal of the second upper arm switch is connected to the first electric path. A second inverter (30) in which the low potential side terminal of the second lower arm switch is connected to the second electric path, and
The armature winding (14) is provided, and the first end of the armature winding is connected to the low potential side terminal of the first upper arm switch and the high potential side terminal of the first lower arm switch, and the first end is connected. 2 A rotary electric machine (10) in which the second end of the armature winding is connected to the low potential side terminal of the upper arm switch and the high potential side terminal of the second lower arm switch.
An open / close switch (60) provided between a connection point with the first inverter and a connection point with the second inverter in at least one of the first electric path and the second electric path.
A first capacitor (25) connecting between the first electric path and the second electric path on the first inverter side of the open / close switch.
A rotary electric system including a second capacitor (35) that connects the first electric path and the second electric path on the second inverter side of the open / close switch. The open / close switch is the first open / close switch (60).
A second open / close switch (64) connected in series to the second capacitor,
A control device (50) for turning on / off the first open / close switch and the second open / close switch is provided.
The series connection body of the second capacitor and the second open / close switch is connected between the first electric path and the second electric path.
The rotary electric system according to claim 1, wherein the control device turns on the second open / close switch during the on period of the first open / close switch, and turns off the second open / close switch during the off period of the first open / close switch. A current determination unit (50) for determining whether or not the current flowing through the armature winding is larger than the threshold value is provided.
The rotary electric system according to claim 2, wherein the control device turns on the second open / close switch on condition that the current determination unit determines that the threshold value is larger than the threshold value. The control device switches the first open / close switch when at least one of a first condition that the rotary electric machine is in a high rotation drive state and a second condition that the rotary electric machine is in a high torque drive state is satisfied. The rotary electric machine system according to claim 3, wherein the rotary electric machine system is turned on and the first open / close switch is turned off when both the first condition and the second condition are not satisfied. The rotary electric system according to any one of claims 1 to 4, wherein the withstand voltage value of the second inverter is equal to or less than the withstand voltage value of the first inverter. The first upper arm switch and the second upper arm switch are switching elements having the same specifications, and the first lower arm switch and the second lower arm switch are switching elements having the same specifications. The rotary electric system according to any one of 1 to 5.

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