JP7474045B2 - Rotating Electric Machine System - Google Patents

Description

The present invention relates to a rotating electrical machine system.

Conventionally, a system is known that includes a battery, an inverter connected to the battery, and a motor that is connected to the inverter and inputs and outputs power to and from the battery via the inverter (for example, see Patent Document 1). In this system, if a failure in the inverter occurs during the rotational driving of the motor, the voltage applied to the motor from the inverter decreases, causing an increase in the motor's back electromotive voltage applied to the inverter. In this case, if this back electromotive voltage exceeds the withstand voltage of the battery, the battery will suffer an overvoltage failure.

In the above system, at least one of the upper and lower arm switches that make up the inverter is provided with a reverse switch that reverses the direction of current flow relative to this arm switch. When motor control fails, the upper and lower arm switches and the reverse switch are turned off, preventing the motor's back electromotive force from being applied to the battery, and preventing the battery from overvoltage failure due to this back electromotive force.

Japanese Patent No. 5017529

The above-mentioned system cannot suppress the increase in the back electromotive voltage of a rotating electric machine that occurs when control of the rotating electric machine such as a motor fails. Therefore, when the back electromotive voltage of the rotating electric machine is applied to the upper and lower arm switches, and this back electromotive voltage exceeds the withstand voltage of the upper and lower arm switches, the inverter will fail due to overvoltage. In addition, if the electrical connection between the rotating electric machine and a storage device such as a battery is cut off when control of the rotating electric machine fails, the release path for the electromagnetic energy stored in the rotating electric machine is lost. Therefore, an excessive surge voltage is generated when the upper and lower arm switches and the reverse switch are turned off, and this surge voltage causes an overvoltage failure of the inverter.

The present invention was made in consideration of the above circumstances, and its purpose is to provide a rotating electric machine system that can suppress overvoltage failures in the inverter and the power storage device when control of the rotating electric machine fails.

The first means for solving the above problem includes an inverter having a first electrical path connected to the positive electrode side of a power storage device, a second electrical path connected to the negative electrode side of the power storage device, and an upper arm switch and a lower arm switch connected in series for each phase, with the high potential side terminal of the upper arm switch connected to the first electrical path and the low potential side terminal of the lower arm switch connected to the second electrical path, a rotating electric machine having an armature winding including a first winding and a second winding for each phase, with one end of the armature winding connected to the low potential side terminal of the upper arm switch and the high potential side terminal of the lower arm switch in each phase, an open/close switch connecting between the first winding and the second winding in each phase, and a rectifier element connecting between the first electrical path and the second electrical path and one end of at least one of the first winding and the second winding on the open/close switch side, or between one of the first electrical path and the second electrical path and one end of the first winding and the second winding on the open/close switch side in each phase.

In the first method, the rotating electric machine has an armature winding including a first winding and a second winding for each phase, and an open/close switch is connected between the first winding and the second winding for each phase. Therefore, when the rotating electric machine fails to control, the open/close switch is turned off, thereby reducing the number of turns of the armature winding for each phase. The number of turns of the armature winding for each phase is proportional to the back electromotive voltage of the rotating electric machine that occurs when the rotating electric machine fails to control. Therefore, by reducing the number of turns of the armature winding for each phase, it is possible to suppress an increase in the back electromotive voltage of the rotating electric machine that occurs when the rotating electric machine fails to control, and it is possible to suppress overvoltage failure of the inverter and the power storage device due to this back electromotive voltage.

In addition, the first means includes a rectifier element connected to at least one of the first and second windings of each phase, and when the open/close switch is turned off, the electromagnetic energy stored in the armature winding can be released to the storage device via this rectifier element. Therefore, even if the open/close switch is turned off when the rotating electric machine fails to be controlled, the generation of an excessive surge voltage can be suppressed, and overvoltage failure of the inverter and storage device due to this surge voltage can be suppressed.

In the second means, in each phase, a first end of the first winding is connected to the low potential side terminal of the upper arm switch and the high potential side terminal of the lower arm switch, and a first end of the second winding is connected to a neutral point. The rectifier element has, in each phase, a high potential side rectifier element that connects the first electrical path and the second end of the second winding, and in each phase, a low potential side rectifier element that connects the second electrical path and the second end of the second winding. The high potential side rectifier element allows the flow of current in a first specified direction from the second winding side to the first electrical path side and blocks the flow of current in a direction opposite to the first specified direction. The low potential side rectifier element allows the flow of current in a second specified direction from the second electrical path side to the second winding side and blocks the flow of current in a direction opposite to the second specified direction.

In the second method, in a rotating electric machine having star-connected windings, the electromagnetic energy stored in the armature winding is released when the open/close switch is turned off using a high-side rectifier element and a low-side rectifier element. In the second method, since no current flows through the inverter when the electromagnetic energy is released, the electromagnetic energy stored in the first and second windings can be properly released even when the rotating electric machine loses control due to an inverter failure, such as an open failure of the upper arm switch or a close failure of the lower arm switch.

In the third means, in each phase, a first end of the first winding is connected to a low potential side terminal of the upper arm switch and a high potential side terminal of the lower arm switch, a first end of the second winding is connected to a neutral point, and diodes are connected in reverse parallel to the upper arm switch and the lower arm switch. The rectifier element has, in each phase, a high potential side rectifier element that connects between the first electrical path and the second end of the first winding, and in each phase, a low potential side rectifier element that connects between the second electrical path and the second end of the first winding, and the high potential side rectifier element allows the flow of current in a first specified direction from the first winding side to the first electrical path side and blocks the flow of current in a direction opposite to the first specified direction, and the low potential side rectifier element allows the flow of current in a second specified direction from the first electrical path side to the second winding side and blocks the flow of current in a direction opposite to the second specified direction.

In the third method, in a rotating electric machine having star-connected windings, the electromagnetic energy stored in the armature winding is released when the opening/closing switch is turned off using a diode connected in anti-parallel to the high-potential side rectifier element and the lower arm switch, or a diode connected in anti-parallel to the upper arm switch and a low-potential side rectifier element. In the third method, when the electromagnetic energy is released, a current flows in the wiring between the inverter and the rotating electric machine. Therefore, the generation of surge voltage caused by the inductance of this wiring can be suppressed.

In a fourth means, the inverter includes a first inverter having a first upper arm switch and a first lower arm switch connected in series for each phase, the high potential side terminal of the first upper arm switch being connected to the first electrical path and the low potential side terminal of the first lower arm switch being connected to the second electrical path, and a second inverter having a second upper arm switch and a second lower arm switch connected in series for each phase, the high potential side terminal of the second upper arm switch being connected to the first electrical path and the low potential side terminal of the second lower arm switch being connected to the second electrical path, and diodes are connected in reverse parallel to the first upper arm switch and the first lower arm switch, and in each phase, a first end of the first winding is connected to the low potential side terminal of the first upper arm switch and the low potential side terminal of the The first end of the second winding is connected to the high potential terminal of the first lower arm switch, and the first end of the second winding is connected to the low potential terminal of the second upper arm switch and the high potential terminal of the second lower arm switch. The rectifier element has a high potential side rectifier element that connects the first electrical path and the second end of the first winding in each phase, and a low potential side rectifier element that connects the second electrical path and the second end of the first winding in each phase. The high potential side rectifier element allows the flow of current in a first specified direction from the first winding side to the first electrical path side and blocks the flow of current in a direction opposite to the first specified direction. The low potential side rectifier element allows the flow of current in a second specified direction from the second electrical path side to the first winding side and blocks the flow of current in a direction opposite to the second specified direction.

In the fourth method, in a rotating electric machine having an open-connected winding, the electromagnetic energy stored in the armature winding is released when the opening/closing switch is turned off using a diode connected in anti-parallel to the high-potential side rectifier element and the lower arm switch, or a diode connected in anti-parallel to the upper arm switch and a low-potential side rectifier element. In the fourth method, when the electromagnetic energy is released, a current flows only through the first inverter out of the first and second inverters. Therefore, it is possible to suppress thermal stress being applied to the second inverter when the electromagnetic energy is released.

In the fifth means, the inverter includes a first inverter having a first upper arm switch and a first lower arm switch connected in series for each phase, the high potential side terminal of the first upper arm switch being connected to the first electrical path and the low potential side terminal of the first lower arm switch being connected to the second electrical path, and a second inverter having a second upper arm switch and a second lower arm switch connected in series for each phase, the high potential side terminal of the second upper arm switch being connected to the first electrical path and the low potential side terminal of the second lower arm switch being connected to the second electrical path, and diodes are connected in reverse parallel to the first upper arm switch and the second upper arm switch, and in each phase, a first end of the first winding is connected to the low potential side terminal of the first upper arm switch and the low potential side terminal of the first lower arm switch. The first end of the second winding is connected to the high potential terminal of the second upper arm switch, and the first end of the second winding is connected to the low potential terminal of the second upper arm switch and the high potential terminal of the second lower arm switch. The rectifier element has a first low potential side rectifier element that connects the second electrical path and the second end of the first winding in each phase, and a second low potential side rectifier element that connects the second electrical path and the second end of the second winding in each phase. The first low potential side rectifier element allows the flow of current in a first specified direction from the second electrical path side to the first winding side and blocks the flow of current in a direction opposite to the first specified direction. The second low potential side rectifier element allows the flow of current in a second specified direction from the second electrical path side to the second winding side and blocks the flow of current in a direction opposite to the second specified direction.

In the fifth means, in a rotating electric machine having an open-connected winding, a diode connected in inverse parallel to the upper arm switch and a first low-potential side rectifier element or a second low-potential side rectifier element are used to release electromagnetic energy stored in the armature winding when the open/close switch is turned off. In the fifth means, the rectifier elements are provided in a distributed manner between the first winding and the open/close switch, and between the open/close switch and the second winding, and when electromagnetic energy is released, current flows in both the first inverter and the second inverter. Therefore, the thermal stress applied to the first inverter and the second inverter when electromagnetic energy is released can be distributed, and failure of the first inverter and the second inverter due to this thermal stress can be suppressed.

In the sixth means, the inverter includes a first inverter having a first upper arm switch and a first lower arm switch connected in series for each phase, the high potential side terminal of the first upper arm switch being connected to the first electrical path and the low potential side terminal of the first lower arm switch being connected to the second electrical path, and a second inverter having a second upper arm switch and a second lower arm switch connected in series for each phase, the high potential side terminal of the second upper arm switch being connected to the first electrical path and the low potential side terminal of the second lower arm switch being connected to the second electrical path, and diodes are connected in reverse parallel to the first lower arm switch and the second lower arm switch, and in each phase, a first end of the first winding is connected to the low potential side terminal of the first upper arm switch and the low potential side terminal of the first lower arm switch. The first end of the second winding is connected to the high potential terminal of the second upper arm switch, and the first end of the second winding is connected to the low potential terminal of the second upper arm switch and the high potential terminal of the second lower arm switch. The rectifier element has a first high potential side rectifier element that connects the first electrical path and the second end of the first winding in each phase, and a second high potential side rectifier element that connects the first electrical path and the second end of the second winding in each phase. The first high potential side rectifier element allows the flow of current in a first specified direction from the first winding side to the first electrical path side and blocks the flow of current in a direction opposite to the first specified direction. The second high potential side rectifier element allows the flow of current in a second specified direction from the second winding side to the first electrical path side and blocks the flow of current in a direction opposite to the second specified direction.

In the sixth aspect, in a rotating electric machine having an open-connected winding, the electromagnetic energy stored in the armature winding is released when the open-close switch is turned off by using a diode connected in inverse parallel to the first low-potential side rectifier element or the second low-potential side rectifier element and the lower arm switch. In the sixth aspect, the rectifier elements are provided in a distributed manner between the first winding and the open-close switch, and between the open-close switch and the second winding, and when the electromagnetic energy is released, a current flows in both the first inverter and the second inverter. Therefore, the thermal stress applied to the first inverter and the second inverter when the electromagnetic energy is released can be distributed, and the failure of the first inverter and the second inverter due to this thermal stress can be suppressed.

In the seventh aspect, the rectifying element is a diode. Therefore, the rectifying function of the diode allows the flow of current in a specified direction and prevents the flow of current in the opposite direction to the specified direction.

In the eighth aspect, the first winding and the second winding are magnetically coupled to each other. Therefore, even if, for example, a rectifying element is provided connected to the first winding and no rectifying element is provided connected to the second winding, the electromagnetic energy stored in the second winding can be released via the magnetically coupled first winding when the opening/closing switch is turned off. This simplifies the configuration of the rotating electric machine system while suppressing the generation of excessive surge voltage.

The ninth means includes a control device that switches the open/close switch off when it is determined that a control failure of the rotating electric machine has occurred. Therefore, when no control failure of the rotating electric machine has occurred, the open/close switch is turned on, so that the number of turns of the armature winding of each phase can be increased. Then, when a control failure of the rotating electric machine has occurred, the open/close switch is turned off, so that an increase in the back electromotive voltage of the rotating electric machine can be suppressed.

In a tenth embodiment, the control device determines whether the potential difference between the first electrical path and the second electrical path is higher than a threshold voltage, and if it determines that the potential difference is higher than the threshold voltage, determines that the control failure has occurred.

When an open fault occurs in one of the upper arm switch and the lower arm switch of each phase, the voltage applied from the inverter to the rotating electric machine decreases, causing the back electromotive voltage of the rotating electric machine applied to the inverter to increase, and the potential difference between the first electrical path and the second electrical path increases. In the tenth means, when it is determined that this potential difference is higher than the threshold voltage, the open/close switch is turned off. Therefore, it is possible to prevent an open fault in one switch from causing an overvoltage fault in the other normal switch.

The eleventh means includes a power switch provided in at least one of the first electrical path and the second electrical path on the inverter side of the connection point with the power storage device, and a capacitor connecting the first electrical path and the second electrical path on the inverter side of the power switch.

The power switch is on while the rotating electric machine is running. When an open fault occurs in this power switch, the voltage applied from the inverter to the rotating electric machine decreases, causing the back electromotive voltage of the rotating electric machine applied to the inverter to increase, and the potential difference between the first electrical path and the second electrical path increases. In the eleventh means, when it is determined that this potential difference is higher than the threshold voltage, the open/close switch is turned off. Therefore, it is possible to prevent an overvoltage fault in the switch included in the inverter due to an open fault in the power switch.

In the twelfth means, the control device determines whether the current flowing through the armature winding is greater than a threshold current, and if it determines that the current is greater than the threshold current, determines that the control failure has occurred.

In an inverter having upper and lower arm switches connected in series, when a closed fault occurs in one of the switches, an excessive current flows in the armature winding due to an upper and lower arm short circuit in which both the upper and lower arm switches are turned on simultaneously. In the twelfth means, when it is determined that the current flowing in the armature winding is greater than the threshold current, the open/close switch is turned off. Therefore, when a control loss of the rotating electric machine occurs due to a closed fault in one of the switches, it is possible to prevent an overvoltage fault in the other normal switch.

In a thirteenth aspect, when the control device determines that the control failure has occurred while performing field weakening control of the rotating electric machine, the control device switches the open/close switch to OFF.

If a control failure occurs in the rotating electric machine while field-weakening control is being performed on the rotating electric machine, the field-weakening control is stopped, causing an excessive back electromotive force to be generated in the rotating electric machine. In the thirteenth means, if it is determined that a control failure has occurred while field-weakening control is being performed on the rotating electric machine, the opening/closing switch is turned off. This makes it possible to suppress the excessive back electromotive force of the rotating electric machine caused by the stop of field-weakening control, and to suppress overvoltage failures of the inverter and the power storage device caused by this back electromotive force.

In the fourteenth embodiment, the open/close switch is a normally open switching element capable of cutting off current in both directions.

In the fourteenth means, the open/close switch is a switching element capable of bidirectional current interruption. Therefore, by turning off the open/close switch when control of the rotating electric machine fails, the first winding and the second winding can be reliably separated, and the number of turns of the armature winding of each phase can be reduced. In addition, in the fourteenth means, the open/close switch is a normally open switching element. Therefore, when the control device loses power, the open/close switch can be turned off. This makes it possible to suppress the back electromotive voltage of the rotating electric machine when the control device loses power, and to suppress overvoltage failure of the inverter and the power storage device due to this back electromotive voltage.

1 is an overall configuration diagram of a rotating electrical machine system according to a first embodiment; 5 is a flowchart showing a procedure of a cutoff process according to the first embodiment. 5 is a diagram showing a transition of a back electromotive voltage of a rotating electric machine when a control failure of the rotating electric machine occurs; FIG. 6 is a diagram showing a transition of a back electromotive force of a rotating electric machine in a comparative example. FIG. 13 is an overall configuration diagram of a rotating electrical machine system according to a second embodiment. FIG. 13 is an overall configuration diagram of a rotating electrical machine system according to a third embodiment. 13 is a flowchart showing a procedure of a cutoff process according to a third embodiment. FIG. 13 is an overall configuration diagram of a rotating electric machine system according to a fourth embodiment. FIG. 13 is an overall configuration diagram of a rotating electric machine system according to a fifth embodiment.

First Embodiment
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of a rotating electric machine system according to the present invention, which is embodied as an on-vehicle rotating electric machine system 100, will be described below with reference to the drawings.

As shown in FIG. 1, the rotating electric machine system 100 according to this embodiment includes a rotating electric machine 10, an inverter 20, a battery 40 as a power storage device, and a control device 50 that controls the rotating electric machine 10.

The rotating electric machine 10 has the functions of power driving and regenerative driving, and is specifically an MG (Motor Generator). The rotating electric machine 10 inputs and outputs electric power between the battery 40. Specifically, during power driving, the rotating electric machine 10 is driven by electric power input from the battery 40 and provides propulsive force to the vehicle, and during regenerative driving, the rotating electric machine 10 generates electric power using the deceleration energy of the vehicle and outputs the electric power to the battery 40.

The rotating electric machine 10 includes a rotor 11 and a stator 13. The rotor 11 is provided with a permanent magnet 12 that generates a field. In other words, the rotating electric machine 10 is a permanent magnet field type rotating electric machine. The permanent magnet 12 is, for example, a neodymium magnet or a ferrite magnet.

The stator 13 is provided with three-phase windings 14. Each winding 14 is, for example, a wave winding, and includes a first winding 15 and a second winding 16. The first winding 15 and the second winding 16 are connected via an opening/closing unit 62, and are magnetically coupled to each other via a stator core (not shown). The configuration of the opening/closing unit 62 will be described later. In this embodiment, the winding 14 corresponds to the "armature winding."

The first end of the first winding 15 of each phase is connected to the battery 40 via the inverter 20. The battery 40 is a rechargeable storage battery, for example, a battery pack in which multiple lithium ion storage batteries are connected in series. Note that the battery 40 may be another type of storage battery.

The first end of the second winding 16 of each phase is connected to the neutral point PN. In other words, the three-phase windings 14 of the stator 13 are star-connected. The second end of the first winding 15 of each phase is connected to the second end of the second winding 16 via the opening/closing unit 62.

The inverter 20 is configured by connecting in parallel a series connection of upper arm switches 22 (22A, 22B, 22C) which are high-potential side switching elements, and lower arm switches 23 (23A, 23B, 23C) which are low-potential side switching elements. In this embodiment, voltage-controlled semiconductor switching elements, more specifically IGBTs, are used as the switches 22 and 23. In each phase, the first end of the first winding 15 is connected to the emitter terminal of the upper arm switch 22 and the collector terminal of the lower arm switch 23. The upper arm diode 24, which is a freewheel diode, is connected in inverse parallel to the upper arm switch 22, and the lower arm diode 25, which is a freewheel diode, is connected in inverse parallel to the lower arm switch 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 positive electrode side of the battery 40 and the collector terminal of the upper arm switch 22 are connected by a power line LE as a first electrical path, and the negative electrode side of the battery 40 and the emitter terminal of the lower arm switch 23 are connected by a ground line LG as a second electrical path. In other words, the inverter 20 is connected to the battery 40 via the power line LE and the ground line LG. A power switch 60 is provided on the power line LE on the inverter 20 side of the connection point with the battery 40. The power switch 60 is normally on when the rotating electric machine 10 is driven. In addition, the power line LE and the ground line LG are connected by a capacitor 26. The capacitor 26 connects between the power line LE and the ground line LG on the inverter 20 side of the power switch 60.

The control device 50 is equipped with a well-known microcomputer consisting of a CPU, ROM, RAM, flash memory, etc. The control device 50 acquires various signals and performs various controls based on the acquired information.

Specifically, when the rotating electric machine 10 is driven, the control device 50 acquires detection values from a voltage sensor 51 that detects the voltage VB of the capacitor 26, a phase current sensor 53 that detects the current IM flowing through the windings 14 of each phase of the rotating electric machine 10, a rotation angle sensor 54 that detects the electrical angle θ of the rotating electric machine 10, and the like. Based on the acquired detection values, the control device 50 controls the inverter 20 to control the control variable of the rotating electric machine 10 to its command value. In this embodiment, the control variable is the output torque TE.

Specifically, in controlling the inverter 20, the control device 50 outputs drive signals SG corresponding to the switches 22 and 23 to the switches 22 and 23 so that the switches 22 and 23 are alternately turned on with dead times in between. The drive signal SG is either an ON command that turns on the switches 22 and 23, or an OFF command that turns off the switches 22 and 23.

The control device 50 also generates a switching signal SC to switch the power switch 60 on and off based on the acquired detection value, and outputs the generated switching signal SC to the power switch 60.

In the rotating electric machine system 100, when the rotating electric machine 10 is rotated and driven, a control failure of the rotating electric machine 10 may occur due to a failure of the switches 22 and 23 constituting the inverter 20. In this case, a back electromotive voltage VR of the rotating electric machine 10 applied to the inverter 20 is generated according to the rotation speed of the rotor 11, specifically, the electrical angular velocity ω as the time differential value of the electrical angle θ of the rotating electric machine 10. In particular, when the rotating electric machine 10 is in a high rotation speed drive and field weakening control is being performed, the control failure of the rotating electric machine 10 cuts off the power supply from the battery 40, stops the field weakening control, and generates an excessive back electromotive voltage VR in the rotating electric machine 10. Here, the field weakening control is a control that reduces the back electromotive voltage VR generated in the winding 14 of the rotating electric machine 10 by setting the d-axis current Id in the dq coordinate system of the rotating electric machine 10 to a predetermined negative value.

When the counter electromotive voltage VR of the rotating electric machine 10 is applied to the battery 40 and the switches 22 and 23 included in the inverter 20, and this counter electromotive voltage VR exceeds the withstand voltage VL (see Figure 4) of the battery 40 and the switches 22 and 23, the battery 40 and the switches 22 and 23 suffer an overvoltage failure.

Therefore, in this embodiment, the rotating electric machine system 100 is provided with an opening/closing unit 62 and a diode rectifier circuit 70. The opening/closing unit 62 includes opening/closing switches 64 (64A, 64B, 64C). In each phase, the opening/closing switch 64 connects between the first winding 15 and the second winding 16. Specifically, of both terminals of the opening/closing switch 64, the first terminal X (XA, XB, XC) is connected to the second end of the first winding 15, and the second terminal Z (ZA, ZB, ZC) is connected to the second end of the second winding 16. The opening/closing switch 64 is a switching element capable of bidirectional current interruption, and is, for example, an element in which two IGBTs are connected in series so that the directions of current flow are opposite to each other. Here, being capable of bidirectional current interruption means that no parasitic diode or the like is formed in the opening/closing switch 64, and there is no unintended current flow due to this parasitic diode. In addition, the opening/closing switch 64 is a normally open switching element.

The control device 50 generates a control signal SA to switch the opening/closing switch 64 on and off based on the voltage VB of the capacitor 26 and the current IM flowing through the rotating electric machine 10, and outputs the generated control signal SA to the opening/closing switch 64.

The diode rectifier circuit 70 is configured by connecting in parallel a series connection of high-side diodes 72 (72A, 72B, 72C) as high-side rectifier elements and low-side diodes 73 (73A, 73B, 73C) as low-side rectifier elements. In each phase, the diode rectifier circuit 70 is connected between the open/close switch 64 and the second winding 16.

In each phase, the high-side diode 72 connects the power line LE to the second end of the second winding 16, i.e., the end of the second winding 16 on the open/close switch 64 side. The high-side diode 72 is connected so that the forward direction is from the second winding 16 side to the power line LE side. The low-side diode 73 connects the ground line LG to the second end of the second winding 16. The low-side diode 73 is connected so that the forward direction is from the ground line LG side to the second winding 16 side.

In this embodiment, the control device 50 performs a cutoff process of switching the open/close switch 64 off when the rotating electric machine 10 fails to be controlled. As a result, the number of turns of the winding 14 of each phase is reduced from the number of turns (=NA1+NA2) obtained by adding the first number of turns NA1 of the first winding 15 and the second number of turns NA2 of the second winding 16 to the number of turns NA1 and NA2 of the windings 15 and 16. The number of turns of the winding 14 of each phase is proportional to the back electromotive voltage VR of the rotating electric machine 10 that occurs when the rotating electric machine 10 fails to be controlled. Therefore, by reducing the number of turns of the winding 14 of each phase, the back electromotive voltage VR of the rotating electric machine 10 that occurs when the rotating electric machine 10 fails to be controlled can be suppressed, and overvoltage failure of the inverter 20 and the battery 40 due to this back electromotive voltage VR can be suppressed. In this embodiment, the first number of turns NA1 and the second number of turns NA2 are set to be equal.

The rotating electric machine system 100 is also provided with a diode rectifier circuit 70, which includes diodes 72 and 73 connected to the second winding 16. Therefore, when the open/close switch 64 is turned off, the electromagnetic energy stored in the first winding 15 can be released to the capacitor 26 via the diodes 72 and 73. Furthermore, since the second winding 16 is magnetically coupled to the first winding 15, the electromagnetic energy stored in the second winding 16 can be released to the capacitor 26 via the first winding 15 when the open/close switch 64 is turned off. Therefore, even if the open/close switch 64 is turned off when the rotating electric machine 10 fails to be controlled, the generation of an excessive surge voltage can be suppressed, and overvoltage failure of the inverter 20 and the battery 40 due to this surge voltage can be suppressed.

Figure 2 shows a flowchart of the cutoff process in this embodiment. When the rotating electric machine 10 is driven, the control device 50 repeatedly performs the cutoff process at each predetermined control period.

When the cutoff process is started, first in step S10, the voltage VB of the capacitor 26 is acquired using the voltage sensor 51. Then in step S12, it is determined whether the voltage VB acquired in step S10 is higher than the threshold voltage Vth.

In the rotating electric machine 10, if an open circuit failure occurs in the power switch 60 or in one of the switches 22 and 23 included in the inverter 20, the voltage applied from the inverter 20 to the rotating electric machine 10 drops. This causes the back electromotive voltage VR of the rotating electric machine 10 applied to the inverter 20 to increase, and the voltage VB of the capacitor 26 to increase above the threshold voltage Vth.

If an open circuit fault has occurred in the power switch 60 or in one of the switches 22, 23 included in the inverter 20, a positive determination is made in step S12. In this case, proceed to step S20. On the other hand, if an open circuit fault has not occurred in either the power switch 60 or the switches 22, 23 included in the inverter 20, a negative determination is made in step S12. In this case, in step S14, the current IM flowing through the rotating electric machine 10 is acquired using the phase current sensor 53. In the following step S16, it is determined whether the current IM acquired in step S14 is greater than the threshold current Ith.

In the rotating electric machine 10, when a closed fault occurs in one of the switches 22, 23 included in the inverter 20, an upper arm short circuit occurs in which both the upper arm switch 22 and the lower arm switch 23 are simultaneously turned on, causing an excessive current IM to flow through the rotating electric machine 10. As a result, the current IM flowing through the rotating electric machine 10 increases above the threshold current Ith.

If a close fault has occurred in either one of the switches 22, 23 included in the inverter 20, a positive determination is made in step S16. In this case, the process proceeds to step S20. On the other hand, if a close fault has not occurred in either of the switches 22, 23 included in the inverter 20, a negative determination is made in step S16. In this case, in the subsequent step S18, the open/close switch 64 is kept on, and the shutoff process is terminated.

If the determination in step S12 or step S14 is affirmative, the process proceeds to step S20. In other words, if a failure occurs in the power switch 60 or the switches 22 and 23 included in the inverter 20, causing a control failure of the rotating electric machine 10, the process proceeds to step S20. In step S20, the inverter 20 is stopped. Specifically, a switching signal SC for turning off the power switch 60 is output to the power switch 60. In addition, a drive signal SG for turning off all of the switches 22 and 23 included in the inverter 20 is output to the switches 22 and 23. In the following step S22, the open/close switch 64 is switched off, and the cutoff process is terminated. Specifically, a control signal SA for turning off the open/close switch 64 is output to the open/close switch 64.

Next, FIG. 3 shows an example of the cutoff process of this embodiment. FIG. 3 shows the transition of the element voltage VA applied to each switch 22, 23 included in the inverter 20 and its peak value. Here, the switches 22, 23 are alternately turned on with dead time in between. Therefore, the peak value of the element voltage VA is equal to the voltage VB of the capacitor 26.

Figure 4 shows the transition of the element voltage VA and its peak value VB in a configuration (hereinafter, a comparative example) in which the opening/closing unit 62 and the diode rectifier circuit 70 are not provided. Here, in Figures 3 and 4, (A) shows the transition of the element voltage VA and its peak value VB, (B) shows the transition of the first current IM1 flowing through the first winding 15 of the rotating electric machine 10, and (C) shows the transition of the second current IM2 flowing through the second winding 16 of the rotating electric machine 10. Also, Figure 3 (D) shows the transition of the emission current ID flowing through the diodes 72 and 73 included in the diode rectifier circuit 70.

As shown in the period from time t1 to time t2 in FIG. 3, when no failure occurs in either the power switch 60 or the switches 22 and 23 included in the inverter 20, the power switch 60 and the open/close switch 64 are turned on. The rotating electric machine 10 is, for example, PWM controlled. In PWM control, the state of the switches 22 and 23 included in the inverter 20 is controlled based on a comparison of the magnitude between the voltage command value to the rotating electric machine 10 and a carrier signal such as a triangular wave signal.

Specifically, as shown in FIG. 3(A), an element voltage VA having an amplitude equal to the voltage VD of the battery 40 is applied to each switch 22, 23 of the inverter 20. The threshold voltage Vth is set to a value greater than the voltage VD of the battery 40. As shown in FIG. 3(B) and (C), currents IM1, IM2 of each phase, which are sinusoidal signals with a phase difference of 120°, flow through the first winding 15 and the second winding 16 of the rotating electric machine 10. As shown in FIG. 3(D), if no failure occurs in either the power switch 60 or the switches 22, 23 included in the inverter 20, no discharge current ID flows.

At time t2, an open fault occurs in the power switch 60, causing a control failure of the rotating electric machine 10. The voltage applied to the rotating electric machine 10 from the inverter 20 decreases, and the currents IM1 and IM2 flowing through the first winding 15 and the second winding 16 of the rotating electric machine 10 decrease. In addition, the back electromotive voltage VR of the rotating electric machine 10 applied to the inverter 20 increases, causing the peak value VB to increase above the voltage VD of the battery 40.

Then, at time t3, when the crest value VB, that is, the potential difference between the power supply line LE and the ground line LG, becomes higher than the threshold voltage Vth, the switches 22 and 23 included in the inverter 20 are turned off. Also, the open/close switch 64 is turned off. In this embodiment, the second winding 16 is connected to the capacitor 26 via the diodes 72 and 73 included in the diode rectifier circuit 70. Therefore, when the open/close switch 64 is turned off, the electromagnetic energy stored in the second winding 16 can be released to the capacitor 26. Also, the first winding 15 is magnetically coupled to the second winding 16, and when the open/close switch 64 is turned off, the electromagnetic energy stored in the first winding 15 can be released to the capacitor 26 via the second winding 16. Therefore, when the open/close switch 64 is turned off, the generation of an excessive surge voltage is suppressed.

At time t3, the switches 22, 23 and the open/close switch 64 included in the inverter 20 are turned off, and the first current IM1 flowing through the first winding 15 of the rotating electric machine 10 stops. Meanwhile, the second current IM2 flowing through the second winding 16 of the rotating electric machine 10 continues to flow through the diodes 72, 73 included in the diode rectifier circuit 70. As a result, the electromagnetic energy stored in the first winding 15 and the second winding 16 is discharged to the capacitor 26, and at this time, a discharge current ID flows. Then, at time t5, when the crest value VB, that is, the voltage VB of the capacitor 26, increases to the maximum value VX of the back electromotive voltage VR of the rotating electric machine 10, the voltage VB of the capacitor 26 and the back electromotive voltage VR of the rotating electric machine 10 are balanced, and the second current IM2 and the discharge current ID stop.

As shown in FIG. 4, in the comparative example in which the opening/closing unit 62 is not provided, the maximum value VX of the counter electromotive force VR of the rotating electric machine 10 is proportional to the number of turns (=NA1+NA2) obtained by adding the first number of turns NA1 of the first winding 15 and the second number of turns NA2 of the second winding 16. Therefore, at time t4 before time t5 at which the crest value VB increases to the maximum value VX of the counter electromotive force VR of the rotating electric machine 10, the counter electromotive force VR of the rotating electric machine 10 increases beyond the withstand voltage VL of the switches 22 and 23 included in the battery 40 and the inverter 20, causing an overvoltage failure of the inverter 20 and the battery 40.

In this embodiment, an opening/closing unit 62 is provided, and an opening/closing switch 64 is connected between the first winding 15 and the second winding 16 of the rotating electric machine 10. Therefore, by turning off the opening/closing switch 64 when the rotating electric machine 10 fails to be controlled, the maximum value VX of the back electromotive voltage VR of the rotating electric machine 10 is reduced to a value proportional to the number of turns NA1 and NA2 of each winding 15 and 16. Therefore, the back electromotive voltage VR generated in the rotating electric machine 10 when the rotating electric machine 10 fails to be controlled is prevented from increasing beyond the withstand voltage VL of the battery 40 and the switches 22 and 23. This makes it possible to prevent overvoltage failures of the inverter 20 and the battery 40.

The present embodiment described above provides the following advantages:

- In this embodiment, the rotating electric machine 10 has a winding 14 including a first winding 15 and a second winding 16 for each phase, and an open/close switch 64 is connected between the first winding 15 and the second winding 16 of each phase. Therefore, when the rotating electric machine 10 fails to control, the open/close switch 64 is turned off, and the number of turns of the winding 14 of each phase is reduced. The number of turns of the winding 14 of each phase is proportional to the back electromotive voltage VR of the rotating electric machine 10 that occurs when the rotating electric machine 10 fails to control. Therefore, by reducing the number of turns of the winding 14 of each phase, it is possible to suppress an increase in the back electromotive voltage VR of the rotating electric machine 10 that occurs when the rotating electric machine 10 fails to control, and it is possible to suppress overvoltage failure of the inverter 20 and the battery 40 due to this back electromotive voltage VR.

- In this embodiment, diodes 72, 73 are provided connected to the second winding 16, and the electromagnetic energy stored in the winding 14 can be released to the capacitor 26 via these diodes 72, 73 when the opening/closing switch 64 is turned off. Therefore, even if the opening/closing switch 64 is turned off when there is a control failure of the rotating electric machine 10, the generation of an excessive surge voltage can be suppressed, and overvoltage failure of the inverter 20 and the battery 40 due to this surge voltage can be suppressed.

- Specifically, the diodes 72 and 73 are connected to the second winding 16. Therefore, when the opening/closing switch 64 is off, the electromagnetic energy stored in the second winding 16 can be released to the capacitor 26 via the diodes 72 and 73. On the other hand, no diode is connected to the first winding 15. In this embodiment, the first winding 15 and the second winding 16 are magnetically coupled to each other. Therefore, when the opening/closing switch 64 is off, the electromagnetic energy stored in the first winding 15 can be released via the second winding 16. This simplifies the configuration of the rotating electric machine system 100 while suppressing the generation of excessive surge voltage.

- In this embodiment, in a rotating electric machine 10 having star-connected windings 14, the diodes 72, 73 included in the diode rectifier circuit 70 are used to release the electromagnetic energy stored in the first winding 15 and the second winding 16 when the open/close switch 64 is turned off. In this configuration, no current IM flows through the inverter 20 when the electromagnetic energy is released. Therefore, even when control of the rotating electric machine 10 is lost due to a failure of the inverter 20, such as an open failure of the upper arm switch 22 or a close failure of the lower arm switch 23, the electromagnetic energy stored in the first winding 15 and the second winding 16 can be properly released.

- In this embodiment, in the interruption process, it is determined whether or not a control failure of the rotating electric machine 10 has occurred, and if it is determined that a control failure has occurred, the open/close switch 64 is switched off. Therefore, when a control failure of the rotating electric machine 10 has not occurred, the open/close switch 64 is turned on, so that the number of turns of the winding 14 of each phase can be increased. Then, when a control failure of the rotating electric machine 10 has occurred, the open/close switch 64 is turned off, so that an increase in the back electromotive voltage VR of the rotating electric machine 10 can be suppressed.

- Specifically, when an open fault occurs in any one of the multiple switches 22, 23 included in the inverter 20 or in the power switch 60, the back electromotive voltage VR generated in the rotating electric machine 10 increases, and the voltage VB of the capacitor 26 increases. In this embodiment, when it is determined that the voltage VB of the capacitor 26 is higher than the threshold voltage Vth, the open switch 64 is turned off. Therefore, when control of the rotating electric machine 10 is lost due to an open fault in the switches 22, 23 included in the inverter 20 or the power switch 60, it is possible to prevent the other normal switches 22, 23 from suffering an overvoltage fault.

- In addition, in an inverter 20 having an upper arm switch 22 and a lower arm switch 23 connected in series, when a close fault occurs in one of the switches 22, 23, an excessive current IM flows in the winding 14 due to an upper and lower arm short circuit in which both the upper arm switch 22 and the lower arm switch 23 are simultaneously turned on. In this embodiment, when it is determined that the current IM flowing in the winding 14 is greater than the threshold current Ith, the open/close switch 64 is turned off. Therefore, when a control failure of the rotating electric machine 10 occurs due to a close fault in one of the switches 22, 23, it is possible to prevent an overvoltage fault in the other normal switch 22, 23.

- In this embodiment, the open/close switch 64 is a switching element capable of bidirectional current interruption. Therefore, by turning off the open/close switch 64 when control of the rotating electric machine 10 fails, the first winding 15 and the second winding 16 can be reliably separated, and the number of turns of the winding 14 of each phase can be reduced. Also, in this configuration, since the open/close switch 64 is a normally open switching element, the open/close switch 64 can be turned off when the control device 50 loses power. This makes it possible to suppress the back electromotive voltage VR of the rotating electric machine 10 when the control device 50 loses power, and to suppress overvoltage failures of the inverter 20 and the battery 40 caused by this back electromotive voltage VR.

Second Embodiment
Hereinafter, the second embodiment will be described with reference to Fig. 5, focusing on the differences from the first embodiment. In Fig. 5, the same components as those shown in Fig. 1 are denoted by the same reference numerals and the description thereof will be omitted for convenience.

This embodiment differs from the first embodiment in that the diode rectifier circuit 70 is provided between the first winding 15 and the open/close switch 64, and not between the open/close switch 64 and the second winding 16.

In each phase, the high-side diode 72 connects the power line LE to the second end of the first winding 15, i.e., the end of the first winding 15 on the open/close switch 64 side. The high-side diode 72 is connected so that the forward direction is from the first winding 15 side to the power line LE side. The low-side diode 73 connects the ground line LG to the second end of the first winding 15. The low-side diode 73 is connected so that the forward direction is from the ground line LG side to the first winding 15 side.

In this embodiment, in the interruption process, the switches 22, 23 and the open/close switch 64 included in the inverter 20 are turned off to stop the second current IM2 flowing through the second winding 16 of the rotating electric machine 10. Meanwhile, the first current IM1 flowing through the first winding 15 of the rotating electric machine 10 continues to flow through the diodes 72, 73 included in the diode rectifier circuit 70 and the diodes 24, 25 included in the inverter 20.

Specifically, as shown by the arrow YA in FIG. 5, when the first current IM1 flows from the inverter 20 toward the diode rectifier circuit 70, the first current IM1 flows through the high-side diode 72 and the lower-arm diode 25. Also, as shown by the arrow YB in FIG. 5, when the first current IM1 flows from the diode rectifier circuit 70 toward the inverter 20, the first current IM1 flows through the upper-arm diode 24 and the low-side diode 73.

Therefore, in this embodiment, even after the switches 22, 23, and 64 are turned off, the first current IM1 continues to flow through the wiring LS (LSA, LSB, and LSC) that connects the inverter 20 and the rotating electric machine 10.

According to the present embodiment described above in detail, in a rotating electric machine 10 having a star-connected winding 14, the electromagnetic energy stored in the first winding 15 and the second winding 16 is released when the opening/closing switch 64 is turned off, using the high-side diode 72 and the lower-arm diode 25, or the upper-arm diode 24 and the low-side diode 73. In this configuration, the first current IM1 continues to flow through the wiring LS between the inverter 20 and the rotating electric machine 10 when the electromagnetic energy is released. Therefore, the generation of a surge voltage caused by the inductance of this wiring LS can be suppressed.

Third Embodiment
The third embodiment will be described below with reference to Figures 6 and 7, focusing on the differences from the second embodiment. In Figure 6, the same components as those shown in Figure 5 are denoted by the same reference numerals and will not be described for the sake of convenience.

This embodiment differs from the second embodiment in that the rotating electric machine system 100 includes an inverter 30 in addition to the inverter 20. In the following, for the sake of distinction, the inverter 20 will be referred to as the first inverter 20, and the inverter 30 will be referred to as the second inverter 30. In addition, the upper arm switch 22 of the first inverter 20 will be referred to as the first upper arm switch 22, and the lower arm switch 23 of the first inverter 20 will be referred to as the first lower arm switch 23.

The second inverter 30 is configured by connecting in parallel a series connection of the second upper arm switch 32 (32A, 32B, 32C) which is a high-potential side switching element and the second lower arm switch 33 (33A, 33B, 33C) which is a low-potential side switching element. In this embodiment, voltage-controlled semiconductor switching elements, more specifically, IGBTs, are used as the switches 32 and 33. In each phase, the second end of the second winding 16, that is, the end of the second winding 16 opposite to the open/close switch 64, is connected to the emitter terminal of the second upper arm switch 32 and the collector terminal of the second lower arm switch 33. In other words, the three-phase winding 14 of the stator 13 is open-wired. The upper arm diode 34, which is a freewheel diode, is connected in inverse parallel to the second upper arm switch 32, and the lower arm diode 35, which is a freewheel diode, is connected in inverse parallel to the second lower arm switch 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 line LE. In addition, 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 line LG.

In controlling the second inverter 30, the control device 50 outputs drive signals SG corresponding to the switches 32 and 33 to the switches 32 and 33 so as to alternately turn on the switches 32 and 33 with dead times in between. In the following, for the sake of distinction, the drive signal SG of the first inverter 20 is referred to as the first drive signal SG1, and the drive signal SG of the second inverter 30 is referred to as the second drive signal SG2.

Next, FIG. 7 shows a flowchart of the blocking process of this embodiment. In FIG. 7, the same processes as those shown in FIG. 2 above are given the same step numbers for convenience, and the explanation is omitted.

In the shutoff process of this embodiment, if the determinations in steps S12 and S16 are positive, that is, when the rotating electric machine 10 fails to be controlled, the inverters 20 and 30 are stopped in step S30. Specifically, a switching signal SC for turning off the power switch 60 is output to the power switch 60. In addition, a first drive signal SG1 for turning off all of the switches 22 and 23 included in the first inverter 20 is output to the switches 22 and 23, and a second drive signal SG2 for turning off all of the switches 32 and 33 included in the second inverter 30 is output to the switches 32 and 33.

In the next step S32, it is determined whether or not the field-weakening control of the rotating electric machine 10 is being performed in step S46. The control device 50 performs the field-weakening control of the rotating electric machine 10 using the inverters 20 and 30, and in particular performs the field-weakening control of the rotating electric machine 10 when the rotating electric machine 10 is driven at high speed.

If the determination in step S32 is negative, the process proceeds to step S18, where the open/close switch 64 is kept on. On the other hand, if the determination in step S32 is positive, that is, if it is determined that a control failure has occurred while field-weakening control of the rotating electric machine 10 is being performed, the process proceeds to step S22, where the open/close switch 64 is turned off.

The present embodiment described above provides the following advantages:

- In this embodiment, in a rotating electric machine 10 having an open-connected winding 14, the electromagnetic energy stored in the first winding 15 and the second winding 16 is released when the opening/closing switch 64 is turned off, using the high-side diode 72 and the lower-arm diode 25, or the upper-arm diode 24 and the low-side diode 73. In this configuration, when the electromagnetic energy is released, the current IM flows only through the first inverter 20 of the first inverter 20 and the second inverter 30. Therefore, it is possible to suppress thermal stress being applied to the second inverter 30 when the electromagnetic energy is released.

- If a control failure occurs in the rotating electric machine 10 while the field-weakening control of the rotating electric machine 10 is being performed, the power supply from the battery 40 is cut off and the field-weakening control is stopped, causing an excessive back electromotive force VR to be generated in the rotating electric machine 10. In this embodiment, if it is determined that a control failure has occurred while the field-weakening control of the rotating electric machine 10 is being performed, the opening/closing switch 64 is turned off. Therefore, the excessive back electromotive force VR of the rotating electric machine 10 caused by the stop of the field-weakening control can be suppressed, and overvoltage failure of the inverters 20, 30 and the battery 40 due to this back electromotive force VR can be suppressed.

Fourth Embodiment
Hereinafter, the fourth embodiment will be described with reference to Fig. 8, focusing on the differences from the third embodiment. In Fig. 8, the same components as those shown in Fig. 6 are denoted by the same reference numerals and the description thereof will be omitted for convenience.

This embodiment differs from the third embodiment in that a diode rectifier circuit 70 is provided between the first winding 15 and the open/close switch 64, and between the open/close switch 64 and the second winding 16. The diode rectifier circuit 70 includes a first rectifier circuit 71 provided between the first winding 15 and the open/close switch 64, and a second rectifier circuit 74 provided between the open/close switch 64 and the second winding 16.

The first rectifier circuit 71 includes a first low-potential side diode 73 as a first low-potential side rectifier element. The first low-potential side diode 73 connects the ground line LG to the second end of the first winding 15, i.e., the end of the first winding 15 on the open/close switch 64 side. The first low-potential side diode 73 is connected so that the forward direction is from the ground line LG side to the first winding 15 side.

The second rectifier circuit 74 includes second low-potential side diodes 75 (75A, 75B, 75C) as second low-potential side rectifier elements. The second low-potential side diodes 75 connect the ground line LG to the second end of the second winding 16, i.e., the end of the second winding 16 on the open/close switch 64 side. The second low-potential side diodes 75 are connected such that the forward direction is from the ground line LG side to the second winding 16 side.

On the other hand, the first rectifier circuit 71 and the second rectifier circuit 74 are not provided with high-potential side diodes. In other words, in this embodiment, the winding 14 of the rotating electric machine 10 is not connected to the power supply line LE via the diode rectifier circuit 70.

In this embodiment, in the cutoff process, the switches 22 and 23 included in the first inverter 20, the switches 32 and 33 included in the second inverter 30, and the open/close switch 64 are turned off, so that in each phase, one of the first current IM1 and the second current IM2 stops flowing while the other continues to flow.

Specifically, as shown by the arrow YC in FIG. 8, when the first current IM1 flows from the first inverter 20 to the first rectifier circuit 71 and the second current IM2 flows from the second rectifier circuit 74 to the second inverter 30, the first current IM1 stops and the second current IM2 continues to flow. In this case, the second current IM2 continues to flow through the upper arm diode 34 of the second inverter 30 and the second low-side diode 75 of the second rectifier circuit 74.

Also, as shown by the arrow YD in FIG. 8, when the first current IM1 flows from the first rectifier circuit 71 to the first inverter 20 and the second current IM2 flows from the second inverter 30 to the second rectifier circuit 74, the second current IM2 stops and the first current IM1 continues to flow. In this case, the first current IM1 continues to flow through the upper arm diode 24 of the first inverter 20 and the first low-potential side diode 73 of the first rectifier circuit 71.

In the rotating electric machine 10, there are phases in which the currents IM1 and IM2 flow in the direction indicated by the arrow YC, and phases in which the currents IM1 and IM2 flow in the direction indicated by the arrow YD. Therefore, after the switches 22, 23, 32, 33, and 64 are turned off, the currents IM1 and IM2 flow in both the first inverter 20 and the second inverter 30.

According to the embodiment described above in detail, in the rotating electric machine 10 having the open-connected winding 14, the electromagnetic energy stored in the first winding 15 and the second winding 16 is released when the open-close switch 64 is turned off, using the upper arm diode 24 and the first low potential side diode 73 of the first inverter 20, or the upper arm diode 34 and the second low potential side diode 75 of the second inverter 30. In this configuration, the diode rectifier circuit 70 is provided between the first winding 15 and the open-close switch 64, and between the open-close switch 64 and the second winding 16, and when the electromagnetic energy is released, the current IM flows through both the first inverter 20 and the second inverter 30. Therefore, the thermal stress applied to the first inverter 20 and the second inverter 30 when the electromagnetic energy is released can be distributed, and the failure of the first inverter 20 and the second inverter 30 due to this thermal stress can be suppressed.

Fifth Embodiment
Hereinafter, the fifth embodiment will be described with reference to Fig. 9, focusing on the differences from the fourth embodiment. In Fig. 9, the same components as those shown in Fig. 8 are denoted by the same reference numerals and will not be described for the sake of convenience.

This embodiment differs from the fourth embodiment in that the first rectifier circuit 71 includes a first high-potential side diode 72 as a first high-potential side rectifier element. The first high-potential side diode 72 connects the power supply line LE and the second end of the first winding 15. The first high-potential side diode 72 is connected so that the direction from the first winding 15 side to the power supply line LE side is the forward direction.

This embodiment also differs from the fourth embodiment in that the second rectifier circuit 74 includes second high-potential side diodes 76 (76A, 76B, 76C) as second high-potential side rectifier elements. The second high-potential side diodes 76 connect the power supply line LE and the second end of the second winding 16. The second high-potential side diodes 76 are connected such that the forward direction is from the second winding 16 side toward the power supply line LE side.

On the other hand, the first rectifier circuit 71 and the second rectifier circuit 74 are not provided with low-potential side diodes. In other words, in this embodiment, the winding 14 of the rotating electric machine 10 is not connected to the ground line LG via the diode rectifier circuit 70.

In this embodiment, as shown by the arrow YC in FIG. 9, when the first current IM1 flows from the first inverter 20 to the first rectifier circuit 71 and the second current IM2 flows from the second rectifier circuit 74 to the second inverter 30, the second current IM2 stops and the first current IM1 continues to flow. In this case, the first current IM1 continues to flow through the lower arm diode 25 of the first inverter 20 and the first high potential side diode 72 of the first rectifier circuit 71.

Also, as shown by the arrow YD in FIG. 9, when the first current IM1 flows from the first rectifier circuit 71 to the first inverter 20 and the second current IM2 flows from the second inverter 30 to the second rectifier circuit 74, the first current IM1 stops and the second current IM2 continues to flow. In this case, the second current IM2 continues to flow through the lower arm diode 35 of the second inverter 30 and the second high potential side diode 76 of the second rectifier circuit 74.

According to the present embodiment described above in detail, in the rotating electric machine 10 having the open-connected winding 14, the electromagnetic energy stored in the first winding 15 and the second winding 16 is released when the open-close switch 64 is turned off, using the lower arm diode 25 and the first high potential side diode 72 of the first inverter 20, or the lower arm diode 35 and the second high potential side diode 76 of the second inverter 30. In this configuration, the diode rectifier circuit 70 is provided between the first winding 15 and the open-close switch 64, and between the open-close switch 64 and the second winding 16, and when the electromagnetic energy is released, the current IM flows through both the first inverter 20 and the second inverter 30. Therefore, the thermal stress applied to the first inverter 20 and the second inverter 30 when the electromagnetic energy is released can be distributed, and the failure of the first inverter 20 and the second inverter 30 due to this thermal stress can be suppressed.

Other Embodiments
The above embodiment may be modified as follows.

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

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

- The winding 14 may have a third winding and a fourth winding in addition to the first winding 15 and the second winding 16. In other words, it is sufficient that the number of turns of the winding 14 is reduced by turning off the opening/closing switch 64 compared to when it is on.

The diode rectifier circuit 70 is not limited to a configuration in which the electromagnetic energy stored in the first winding 15 and the second winding 16 is released to the capacitor 26, but may be released, for example, to a ground line LG connected to ground.

- The elements constituting the diode rectifier circuit 70 are not limited to the diodes 72, 73, 75, and 76, and may be constituted by switches such as thyristors or relays. In this case, the control device 50 normally keeps the switch off when the rotating electric machine 10 is driven, and in step S22 of the cutoff process, turns the switch on at the same time as switching off the opening/closing switch 64 or a predetermined period before switching off the opening/closing switch 64. Here, this switch may be capable of cutting off current in both directions by being turned off.

- It is preferable to use diodes 72, 73, 75, and 76 as elements constituting the diode rectifier circuit 70. By using diodes 72, 73, 75, and 76, the rectification function of diodes 72, 73, 75, and 76 allows the flow of forward current IM as the first specified direction and the second specified direction, and prevents the flow of current IM in the direction opposite to the forward direction, without implementing control by the control device 50.

In the third embodiment, a diode rectifier circuit 70 may be provided between the open/close switch 64 and the second winding 16.

10... rotating machine, 14... winding, 15... first winding, 16... second winding, 20, 30... inverter, 22, 32... upper arm switch, 23, 33... lower arm switch, 40... battery, 64... open/close switch, 72, 73, 75, 76... diode, LE... power line, LG... ground line.

Claims (15)

A first electrical path (LE) connected to a positive electrode side of the storage device (40);
A second electrical path (LG) connected to a negative electrode side of the power storage device;
an inverter (20, 30) including, for each phase, a series connection of upper arm switches (22A to 22C ) with upper arm diodes (24) connected in anti-parallel and lower arm switches (23A to 23C) with lower arm diodes (25) connected in anti-parallel, a high potential side terminal of the upper arm switch being connected to the first electrical path, and a low potential side terminal of the lower arm switch being connected to the second electrical path;
A rotating electric machine (10) having an armature winding (14) including a first winding (15) and a second winding (16) for each phase;
Equipped with
In each phase, a first end of the first winding is connected to a low potential terminal of the upper arm switch and a high potential terminal of the lower arm switch, and a first end of the second winding is connected to a neutral point (PN),
an open/close switch (64A to 64C) for connecting between a second end of the first winding and a second end of the second winding in each phase;
a high-potential side rectifier element (72A to 72C) for connecting only the second end of the second winding, among the second end of the first winding and the second end of the second winding, between the first electrical path and the second end of the second winding in each phase;
a low-potential side rectifier element (73A to 73C) for connecting only the second end of the second winding, among the second end of the first winding and the second end of the second winding, to the second electrical path in each phase;
a control device (50) that switches off the open/close switch when it is determined that a control failure of the rotating electric machine has occurred;
Equipped with
the high potential side rectifier element permits a current to flow in a first specified direction from the second winding side to the first electrical path side and blocks a current to flow in a direction opposite to the first specified direction;
A rotating electric system, wherein the low potential side rectifier element allows current to flow in a second specified direction from the second electrical path side to the second winding side, and blocks current to flow in a direction opposite to the second specified direction. A first electrical path (LE) connected to a positive electrode side of the storage device (40);
A second electrical path (LG) connected to a negative electrode side of the power storage device;
an inverter (20, 30) having upper arm switches (22A to 22C, 32A to 32C) and lower arm switches (23A to 23C, 33A to 33C) connected in series for each phase, with high potential side terminals of the upper arm switches connected to the first electrical path and low potential side terminals of the lower arm switches connected to the second electrical path;
A rotating electric machine (10) having an armature winding (14) including a first winding (15) and a second winding (16) for each phase;
Equipped with
Diodes (24, 25) are connected in inverse parallel to the upper arm switch and the lower arm switch,
In each phase, a first end of the first winding is connected to a low potential terminal of the upper arm switch and a high potential terminal of the lower arm switch, and a first end of the second winding is connected to a neutral point (PN),
an open/close switch (64A to 64C) for connecting between a second end of the first winding and a second end of the second winding in each phase;
a high-potential side rectifier element (72A to 72C) for connecting only the second end of the first winding, among the second end of the first winding and the second end of the second winding, between the first electrical path and the high-potential side rectifier element (72A to 72C) for each phase;
a low-potential side rectifier element (73A to 73C) for connecting only the second end of the first winding, among the second end of the first winding and the second end of the second winding, between the second electric path and the low-potential side rectifier element (73A to 73C) for each phase;
a control device (50) that switches off the open/close switch when it is determined that a control failure of the rotating electric machine has occurred;
Equipped with
the high potential side rectifier element permits a current to flow in a first specified direction from the first winding side to the first electrical path side and blocks a current to flow in a direction opposite to the first specified direction;
A rotating electric system, wherein the low potential side rectifier element allows current to flow in a second specified direction from the second electrical path side to the first winding side, and blocks current to flow in a direction opposite to the second specified direction. A first electrical path (LE) connected to a positive electrode side of the storage device (40);
A second electrical path (LG) connected to a negative electrode side of the power storage device;
a first inverter (20) having a first upper arm switch (22A to 22C) and a first lower arm switch (23A to 23C) connected in series for each phase, the high potential side terminal of the first upper arm switch being connected to the first electrical path and the low potential side terminal of the first lower arm switch being connected to the second electrical path;
a second inverter (30) having second upper arm switches (32A to 32C) and second lower arm switches (33A to 33C) connected in series for each phase, the high potential side terminal of the second upper arm switch being connected to the first electrical path and the low potential side terminal of the second lower arm switch being connected to the second electrical path;
A rotating electric machine (10) having an armature winding (14) including a first winding (15) and a second winding (16) for each phase;
Equipped with
Diodes (24, 25) are connected in inverse parallel to the first upper arm switch and the first lower arm switch,
In each phase, a first end of the first winding is connected to a low potential terminal of the first upper arm switch and a high potential terminal of the first lower arm switch, and a first end of the second winding is connected to a low potential terminal of the second upper arm switch and a high potential terminal of the second lower arm switch,
an open/close switch (64A to 64C) for connecting between a second end of the first winding and a second end of the second winding in each phase;
a high-potential side rectifier element (72A to 72C) connected between the first electrical path and a second end of the first winding in each phase;
a low-potential side rectifier element (73A to 73C) for connecting between the second electrical path and a second end of the first winding in each phase;
Equipped with
the high potential side rectifier element permits a current to flow in a first specified direction from the first winding side to the first electrical path side and blocks a current to flow in a direction opposite to the first specified direction;
A rotating electric system, wherein the low potential side rectifier element allows current to flow in a second specified direction from the second electrical path side to the first winding side, and blocks current to flow in a direction opposite to the second specified direction. A first electrical path (LE) connected to a positive electrode side of the storage device (40);
A second electrical path (LG) connected to a negative electrode side of the power storage device;
a first inverter (20) having a first upper arm switch (22A to 22C) and a first lower arm switch (23A to 23C) connected in series for each phase, the high potential side terminal of the first upper arm switch being connected to the first electrical path and the low potential side terminal of the first lower arm switch being connected to the second electrical path;
a second inverter (30) having second upper arm switches (32A to 32C) and second lower arm switches (33A to 33C) connected in series for each phase, the high potential side terminal of the second upper arm switch being connected to the first electrical path and the low potential side terminal of the second lower arm switch being connected to the second electrical path;
A rotating electric machine (10) having an armature winding (14) including a first winding (15) and a second winding (16) for each phase;
Equipped with
Diodes (24, 34) are connected in inverse parallel to the first upper arm switch and the second upper arm switch,
In each phase, a first end of the first winding is connected to a low potential terminal of the first upper arm switch and a high potential terminal of the first lower arm switch, and a first end of the second winding is connected to a low potential terminal of the second upper arm switch and a high potential terminal of the second lower arm switch,
an open/close switch (64A to 64C) for connecting between a second end of the first winding and a second end of the second winding in each phase;
a first low potential side rectifier element (73A to 73C) for connecting between the second electrical path and a second end of the first winding in each phase;
a second low potential side rectifier element (75A to 75C) for each phase, the second electric path being connected between the second end of the second winding;
Equipped with
the first low potential side rectifier element permits a current to flow in a first specified direction from the second electrical path side to the first winding side and blocks a current to flow in a direction opposite to the first specified direction;
A rotating electric system, wherein the second low potential side rectifier element allows current to flow in a second specified direction from the second electrical path side to the second winding side and blocks current to flow in a direction opposite to the second specified direction. A first electrical path (LE) connected to a positive electrode side of the storage device (40);
A second electrical path (LG) connected to a negative electrode side of the power storage device;
a first inverter (20) having a first upper arm switch (22A to 22C) and a first lower arm switch (23A to 23C) connected in series for each phase, the high potential side terminal of the first upper arm switch being connected to the first electrical path and the low potential side terminal of the first lower arm switch being connected to the second electrical path;
a second inverter (30) having second upper arm switches (32A to 32C) and second lower arm switches (33A to 33C) connected in series for each phase, the high potential side terminal of the second upper arm switch being connected to the first electrical path and the low potential side terminal of the second lower arm switch being connected to the second electrical path;
A rotating electric machine (10) having an armature winding (14) including a first winding (15) and a second winding (16) for each phase;
Equipped with
Diodes (25, 35) are connected in inverse parallel to the first lower arm switch and the second lower arm switch,
In each phase, a first end of the first winding is connected to a low potential terminal of the first upper arm switch and a high potential terminal of the first lower arm switch, and a first end of the second winding is connected to a low potential terminal of the second upper arm switch and a high potential terminal of the second lower arm switch,
an open/close switch (64A to 64C) for connecting between a second end of the first winding and a second end of the second winding in each phase;
a first high potential side rectifier element (72A to 72C) for each phase, the first electric path being connected between the second end of the first winding;
a second high potential side rectifier element (76A to 76C) for each phase, the second high potential side rectifier element (76A to 76C) being connected between the first electrical path and a second end of the second winding;
Equipped with
the first high potential side rectifier element permits a current to flow in a first specified direction from the first winding side to the first electrical path side and blocks a current to flow in a direction opposite to the first specified direction;
A rotating electric system, wherein the second high potential side rectifier element allows current to flow in a second specified direction from the second winding side to the first electrical path side, and blocks current to flow in a direction opposite to the second specified direction. The rotating electric machine system according to any one of claims 3 to 5, further comprising a control device (50) that switches the open/close switch to OFF when it is determined that a control failure of the rotating electric machine has occurred. The rotating electric machine system according to claim 6, wherein the control device determines whether the potential difference between the first electrical path and the second electrical path is higher than a threshold voltage (Vth), and when it determines that the potential difference is higher than the threshold voltage, determines that the control failure has occurred. a power switch (60) provided on at least one of the first electrical path and the second electrical path closer to the inverter than a connection point with the power storage device;
a capacitor (26) connecting the first electrical path and the second electrical path on the inverter side of the power switch,
The rotating electric system according to claim 7 , wherein the control device determines whether or not the voltage of the capacitor is higher than the threshold voltage. The rotating electric machine system according to any one of claims 6 to 8, wherein the control device determines whether the current flowing through the armature winding is greater than a threshold current (Ith), and when it is determined that the current is greater than the threshold current, it determines that the control failure has occurred. The rotating electric machine system according to any one of claims 6 to 9, wherein the control device switches off the open/close switch when it determines that the control failure has occurred while performing field weakening control of the rotating electric machine. The rotating electric system according to any one of claims 1 to 3, wherein the high-side rectifying element and the low-side rectifying element are diodes. The rotating electric system according to claim 4, wherein the first low-potential side rectifying element and the second low-potential side rectifying element are diodes. The rotating electric system according to claim 5, wherein the first high-potential side rectifying element and the second high-potential side rectifying element are diodes. The rotating electric machine system according to any one of claims 1 to 13, wherein the first winding and the second winding are magnetically coupled to each other. The rotating electric machine system according to any one of claims 1 to 14, wherein the open/close switch is a normally open switch capable of cutting off current in both directions.

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