WO2018142867A1

WO2018142867A1 - Switch control device

Info

Publication number: WO2018142867A1
Application number: PCT/JP2018/000454
Authority: WO
Inventors: 猪熊　賢二; 拓人鈴木
Original assignee: 株式会社デンソー
Priority date: 2017-01-31
Filing date: 2018-01-11
Publication date: 2018-08-09
Also published as: JP6690567B2; JP2018125959A

Abstract

Switch control devices (24, 70) turn a pair of switches (Sp, Sn, 51, 52) on and off alternately according to a duty signal, so that both are not on simultaneously. The switches (Sp, Sn, 51, 52) are provided in series between a power supply unit and a ground. The switch control device comprises: a signal generating unit (24) that generates duty signals; a determination unit (71) that determines that overcurrent is flowing in a route passing through the pair of switches, in a state for which after an on failure has occurred with one switch of the pair of switches, the other switch is turned on; a break operation unit (72) that, when it is determined by the determination unit that overcurrent is flowing, breaks at a slower speed than the normal break speed of the other switch; and a restriction unit (24) that restricts the on time of the duty signal so as to ensure at least the time required for overcurrent determination by the determination unit and starting of the break operation by the break operation unit.

Description

Switch control device

Cross-reference of related applications

This application is based on Japanese Application No. 2017-016080 filed on Jan. 31, 2017, the contents of which are incorporated herein by reference.

This disclosure relates to a switch control device that turns on and off a pair of switches provided in series between a power supply unit and a ground.

Conventionally, there has been known a technique for determining whether or not there is an abnormality in a rotating electric machine (AC motor) and performing a countermeasure corresponding to the abnormality when the abnormality occurs. For example, Patent Document 1 detects a voltage value for determination according to the current of the power conversion device and the amount of current change, and instructs to stop the operation of power conversion when the voltage value for determination exceeds a first determination threshold value. On the other hand, a technique is disclosed that restricts restarting of power conversion after the power conversion operation is stopped when the determination voltage value exceeds a second determination threshold value that is larger than the first determination threshold value.

Japanese Unexamined Patent Publication No. 2016-178802

By the way, a power conversion device such as an inverter generally uses a configuration in which a pair of semiconductor switches for current control are connected in series between a power supply unit and a ground, and the pair of semiconductor switches are alternately turned on and off. In such a configuration, it is considered that an excessive current (through current) flows through the pair of semiconductor switches when one of the pair of semiconductor switches is turned on, so when it is determined that an overcurrent has flowed, the determination In response to this, the switch is turned off.

Here, it takes a certain amount of time to determine overcurrent. For this reason, the semiconductor switch may be interrupted as a normal operation after the overcurrent starts to flow until the overcurrent determination is completed. In such a case, there is a concern that surge destruction of the semiconductor switch due to large current interruption may occur with the switch interruption.

This indication is made in view of the above-mentioned subject, and the main purpose is to provide a switch control device which can perform switch interception appropriately at the time of overcurrent generation in a course containing a pair of switches. It is in.

Hereinafter, the means for solving the above-mentioned problems and the effects thereof will be described.

In the first means,
A switch control device that alternately turns on and off a pair of switches provided in series between a power supply unit and a ground by a duty signal so that both are not simultaneously turned on,
A signal generator for generating the duty signal;
A determination unit that determines that an overcurrent has flowed in a path leading to the pair of switches in a state where the other switch is turned on after an on failure of one of the pair of switches occurs;
When it is determined by the determination unit that the overcurrent has flowed, a shut-off operation unit that shuts off the other switch at a speed slower than a normal shut-off speed;
A limiting unit that limits the on-time of the duty signal so as to secure at least the time required for the overcurrent determination by the determination unit and the start of the cutoff operation by the cutoff operation unit.

When an on failure of one of the pair of switches occurs and the other switch is turned on, an excessive current (through current) flows through the pair of switches. Further, if the switch is shut off in a state where a large current is flowing, there is a concern that the switch is broken due to a surge voltage. Therefore, in a state where a large current is flowing, it is preferable that the switch cutoff (so-called soft cutoff) is performed at a speed slower than the normal cutoff speed. However, in each switch that is turned on / off by the duty signal, if the on-time is too short, the overcurrent determination and the accompanying switch-off operation are not properly performed, and as a result, there is a concern that a large current is cut off.

In this regard, in the above configuration, the on-time of the duty signal is limited so that at least the time required for the overcurrent determination by the determination unit and the start of the cutoff operation by the cutoff operation unit is secured. As a result, when one of the switches is on-failed, it is possible to appropriately determine the overcurrent and appropriately perform the switch cutoff (soft cutoff) in the state where the overcurrent flows. As a result, when an overcurrent occurs in a path including a pair of switches, the switch can be properly cut off, and thus the switch can be protected.

The second means is applied to a rotating electrical machine unit having a field circuit for energizing a field winding of a wound field type rotating electrical machine, and the field circuit is used as a pair of switches on the power supply side. A first field switch and a second field switch on the ground side, and the determination unit determines that the overcurrent flows through the first field switch and the second field switch, The restriction unit performs at least one of restriction by a duty upper limit value for the duty signal for turning on and off the first field switch and restriction by a duty lower limit value for the duty signal.

In the field circuit of the wound field type rotary electric machine, the first field switch and the second field switch are alternately turned on and off in the field current control. In this case, by limiting the duty signal for the first field switch by the duty upper limit value, it is assumed that an overcurrent flows due to an ON failure of the first field switch, and then the second field switch. Overcurrent determination and switch shut-off operation can be performed properly within the on-period of the magnetic switch. Alternatively, by limiting the duty signal for the first field switch by the duty lower limit value, it is assumed that an overcurrent flows due to an ON failure of the second field switch, and then the first field switch. Overcurrent determination and switch cutoff operation can be properly performed within the switch ON period.

If the first field switch and the second field switch are alternately turned on and off, the duty field limit for the first field switch duty signal is limited to the second field switch. It is agreed that the duty signal is limited by the duty lower limit value. Similarly, the restriction by the duty lower limit value for the duty signal for the first field switch is equivalent to the restriction by the duty upper limit value for the duty signal for the second field switch. The duty upper limit value is a value smaller than the duty ratio 100%, and the duty lower limit value is a value larger than the duty ratio 0%. The same applies to the means 3 described later.

The third means is applied to a rotating electrical machine unit having a rotating electrical machine having a three-phase armature winding group and an inverter circuit for energizing each phase of the armature winding of the rotating electrical machine for each phase. The circuit includes an upper arm switch and a lower arm switch for each phase as the pair of switches, and the determination unit determines that the overcurrent flows through the upper arm switch and the lower arm switch. The restriction unit performs at least one of restriction by a duty upper limit value for the duty signal for turning on and off the upper arm switch and restriction by a duty lower limit value for the duty signal.

In the inverter circuit of a rotating electrical machine, the upper arm switch and the lower arm switch are alternately turned on and off in the current control of each phase. In this case, by limiting the duty signal for the upper arm switch by the duty upper limit value, it is assumed that an overcurrent will flow due to an on failure of the upper arm switch, and then within the on period of the lower arm switch. Thus, it is possible to properly carry out overcurrent determination and switch breaking operation. Or, by limiting the duty signal for the upper arm switch by the duty lower limit value, it is assumed that an overcurrent flows due to an on failure of the lower arm switch, and within the on period of the upper arm switch. Overcurrent determination and switch cutoff operation can be performed properly.

According to a fourth means, the switch control device is provided with the pair of switches in an energization path connected to at least one of the armature winding and the field winding of the rotating electric machine, and controls on / off of the pair of switches. The duty signal is generated on the basis of a comparison between a command signal calculated according to a required value of an energization current to at least one of the armature winding and the field winding and a carrier signal having a predetermined frequency. The limiting unit limits the duty ratio of the duty signal by a duty limit value determined according to the frequency of the carrier signal.

In a rotating electrical machine, for example, the frequency of a carrier signal used when generating a duty signal for armature control may be different from the frequency of a carrier signal used when generating a duty signal for field control. Also, it is conceivable to vary the frequency of the carrier signal used when generating the duty signal for armature control, or to vary the frequency of the carrier signal used when generating the duty signal for field control. . Considering this point, the duty ratio of the duty signal may be limited by a duty limit value determined according to the frequency of the carrier signal. As a result, it is possible to achieve an appropriate on-time limit while ensuring the time required for the overcurrent determination and the switch cutoff operation. For example, the duty upper limit value is decreased as the frequency of the carrier signal is increased. Further, the duty lower limit value is increased as the frequency of the carrier signal is increased.

In the fourth means, a pair of switches are provided in each of the energization path connected to the armature winding and the energization path connected to the field winding, and in the switch control device for controlling on / off of each pair of switches, the armature It is conceivable that the frequency of the carrier signal used when generating the control duty signal is different from the frequency of the carrier signal used when generating the field control duty signal. In such a case, as in the fifth means, the duty limit value may be determined as a value different between the duty signal for armature control and the duty signal for field control.

The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description with reference to the accompanying drawings. The drawing
FIG. 1 is an electric circuit diagram showing a vehicle system. FIG. 2 is a circuit diagram showing an electrical configuration of the rotating electrical machine unit. FIG. 3 is a circuit diagram showing energization paths in the field circuit, FIG. 4 is a circuit diagram schematically showing the configuration of the driver. FIG. 5 is a flowchart showing a processing procedure for generating an operation signal. FIG. 6 is a time chart showing the switching operation of the first switch and the second switch in the field circuit, FIG. 7 is a diagram for explaining the two-phase modulation method. FIG. 8 is a diagram for explaining the two-phase modulation method. FIG. 9 is a diagram for explaining the duty limit value. FIG. 10 is a circuit diagram showing a field circuit having a half-bridge configuration.

Hereinafter, embodiments will be described with reference to the drawings. In the present embodiment, in a vehicle system that supplies electric power to various devices of a vehicle that travels using an engine (internal combustion engine) as a drive source, a control device that performs control of the system is embodied. In the following embodiments, parts that are the same or equivalent to each other are given the same reference numerals in the drawings, and the description of the same reference numerals is used.

As shown in FIG. 1, the vehicle system is a two-power supply system having a lead storage battery 11 and a lithium ion storage battery 12 as a power supply unit. Each storage battery 11, 12 can supply power to the starter 13, various electric loads 14, 15, and the rotating electrical machine unit 16. Further, each of the storage batteries 11 and 12 can be charged by the rotating electrical machine unit 16. In this system, a lead storage battery 11 and a lithium ion storage battery 12 are connected in parallel to the rotating electrical machine unit 16 and the electrical loads 14 and 15, respectively.

The lead storage battery 11 is a well-known general-purpose storage battery. The lithium ion storage battery 12 is a high-density storage battery that has less power loss during charging / discharging and higher output density and energy density than the lead storage battery 11. The lithium ion storage battery 12 is desirably a storage battery having higher energy efficiency during charging / discharging than the lead storage battery 11. The lithium ion storage battery 12 is configured as an assembled battery having a plurality of single cells. These storage batteries 11 and 12 have the same rated voltage, for example, 12V.

The lithium ion storage battery 12 is housed in a housing case and configured as a battery unit U integrated with a substrate. The battery unit U has output terminals P1, P2 and P3, of which the lead storage battery 11, the starter 13 and the electric load 14 are connected to the output terminals P1 and P3, and the electric load 15 and the rotation are connected to the output terminal P2. The electric unit 16 is connected.

The electric loads 14 and 15 have different requirements for the voltage of power supplied from the storage batteries 11 and 12. Among these, the electric load 14 includes a constant voltage required load that is required to be stable so that the voltage of the supplied power is constant or at least fluctuates within a predetermined range. On the other hand, the electric load 15 is a general electric load other than the constant voltage required load.

Specific examples of the electric load 14 that is a constant voltage required load include various ECUs such as a navigation device, an audio device, a meter device, and an engine ECU. In this case, by suppressing the voltage fluctuation of the supplied power, it is possible to suppress the occurrence of unnecessary reset and the like in each of the above devices, and ensure stable operation. The electric load 14 may include a travel system actuator such as an electric steering device or a brake device. Specific examples of the electric load 15 include a seat heater, a heater for a defroster for a rear window, a headlight, a wiper for a front window, and a blower fan for an air conditioner.

The rotating electrical machine unit 16 includes a rotating electrical machine 21, an inverter 22, a field circuit 23, and a rotating electrical machine ECU 24 that controls the operation of the rotating electrical machine 21. The rotating electrical machine unit 16 is a generator with a motor function, and is configured as an electromechanically integrated ISG (Integrated / Starter / Generator). Details of the rotating electrical machine unit 16 will be described later.

The battery unit U is provided with an electrical path L1 that connects the output terminals P1 and P2 and an electrical path L2 that connects the point N1 on the electrical path L1 and the lithium ion storage battery 12 as an in-unit electrical path. Among these, the switch 31 is provided in the electrical path L1, and the switch 32 is provided in the electrical path L2.

The battery unit U is provided with a bypass path L3 that bypasses the switch 31. The bypass path L3 is provided so as to connect the output terminal P3 and the point N1 on the electrical path L1. The output terminal P3 is connected to the lead storage battery 11 via the fuse 35. By this bypass path L3, the lead storage battery 11, the electric load 15, and the rotating electrical machine unit 16 can be connected without using the switch 31. In the bypass path L3, for example, a bypass switch 36 composed of a normally closed mechanical relay is provided. By turning on (closing) the bypass switch 36, the lead storage battery 11, the electrical load 15, and the rotating electrical machine unit 16 are electrically connected even when the switch 31 is turned off (opened).

The battery unit U includes a battery ECU 37 that controls on / off (opening / closing) of the

switches

31 and 32. The battery ECU 37 is constituted by a microcomputer including a CPU, a ROM, a RAM, an input / output interface, and the like. The battery ECU 37 controls the on / off of the

switches

31 and 32 based on the storage state of each of the storage batteries 11 and 12 and the command value from the engine ECU 40 that is the host controller. Thereby, charging / discharging is implemented using the lead storage battery 11 and the lithium ion storage battery 12 selectively. For example, the battery ECU 37 calculates the SOC (State Of Charge) of the lithium ion storage battery 12 and controls the charge amount and discharge amount of the lithium ion storage battery 12 so that the SOC is maintained within a predetermined use range.

The rotating electrical machine ECU 24 of the rotating electrical machine unit 16 and the battery ECU 37 of the battery unit U are connected to an engine ECU 40 as a host controller that manages the ECUs 24 and 37 in an integrated manner. The engine ECU 40 is composed of a microcomputer including a CPU, ROM, RAM, input / output interface, and the like, and controls the operation of the engine 42 based on the engine operating state and the vehicle traveling state each time. Each of the

ECUs

24, 37, 40 and other various in-vehicle ECUs (not shown) are connected to each other via a communication line 41 that constructs a communication network such as a CAN and can communicate with each other, and bidirectional communication is performed at a predetermined cycle. Is done. Thereby, the various data memorize | stored in each ECU24,37,40 can be shared mutually.

Next, the electrical configuration of the rotating electrical machine unit 16 will be described with reference to FIG. The rotating electrical machine 21 is a three-phase AC motor (synchronous machine) and includes U-phase, V-phase, and W-

phase phase windings

25U, 25V, and 25W as a three-phase armature winding 25, and a field winding 26. ing. Each phase winding 25U, 25V, 25W corresponds to an armature winding group. Each phase winding 25U, 25V, 25W is star-connected and connected to each other at a neutral point. The rotating shaft of the rotating electrical machine 21 is drivingly connected to an engine output shaft (not shown) by a belt, and the rotating shaft of the rotating electrical machine 21 is rotated by the rotation of the engine output shaft. The engine output shaft rotates. That is, the rotating electrical machine 21 has a power generation function that generates power (regenerative power generation) by rotating the engine output shaft and the axle, and a power running function that applies rotational force to the engine output shaft. For example, the rotating electrical machine 21 is driven by powering at the time of engine restart in idling stop control or power assist for vehicle acceleration.

The inverter 22 converts the AC voltage output from each phase winding 25U, 25V, 25W into a DC voltage and outputs it to the battery unit U. The inverter 22 converts the DC voltage input from the battery unit U into an AC voltage and outputs the AC voltage to the

phase windings

25U, 25V, and 25W. The inverter 22 is a bridge circuit having the same number of upper and lower arms as the number of phases of the phase winding, and constitutes a three-phase full-wave rectifier circuit. The inverter 22 constitutes a drive circuit that drives the rotating electrical machine 21 by adjusting the electric power supplied to the rotating electrical machine 21.

The inverter 22 includes an upper arm switch Sp and a lower arm switch Sn for each phase. When the switches Sp and Sn of each phase are alternately turned on and off, time-series energization is performed for each phase. In the present embodiment, voltage controlled semiconductor switching elements are used as the switches Sp and Sn, and specifically, N-channel MOSFETs are used. An upper arm diode Dp is connected in antiparallel to the upper arm switch Sp, and a lower arm diode Dn is connected in antiparallel to the lower arm switch Sn. That is, each of the diodes Dp and Dn is provided in such a direction that the cathode is the power supply side and the anode is the ground side. In the present embodiment, parasitic diodes of the switches Sp and Sn are used as the diodes Dp and Dn. The diodes Dp and Dn are not limited to parasitic diodes, and may be diodes that are separate from the switches Sp and Sn, for example. An intermediate point of the series connection body of the switches Sp and Sn in each phase is connected to one end of each phase winding 25U, 25V, and 25W.

The inverter 22 is provided with a current detector 29 that detects the phase currents Iu, Iv, and Iw in the current path for each phase. The current detection unit 29 has a configuration including, for example, a shunt resistor and a current transformer.

The field circuit 23 energizes the field winding 26 in accordance with on / off of a plurality of switching elements. The field circuit 23 includes one cutoff switch 50 and four

field switches

51, 52, 53, and 54, and the field switches 51 to 54 constitute an H-bridge rectifier circuit. The basic configuration of each of the switches 50 to 54 is the same as that of each switch of the inverter 22, and a diode Di is connected to the semiconductor switching element in antiparallel.

In the field circuit 23, the field switches 51 and 52 are connected in series between the power supply unit (battery unit U in FIG. 2) and the ground, and the field switches 53 and 54 are connected between the power supply unit and the ground. Are connected in series. Then, the high side of the field switches 51 and 53, the intermediate points of the field switches 51 and 52 and the field switches 53 and 54, and the low side of the field switches 52 and 54 are electrically connected to each other. The field switches 51 to 54 are connected in an H bridge shape. In this case, the field switch 53 is provided in parallel with the field switch 51, and the field switch 54 is provided in parallel with the field switch 52. In the following, for convenience of explanation, the field switches 51 to 54 are also referred to as a first switch 51, a second switch 52, a third switch 53, and a fourth switch 54, respectively.

The field winding 26 is provided in a path portion connecting the intermediate point of the field switches 51 and 52 and the intermediate point of the field switches 53 and 54. Speaking on the basis of the second switch 52, the field winding 26 is connected to both ends of the second switch 52 and is provided in a parallel path section that is in parallel with the second switch 52. One of both ends of the field winding 26 is connected to an F + terminal that is an intermediate point between the field switches 51 and 52, and the other is connected to an F− terminal that is an intermediate point between the field switches 53 and 54. The F + terminal is a power supply side terminal (high side terminal), and the F− terminal is a ground side terminal (low side terminal). The field winding 26 is connected to the F + terminal and the F− terminal via a brush (not shown).

The cut-off switch 50 is provided between the power supply unit and the first switch 51, and more specifically, between the bus connected to the battery unit U and the branch point of the first switch 51 and the third switch 53. The power supply to the field circuit 23 and the power cutoff are switched by turning on and off the cutoff switch 50.

When the field winding 26 is energized by the field circuit 23, the switches 50 to 54 are turned on and off as follows. FIG. 3 shows an energization path in the field circuit 23. When the field winding 26 is energized due to the operation of the rotating electrical machine 21, the cutoff switch 50 is always on (fixed on), the third switch 53 is always off (fixed off), and the fourth switch 54 is always on ( On-fixed). In this state, the first switch 51 and the second switch 52 are turned on and off in a conflicting period. In this case, when the first switch 51 is turned on and the second switch 52 is turned off, as shown by a broken line in FIG. 3, the cutoff switch 50 → the first switch 51 → the field winding 26 → the fourth switch 54 → A current flows through the path Y1 in the order of the ground. Thereafter, when the first switch 51 is turned off and the second switch 52 is turned on, the field winding 26 → the fourth switch 54 → the second switch 52 → the field as shown by a two-dot chain line in FIG. A current (reflux current) flows through the return path Y2 in the order of the magnetic winding 26.

Here, a field current detector 55 for detecting a field current If flowing in the field winding 26 is provided on the ground side of the electric path at both ends of the fourth switch 54. In addition, on the ground side of the electrical path at both ends of the second switch 52, a return current detection unit 56 that detects the return current Ir that flows while the first switch 51 is off and the second switch 52 is on is provided. ing. If the direction from the power supply side to the ground is positive, the field current If is detected as a positive current, and the return current Ir is detected as a negative current. The

current detection units

55 and 56 have a configuration including, for example, a shunt resistor and a current transformer.

2, a voltage sensor 45 that detects an input / output voltage (that is, a power supply voltage) of the inverter 22 is provided on the high-voltage side path of the inverter 22. Detection signals of the sensors including the voltage sensor 45 are appropriately input to the rotating electrical machine ECU 24.

Each switch constituting the inverter 22 and the field circuit 23 is independently switched on / off via a driver 27.

The rotating electrical machine ECU 24 is configured by a microcomputer including a CPU, a ROM, a RAM, an input / output interface, and the like. The rotating electrical machine ECU 24 adjusts the excitation current flowing through the field winding 26 by an IC regulator (not shown) inside. Thereby, the power generation voltage (output voltage with respect to the battery unit U) of the rotating electrical machine unit 16 is controlled. The rotating electrical machine ECU 24 controls on / off of the switches Sp and Sn of each phase according to the energization phase, and controls the energization current by adjusting the on / off ratio (for example, duty ratio) when energizing each phase. Here, the rotating electrical machine ECU 24 assists the driving force of the engine by controlling the inverter 22 to drive the rotating electrical machine 21 after the vehicle starts running. The rotating electrical machine 21 can apply initial rotation to the crankshaft when starting the engine, and also has a function as an engine starting device.

Supplementary explanation will be given on the current control of the inverter 22 by the rotating electrical machine ECU 24. The rotating electrical machine ECU 24 calculates an energization current command value based on the power running torque command value and the generated voltage command value from the engine ECU 40, which is the host controller, and the energization current command value and the actual energization current (current detection unit 29). The operation signal is generated as a duty signal for energization current control for each phase based on the deviation from the detected current value). Specifically, the command voltage is calculated for each phase based on the deviation between the energized current command value and the detected current value, and the operation is performed by PWM processing based on the magnitude comparison between the command voltage and a carrier signal (for example, a triangular wave signal). A signal (PWM signal) is generated. In the present embodiment, the operation signal is generated by three-phase modulation, but pulse width modulation using a third-order harmonic superposition pattern can also be performed. Then, the rotating electrical machine ECU 24 turns on and off the upper arm switch Sp and the lower arm switch Sn for each phase according to the operation signal of each phase. Thereby, each phase current of the rotating electrical machine 21 is feedback-controlled.

In addition, at the time of powering of the rotating electrical machine 21 and power generation, the above-described PWM control may be performed in a rotation range that is a predetermined rotation speed or less. In this case, for example, rectangular wave control (control that is turned on / off at the zero cross point of the target voltage) may be performed in a rotation range that exceeds a predetermined rotation speed.

Supplementary information on field current control by the rotating electrical machine ECU 24 will be provided. The rotating electrical machine ECU 24 calculates a field current command value based on the power running torque command value and the generated voltage command value from the engine ECU 40, and the field current command value and the actual field current (field current detection unit). The operation signal is generated as a duty signal for field current control based on the deviation from the current detection value of 55). Specifically, the command voltage is calculated based on the deviation between the field current command value and the detected current value, and the operation signal (PWM signal) is generated by PWM processing based on the magnitude comparison between the command voltage and the carrier signal. To do. Then, the rotating electrical machine ECU 24 turns on and off each of the first switch 51 and the second switch 52 according to the operation signal. Thereby, the field current is feedback controlled.

Here, the configuration of the driver 27 will be described with reference to FIG. The driver 27 charges and discharges the gate terminals (conduction control terminals) of the switching elements constituting the switches Sp and Sn of the inverter 22 and the switches 51 to 54 of the field circuit 23, and turns on the switching elements. It is the drive device which switches between a state and an off state. Here, the configuration of the driver 27 will be described by taking the switch Sp as an example.

The driver 27 includes a resistor 62 and a charging switch 63 connected to a power source 61 as a charging circuit. When the charging switch 63 is turned on, a constant current flows through the gate of the switch Sp, and the switch 27 Sp gate charging is performed. As a result, the switch Sp is turned on.

Further, the driver 27 has two discharge parts as a discharge circuit, one of which is a first discharge part 64 for normal interruption by an operation signal, and the other is a second discharge part 65 for soft interruption. It has become. The first discharge unit 64 includes a first discharge resistor 66 and a first discharge switch 67, and the second discharge unit 65 includes a second discharge resistor 68 and a second discharge switch 69. The first discharge resistor 66 and the second discharge resistor 68 have different resistance values, and the resistance value R1 of the first discharge resistor 66 and the resistance value R2 of the second discharge resistor 68 satisfy R1 <R2. It has become a relationship. These discharge resistors 66 and 68 are resistors for adjusting the discharge speed (cutoff speed). From the relationship of R1 <R2, the second discharge is more effective than the case where the gate discharge is performed via the first discharge switch 67. When the gate discharge is performed through the switch 69, the discharge rate is slower.

That is, when the switch Sp is turned off (cut off), the first discharge switch 67 and the second discharge switch 69 are alternatively turned on, and the first discharge switch 67 is turned on. As a result, the normal interruption is performed, and the second discharge switch 69 is turned on, so that the soft interruption with the interruption speed slower than the normal interruption is performed. The charging switch 63 and the first discharging switch 67 are turned on / off based on an operation signal from the rotating electrical machine ECU 24.

By the way, in the inverter 22, for each phase, an upper arm switch Sp and a lower arm switch Sn are provided as a pair of switches that are a series connection body. In the field circuit 23, a first pair of switches that are a series connection body is provided. A first switch 51 and a second switch 52 are provided. Each of the pair of switches is alternately turned on and off by an operation signal. In such a case, if the other switch is turned on after an on failure of one of the pair of switches occurs, an excessive current (through current) flows through the pair of switches. Further, as a countermeasure against overcurrent, the switch is cut off. However, if the switch is cut off in a state where a large current flows, there is a concern that the switch is broken due to a surge voltage. Therefore, in a state where a large current is flowing, the switch is turned off by the soft cutoff. However, if the ON time of the operation signal is too short, the overcurrent determination and the accompanying switch interruption operation are not performed properly, and there is a concern that a large current interruption may be performed as a result.

Therefore, in this embodiment, the ON time of the operation signal is limited so that at least the time required for the overcurrent determination and the interruption operation start is secured. Thereby, when one of the switches is turned on, the overcurrent is appropriately determined, and the switch cutoff (soft cutoff) in the state where the overcurrent is flowing is appropriately performed.

In the configuration of FIG. 2, when it is determined by the determination unit 71 that the overcurrent has flowed to the rotating electrical machine unit 16 through the path leading to the pair of switches, and the determination unit 71 determines that the overcurrent has flowed, There is provided a shut-off operation unit 72 for softly shutting off the switches. The determination unit 71 is configured using, for example, a comparator. The determination unit 71 and the shut-off operation unit 72 are realized by, for example, an ASIC 70 that is a dedicated IC circuit. In the present embodiment, the rotary electric machine ECU 24 and the ASIC 70 constitute a “switch control device”.

Speaking of the upper arm switch Sp and the lower arm switch Sn of the inverter 22, the determination unit 71 inputs the current detection value detected by the current detection unit 29, and based on the current detection value exceeding a predetermined threshold, It is determined that an overcurrent has flowed. Based on the determination result of the determination unit 71, the cutoff operation unit 72 outputs a command signal for turning on the second discharge switch 69 to the soft discharge second discharge unit 65 in the driver 27. As a result, the soft cutoff is performed for the switch on the side where the ON failure has not occurred among the upper arm switch Sp and the lower arm switch Sn.

As for the first switch 51 and the second switch 52 of the field circuit 23, the determination unit 71 inputs the current detection value detected by the return current detection unit 56, and the current detection value exceeds a predetermined threshold value. Based on this, it is determined that an overcurrent has flowed. Based on the determination result of the determination unit 71, the cutoff operation unit 72 outputs a command signal for turning on the second discharge switch 69 to the soft discharge second discharge unit 65 in the driver 27. Thereby, soft interruption | blocking is implemented about the switch by which the ON failure has not arisen among the 1st switch 51 and the 2nd switch 52. FIG.

Here, for example, in the field circuit 23, assuming an ON failure that occurs in the first switch 51 out of the first switch 51 and the second switch 52, the second switch 52 can be used to properly perform overcurrent determination and soft interruption. It is necessary to secure the minimum necessary time as the on-time in. Therefore, an upper limit guard for the duty ratio is performed on the operation signal of the first switch 51. This upper limit guard is performed by a duty upper limit value having a duty ratio smaller than 100%. By this upper limit guard, the operation signal of the second switch 52 becomes a signal having a duty ratio larger than 0%. Further, assuming an on-failure that occurs in the second switch 52, it is necessary to secure a minimum necessary time as the on-time in the first switch 51 in order to properly perform overcurrent determination and soft interruption. Therefore, a lower limit guard of the duty ratio is performed on the operation signal of the first switch 51. This lower limit guard is performed by a duty lower limit value having a duty ratio larger than 0%. By this lower limit guard, the operation signal of the second switch 52 becomes a signal having a duty ratio smaller than 100%.

FIG. 5 is a flowchart showing a processing procedure of operation signal generation performed by the rotating electrical machine ECU 24, and this processing is repeatedly performed at a predetermined cycle. Here, the operation signal for controlling the field current will be described as an example.

In FIG. 5, in step S11, a PWM signal is generated by PWM processing based on the power running torque command value and the generated voltage command value. In the subsequent step S12, it is determined whether or not the PWM duty ratio of the first switch 51 of the first switch 51 and the second switch 52 exceeds a predetermined upper limit value. The upper limit is 95%, for example. If step S12 is affirmed, the process proceeds to step S13, and the PWM duty ratio of the first switch 51 is limited to a predetermined upper limit value (duty ratio = upper limit value).

In step S14, it is determined whether the PWM duty ratio of the first switch 51 of the first switch 51 and the second switch 52 is less than a predetermined lower limit value. The lower limit is, for example, 5%. When step S14 is affirmed, the process proceeds to step S15, where the PWM duty ratio of the first switch 51 is limited to a predetermined lower limit value (duty ratio = lower limit value). After that, in step S16, an operation signal is generated and output based on the PWM duty ratio that has been limited as described above or the PWM duty ratio that has not been limited.

If the first switch 51 and the second switch 52 are alternately turned on and off, the operation limit for the first switch is limited by the duty upper limit value. The duty lower limit is set for the operation signal for the second switch. Agree to enforce value restrictions. Similarly, the restriction by the duty lower limit value for the operation signal for the first switch is the same as the restriction by the duty upper limit value for the operation signal for the second switch.

In the process of FIG. 5, the upper limit guard of the duty ratio is implemented assuming that the first switch 51 is on, and the lower limit guard of the duty ratio is implemented assuming that the second switch 52 is on. However, the structure which assumed only any one of these may be sufficient. It is also possible to apply to each of the switches Sp and Sn of the inverter 22 using the process of FIG. In this case, if the PWM duty ratio of the upper arm switch Sp exceeds a predetermined upper limit value, the duty ratio is limited by the predetermined upper limit value. If the PWM duty ratio of the upper arm switch Sp is less than a predetermined lower limit value, the duty ratio is limited to a predetermined lower limit value.

FIG. 6 is a time chart showing the switching operation of the first switch 51 and the second switch 52 in the field circuit 23. The first operation signal for the first switch and the second operation signal for the second switch are alternately turned on and off and have a predetermined dead time. The carrier signal is 1 kHz, for example, and the PWM cycle determined by the carrier signal is 1 msec.

In FIG. 6, the first switch 51 is turned on during the on period T1 of the first operation signal, and the second switch 52 is turned on during the on period T2 of the second operation signal. FIG. 6 shows the transition of the current detected by the return current detection unit 56, and this current is detected as a negative current during the period when the first switch 51 is turned off. For example, when an on failure of the first switch 51 occurs at the timing ta, an excessive current (through current) starts to flow through both the

switches

51 and 52 as the second switch 52 is subsequently turned on. At this time, the determination unit 71 performs overcurrent determination. For example, it takes about 10 μsec to determine that an overcurrent has flowed.

When it is determined in the determination unit 71 that an overcurrent has flowed, the cutoff operation unit 72 performs soft cutoff on either the first switch 51 or the second switch 52 based on the determination result. At this time, the upper limit guard of the duty ratio of the first operation signal is implemented assuming the ON failure of the first switch 51. Conversely, the lower limit guard of the duty ratio of the second operation signal is implemented. Thus, the overcurrent determination and the switch breaking operation are appropriately performed in the ON period of the second switch 52. At this time, for example, at least 20 μsec is preferably secured as the ON time of the second switch 52.

In the inverter 22, energization current control using two-phase modulation may be performed. Specifically, the rotating electrical machine ECU 24 sequentially fixes the operation states of the upper arm switch Sp and the lower arm switch Sn of each phase one phase at a predetermined period, and configures two phases other than the fixed phase. The upper arm switch Sp and the lower arm switch Sn are turned on / off by PWM processing.

More specifically, as shown in FIG. 7, the upper arm switch Sp is turned off and the lower arm switch Sn is turned on and off one by one for each electrical angle of 120 ° of the rotating electrical machine 21. A command signal for each phase (a feedforward operation amount calculated according to the energization current command value for each phase and the electrical angular velocity of the rotating electrical machine 21) is set. Based on this command signal, an operation signal is generated for each phase. A two-phase command signal for fixing the operation state may be set so that the interphase voltage becomes a sine wave. In this case, on the assumption that the maximum value of the carrier signal is “1” and the minimum value is “0”, the command signal of the upper arm switch Sp fixed to the off operation is fixed to the lower limit value and fixed to the on operation. The command signal of the lower arm switch Sn is fixed to the upper limit value.

Alternatively, as shown in FIG. 8, each phase command so that the upper arm switch Sp is turned on and the lower arm switch Sn is turned on and off one by one for each electrical angle of 120 ° of the rotating electrical machine 21. The signal is set. Based on this command signal, an operation signal is generated for each phase. In this case, the command signal of the upper arm switch Sp that is fixed to the ON operation is fixed to the upper limit value, and the command signal of the lower arm switch Sn that is fixed to the ON operation is fixed to the upper limit value.

Even in the configuration in which the two-phase modulation is performed as described above, by limiting the duty ratio as described above, when the upper arm switch Sp is turned on or when the lower arm switch Sn is turned on, an overcurrent is generated. Judgment and switching off are preferably performed.

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

The on time of the operation signal for turning on and off the pair of switches in the rotating electrical machine 21 is configured to limit at least the time required for the overcurrent determination by the determination unit 71 and the start of the interruption operation by the interruption operation unit 72. As a result, when one of the pair of switches has an on-failure, it is possible to properly determine the overcurrent and properly perform the switch cutoff (soft cutoff) in the state where the overcurrent flows. it can. As a result, when an overcurrent occurs in a path including a pair of switches, the switch can be properly cut off, and thus the switch can be protected.

Speaking of the switch control in the field circuit 23, it is assumed that the operation signal for the first switch 51 is limited by the duty upper limit value, thereby causing an overcurrent to flow due to the ON failure of the first switch 51. In addition, it is possible to appropriately perform the overcurrent determination and the switch cutoff operation within the ON period of the second switch 52. Alternatively, by limiting the operation signal for the first switch 51 by the duty lower limit value, it is assumed that an overcurrent flows due to an ON failure of the second switch 52, and then the first switch 51 is turned on. Overcurrent determination and switch-off operation can be performed properly within the period.

Further, in terms of switch control in the inverter 22, it is assumed that an overcurrent flows due to an on-failure of the upper arm switch Sp by limiting the operation signal for the upper arm switch Sp by the duty upper limit value. In addition, it is possible to appropriately perform the overcurrent determination and the switch cutoff operation within the ON period of the lower arm switch Sn. Alternatively, by limiting the operation signal for the upper arm switch Sp by the duty lower limit value, it is assumed that an overcurrent flows due to an on failure of the lower arm switch Sn, and then the upper arm switch Sp is turned on. Overcurrent determination and switch-off operation can be performed properly within the period.

(Other embodiments)
You may change the said embodiment as follows, for example.

In the rotating electrical machine 21, for example, the frequency f1 of the carrier signal used for generating the operation signal used for the on / off control of the armature winding 25 and the carrier signal used for generating the operation signal used for the on / off control of the field winding 26 It is conceivable that the frequency f2 is different from each other. For example, it can be considered that f1> f2 or f1 <f2. Further, it is conceivable to vary the frequency f1 of the carrier signal used for generating the operation signal for armature control, or to vary the frequency f2 of the carrier signal used for generating the operation signal for field control. Considering this point, it is preferable to determine a duty limit value according to the frequency of the carrier signal and limit the duty ratio of the operation signal by the duty limit value. For example, the duty upper limit value is decreased as the frequency of the carrier signal is increased. Further, the duty lower limit value is increased as the frequency of the carrier signal is increased.

In FIG. 9, the frequency f1 of the carrier signal used to generate the operation signal for armature control (inverter control) and the frequency f2 of the carrier signal used to generate the operation signal for field control have a relationship of f1> f2. In some cases, the difference in duty limit value is shown. In this case, the duty limit value is different between the armature control and the field control. Specifically, in the armature control on the high frequency side, the duty upper limit value is smaller and the duty lower limit value is larger than in the field control on the low frequency side.

According to the above configuration, it is possible to achieve an appropriate on-time limit while securing the time required for the overcurrent determination and the switch cutoff operation.

In the above embodiment, the field circuit 23 is configured with an H-bridge circuit, but the field circuit 23 may be configured with a half-bridge circuit instead. FIG. 10 shows a field circuit 23 having a half-bridge circuit configuration. In the field circuit 23 of FIG. 10, a first switch 51 and a second switch 52 are connected in series between the power supply unit and the ground, and the field winding 26 is provided in a parallel path portion in parallel with the second switch 52. Is provided. Also in this configuration, the duty ratio of the operation signal (duty signal) may be limited as described above.

In the above embodiment, the application example to the three-phase AC motor as the rotating electrical machine 21 has been described, but this may be changed. For example, it can be applied to a six-phase AC motor having two sets of three-phase armature winding groups. In short, it can be applied to an AC motor having n sets of three-phase armature winding groups (n is 1 or more).

In the above embodiment, the rotating electrical machine that performs the power generation operation and the power running operation has been described, but the present invention can also be applied to a rotating electrical machine that performs only the power generation operation or the power running operation.

The power supply system to which the present disclosure is applied can also be used for uses other than vehicles, for example, for ships, aircraft, robots, and the like.

-Each said component is conceptual and is not limited to the said embodiment. For example, the functions of one component may be realized by being distributed to a plurality of components, or the functions of a plurality of components may be realized by one component.

Although the present disclosure has been described based on the embodiments, it is understood that the present disclosure is not limited to the embodiments and structures. The present disclosure includes various modifications and modifications within the equivalent range. In addition, various combinations and forms, as well as other combinations and forms including only one element, more or less, are within the scope and spirit of the present disclosure.

Claims

Switch control devices (24, 70) for alternately turning on and off a pair of switches (Sp, Sn, 51, 52) provided in series between the power supply unit and the ground by a duty signal so that both are not turned on simultaneously. Because
A signal generator (24) for generating the duty signal;
A determination unit (71) for determining that an overcurrent has flowed in a path leading to the pair of switches in a state where the other switch is turned on after an on failure of one of the pair of switches occurs;
A shut-off operation unit (72) for shutting off the other switch at a speed slower than a normal shut-off speed when the judging unit judges that the overcurrent has flowed;
A switch control device comprising: a limiting unit (24) for limiting an ON time of the duty signal so as to secure at least a time required for an overcurrent determination by the determination unit and a start of a cutoff operation by the cutoff operation unit.
Applied to a rotating electrical machine unit (16) having a field circuit (23) for energizing a field winding (26) of a wound field type rotating electrical machine (21), the field circuit being connected to the pair of switches A first field switch (51) on the power supply side and a second field switch (52) on the ground side,
The determination unit determines that the overcurrent flows through the first field switch and the second field switch,
2. The switch control device according to claim 1, wherein the restriction unit performs at least one of a restriction by a duty upper limit value for the duty signal for turning on and off the first field switch and a restriction by a duty lower limit value for the duty signal. .
A rotating electrical machine unit (16) having a rotating electrical machine (21) having a three-phase armature winding group and an inverter circuit (22) for energizing each phase of the armature winding (25) of the rotating electrical machine for each phase. The inverter circuit has an upper arm switch (Sp) and a lower arm switch (Sn) for each phase as the pair of switches,
The determination unit determines that the overcurrent flows through the upper arm switch and the lower arm switch,
3. The switch control device according to claim 1, wherein the restriction unit performs at least one of a restriction by a duty upper limit value for the duty signal for turning on and off the upper arm switch and a restriction by a duty lower limit value for the duty signal. .
A switch control device is provided with the pair of switches in an energization path connected to at least one of the armature winding (25) and the field winding (26) of the rotating electrical machine (21), and controls on / off of the pair of switches. Because
The duty signal is generated based on a comparison between a command signal calculated according to a required value of an energization current to at least one of the armature winding and the field winding and a carrier signal having a predetermined frequency. ,
4. The switch control device according to claim 1, wherein the limiter limits a duty ratio of the duty signal by a duty limit value determined according to a frequency of the carrier signal. 5.
The pair of switches are respectively provided in the energization path connected to the armature winding and the energization path connected to the field winding, and the switch control device controls on / off of each of the pair of switches,
The frequency of the carrier signal used when generating the duty signal for armature control is different from the frequency of the carrier signal used when generating the duty signal for field control,
The switch control device according to claim 4, wherein the duty limit value is determined as a value different between the duty signal for armature control and the duty signal for field control.