JP2023015941A - Control device for vehicle - Google Patents

Abstract

To provide a control device for a vehicle that is able to open a relay while suppressing welding of the relay, when a predetermined anomaly that needs to open the relay occurs.SOLUTION: An electronic control device 100 is for a vehicle 10 including: a first electric motor MG1; a battery 20; a first inverter 30 that performs power conversion between the first electric motor MG1 and the battery 20 to exchange electric power; and a relay 80 that connects/disconnects the first inverter 30 and the battery 20. When it is detected that counter-electromotive force Vbef1 generated in the first electric motor MG1 is higher than a battery voltage Vbat in a case where a predetermined anomaly that needs to open the relay 80 occurs, this electronic control device opens the relay 80 after turning on switching elements 40a, 40c, 40e of an upper arm 32 of the first inverter 30 and turning off switching elements 40b, 40d, 40f of a lower arm 34.SELECTED DRAWING: Figure 1

Description

The present invention relates to a control device for a vehicle that includes a power conversion device that transfers electric power between an electric motor and a battery, and a relay that connects and disconnects the power conversion device and the battery.

In a vehicle equipped with a power conversion device for transferring electric power between an electric motor and a battery and a relay for connecting and disconnecting between the power conversion device and the battery, the relay is opened and the power conversion device is opened in the event of a collision of the vehicle. A control device for a vehicle is known which turns off the switching element of the upper arm and turns on the switching element of the lower arm. For example, the one described in Patent Document 1 is it.

JP-A-2005-94883

For example, when the battery fails, the vehicle control device described in Patent Document 1 can be applied. be. If the relay is welded, it will not be possible to cut off power transfer between the battery and the electric motor, and the battery may overheat.

The present invention has been made against the background of the above circumstances, and its object is to open the relay while suppressing the welding of the relay when a predetermined abnormality requiring the opening of the relay occurs. To provide a control device for a vehicle capable of

The gist of the present invention is to provide an electric motor, a battery, a power conversion device that performs power conversion between the electric motor and the battery to transfer electric power, and a device that connects the power conversion device and the battery. A control device for a vehicle, comprising: a relay that connects and disconnects, and detects that the back electromotive force generated by the electric motor is higher than the voltage of the battery when a predetermined abnormality requiring opening of the relay occurs. Then, after one of the upper arm switching element and the lower arm switching element of the power converter is turned on and the other is turned off, the relay is opened.

According to the vehicle control device of the present invention, when a predetermined abnormality requiring opening of the relay occurs and it is detected that the back electromotive force generated by the electric motor is higher than the voltage of the battery, the After one of the upper arm switching element and the lower arm switching element of the power converter is turned on and the other is turned off, the relay is opened. One of the switching element of the upper arm and the switching element of the lower arm of the power conversion device is turned on and the other is turned off, so that the electric circuit is closed between the electric motor and the power conversion device, and the electric current is generated in the electric motor. Back electromotive force is prevented from being applied to the battery through the relay. This prevents arcing between the open and closed terminals of the relay when the relay is opened. Therefore, when a predetermined abnormality occurs, the relay can be opened while suppressing welding of the relay.

FIG. 2 is a schematic configuration diagram for explaining electric power transfer in a vehicle equipped with an electronic control unit according to an embodiment of the present invention, and is a functional block diagram showing a main part of a control function for controlling electric power transfer in the vehicle; . FIG. 2 is an example of a flow chart for explaining the main part of the control operation of the electronic control unit shown in FIG. 1; FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following examples, the drawings are appropriately simplified or modified, and the dimensional ratios, shapes, etc. of each part are not necessarily drawn accurately.

FIG. 1 is a schematic configuration diagram for explaining power transmission and reception in a vehicle 10 equipped with an electronic control unit 100 according to an embodiment of the present invention. It is a functional block diagram showing.

The vehicle 10 includes, for example, an engine (not shown), a first electric motor MG1, a second electric motor MG2, a battery 20, a first inverter 30, a second inverter 50, a power line pair 70, a DC/DC converter 72, a relay 80, and an electronic control device. It is a hybrid car with 100. Further, the vehicle 10 includes, for example, a power splitting mechanism that splits the power of the engine between the second electric motor MG2 and a transmission member connected to a pair of driving wheels, and the first electric motor MG1 is connected to the transmission member so as to be capable of transmitting power. It is

The first electric motor MG1 and the second electric motor MG2 are rotary electric machines having a function as a motor and a function as a generator, that is, a so-called motor-generator, such as a three-phase synchronous motor-generator. The first electric motor MG1 and the second electric motor MG2 respectively correspond to the "electric motor" in the present invention.

The battery 20 is a chargeable/dischargeable secondary battery that mainly discharges (supplies) electric power for driving the first electric motor MG1 and the second electric motor MG2, and regenerates the first electric motor MG1 and the second electric motor MG2. It is used for charging the power generated by MG2.

Relay 80 is provided between battery 20 and power line pair 70 . That is, battery 20 is connected to power line pair 70 via relay 80 . The power line pair 70 has a pair of positive and negative lines. The relay 80 is, for example, a mechanical relay that can be switched between a closed state (connected state) in which the relay 80 is closed and an open state (disconnected state) in which the relay 80 is opened by the electronic control unit 100. It is provided between the positive electrode line of the power line pair 70 and between the negative electrode of the battery 20 and the negative electrode line of the power line pair 70 . Relay 80 is a switching device that connects and disconnects between battery 20 and power line pair 70 .

The first inverter 30 is a power supply circuit provided between the first electric motor MG1 and the power line pair 70 and controlled by the electronic control unit 100 to convert direct current into alternating current or convert alternating current into direct current. It is a power conversion device that performs power conversion between the first electric motor MG1 and the battery 20 to transfer power. For example, the first inverter 30 converts the direct current supplied from the battery 20 to the power line pair 70 into three-phase alternating current and outputs it to the first electric motor MG1, or converts the three-phase alternating current generated by the first electric motor MG1 into direct current. It converts and outputs to the power line pair 70 . A smoothing capacitor C<b>1 is provided near the first inverter 30 in the power line pair 70 . The first inverter 30 corresponds to the "power converter" in the present invention.

The first electric motor MG1 is rotationally driven by, for example, electric power stored in the battery 20 or all or part of the electric power generated by the second electric motor MG2 in addition to the electric power, and outputs a driving force for running the vehicle 10. Power source. In addition, the first electric motor MG1 generates electric power by converting the driven force input from the pair of drive wheels into electric power through regeneration. The generated power charges battery 20 via first inverter 30 , power line pair 70 and relay 80 .

The second inverter 50 is a power supply circuit provided between the second electric motor MG2 and the power line pair 70 and controlled by the electronic control unit 100 to convert direct current to alternating current or convert alternating current to direct current. It is a power conversion device that performs power conversion between the second electric motor MG2 and the battery 20 to transfer power. For example, the second inverter 50 converts the direct current supplied from the battery 20 to the power line pair 70 into a three-phase alternating current for output to the second electric motor MG2, or converts the three-phase alternating current generated by the second electric motor MG2 into direct current. It converts and outputs to the power line pair 70 . A smoothing capacitor C<b>2 is provided near the second inverter 50 in the power line pair 70 . The second inverter 50 corresponds to the "power converter" in the present invention.

The second electric motor MG2 generates power by driving force input from the engine. The electric power generated by the second electric motor MG2 is charged to the battery 20 via the second inverter 50, the power line pair 70, and the relay 80, or all or part of the electric power generated by the second electric motor MG2 or the second In addition to the electric power generated by the electric motor MG2, the electric power from the battery 20 is used for rotationally driving the first electric motor MG1. Further, like the first electric motor MG1, the second electric motor MG2 regenerates the driven power input from the pair of drive wheels, and the generated electric power is supplied to the second inverter 50, the power line pair 70, and the Battery 20 is charged through relay 80 .

As described above, relay 80 is provided between battery 20 and power line pair 70 . The power line pair 70 is branched and connected to each of the first inverter 30 and the second inverter 50 . Power line pair 70 is directly connected to first inverter 30 , and no relay (switching device) is provided between first inverter 30 and relay 80 . Similarly, power line pair 70 is directly connected to second inverter 50 , and no relay (switching device) is provided between second inverter 50 and relay 80 .

The DC/DC converter 72 is a power supply circuit that is provided, for example, between the power line pair 70 and an auxiliary battery (not shown), and steps up or down a direct current. For example, the DC/DC converter 72 steps down the DC voltage of the power line pair 70 and outputs a DC voltage lower than the DC voltage to the auxiliary battery, or steps up the DC voltage supplied from the auxiliary battery. A direct current having a voltage higher than that of the auxiliary battery is output to the power line pair 70 .

In the vehicle 10, for example, of the first electric motor MG1 and the second electric motor MG2, the driving force for driving is output from only the first electric motor MG1, or the driving force for driving is output from both the first electric motor MG1 and the second electric motor MG2. can be selected.

The first inverter 30 is a circuit that converts direct current supplied from the battery 20, which is a direct current power supply, into alternating current in order to control the drive current flowing through the first electric motor MG1. In the first inverter 30, a pair of switching elements 40a and 40b, a pair of switching elements 40c and 40d, and a pair of switching elements 40e and 40f are connected in series between the positive line and the negative line of the power line pair 70. . The switching elements 40a to 40f are, for example, insulated gate bipolar transistors (IGBT), power MOSFETs, etc. In this embodiment, they are N-channel power MOSFETs. Diodes 42a-42f are connected in parallel to the switching elements 40a-40f, respectively. A connection point between the switching element 40a and the switching element 40b, a connection point between the switching element 40c and the switching element 40d, and a connection point between the switching element 40e and the switching element 40f correspond to the U phase, the V phase, and the W phase of the first electric motor MG1. are connected to the phase connection terminals. The upper arm 32 of the first inverter 30 is a circuit that supplies current from the positive electrode line of the power line pair 70, that is, the positive electrode of the battery 20 to the first electric motor MG1, which is a load. , 42e. The lower arm 34 of the first inverter 30 is a circuit that draws current from the load, the first electric motor MG1, to the negative electrode line of the power line pair 70, that is, the negative electrode of the battery 20. 42f.

The second inverter 50 is a circuit that converts direct current supplied from the battery 20, which is a direct current power supply, into alternating current in order to control the drive current flowing through the second electric motor MG2. The second inverter 50 has the same configuration as the first inverter 30 . In the second inverter 50, a pair of switching elements 60a and 60b, a pair of switching elements 60c and 60d, and a pair of switching elements 60e and 60f are connected in series between the positive line and the negative line of the power line pair 70. . Diodes 62a-62f are connected in parallel to the switching elements 60a-60f, respectively. A connection point between the switching element 60a and the switching element 60b, a connection point between the switching element 60c and the switching element 60d, and a connection point between the switching element 60e and the switching element 60f correspond to the U phase, the V phase, and the W phase of the second electric motor MG2. are connected to the phase connection terminals. The upper arm 52 of the second inverter 50 is a circuit that supplies current from the positive electrode line of the power line pair 70, that is, the positive electrode of the battery 20 to the second electric motor MG2, which is a load. , 62e. The lower arm 54 of the second inverter 50 is a circuit that draws current from the second electric motor MG2, which is a load, to the negative electrode line of the power line pair 70, that is, the negative electrode of the battery 20. 62f.

The electronic control unit 100 includes, for example, a so-called microcomputer having a CPU, a RAM, a ROM, and an input/output interface. Various controls of the vehicle 10 are executed by performing signal processing. The electronic control device 100 corresponds to the "control device" in the present invention.

The electronic control unit 100 includes various signals (for example, the battery 20 battery voltage Vbat [V], which is the voltage, battery current Ibat [A], which is the charging and discharging current of the battery 20, battery temperature THbat [° C.], which is the temperature of the battery 20, and MG1 rotation, which is the rotation speed of the first electric motor MG1. speed Nmg1 [rpm], MG2 rotation speed Nmg2 [rpm] which is the rotation speed of the second electric motor MG2, etc.) are respectively input.

From the electronic control unit 100, various command signals (for example, the first inverter 30 is A first inverter control signal Sinv1 for controlling the rotation of the first motor MG1 via the second inverter 50, a second inverter control signal Sinv2 for controlling the rotation of the second motor MG2 via the second inverter 50, and opening and closing of the relay 80. relay control signal Srly for DC/DC converter 72, converter control signal Scon for controlling voltage conversion of DC/DC converter 72, etc.) are output.

The electronic control unit 100 controls the first inverter 30 and the second inverter 50, respectively, to control the rotation of the first electric motor MG1 and the second electric motor MG2 so that the required torque is transmitted to the pair of driving wheels, for example. do.

The electronic control unit 100 functionally includes an inverter control section 100a, a relay control section 100b, an abnormality detection section 100c, and a back electromotive force determination section 100d.

When the inverter control unit 100a rotationally drives the first electric motor MG1, for example, the U-phase, V-phase, and W-phase voltages from the first inverter 30 are pseudo sine waves having phases different from each other by 2π/3 [rad]. A first inverter control signal Sinv1 for outputting a PWM (Pulse Width Modulation) signal is output.

When the inverter control unit 100a rotationally drives the second electric motor MG2, for example, the U-phase, V-phase, and W-phase voltages from the second inverter 50 are pseudo sine waves having phases different from each other by 2π/3 [rad]. A second inverter control signal Sinv2 for outputting a PWM signal of

Relay control unit 100 b controls opening and closing of relay 80 to control connection and disconnection between battery 20 and power line pair 70 . When the relay 80 is closed, power can be transferred between the battery 20 and the first inverter 30, and power can be transferred between the battery 20 and the second inverter 50. It is said that When relay 80 is in the open state, power is not transferred between battery 20 and first inverter 30, and power is transferred between battery 20 and second inverter 50. do not have.

In the following description, the control of the second inverter 50 and the relay 80 when a predetermined abnormality occurs is the same as the control of the first inverter 30 and the relay 80 when a predetermined abnormality occurs. Therefore, the control of the first inverter 30 and the relay 80 when a predetermined abnormality occurs will be described representatively, and the description of the control of the second inverter 50 and the relay 80 when a predetermined abnormality occurs will be omitted as appropriate. .

The abnormality detection unit 100c detects whether or not a predetermined abnormality has occurred. The predetermined abnormality is an abnormality that requires the relay 80 to be opened, such as a failure of the battery 20 . Failure of battery 20 is detected based on battery voltage Vbat, battery current Ibat, and battery temperature THbat.

When a predetermined abnormality occurs, relay 80 provided between battery 20 and power line pair 70 is opened by control described below. By opening the relay 80 , the connection between the first inverter 30 and the battery 20 is cut off and the connection between the second inverter 50 and the battery 20 is cut off.

An example of opening the relay 80 when the back electromotive force Vbef1 [V] generated by the first electric motor MG1 becomes higher than the battery voltage Vbat will be described below. For an example in which the relay 80 is opened when the back electromotive force Vbef2 [V] generated by the second electric motor MG2 becomes higher than the battery voltage Vbat, instead of the "first electric motor MG1" and the "first inverter 30", " Since the same control is performed for the second electric motor MG2 and the second inverter 50, description thereof will be omitted.

When the abnormality detection unit 100c detects the occurrence of a predetermined abnormality, the counter electromotive force determination unit 100d detects whether the counter electromotive force Vbef1 generated by the first electric motor MG1 is higher than the battery voltage Vbat.

The back electromotive force Vbef1 generated by the first electric motor MG1 is proportional to the MG1 rotational speed Nmg1. Therefore, there are several methods for detecting whether or not the back electromotive force Vbef1 generated by the first electric motor MG1 is higher than the battery voltage Vbat.

For example, the counter electromotive force Vbef1 is calculated by applying the actual MG1 rotational speed Nmg1 to a map in which the relationship between the MG1 rotational speed Nmg1 and the counter electromotive force Vbef1 is predetermined experimentally or by design. be. By determining whether or not the calculated counter electromotive force Vbef1 is higher than the battery voltage Vbat, it is detected that the counter electromotive force Vbef1 generated by the first electric motor MG1 is higher than the battery voltage Vbat.

For example, the relationship between the battery voltage Vbat and the predetermined rotational speed Nbef1, which is the MG1 rotational speed Nmg1 that generates the same back electromotive force Vbef1 as the battery voltage Vbat, is determined in a map that is experimentally or designed in advance. is applied, the predetermined rotation speed Nbef1 is calculated. When the MG1 rotation speed Nmg1 is higher than the calculated predetermined rotation speed Nbef1, it is detected that the back electromotive force Vbef1 generated by the first electric motor MG1 is higher than the battery voltage Vbat.

When the counter electromotive force determination unit 100d detects that the counter electromotive force Vbef1 generated by the first electric motor MG1 is higher than the battery voltage Vbat, the inverter control unit 100a controls the switching element 40a of the upper arm 32 of the first inverter 30. , 40c and 40e are turned on and the switching elements 40b, 40d and 40f of the lower arm 34 of the first inverter 30 are turned off. As a result, the U-phase, V-phase, and W-phase connection terminals of the first electric motor MG1 are electrically connected to each other by the upper arm 32, and the positive line of the power line pair 70 in the first inverter 30. and the negative line are cut off. That is, the electric circuit is closed between the first electric motor MG1 and the first inverter 30, and the counter electromotive force Vbef1 generated by the first electric motor MG1 is no longer applied to the battery 20 via the power line pair 70 and the relay 80.

After the switching elements 40a, 40c, 40e of the upper arm 32 of the first inverter 30 are turned on and the switching elements 40b, 40d, 40f of the lower arm 34 of the first inverter 30 are turned off, the relay control unit 100b Open relay 80; That is, after the electric circuit is closed between the first electric motor MG1 and the first inverter 30 and the counter electromotive force Vbef1 generated by the first electric motor MG1 is no longer applied to the battery 20 via the power line pair 70 and the relay 80, Relay 80 is opened. After the back electromotive force Vbef1 generated by the first motor MG1 is no longer applied to the battery 20 via the power line pair 70 and the relay 80, arc discharge occurs between the open/close terminals of the relay 80 when the relay 80 is opened. do not.

FIG. 2 is an example of a flowchart for explaining the main part of the control operation of the electronic control unit 100 shown in FIG. The flowchart of FIG. 2 is executed, for example, when the battery 20 is charged with electric power generated by the first electric motor MG1 through regeneration. In this case, the relay 80 is closed, and the switching elements 40a to 40a of the first inverter 30 are switched so that the alternating current generated by the first electric motor MG1 through regeneration is rectified into direct current and output to the power line pair 70. 40f is controlled on and off.

First, in step S10 (hereinafter, "step" is omitted) corresponding to the function of the abnormality detection section 100c, it is detected whether or not a predetermined abnormality requiring opening of the relay 80 has occurred. If the detection in S10 is affirmative, in S20 corresponding to the function of the counter electromotive force determination unit 100d, it is detected whether or not the counter electromotive force Vbef1 is the MG1 rotational speed Nmg1 that exceeds the battery voltage Vbat. If the detection in S10 is negative, the process ends.

If the detection in S20 is affirmative, in S30 corresponding to the function of the inverter control section 100a, the switching elements 40a, 40c, and 40e of the upper arm 32 of the first inverter 30 are turned on and the switching elements of the lower arm 34 are turned on. 40b, 40d and 40f are turned off. If the detection of S20 is negative and after the execution of S30, the relay 80 is opened in S40 corresponding to the function of the relay control section 100b. And it ends.

According to this embodiment, when a predetermined abnormality requiring opening of the relay 80 occurs and it is detected that the back electromotive force Vbef1 generated by the first electric motor MG1 is higher than the battery voltage Vbat, the first inverter After switching elements 40a, 40c, 40e of upper arm 32 of inverter 30 are turned on and switching elements 40b, 40d, 40f of lower arm 34 of first inverter 30 are turned off, relay 80 is opened. By turning on the switching elements 40a, 40c and 40e of the upper arm 32 of the first inverter 30 and turning off the switching elements 40b, 40d and 40f of the lower arm 34 of the first inverter 30, the first electric motor MG1 and An electric circuit is closed between first inverter 30 and counter electromotive force Vbef1 generated by first electric motor MG1 is prevented from being applied to battery 20 via power line pair 70 and relay 80 . As a result, arc discharge does not occur between the open/close terminals of the relay 80 when the relay 80 is opened. Therefore, when a predetermined abnormality occurs, the relay 80 can be opened while suppressing welding of the relay 80 . Further, even if the battery 20 fails, the vehicle 10 can continue to run.

Although the embodiments of the present invention have been described in detail above with reference to the drawings, the present invention is also applicable to other aspects.

In the above-described embodiment, when a predetermined abnormality occurs, the switching elements 40a, 40c, 40e of the upper arm 32 of the first inverter 30 are turned on, and the switching elements 40b, 40d, 40b, 40d, Although relay 80 was opened after 40f was turned off, the invention is not limited to this aspect. For example, after the switching elements 40b, 40d, 40f of the lower arm 34 of the first inverter 30 are turned on and the switching elements 40a, 40c, 40e of the upper arm 32 of the first inverter 30 are turned off, the relay 80 is opened. It may be in a mode where In this embodiment as well, the U-phase, V-phase, and W-phase connection terminals of the first electric motor MG1 are electrically connected to each other by the lower arm 34, and the power line pair 70 is connected to the first inverter 30. The positive line and the negative line are cut off. That is, after the electric circuit is closed between the first electric motor MG1 and the first inverter 30 and the counter electromotive force Vbef1 generated by the first electric motor MG1 is no longer applied to the battery 20 via the power line pair 70 and the relay 80, Relay 80 is opened. Therefore, according to the present invention, one of the switching elements 40a, 40c and 40e of the upper arm 32 of the first inverter 30 and the switching elements 40b, 40d and 40f of the lower arm 34 is turned on and The relay 80 should be opened after the other is turned off.

Although the battery 20 and the relay 80 are directly connected in the above embodiment, the present invention is not limited to this aspect. For example, a mode in which a boost converter is provided between battery 20 and relay 80 may be employed. In this embodiment, the voltage of battery 20 is boosted by the boost converter, and the boosted voltage is output to first inverter 30 and second inverter 50 via relay 80 and power line pair 70 .

Although the vehicle 10 was a hybrid vehicle in the above embodiment, it may be, for example, a plug-in hybrid vehicle, a fuel cell vehicle, or an electric vehicle. Although the vehicle 10 includes two electric motors, the first electric motor MG1 and the second electric motor MG2, the number of electric motors is not particularly limited in the present invention. The point is that the "vehicle" in the present invention should be equipped with an electric motor that generates power through regeneration when a predetermined abnormality requiring opening of the relay occurs.

In the above-described embodiment, the single electronic control unit 100 controls the first inverter 30, the second inverter 50, the relay 80, and the DC/DC converter 72, but the electronic control unit 100 may be A first inverter control ECU (Electronic Control Unit) that controls the first inverter 30, a second inverter control ECU that controls the second inverter 50, a relay control ECU that controls the relay 80, and a DC/DC converter 72 may be divided into converter control ECUs for controlling .

It should be noted that what has been described above is merely an embodiment of the present invention, and the present invention can be implemented in a mode with various modifications and improvements based on the knowledge of those skilled in the art without departing from the scope of the invention.

10: Vehicle 20: Battery 30: First Inverter (Power Converter)
32: upper arm 34: lower arms 40a to 40f: switching element 50: second inverter (power converter)
52: upper arm 54: lower arms 60a to 60f: switching element 80: relay 100: electronic control device (control device)
MG1: First electric motor (electric motor)
MG2: Second electric motor (electric motor)
Vbat: battery voltage (battery voltage)
Vbef1: back electromotive force Vbef2: back electromotive force

Claims (1)

A vehicle comprising: an electric motor; a battery; a power conversion device that performs power conversion between the electric motor and the battery to transfer electric power; and a relay that connects and disconnects the power conversion device and the battery. , a controller,
When a predetermined abnormality requiring opening of the relay occurs and it is detected that the back electromotive force generated by the electric motor is higher than the voltage of the battery, the switching element of the upper arm and the lower arm of the power conversion device A control device for a vehicle, wherein the relay is opened after one switching element is turned on and the other is turned off.

Images