JP2021027682A - Driving device of vehicle - Google Patents

Abstract

To provide a driving device of a vehicle, which improves travelling safety of the vehicle upon the occurrence of failure in the driving device.SOLUTION: A driving device 10 of a vehicle includes a left motor 1 and a right motor 2 which drive left and right wheels of the vehicle and a left inverter 4 and a right inverter 5 which control the motors. The driving device 10 comprises a left detection circuit 6 that detects a failure of the left motor 1 or of the left inverter 4 and a right detection circuit 7 that detects a failure of the right motor 2 or of the right inverter 5. The driving device 10 further comprises a left control circuit 8 that decreases torque of the left motor 1 when the right detection circuit 7 detects the failure, and a right control circuit 9 that decreases torque of the right motor 2 when the left detection circuit 6 detects the failure.SELECTED DRAWING: Figure 2

Description

The present invention relates to a drive device including a pair of motors and a pair of inverters for driving the left and right wheels of a vehicle.

Conventionally, a drive device for driving the left and right wheels of a vehicle with two motors (electric motors) is known. For example, it has been proposed that individual motors are connected to each of the left and right wheels so that the left and right wheels can be driven independently of each other. In such a drive device, by making the driving force of the left and right motors different, it is possible to cause a difference in rotation speed and a difference in torque between the left and right wheels. As a result, the turning performance of the vehicle and the stability of the vehicle body during turning can be improved (see Patent Document 1).

JP-A-2017-184523

If either the left or right motor (or inverter) of the driving device of a moving vehicle fails, an unintended torque difference may occur between the left and right wheels and the vehicle behavior may become unstable. In particular, in a drive device having a built-in gear mechanism for amplifying the difference between the left and right motor torques, the amplified torque difference is transmitted to the left and right drive wheels, so that the moment (yaw moment) in the turning direction acting on the vehicle body. There is a problem that the running stability tends to decrease.

One of the purposes of this case is to provide a vehicle drive device having improved running stability in the event of a failure, which was devised in view of the above problems. Not limited to this purpose, it is also an action and effect derived from each configuration shown in the "mode for carrying out the invention" described later, and it is also another purpose of the present invention to exert an action and effect that cannot be obtained by the conventional technique. Can be positioned as.

The vehicle drive device of the disclosure includes a left motor and a right motor for driving the left and right wheels of the vehicle, and a left inverter and a right inverter for controlling each of the left motor and the right motor. This drive device includes a left detection circuit that detects a failure of the left motor or the left inverter, and a right detection circuit that detects a failure of the right motor or the right inverter. Further, it includes a left control circuit that reduces the torque of the left motor when a failure is detected by the right detection circuit, and a right control circuit that reduces the torque of the right motor when a failure is detected by the left detection circuit.

When one of the left and right drive system devices (motor, inverter) fails, the torque difference between the left and right wheels can be reduced by reducing the torque of the other motor. As a result, instability of vehicle behavior due to failure can be suppressed, and running stability can be improved.

It is a perspective view of the drive device of a vehicle as an embodiment. It is a block diagram of a drive device. It is a flowchart for demonstrating the control content at the time of failure detection of a drive device.

[1. Constitution]
Hereinafter, the vehicle drive device 10 as an embodiment will be described with reference to the drawings. The drive device 10 is interposed between the left and right wheels of a vehicle having a yaw control function. In this embodiment, the drive device 10 is applied to a four-wheel drive vehicle. The drive device 10 is interposed between the left and right wheels of the front wheels and between the left and right wheels of the rear wheels. When the drive device 10 is applied to a two-wheel drive vehicle, the drive device 10 may be interposed between the left and right wheels of either the front wheels or the rear wheels.

The yaw control function is a function that adjusts the magnitude of the yaw moment by actively controlling the magnitude of the driving force (driving torque) of the left and right wheels to stabilize the posture of the vehicle. As shown in FIGS. 1 to 3, the drive device 10 includes a left motor 1, a right motor 2, a gearbox 3, a left inverter 4, and a right inverter 5. The front, rear, left, right, up and down directions in the drawing represent directions determined with reference to the driver of the vehicle on which the drive device 10 is mounted.

The left motor 1 is connected (or intervened) to at least a power transmission path connected to the left wheel. Similarly, the right motor 2 is connected (or intervened) to at least a power transmission path connected to the right wheel. The left motor 1 and the right motor 2 function as yaw moment generation sources that generate turning force by increasing or decreasing the driving force of at least the left and right wheels in electric vehicles and hybrid vehicles equipped with other driving motors and engines. To do. In an electric vehicle not equipped with another drive motor, in addition to the above functions, it also has a function as a vehicle drive source.

Hereinafter, when it is not necessary to distinguish between the left motor 1 and the right motor 2, they are also simply referred to as motors 1 and 2. The motors 1 and 2 of the present embodiment are synchronous motors (synchronous AC motors) and can operate independently of each other. Further, the motors 1 and 2 have a function as a generator as well as an electric motor. The electric power for operating the motors 1 and 2 is supplied from a traveling battery mounted on the vehicle or an in-vehicle power generation system (generator, fuel cell, diesel power generation system, etc.). In addition, instead of the synchronous motor, another AC motor (induction motor, commutator motor) or DC motor may be used.

The gearbox 3 is a driving force transmission device sandwiched between the left motor 1 and the right motor 2. The output shafts of the motors 1 and 2 and the drive shafts connected to the left and right wheels are connected to the gearbox 3. Further, the gearbox 3 has a built-in gear mechanism for increasing the torque of the motors 1 and 2. The gear mechanism referred to here includes gear trains such as a differential gear mechanism and a planetary gear mechanism. The driving force input from the motors 1 and 2 to the gearbox 3 is transmitted to the left and right wheels via the gear mechanism or distributed to the left and right wheels.

The left inverter 4 and the right inverter 5 are converters (DC-AC inverters) that mutually convert the electric power of the DC circuit (DC power) and the electric power of the AC circuit in which the motors 1 and 2 are interposed (AC power). is there. The left inverter 4 has a function of converting DC power into AC power and supplying it to the left motor 1, and the right inverter 5 has a function of supplying it to the right motor 2. Hereinafter, when it is not necessary to distinguish between the left inverter 4 and the right inverter 5, they are also simply referred to as inverters 4 and 5. When the motors 1 and 2 are power running, the DC power is converted into AC power by the inverters 4 and 5 and supplied to the motors 1 and 2. When the motors 1 and 2 generate electricity, the AC power generated on the motors 1 and 2 side is converted into DC power by the inverters 4 and 5. The inverters 4 and 5 and the motors 1 and 2 are connected by a three-phase alternating current conductive member (a power supply line such as a power supply cable or a bus bar).

A semiconductor module is built in each of the inverters 4 and 5. A semiconductor module is a power module in which a three-phase bridge circuit including a plurality of switching elements and diodes is formed on a substrate (board for an electronic circuit, substrate). By intermittently switching the connection state of each switching element, three-phase AC power is generated. As the switching element, a semiconductor element such as a thyristor, an IGBT (Insulated Gate Bipolar Transistor), or a power MOSFET (Metal Oxide Semiconductor Field-Effect Transistor) is used.

As shown in FIG. 2, the left inverter 4 is provided with a left detection circuit 6 and a left control circuit 8, and the right inverter 5 is provided with a right detection circuit 7 and a right control circuit 9.
The left detection circuit 6 is a circuit that detects a failure of the left motor 1 and the left inverter 4 itself. Similarly, the right detection circuit 7 is a circuit that detects a failure of the right motor 2 and the right inverter 5 itself. The failure referred to here includes not only unintentional operation of the motors 1 and 2 and the inverters 4 and 5, but also an unexpected abnormality related to the drive system device. For example, input of overcurrent (overvoltage) to inverters 4 and 5, insufficient current (voltage), error of motors 1 and 2, input of overload to motors 1 and 2, error of semiconductor module, control of semiconductor module. Includes electronic control device (processor) errors, memory errors, high temperature abnormalities, low temperature abnormalities, communication errors with other electronic control devices, and so on.

The left control circuit 8 is a circuit that reduces the torque of the left motor 1 when a failure is detected by the right detection circuit 7. The left control circuit 8 has a built-in first processor that outputs a signal for reducing the torque of the left motor 1 when a failure is detected by the right detection circuit 7. The left control circuit 8 of the present embodiment has a function of not only reducing the torque of the left motor 1 but also cutting off the power supply to the left motor 1 (making the torque of the left motor 1 zero). For example, when a failure is detected by the right detection circuit 7 and the right motor 2 is in the output stop state, the gate of the left inverter 4 is shut off (the connection state of the switching element is turned off) to turn off the left motor 1. Stop driving. On the other hand, when the right detection circuit 7 detects a failure and the right motor 2 is not in the output stop state, the torque upper limit of the left motor 1 is lowered to a predetermined value.

Similarly, the right control circuit 9 is a circuit that reduces the torque of the right motor 2 when a failure is detected by the left detection circuit 6. The right control circuit 9 has a built-in second processor that outputs a signal for reducing the torque of the right motor 2 when a failure is detected by the left detection circuit 6. The right control circuit 9 of the present embodiment has a function of not only reducing the torque of the right motor 2 but also cutting off the power supply to the right motor 2 (making the torque of the right motor 2 zero). For example, when a failure is detected by the left detection circuit 6 and the left motor 1 is in the output stopped state, the gate of the right inverter 5 is shut off (the connection state of the switching element is turned off) so that the right motor 2 is turned off. Stop driving. On the other hand, when a failure is detected by the left detection circuit 6 and the left motor 1 is not in the output stop state, the torque upper limit of the right motor 2 is lowered to a predetermined value.

The communication line between the left inverter 4 and the right inverter 5 includes the first in-vehicle communication network 11 [main CAN (Controller Area Network) bus], the second in-vehicle communication network 12 (local CAN bus), and the first hard wire 13. , The second hard wire 14 is included. Each of the first vehicle-mounted communication network 11 and the second vehicle-mounted communication network 12 is a pair of communication lines for transmitting a differential voltage signal. The first vehicle-mounted communication network 11 is also connected to other devices (electronic control devices and various sensors) mounted on the vehicle. In the first vehicle-mounted communication network 11 in FIG. 2, a vehicle speed sensor 15 that detects a vehicle speed is exemplified. Both the inverters 4 and 5 on the front wheel side and the inverters 4 and 5 on the rear wheel side are connected to the first vehicle-mounted communication network 11. On the other hand, the second vehicle-mounted communication network 12 is connected only between the left inverter 4 and the right inverter 5 on each of the front and rear wheels.

The first hard wire 13 is a communication line connecting the left detection circuit 6 and the right control circuit 9, and transmits a signal from the left detection circuit 6 to the right control circuit 9. The second hard wire 14 is a communication line connecting the right detection circuit 7 and the left control circuit 8, and transmits a signal from the right detection circuit 7 to the left control circuit 8. The failure information detected by the left detection circuit 6 is transmitted to the right control circuit 9 of the right inverter 5 through the three paths of the first vehicle communication network 11, the second vehicle communication network 12, and the first hard wire 13. .. Further, the failure information detected by the right detection circuit 7 is transmitted to the left control circuit 8 of the left inverter 4 through the three paths of the first vehicle communication network 11, the second vehicle communication network 12, and the second hard wire 14. Will be done.

[2. flowchart]
FIG. 3 illustrates the flow of fail-safe control performed by the left control circuit 8 and the right control circuit 9. In step A1, it is determined whether or not there is an abnormality in the drive system devices (motors 1, 2, inverters 4, 5). If this condition is not met, the flow ends. On the other hand, if the condition is satisfied, the process proceeds to step A2, and it is determined whether or not the failure of the left motor 1 or the left inverter 4 is detected by the left detection circuit 6. If the condition of step A2 is not satisfied, the process proceeds to step A6. If the condition of step A2 is satisfied, the process proceeds to step A3, and it is determined whether or not the left motor 1 is in the output stopped state.

If the left motor 1 is in the output stop state in step A3, the process proceeds to step A4, and the gate of the right inverter 5 is shut off. As a result, not only the left motor 1 but also the right motor 2 is in the output stop state. By such control, the torque difference between the left and right wheels becomes zero. On the other hand, if the left motor 1 is not in the output stop state in step A3, the process proceeds to step A5, and the torque of the right motor 2 is suppressed according to the output torque of the left motor 1. For example, when the output torque of the left motor 1 is about 10% of the target torque, the output torque of the right motor 2 is also reduced to about 10% of the target torque. By such control, the torque difference between the left and right wheels is reduced.

In step A6, it is determined whether or not a failure of the right motor 2 or the right inverter 5 is detected by the right detection circuit 7. If the condition of step A6 is not satisfied, the process proceeds to step A9. If the condition of step A6 is satisfied, the process proceeds to step A7, and it is determined whether or not the right motor 2 is in the output stopped state. If the left motor 1 is in the output stop state in step A7, the process proceeds to step A8, and the gate of the left inverter 4 is shut off. As a result, not only the right motor 2 but also the left motor 1 is in the output stop state. By such control, the torque difference between the left and right wheels becomes zero. On the other hand, if the right motor 2 is not in the output stop state in step A8, the process proceeds to step A9, and the torque of the left motor 1 is suppressed according to the output torque of the right motor 2.

After that, in step A10, it is determined whether or not the vehicle speed is equal to or higher than the predetermined vehicle speed. When this condition is satisfied, the process proceeds to step A11, and the total drive torque of the vehicle is reduced. The total drive torque corresponds to the sum of the drive torque on the front wheel side and the drive torque on the rear wheel side. For example, when one of the motors 1 and 2 on the front wheel side fails and the vehicle speed is equal to or higher than a predetermined vehicle speed, the total drive torque of the vehicle is controlled to be small. As a result, the drive torque on the rear wheel side is reduced. Therefore, the occupant can immediately notice the occurrence of the failure, and appropriate maintenance work and inspection work are encouraged.

[3. Action / effect]
(1) In the above-described embodiment, the left and right inverters 4 and 5 that individually control the left and right motors 1 and 2 each include detection circuits 6 and 7 and control circuits 8 and 9. That is, the left inverter 4 is provided with the left detection circuit 6 and the left control circuit 8, and the right inverter 5 is provided with the right detection circuit 7 and the right control circuit 9. Each of the detection circuits 6 and 7 detects a failure of one of the left and right drive system devices (motor and inverter), and each of the control circuits 8 and 9 functions to reduce the motor torque on the normal side that has not failed. To do. With such a configuration, it is possible to reduce the torque difference between the left and right wheels when one of the left and right drive system devices fails. Therefore, instability of vehicle behavior due to failure can be suppressed, and running stability can be improved.

Further, by distributing the detection circuits 6 and 7 and the control circuits 8 and 9 to the left and right, it is possible to reliably control the motors 1 and 2 on the side that has not failed, and the torque difference between the left and right wheels can be more reliably controlled. Can be reduced. For example, even if the left inverter 4 or the left control circuit 8 fails due to the failure of the left motor 1, the right control circuit 9 can reduce the torque of the right motor 2. Therefore, the running stability at the time of failure can be maintained at a higher level, and the reliability of control can be improved. In particular, the fail-safe performance against failure of the inverters 4 and 5 themselves can be improved.

(2) In the above-described embodiment, the first hard wire 13 and the second hard wire 14 are connected between the left and right inverters 4 and 5. By using these hard wires 13 and 14, a communication line at the time of failure can be realized at low cost. Further, the first hard wire 13 functions as a dedicated communication line from the left detection circuit 6 to the right control circuit 9, and the second hard wire 14 functions as a dedicated communication line from the right detection circuit 7 to the left control circuit 8. Therefore, the reliability of information transmission can be improved.

(3) In the above-described embodiment, the first vehicle-mounted communication network 11 and the second vehicle-mounted communication network 12 are connected between the left and right inverters 4 and 5. By using these in-vehicle communication networks 11 and 12, a communication line at the time of failure can be realized inexpensively and easily. Further, by using the in-vehicle communication networks 11 and 12 together with the above-mentioned hard wires 13 and 14, the reliability of information transmission can be improved. Further, since the second vehicle-mounted communication network 12 functions as a dedicated communication line connecting only between the left inverter 4 and the right inverter 5, the reliability of information transmission can be further improved.

(4) In the above-described embodiment, the control circuits 8 and 9 have a function of shutting off the gates of the inverters 4 and 5 to cut off the power supply to the motors 1 and 2. That is, it has a function of reducing the torque of the motors 1 and 2. As a result, for example, when one of the motors 1 and 2 fails and does not move (torque becomes zero), the torque of the normal motors 1 and 2 can be immediately reduced to zero, and the torque difference between the left and right can be reduced. Can be zero. Therefore, destabilization of vehicle behavior can be suppressed, and running stability can be improved. As shown in steps A3 and A7 of FIG. 3, by confirming that the motors 1 and 2 are in the output stopped state and then setting the torque of the motors 1 and 2 to zero, the torque difference between the left and right is surely obtained. It can be set to zero and the running stability can be improved.

(5) In the above-described embodiment, control is performed to reduce the total drive torque of the vehicle when the drive system device of the four-wheel drive vehicle fails. For example, if the right motor 2 of the front wheel fails, not only the drive torque of the left motor 1 is suppressed (or the torque becomes zero), but also the drive torque of the rear wheel side is suppressed. Therefore, it is possible to make the occupants aware of the occurrence of the failure at an early stage, and to encourage appropriate maintenance work and inspection work.

(6) In the above-described embodiment, the total drive torque is reduced when the vehicle speed is equal to or higher than a predetermined speed. By adding the speed condition in this way, it is possible to secure the runnability at low speed while stabilizing the vehicle behavior. For example, if the total drive torque is unconditionally kept low when moving a failed vehicle to a maintenance shop, it is inconvenient because the moving time is long. On the other hand, by restricting driving at high speeds while allowing driving at medium and low speeds to some extent, it arrives at the maintenance shop in a relatively short time while suppressing instability of vehicle behavior due to breakdowns. It can be done and convenience can be improved.

[4. Modification example]
The above embodiment is merely an example, and there is no intention of excluding the application of various modifications and techniques not specified in the present embodiment. Each configuration of the present embodiment can be variously modified and implemented without departing from the gist thereof. In addition, it can be selected as needed, or can be combined as appropriate.

In the above-described embodiment, it is determined whether or not the motors 1 and 2 are in the output stop state as a condition for shutting off the gates of the inverters 4 and 5 (steps A3 and A7 in FIG. 3). The condition is optional. That is, when one of the left and right drive system devices fails, the torque of the other motor may be reduced to a predetermined value, may be reduced at a predetermined rate, may be reduced to zero, or may be failed. It may be reduced according to the actual torque that can be output by the motor. At least, by reducing the torque of the motors 1 and 2 on the normal side, the torque difference between the left and right wheels can be reduced, and the vehicle behavior can be stabilized.

Further, in the above-described embodiment, it is determined whether or not the vehicle speed is equal to or higher than the predetermined vehicle speed as a condition for reducing the total drive torque (step A10 in FIG. 3), but this condition can be omitted. .. That is, when one of the left and right drive system devices fails, the total drive torque may be reduced regardless of the speed of the vehicle. At least, by reducing the total drive torque when one of the left and right drive system devices fails in the four-wheel drive vehicle, the same effect as that of the above-described embodiment can be obtained.

1 Left motor 2 Right motor 3 Gearbox 4 Left inverter 5 Right inverter 6 Left detection circuit 7 Right detection circuit 8 Left control circuit 9 Right control circuit 10 Drive device 11 First in-vehicle communication network 12 Second in-vehicle communication network 13 First hardware Wire 14 Second hard wire 15 Vehicle speed sensor

Claims (6)

A failure of the left motor or the left inverter is detected in a vehicle drive device including a left motor and a right motor for driving the left and right wheels of the vehicle and a left inverter and a right inverter for controlling each of the left motor and the right motor. Left detection circuit and
A right detection circuit that detects a failure of the right motor or the right inverter,
A left control circuit that reduces the torque of the left motor when a failure is detected by the right detection circuit,
A right control circuit that reduces the torque of the right motor when a failure is detected in the left detection circuit,
A vehicle drive device, characterized in that it comprises. A first hard wire that connects the left detection circuit and the right control circuit and transmits a signal from the left detection circuit to the right control circuit.
A second hard wire that connects the right detection circuit and the left control circuit and transmits a signal from the right detection circuit to the left control circuit.
The vehicle driving device according to claim 1, wherein the vehicle is provided with. A first in-vehicle communication network that connects between the left inverter and the right inverter and is connected to other devices mounted on the vehicle.
A second vehicle-mounted communication network that is provided independently of the first vehicle-mounted communication network and connects only between the left inverter and the right inverter.
The vehicle driving device according to claim 1 or 2. The left control circuit cuts off the power supply to the left motor when the right motor or the right inverter fails.
The vehicle drive device according to any one of claims 1 to 3, wherein the right control circuit cuts off the power supply to the right motor when the left motor or the left inverter fails. The vehicle is a four-wheel drive vehicle
The left control circuit reduces the total drive torque of the vehicle in the event of a failure of the right motor or the right inverter.
The vehicle drive device according to any one of claims 1 to 4, wherein the right control circuit reduces the total drive torque of the vehicle when the left motor or the left inverter fails. The vehicle drive according to claim 5, wherein the condition for the left control circuit and the right control circuit to reduce the total drive torque of the vehicle includes a vehicle speed of a predetermined speed or higher. apparatus.

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