Vehicle control device

Abstract

To provide a controller of a vehicle which can suppress increase of surge voltage and secure vehicle requirement output.SOLUTION: A controller of a vehicle including an engine and a power conversion device converting power of a power storage device into drive power of a rotation electrical machine for travel selectively performs: a first travel mode in which the vehicle travels only with torque generated by the engine; a second travel mode in which the vehicle travels only with torque generated by the rotation electrical machine while the engine is stopped; and a third travel mode in which the vehicle travels with torque of both of the engine and the rotation electrical machine. When relation between atmospheric pressure of the vehicle and system voltage is within a prescribed area of a map representing a relation between the atmospheric pressure and the system voltage set in advance, switching speed of a switching element included in the power conversion device is made to become lower than usual, and the engine is activated and torque of the rotation electrical machine is restricted to perform the third travel mode.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a vehicle control device. [Background technology]

[0002] Patent Document 1 discloses a control device for a power converter that sets the switching speed of a switching element of the power converter to a slower speed as the atmospheric pressure decreases, thereby ensuring the withstand voltage of the motor (motor withstand voltage) by suppressing surge voltage. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-028900 A Summary of the Invention [Problem to be solved by the invention]

[0004] Slowing the switching speed increases the amount of heat generated by the switching elements. Therefore, it is conceivable to limit the motor torque in order to suppress the amount of heat generated by the switching elements. However, this motor torque limiting may make it difficult to ensure the vehicle required output, which is the required value of the output required for the vehicle to run.

[0005] The present invention has been made in consideration of the above-mentioned problems, and an object of the present invention is to provide a vehicle control device that can ensure the vehicle's required output while suppressing an increase in surge voltage. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the vehicle control device of the present invention is a vehicle control device that includes an engine and a power converter that converts the power of an electric storage device into driving power for a rotating electric motor for driving, and is capable of selectively executing a first driving mode in which the vehicle runs only on the torque generated by the engine, a second driving mode in which the engine is stopped and the vehicle runs only on the torque generated by the rotating electric motor, and a third driving mode in which the vehicle runs on the torque of both the engine and the rotating electric motor, and is characterized in that when the air pressure and system voltage surrounding the vehicle are within a predetermined area of ​​a pre-set map showing the relationship between the air pressure and the system voltage, the switching speed of the switching elements of the power converter is reduced below normal, and the engine is operated while limiting the torque of the rotating electric motor, thereby executing the third driving mode.

[0007] This makes it possible to ensure the required vehicle output while suppressing an increase in surge voltage.

[0008] In the above, intermittent operation of the engine may be prohibited in the predetermined region.

[0009] As a result, even if the torque of the rotating electric machine is limited, the engine is allowed to continue operating, so that the vehicle required output can be more reliably ensured by the engine torque. Effect of the Invention

[0010] The vehicle control device according to the present invention has an effect of ensuring the required vehicle output while suppressing an increase in surge voltage. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of a vehicle to which a vehicle control device according to an embodiment is applied. [Diagram 2] FIG. 2 is a diagram showing the motor withstand voltage at low and high altitudes. [Diagram 3]FIG. 3 is a diagram showing a preset map showing the relationship between atmospheric pressure and system voltage. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] An embodiment of a vehicle control device according to the present invention will be described below, although the present invention is not limited to this embodiment.

[0013] FIG. 1 is a diagram showing a schematic configuration of a vehicle 10 to which a vehicle control device according to an embodiment is applied. As shown in FIG. 1, the vehicle 10 according to the embodiment is a hybrid vehicle including a first rotating electric machine (MG1) 21, a second rotating electric machine (MG2) 22, and an engine 23. Note that the vehicle 10 shown in FIG. 1 includes two rotating electric machines, but is not limited thereto. For example, the vehicle 10 may include one rotating electric machine capable of outputting a driving force for vehicle running, and the engine 23. In other words, the vehicle 10 according to the embodiment may be configured to be capable of running only with the driving force (torque) from the rotating electric machine, to be capable of running only with the driving force (torque) from the engine 23, and to be capable of running with the driving forces (torque) from both the rotating electric machine and the engine 23.

[0014] Each of the first rotating electric machine 21 and the second rotating electric machine 22 has a stator with a three-phase winding (coil) that generates a rotating magnetic field, and a rotor with a permanent magnet that generates torque by magnetic force between the stator and the rotating magnetic field. Each of the first rotating electric machine 21 and the second rotating electric machine 22 is a so-called motor-generator that can operate as both an electric motor and a generator.

[0015] The first rotating electric machine 21 is mainly used as a generator. The first rotating electric machine 21 further cranks the engine 23 when the engine 23 is started. The first rotating electric machine 21 generates "torque acting on the engine 23", and cranking (rotating the crankshaft of the engine 23) is also called "motoring".

[0016] The second rotating electric machine 22 is mainly used as an electric motor, and can generate driving force for the vehicle 10 (torque for running the vehicle 10).

[0017] The engine 23 is, for example, an internal combustion engine such as a gasoline engine or a diesel engine. The engine 23 is provided with a starter motor 24 that cranks the engine 23. Like the second rotating electric machine 22, the engine 23 can also generate driving force for the vehicle 10 (torque for running the vehicle 10).

[0018] The vehicle 10 has a power split mechanism 31. The power split mechanism 31 is a planetary gear mechanism. That is, the power split mechanism 31 includes a sun gear (not shown), a ring gear (not shown) that is arranged concentrically with the sun gear, a plurality of pinion gears (not shown) that mesh with the sun gear and also mesh with the ring gear, and a pinion carrier (not shown) that holds the plurality of pinion gears in a state in which they can rotate on their own axes and revolve around the sun gear.

[0019] An output shaft of the first rotating electric machine 21 is connected to the sun gear so as to be able to transmit torque. A crankshaft of the engine 23 is connected to the pinion carrier so as to be able to transmit torque. An output shaft of the second rotating electric machine 22 is connected to the ring gear via a reduction gear mechanism 32 so as to be able to transmit torque. Furthermore, the output shaft of the second rotating electric machine 22 is connected to an axle 33 via the reduction gear mechanism 32 so as to be able to transmit torque. The axle 33 is connected to driving wheels 35 via a differential gear 34 so as to be able to transmit torque.

[0020] A torsional damper 36 is interposed between the engine 23 and the power split mechanism 31. The torsional damper 36 rotatably couples a shaft on the engine 23 side and a shaft on the power split mechanism 31 side via an elastic body, and is designed to absorb fluctuations in the torque generated by the engine 23.

[0021] The vehicle 10 further includes a battery 41, a boost converter 42, and an inverter 43 which is a power converter. The battery 41 is an electricity storage device, and is, for example, a secondary battery capable of being charged and discharged, such as a lithium ion battery or a nickel-metal hydride battery. DC power output from the battery 41 is voltage converted (boosted) by the boost converter 42. The voltage-converted DC power is converted to AC power by the switching operation of the switching elements in the inverter 43, and is supplied to the first rotating electric machine 21 and the second rotating electric machine 22.

[0022] On the other hand, when at least one of the first rotating electric machine 21 and the second rotating electric machine 22 operates as a generator, AC power generated by them is converted to DC power by the switching operation of the switching elements in the inverter 43. Furthermore, the converted DC power is voltage-converted (stepped down) by the boost converter 42 and supplied to the battery 41. As a result, the battery 41 is charged. Alternatively, the AC power generated by the first rotating electric machine 21 is supplied to the second rotating electric machine 22 via the inverter 43.

[0023] The vehicle 10 is equipped with an air pressure detection sensor 61 for detecting atmospheric pressure. The air pressure detection sensor 61 outputs a detection signal corresponding to the atmospheric pressure around the vehicle 10 to the control device 100. In the following description, the atmospheric pressure is also referred to simply as air pressure. In this embodiment, the method of detecting the atmospheric pressure around the vehicle 10 is not limited to the detection of the atmospheric pressure by the air pressure detection sensor 61, and for example, the atmospheric pressure may be estimated from the altitude at the current position of the vehicle 10 using a car navigation system or an altimeter mounted on the vehicle 10.

[0024] The control device 100 has a plurality of ECUs (Electric Control Units) for controlling the vehicle 10. That is, the control device 100 has an MG-ECU for controlling the first rotating electric machine 21 and the second rotating electric machine 22, an engine-ECU for controlling the engine 23, and a battery-ECU for monitoring the battery 41. The control device 100 selectively executes an engine driving mode which is a first driving mode in which the vehicle 10 runs only by the torque generated by the engine 23, a motor driving mode which is a second driving mode in which the engine 23 is stopped and the vehicle runs only by the torque generated by the second rotating electric machine 22, and a hybrid driving mode which is a third driving mode in which the vehicle runs only by the torque of both the engine 23 and the second rotating electric machine 22.

[0025] The ECU is an electric control device having a microcomputer as a main part, and is connected to be able to transmit and receive information to and from each other via a controller area network (CAN) (not shown). The microcomputer has a central processing unit (CPU), read only memory (ROM), random access memory (RAM), non-volatile memory, and an interface (I / F). The CPU realizes various functions by executing instructions (programs, routines) stored in the ROM. Some or all of these ECUs may be integrated into one ECU.

[0026] The accelerator opening sensor 51 detects the amount of operation of the accelerator pedal 52 and outputs a signal representing this amount of operation. The control device 100 controls the first rotating electric machine 21, the second rotating electric machine 22, the engine 23, etc., to drive the vehicle 10 based on the amount of operation of the accelerator pedal 52, the vehicle speed, etc.

[0027] Fig. 2 is a diagram showing motor withstand voltages at low altitudes and high altitudes. Fig. 2 shows motor withstand voltages, which are withstand voltages of the second rotating electric machine 22, when the system voltage and surge voltage of the vehicle 10 are the same at low altitudes (low altitudes) and high altitudes (high altitudes). The system voltage is the voltage of the power supplied to the inverter 43 that drives the second rotating electric machine 22. The system voltage is detected by a voltage sensor (not shown). The surge voltage is an overshoot voltage that occurs due to continuous switching operations in the inverter 43 when power is supplied from the battery 41 to the second rotating electric machine 22 via the inverter 43.

[0028] 2, the motor withstand voltage decreases as the altitude changes from low altitude to high altitude, in other words, as the atmospheric pressure decreases. Therefore, even if the motor withstand voltage is higher than the total voltage of the system voltage and the surge voltage at low altitude, the total voltage of the system voltage and the surge voltage may exceed the motor withstand voltage at high altitude. Therefore, in the vehicle 10 according to the embodiment, the control device 100 performs control to switch the operation mode of the vehicle 10 according to the atmospheric pressure and the system voltage.

[0029] Fig. 3 is a diagram showing a preset map showing the relationship between atmospheric pressure and system voltage. In the vehicle 10 according to the embodiment, operation modes of regions (1) to (4) are set in accordance with the relationship between the atmospheric pressure detected by the atmospheric pressure detection sensor 61 and the system voltage, as in the preset map showing the relationship between atmospheric pressure and system voltage in Fig. 3. The control device 100 switches to one of the operation modes of regions (1) to (4) according to the atmospheric pressure and the system voltage, and performs control to run the vehicle 10.

[0030] Here, region (1) is a region of an operation mode in which the second rotating electric machine 22 can be used without torque limitation at a switching speed that optimizes the system loss (normal operation region of the second rotating electric machine 22). Region (2) is a region of an operation mode in which the switching speed is slowed down within a range in which element heat is generated, and the second rotating electric machine 22 can be used without torque limitation, although the switching loss and element heat of the inverter 43 are deteriorated (switching speed switching (slowing) region of the inverter 43). Note that element heat is heat of a switching element generated by the switching operation of the inverter 43. Region (3) is a region of an operation mode in which the switching speed is slowed down and the torque of the second rotating electric machine 22 is limited (torque limit region of the second rotating electric machine 22). Region (4) is a region of an operation mode in which the switching operation of the inverter 43 is completely stopped (operation prohibited region of the second rotating electric machine 22 (switching stop region of the inverter 43)).

[0031] In the vehicle 10 according to the embodiment, when the vehicle 10 is driven at a low altitude, such as at an altitude of 0 [m], the engine 23 is stopped and the operation mode is switched to a region (1) in which a motor driving mode is implemented in which the vehicle runs only using the torque generated by the second rotating electric machine 22.

[0032] Then, when the relationship between the air pressure and the system voltage transitions from region (1) to region (2) beyond boundary line a shown in Figure 3 as the vehicle 10 travels, the control device 100 switches to an operating mode in which the motor driving mode is implemented without limiting the torque of the second rotating electric machine 22 while slowing down the switching speed of the inverter 43.

[0033] As a result, in the operating mode of region (2), the switching speed of the inverter 43 is reduced, thereby suppressing the increase in surge voltage and ensuring the motor voltage resistance, while ensuring the required output of the second rotating electric machine 22, allowing the vehicle 10 to run in the motor running mode.

[0034] 3, the control device 10 starts the engine 23 at the boundary line b. In addition, in the operation mode of the region (3), the control device 100 prohibits intermittent operation of the engine 23. That is, in the operation mode of the region (3), the torque of the second rotating electric machine 22 is limited and the drive of the second rotating electric machine 22 is permitted, on the assumption that the engine 23 is operating.

[0035] As a result, in the operating mode of region (3), the switching speed of the inverter 43 is slowed down and the torque of the second rotating electric machine 22 is limited, thereby suppressing an increase in surge voltage and ensuring the motor voltage resistance, while the vehicle 10 is driven in hybrid driving mode to ensure the vehicle required output.

[0036] Furthermore, when the relationship between the air pressure and the system voltage crosses the boundary line c and transitions from region (3) to region (4) as a result of the vehicle 10 running, the control device 100 completely stops the switching operation of the inverter 43, stops driving the second rotating electric machine 22, and switches to an operation mode that implements an engine running mode in which the vehicle runs only using the torque of the operating engine 23. Furthermore, in the operation mode of region (4), intermittent operation of the engine 23 is prohibited.

[0037] As a result, in the operating mode of region (4), under conditions in which the total voltage of the system voltage and the surge voltage is likely to exceed the motor withstand voltage, the second rotating electric machine 22 is stopped and the vehicle 10 is driven in engine driving mode to ensure the vehicle's required output.

[0038] For example, if the vehicle 10 is a plug-in hybrid vehicle, and the battery 41 has been charged by an external charging device at high altitude, when the vehicle is ready-on and the relationship between the air pressure and the system voltage is within region (4), the engine 23 is started using the starter motor 24.

[0039] Furthermore, in the vehicle 10 according to the embodiment, intermittent operation of the engine 23 is prohibited when the relationship between atmospheric pressure and system voltage is in region (3) and region (4), whereas intermittent operation of the engine 23 is permitted when the relationship between atmospheric pressure and system voltage transitions from region (3) to region (2).

[0040] As described above, in the vehicle 10 according to the embodiment, the control device 100 switches the operating mode to one of the regions (1) to (4) depending on the atmospheric pressure and the system voltage to run the vehicle 10, thereby suppressing an increase in surge voltage, ensuring motor voltage resistance, and ensuring the vehicle required output. [Explanation of symbols]

[0041] 10 Vehicles 21 First rotating electric machine 22 No. 2 rotating electric machine 23 Engine 24 Starter motor 31 Power split mechanism 32 Reduction mechanism 33 Axle 34 Differential Gear 35 Drive Wheel 36 Torsional Damper 41 Battery 42 Boost Converter 43 Inverter 51 Accelerator opening sensor 52 Accelerator pedal 61 Air pressure detection sensor 100 Control device

Claims

[Claim 1] A control device for a vehicle, comprising an engine and a power converter that converts power of a power storage device into drive power for a rotating electric machine for traveling, the control device being capable of traveling by selectively executing a first traveling mode in which the vehicle travels only by torque generated by the engine, a second traveling mode in which the engine is stopped and the vehicle travels only by torque generated by the rotating electric machine, and a third traveling mode in which the vehicle travels only by torque generated by both the engine and the rotating electric machine, a control device for a vehicle, characterized in that, when the atmospheric pressure around the vehicle and the system voltage are within a predetermined region of a preset map showing the relationship between the atmospheric pressure and the system voltage, a switching speed of a switching element of the power converter is reduced from a normal speed, and intermittent operation of the engine is prohibited, the engine is operated, and the torque of the rotating electric machine is limited, thereby executing the third driving mode.

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