Hybrid vehicle control device

Abstract

To provide a control device of a hybrid vehicle that can prevents a switching element from becoming overheated, even if a motor is driven while the temperature of the switching element is high.SOLUTION: A control device of a hybrid vehicle is equipped with an engine 2, a motor 4, an inverter 5 that supplies alternating current power to the motor 4 by using a switching element, a temperature sensor that detects the temperature of the switching element, and a control portion 6 that starts the engine 2 when the temperature of the switching element is a predetermined temperature or more at the starting of driving of the motor 4.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Patent Document 1 discloses a technique for resolving motor lock when the engine is stopped by starting the engine and increasing the torque transmitted to the drive wheels.

[0003] It is generally known that if the motor lock state continues, current will concentrate in a specific phase of the inverter's switching elements, causing the switching elements to overheat. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-193557 Summary of the Invention [Problem to be solved by the invention]

[0005] However, because the temperature of the switching element rises rapidly, even if the motor lock is detected and then released as in Patent Document 1 when the temperature of the switching element is high, the switching element may become overheated and may not be protected.

[0006] Therefore, an object of the present invention is to provide a control device for a hybrid vehicle that can prevent switching elements from becoming overheated even when the motor is driven in a state where the temperature of the switching elements is high. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides a control device for a hybrid vehicle including an engine, a motor, an inverter that supplies AC power to the motor using a switching element, and a temperature detection unit that detects a temperature of the switching element, When the motor starts to drive, When a predetermined judgment condition is met, the engine is started if the temperature of the switching element is equal to or higher than a first predetermined temperature, and the engine is started if the temperature of the switching element is equal to or higher than a second predetermined temperature that is higher than the first predetermined temperature, and the control unit limits the torque of the motor. [Effects of the Invention]

[0008] Thus, according to the present invention, even if the motor is driven in a state where the temperature of the switching element is high, the switching element can be prevented from becoming overheated. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram of a hybrid vehicle according to an embodiment of the present invention. [Figure 2] FIG. 2 is a block diagram of an inverter for a hybrid vehicle according to an embodiment of the present invention. [Figure 3] FIG. 3 is a flowchart showing the procedure of the overheat protection control process of the control device for a hybrid vehicle according to one embodiment of the present invention. [Figure 4] FIG. 4 is a time chart showing changes in the rotation speed and torque of the motor when the temperature of the switching element is higher than the first threshold value due to the overheat protection control process of the control device for a hybrid vehicle according to one embodiment of the present invention. [Figure 5] FIG. 5 is a time chart showing changes in the rotation speed and torque of the motor when the temperature of the switching element due to the overheat protection control process of the control device for a hybrid vehicle according to one embodiment of the present invention is higher than the second threshold value. DETAILED DESCRIPTION OF THE INVENTION

[0010] A control device for a hybrid vehicle according to one embodiment of the present invention is a control device for a hybrid vehicle that includes an engine, a motor, an inverter that supplies AC power to the motor using a switching element, and a temperature detection unit that detects the temperature of the switching element, and is configured to include a control unit that starts the engine if the temperature of the switching element is above a predetermined temperature when the motor starts to drive.

[0011] As a result, the control device for a hybrid vehicle according to one embodiment of the present invention can prevent the switching elements from overheating even when the motor is driven in a state where the temperature of the switching elements is high. [Example]

[0012] A hybrid vehicle equipped with a control device according to an embodiment of the present invention will be described in detail below with reference to the drawings.

[0013] In FIG. 1, a hybrid vehicle 1 according to an embodiment of the present invention includes an engine 2, a transmission 3, a motor 4, an inverter 5, and a control unit 6.

[0014] The engine 2 is formed with a plurality of cylinders. In this embodiment, the engine 2 is configured so that each cylinder undergoes a series of four strokes, which are an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke.

[0015] The transmission 3 changes the speed of the rotation output from the engine 2 and drives left and right drive wheels 8 via a differential 7. The transmission 3 includes a constant mesh type speed change mechanism (not shown) made up of a parallel shaft gear mechanism, and an actuator (not shown).

[0016] A dry single-plate clutch 31 is provided between the engine 2 and the transmission 3, and the clutch 31 connects or disconnects the power transmission between the engine 2 and the transmission 3.

[0017] The transmission 3 is configured as a so-called AMT (Automated Manual Transmission), and an actuator (not shown) switches the gear position in the speed change mechanism and engages and disengages the clutch 31.

[0018] The motor 4 functions as an electric motor driven by power supplied from a battery (not shown) via an inverter 5, and also functions as a generator that performs regenerative power generation using a reverse driving force input from a differential 7. The output shaft of the motor 4 is connected to the output shaft of the transmission 3.

[0019] The motor 4 is provided with a rotation sensor 41 that detects the rotation speed of the motor 4. The rotation sensor 41 is connected to the control unit 6.

[0020] Under the control of the control unit 6, the inverter 5 converts the DC power supplied from the battery into three-phase AC power and supplies it to the motor 4, or converts the three-phase AC power generated by the motor 4 into DC power to charge the battery.

[0021] The inverter 5 is provided with a current sensor 51 that detects the current supplied from the inverter 5 to the motor 4. The current sensor 51 is connected to the control unit 6.

[0022] As shown in FIG. 2, the inverter 5 includes a smoothing capacitor 52, switching elements 53a, 53b, 53c, 54a, 54b, and 54c, and temperature sensors 55a, 55b, and 55c as temperature detection units.

[0023] The smoothing capacitor 52 smoothes the voltage of the DC power generated between the positive and negative electrodes.

[0024] The switching elements 53 a , 53 b , 53 c , 54 a , 54 b , and 54 c generate three-phase AC power to be supplied to the motor 4 .

[0025] The switching elements 53a and 54a, the switching elements 53b and 54b, and the switching elements 53c and 54c each generate one-phase AC power.

[0026] The temperature sensors 55a, 55b, and 55c detect the temperatures of the switching elements of the respective phases.

[0027] The inverter 5 controls the three-phase AC power supplied to the motor 4 by controlling the switching elements 53 a , 53 b , 53 c , 54 a , 54 b , and 54 c .

[0028] In FIG. 1, the control unit 6 is composed of a computer unit having a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), flash memory for storing backup data, etc., input ports, and output ports.

[0029] The ROM of this computer unit stores a program for causing the computer unit to function as the control unit 6, along with various constants and maps.

[0030] That is, the CPU executes the program stored in the ROM using the RAM as a work area, and these computer units function as the control unit 6 in this embodiment.

[0031] To the input port of the control unit 6, various sensors including the rotation sensor 41 and current sensor 51 described above are connected.

[0032] On the other hand, the output port of the control unit 6 is connected to the inverter 5, the actuator of the transmission 3, and various control targets including an injector (not shown).

[0033] In this embodiment, when the motor 4 starts to drive, the control unit 6 starts the engine 2 if the temperatures of the switching elements 53a, 53b, 53c, 54a, 54b, 54c detected by the temperature sensors 55a, 55b, 55c are equal to or higher than a predetermined temperature.

[0034] When the motor 4 starts to be driven, the control unit 6 starts the engine 2 if the temperatures of the switching elements 53a, 53b, 53c, 54a, 54b, and 54c are equal to or higher than a first predetermined temperature.

[0035] When the motor 4 starts to drive, if the temperature of the switching elements 53a, 53b, 53c, 54a, 54b, 54c is equal to or higher than a second predetermined temperature that is higher than the first predetermined temperature, the control unit 6 starts the engine 2 and limits the torque of the motor 4.

[0036] The control unit 6 limits the torque of the motor 4 in two stages, for example. In the first stage, the control unit 6 limits the torque of the motor 4 to a first torque limit value. If the temperature of the switching elements 53a, 53b, 53c, 54a, 54b, and 54c does not fall below a second predetermined temperature even after limiting in the first stage, the control unit 6 limits the torque of the motor 4 to a second torque limit value that is lower than the first torque limit value.

[0037] The control unit 6 may limit the torque of the motor 4 to a second torque limit value if the temperature of the switching elements 53a, 53b, 53c, 54a, 54b, and 54c does not drop below the second predetermined temperature for a predetermined period of time even when limited at the first stage.

[0038] When starting to drive the hybrid vehicle 1 using the motor 4, if the temperature of the switching elements 53a, 53b, 53c, 54a, 54b, 54c is equal to or higher than a predetermined temperature, the control unit 6 starts to drive the hybrid vehicle 1 using the engine 2 as a drive source.

[0039] When the control unit 6 starts decelerating the hybrid vehicle 1 using the motor 4, if the temperatures of the switching elements 53a, 53b, 53c, 54a, 54b, and 54c are equal to or higher than a predetermined temperature, the control unit 6 causes the hybrid vehicle 1 to run using the engine 2 as a drive source.

[0040] The control unit 6 may start the engine 2 if, when the motor 4 starts to be driven, the temperature of the switching elements 53a, 53b, 53c, 54a, 54b, and 54c remains at or above a predetermined temperature until the rotation speed of the motor 4 reaches or exceeds a predetermined rotation speed.

[0041] For example, when a predetermined determination condition is met, the control unit 6 determines the temperatures of the switching elements 53a, 53b, 53c, 54a, 54b, and 54c.

[0042] The determination conditions are, for example, that the rotation speed of the motor 4 is equal to or lower than a predetermined motor rotation speed, and that the torque of the motor 4 is equal to or higher than a predetermined motor torque.

[0043] For example, the control unit 6 starts the engine 2 when a predetermined determination condition is met and the temperature of the switching elements 53a, 53b, 53c, 54a, 54b, and 54c remains at or above a predetermined temperature for a predetermined determination time.

[0044] For example, when a predetermined recovery condition is met, the control unit 6 stops determining the temperatures of the switching elements 53a, 53b, 53c, 54a, 54b, and 54c and stops the engine 2.

[0045] The recovery conditions may be, for example, that the rotation speed of the motor 4 is equal to or greater than a predetermined recovery rotation speed, that the torque of the motor 4 is equal to or less than a predetermined recovery torque, or that the temperatures of the switching elements 53a, 53b, 53c, 54a, 54b, and 54c are lower than a predetermined temperature, or that any one or all of the combinations thereof are satisfied.

[0046] For example, when a predetermined return condition is satisfied for a predetermined return determination time, the control unit 6 stops determining the temperatures of the switching elements 53a, 53b, 53c, 54a, 54b, and 54c and stops the engine 2.

[0047] The control unit 6 performs the above-mentioned determination by determining, for example, the maximum value of the temperatures of the switching elements of each phase detected by the temperature sensors 55a, 55b, and 55c as the temperature of the switching elements 53a, 53b, 53c, 54a, 54b, and 54c.

[0048] The overheat protection control process performed by the control device for a hybrid vehicle according to this embodiment configured as described above will be described with reference to Fig. 3. The overheat protection control process described below starts when the control unit 6 starts operation, and is executed at preset time intervals.

[0049] In step S1, the control unit 6 determines whether or not the above-mentioned determination condition is met. If it is determined that the determination condition is met, the control unit 6 executes the process of step S2.

[0050] If it is determined that the determination condition is not met, the control unit 6 executes the process of step S1.

[0051] In step S2, the control unit 6 determines whether the detected temperatures of the switching elements 53a, 53b, 53c, 54a, 54b, and 54c are lower than a first threshold value as a first predetermined temperature. If it is determined that the detected temperatures are lower than the first threshold value, the control unit 6 executes the process of step S4.

[0052] If it is determined that the detected temperature is not lower than the first threshold value, the control unit 6 executes the process of step S3.

[0053] In step S3, the control unit 6 determines whether the detected temperatures of the switching elements 53a, 53b, 53c, 54a, 54b, and 54c are equal to or higher than a second threshold value as a second predetermined temperature. If it is determined that the detected temperatures are equal to or higher than the second threshold value, the control unit 6 executes the process of step S8.

[0054] If it is determined that the detected temperature is not equal to or higher than the second threshold value, the control unit 6 executes the process of step S6.

[0055] In step S4, the control unit 6 sets the determination result to “low temperature.” After executing the process of step S4, the control unit 6 executes the process of step S5.

[0056] In step S5, the control unit 6 executes the existing motor lock protection control process. After executing the process of step S5, the control unit 6 ends the overheat protection control process.

[0057] In step S6, the control unit 6 sets the determination result to "high temperature 1." After executing the process of step S6, the control unit 6 executes the process of step S7.

[0058] In step S7, the control unit 6 performs the first restriction level process by starting the engine 2. After performing the process of step S7, the control unit 6 performs the process of step S5.

[0059] In step S8, the control unit 6 sets the determination result to "high temperature 2." After executing the process of step S8, the control unit 6 executes the process of step S9.

[0060] In step S9, the control unit 6 performs processing at the second restriction level, limiting the start of the engine 2 and the torque of the motor 4. After executing the processing of step S9, the control unit 6 ends the overheat protection control processing.

[0061] The operation of such an overheat protection control process will be described with reference to FIGS. FIG. 4 is a time chart when the detected temperatures of the switching elements 53a, 53b, 53c, 54a, 54b, and 54c are equal to or higher than the first threshold value.

[0062] At time t1, the determination condition based on the rotation speed and torque of the motor 4 is met, and this condition continues for the determination time T1. At time t2, the engine start control is turned on and the engine 2 is started.

[0063] At time t3, the rotation speed of the motor 4 starts to increase, and at time t4, the restoration condition is met. At time t5, after this condition has continued for the restoration determination time T2, the engine start control is turned off and the engine 2 is stopped.

[0064] FIG. 5 is a time chart when the detected temperatures of the switching elements 53a, 53b, 53c, 54a, 54b, and 54c are equal to or higher than the second threshold value.

[0065] At time t11, the judgment condition based on the rotational speed and torque of motor 4 is met, and at time t12, which continues for judgment time T1, engine start control is turned on, engine 2 is started, and the torque of motor 4 is limited to the first torque limit value.

[0066] Thereafter, even at time t13 when the first torque limit time T3 has elapsed, the detected temperatures of the switching elements 53a, 53b, 53c, 54a, 54b, and 54c are still above the second threshold, so the torque of the motor 4 is limited to the second torque limit value and the rotational speed of the motor 4 begins to increase.

[0067] The second torque limit period T4 begins at time t14 when the torque of motor 4 becomes equal to or less than the second torque limit value, and at time t15, the rotational speed of motor 4 becomes equal to or greater than the recovery rotational speed, the engine start control is turned off, engine 2 is stopped, and the period ends.

[0068] Thus, in this embodiment, when the motor 4 starts to be driven, the control unit 6 starts the engine 2 if the temperatures of the switching elements 53a, 53b, 53c, 54a, 54b, 54c detected by the temperature sensors 55a, 55b, 55c are equal to or higher than a predetermined temperature.

[0069] By starting the engine 2 if the temperatures of the switching elements 53a, 53b, 53c, 54a, 54b, and 54c are equal to or higher than a predetermined temperature, it is possible to suppress the temperature rise of the switching elements 53a, 53b, 53c, 54a, 54b, and 54c before it is determined that the motor is locked, thereby preventing the switching elements 53a, 53b, 53c, 54a, 54b, and 54c from overheating.

[0070] In addition, when the motor 4 starts to drive, the control unit 6 starts the engine 2 if the temperatures of the switching elements 53a, 53b, 53c, 54a, 54b, and 54c are equal to or higher than a first predetermined temperature, and starts the engine 2 and limits the torque of the motor 4 if the temperatures of the switching elements 53a, 53b, 53c, 54a, 54b, and 54c are equal to or higher than a second predetermined temperature that is higher than the first predetermined temperature.

[0071] If the temperatures of the switching elements 53a, 53b, 53c, 54a, 54b, and 54c are equal to or higher than a second predetermined temperature that is higher than the first predetermined temperature, the engine 2 is started and the torque of the motor 4 is limited, thereby further preventing overheating of the switching elements 53a, 53b, 53c, 54a, 54b, and 54c.

[0072] In addition, when the control unit 6 starts running the hybrid vehicle 1 using the motor 4, if the temperature of the switching elements 53a, 53b, 53c, 54a, 54b, 54c is equal to or higher than a predetermined temperature, the control unit 6 starts running the hybrid vehicle 1 using the engine 2 as a driving source.

[0073] When starting to run the hybrid vehicle 1 using the motor 4, if the temperature of the switching elements 53a, 53b, 53c, 54a, 54b, 54c is equal to or higher than a predetermined temperature, the hybrid vehicle 1 is started to run using the engine 2 as a driving source, thereby suppressing the temperature rise of the switching elements 53a, 53b, 53c, 54a, 54b, 54c before it is determined that the motor is locked, thereby preventing the switching elements 53a, 53b, 53c, 54a, 54b, 54c from overheating.

[0074] In addition, when the control unit 6 starts decelerating the hybrid vehicle 1 using the motor 4, if the temperature of the switching elements 53a, 53b, 53c, 54a, 54b, 54c is equal to or higher than a predetermined temperature, the control unit 6 causes the hybrid vehicle 1 to run using the engine 2 as a driving source.

[0075] When the hybrid vehicle 1 starts to decelerate using the motor 4, if the temperature of the switching elements 53a, 53b, 53c, 54a, 54b, and 54c is above a predetermined temperature, the hybrid vehicle 1 is driven by the engine 2 as a driving source, thereby suppressing the temperature rise of the switching elements 53a, 53b, 53c, 54a, 54b, and 54c before it is determined that the motor is locked, thereby preventing the switching elements 53a, 53b, 53c, 54a, 54b, and 54c from overheating.

[0076] When the motor 4 starts to be driven, the control unit 6 starts the engine 2 if the temperature of the switching elements 53a, 53b, 53c, 54a, 54b, and 54c remains at or above a predetermined temperature until the rotation speed of the motor 4 reaches or exceeds a predetermined rotation speed.

[0077] If the determination is immediately made when the temperatures of the switching elements 53a, 53b, 53c, 54a, 54b, and 54c are equal to or higher than a predetermined temperature, there is a possibility that the engine 2 may be started more than necessary, resulting in an erroneous determination.

[0078] Therefore, if the temperature of the switching elements 53a, 53b, 53c, 54a, 54b, and 54c remains at or above a predetermined temperature until the rotation speed of the motor 4 reaches or exceeds a predetermined rotation speed, the judgment is made to start the engine 2, thereby preventing erroneous judgment and preventing the switching elements 53a, 53b, 53c, 54a, 54b, and 54c from becoming overheated.

[0079] In this embodiment, an example has been described in which the control unit 6 performs various determinations and calculations based on various sensor information, but this is not limited to this. The hybrid vehicle 1 may also be provided with a communication unit capable of communicating with an external device such as an external server, and various determinations and calculations may be performed by the external device based on the detection information of the various sensors transmitted from the communication unit. The determination results and calculation results may then be received by the communication unit, and various controls may be performed using the received determination results and calculation results.

[0080] While an embodiment of the present invention has been disclosed, it will be apparent to one skilled in the art that modifications may be made thereto without departing from the scope of the present invention, and it is intended that all such modifications and equivalents be included in the following claims. [Explanation of symbols]

[0081] 1 Hybrid vehicle 2 engines 4 motors 5 inverters 6 Control Unit 53a, 53b, 53c, 54a, 54b, 54c Switching elements 55a, 55b, 55c Temperature sensor (temperature detection part)

Claims

1. A control device for a hybrid vehicle including an engine, a motor, an inverter that supplies AC power to the motor using a switching element, and a temperature detection unit that detects a temperature of the switching element, A control device for a hybrid vehicle, comprising: a control unit that, when a predetermined judgment condition is met at the start of driving of the motor, starts the engine if the temperature of the switching element is equal to or higher than a first predetermined temperature, and starts the engine if the temperature of the switching element is equal to or higher than a second predetermined temperature that is higher than the first predetermined temperature, and limits the torque of the motor.

2. 2. The control device for a hybrid vehicle according to claim 1, wherein the predetermined determination conditions include that the rotational speed of the motor is equal to or lower than a predetermined motor rotational speed and that the torque of the motor is equal to or higher than a predetermined motor torque.

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