Control system for hybrid vehicles

Abstract

To provide a control device for a hybrid vehicle that can prevent the temperature of the components of a boost converter from exceeding the allowable temperature. [Solution] When power is supplied to MG2 from battery 3 via boost converter 8, if the temperature of the components of boost converter 8 exceeds a high-temperature threshold, the power supplied to MG2 from battery 3 via boost converter 8 is limited, and the power generated by MG1 is supplied to MG2.

Description

Technical Field

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

Background Art

[0002] Conventionally, there has been proposed in Patent Document 1 a hybrid vehicle including an engine, a generator that generates electric power by the driving force of the engine, a battery that is charged by the electric power generated by the generator, and an electric motor that is driven by the electric power generated by the generator or the electric power output from the battery. The generator is connected to the output shaft of the engine, and the electric motor is connected to a drive shaft that communicates with the drive wheels.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Such a conventional hybrid vehicle starts the engine when the power consumption of the electric motor exceeds a threshold value, taking into account the power that can be output from the high-voltage battery during EV driving in which the vehicle is running on the electric motor, the power used by the electrical loads mounted on the vehicle, and the power required to start the engine.

[0005] A conventional hybrid vehicle has a boost converter that boosts the voltage of the power supplied from the high-voltage battery to the electric motor. However, in a conventional hybrid vehicle, since the boost converter is energized during charging and discharging of the high-voltage battery, if the charging and discharging time of the high-voltage battery becomes long, the temperature of the components of the boost converter may exceed the allowable temperature, and there is still room for improvement.

[0006] This invention has been made in view of the above circumstances, and aims to provide a control device for a hybrid vehicle that can suppress the temperature of the components of a boost converter from exceeding the allowable temperature. [Means for solving the problem]

[0007] The control device for a hybrid vehicle according to the present invention comprises an engine, a generator that generates electricity using the driving force of the engine, a battery that is charged with the electricity generated by the generator, an electric motor that drives the drive wheels using the electricity generated by the generator and the electricity charged in the battery, and a boost converter that increases the voltage of the electricity supplied from the battery to the electric motor, and further comprises a control unit that, when power is being supplied from the battery to the electric motor via the boost converter, the temperature of the components of the boost converter exceeds a high-temperature determination threshold, limits the power supplied from the battery to the electric motor via the boost converter and controls the supply of power generated by the generator to the electric motor. [Effects of the Invention]

[0008] The present invention can provide a control device for a hybrid vehicle that can suppress the temperature of the components of a boost converter from exceeding an allowable temperature. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a schematic diagram of a hybrid vehicle equipped with a control device for a hybrid vehicle according to one embodiment of the present invention. [Figure 2] Figure 2 is a conceptual diagram illustrating the power flow in the first state of a control device for a hybrid vehicle according to one embodiment of the present invention. [Figure 3] Figure 3 is an explanatory diagram illustrating the power flow in the second state of a control device for a hybrid vehicle according to one embodiment of the present invention. [Figure 4]Figure 4 is an explanatory diagram illustrating the power flow in the third state of a control device for a hybrid vehicle according to one embodiment of the present invention. [Figure 5] Figure 5 is an explanatory diagram illustrating the power flow in the fourth state of a control device for a hybrid vehicle according to one embodiment of the present invention. [Figure 6] Figure 6 is a flowchart showing the boost converter protection operation of a control device for a hybrid vehicle according to one embodiment of the present invention. [Figure 7] Figure 7 is a timing diagram showing, in chronological order, a first example of the changes in the state of each part when the boost converter protection operation of the control device of a hybrid vehicle according to one embodiment of the present invention is performed. [Figure 8] Figure 8 is a timing diagram showing a second example of the changes in the state of each part when the boost converter protection operation of the control device of a hybrid vehicle according to one embodiment of the present invention is performed, in chronological order. [Modes for carrying out the invention]

[0010] A control device for a hybrid vehicle according to one embodiment of the present invention comprises an engine, a generator that generates electricity using the driving force of the engine, a battery that is charged with the electricity generated by the generator, an electric motor that drives the drive wheels with the electricity generated by the generator and the electricity charged in the battery, and a boost converter that increases the voltage of the electricity supplied from the battery to the electric motor, and is characterized in that, when power is being supplied from the battery to the electric motor via the boost converter, the control device includes a control unit that limits the power supplied from the battery to the electric motor via the boost converter and controls the supply of power generated by the generator to the electric motor. As a result, the control device for a hybrid vehicle according to one embodiment of the present invention can suppress the temperature of the components of the boost converter from exceeding the allowable temperature. [Examples]

[0011] Hereinafter, a hybrid vehicle equipped with a control device for a hybrid vehicle according to an embodiment of the present invention will be described with reference to the drawings.

[0012] As shown in FIG. 1, the hybrid vehicle 1 includes an engine 2, a battery 3, a first motor 4 (hereinafter also referred to as "MG1"), a first inverter 5, a second motor 6 (hereinafter also referred to as "MG2"), a second inverter 7, a boost converter 8, drive wheels 9, and a hybrid controller (hereinafter simply referred to as "HCU") 10.

[0013] The engine 2 has a plurality of cylinders formed therein. In this embodiment, the engine 2 generates power by performing a series of four strokes including an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke for each cylinder.

[0014] The battery 3 is composed of a rechargeable secondary battery, and for example, it is a lithium-ion battery. The battery 3 stores the power generated by MG1 and MG2 and supplies the power for driving MG1 and MG2.

[0015] MG1 is provided so as to be interlocked with the crankshaft of the engine 2. MG1 is connected to the battery 3 via the first inverter 5 and the boost converter 8. MG1 has a function of an electric motor that starts the engine 2 by rotating when power is supplied from the battery 3, and a function of a generator that converts the power generated by the engine 2 into electric power. MG1 constitutes the generator in the present invention.

[0016] MG2 is provided so as to be interlocked with the drive wheels 9 via a power transmission member such as a gear mechanism. MG2 is connected to the battery 3 via the second inverter 7 and the boost converter 8.

[0017] MG2 rotates by being supplied with power from the battery 3 and MG1, thereby rotating the drive wheels 9. MG2 has the function of an electric motor and the function of a generator that converts the rotational force of the drive wheels 9 into electric power. MG2 constitutes the electric motor in the present invention.

[0018] The boost converter 8 is provided between the battery 3 and the first inverter 5 and the second inverter 7. It boosts the voltage of the power supplied from the battery 3 to the first inverter 5 and the second inverter 7, and降压 the voltage of the power supplied from the first inverter 5 and the second inverter 7 to the battery 3.

[0019] The boost converter 8 includes components such as a capacitor, a coil, and a switching element. In this embodiment, the switching element is constituted by an IGBT (Insulated Gate Bipolar Transistor).

[0020] HCU10 is constituted by a computer unit including a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory for storing backup data, an input port, and an output port.

[0021] In the ROM of this computer unit, in addition to various constants and various maps, a program for causing the computer unit to function as HCU10 is stored. That is, when the CPU executes the program stored in the ROM using the RAM as a work area, this computer unit functions as HCU10 in this embodiment.

[0022] Various sensors, including a temperature sensor 21 that detects the temperature of the components of the boost converter 8, are connected to the input ports of the HCU10. Various control devices, including the first inverter 5, the second inverter 7, the boost converter 8, the injector 31 that supplies fuel to the engine 2, and the spark plug 32 that ignites in the combustion chamber of the engine 2, are connected to the output ports of the HCU10.

[0023] Furthermore, if engine 2 is composed of an engine that does not require a spark plug, such as a diesel engine, the spark plug 32 is omitted from the configuration of hybrid vehicle 1.

[0024] The HCU10 controls various control targets connected to the output ports based on information obtained from various sensors connected to the input ports. When power is supplied to the MG2 from the battery 3 via the boost converter 8, the HCU10 functions as a control unit 40 that limits the power supplied to the MG2 from the battery 3 via the boost converter 8 and controls the supply of power generated by the MG1 to the MG2 if the temperature detected by the temperature sensor 21 (hereinafter also simply referred to as the "boost converter temperature") exceeds a high-temperature threshold.

[0025] The high-temperature threshold is set to a constant value lower than the allowable temperature of the components of the boost converter 8. In this embodiment, the high-temperature threshold is set to a constant value lower than the allowable temperature of the IGBTs that make up the boost converter 8.

[0026] If the boost converter temperature exceeds a high-temperature threshold, the HCU10 limits the power supplied from the battery 3 to the MG2 via the boost converter 8, and controls the boost converter 8 to prevent power from being supplied from the battery 3 to the MG2.

[0027] In other words, if the boost converter temperature exceeds a high-temperature threshold, the HCU10 limits the power supplied from the battery 3 to the MG2 via the boost converter 8, and turns off the boost converter 8.

[0028] When the boost converter temperature exceeds the high-temperature threshold, the HCU10 controls the system to supply power generated by MG1 to MG2, and if engine 2 is stopped, it controls the system to start engine 2.

[0029] When starting engine 2, HCU10 controls the first inverter 5 to drive MG1, thereby rotating the crankshaft of engine 2 and initiating fuel supply by injectors 31 and ignition by spark plugs 32 until engine 2 is running autonomously.

[0030] When the boost converter temperature of the HCU10 falls below the non-high temperature threshold, and the boost converter temperature has been turned off due to the boost converter temperature exceeding the high temperature threshold, the HCU10 stops power generation by the MG1 and removes the restriction on the power supplied from the battery 3 to the MG2 via the boost converter 8. In this embodiment, the non-high temperature threshold is set to the same value as the high temperature threshold.

[0031] In other words, when the boost converter temperature exceeds the high-temperature threshold, the HCU10 turns off the boost converter 8, and when the boost converter temperature falls below the non-high-temperature threshold, it stops power generation by the MG1 and turns on the boost converter 8.

[0032] If the HCU10 started engine 2 because the boost converter temperature exceeded the high-temperature threshold, it will stop engine 2 when the boost converter temperature falls below the non-high-temperature threshold. When stopping engine 2, the HCU10 will stop the fuel supply by the injector 31 and the ignition by the spark plug 32.

[0033] In the hybrid vehicle 1 configured as described above, if the boost converter 8 is in the ON state, the boost converter 8 is energized in the following state.

[0034] (First state) As shown in Figure 2, when MG1 is stopped, MG2 is functioning as an electric motor in a powered state, and battery 3 is discharged, power is supplied from battery 3 to MG2 via the boost converter 8, as indicated by the arrows in the figure.

[0035] (Second state) As shown in Figure 3, when MG1 is functioning as a generator, MG2 is in the powering state, and battery 3 is in the discharge state, power is supplied from MG1 to MG2 as indicated by the dashed arrows in the figure, and power is supplied from battery 3 to MG2 via the boost converter 8 as indicated by the arrows in the figure.

[0036] (Third state) As shown in Figure 4, when MG1 is functioning as a generator, MG2 is in the powering state, and battery 3 is in the charging state, power is supplied from MG1 to MG2 and from MG1 to battery 3 via the boost converter 8, as indicated by the arrows in the figure.

[0037] (Fourth state) As shown in Figure 5, when MG2 is functioning as a generator in a regenerative state and battery 3 is in a charged state, power is supplied from MG2 to battery 3 via the boost converter 8, as indicated by the arrows in the figure.

[0038] In the first to fourth states described above, the temperature of the components of the boost converter 8 may exceed the allowable temperature. Therefore, except for the fourth state which is the regenerative state, in any of the first to third states, if the boost converter temperature exceeds the high temperature threshold, the HCU 10 controls the boost converter 8 to be turned off and supplies the power generated by MG1 to MG2. In the fourth state, if the boost converter temperature exceeds the high temperature threshold, the HCU 10 controls the system to either stop regenerative power generation by MG2 or to consume the power regenerated by MG2 with MG1.

[0039] The boost converter protection operation of the HCU10 configured as described above will be explained with reference to Figure 6. Note that the boost converter protection operation described below will be repeatedly executed throughout the period that the HCU10 is operating.

[0040] First, in S1, the HCU10 determines whether the boost converter temperature has exceeded the high-temperature threshold. If it determines in S1 that the boost converter temperature has exceeded the high-temperature threshold, the HCU10 executes the process in S2.

[0041] In S1, if it is determined that the boost converter temperature has not exceeded the high-temperature threshold, the HCU10 executes the process in S1. In other words, if it is determined in S1 that the boost converter temperature has not exceeded the high-temperature threshold, the HCU10 enters a waiting state, waiting for the boost converter temperature to exceed the high-temperature threshold.

[0042] In S2, HCU10 determines whether engine 2 is stopped or not. If HCU10 determines in S2 that engine 2 is stopped, HCU10 executes the process in S3. If HCU10 determines in S2 that engine 2 is not stopped, HCU10 executes the process in S4.

[0043] In S3, HCU10 starts engine 2. After executing S3, HCU10 executes S4. In S4, HCU10 turns off boost converter 8 and supplies the power generated by MG1, which is driven by engine 2, to MG2. After executing S4, HCU10 executes S5.

[0044] In S5, the HCU10 determines whether the boost converter temperature is below the non-high temperature threshold. If the HCU10 determines in S5 that the boost converter temperature is below the non-high temperature threshold, it executes the process in S6. If the HCU10 determines in S5 that the boost converter temperature is not below the non-high temperature threshold, it executes the process in S5.

[0045] In other words, in S5, if it is determined that the boost converter temperature is not below the non-high temperature threshold, the HCU 10 enters a waiting state, waiting for the boost converter temperature to fall below the non-high temperature threshold, keeping the boost converter 8 in the off state and maintaining the state in which the power generated by MG1 is supplied to MG2.

[0046] In S6, HCU10 stops supplying power from MG1 to MG2 and turns on the boost converter 8. After executing the process in S6, if engine 2 was started in S3, HCU10 stops engine 2 and terminates the boost converter protection operation.

[0047] The operation of the boost converter protection mechanism described above will be explained with reference to Figure 7. Figure 7 shows, in order from top to bottom, an example of the boost converter temperature, vehicle speed, the result of the determination of whether the boost converter temperature has exceeded the high-temperature determination threshold (indicated as "Boost Converter High-Temperature Determination" in the figure), the operating state of the boost converter, and the operating state of MG1 in chronological order.

[0048] In Figure 7, at time t1, the hybrid vehicle 1 begins to move. That is, at time t1, the boost converter 8 turns on, the vehicle speed increases, and the boost converter temperature begins to rise.

[0049] At time t2, if the boost converter temperature exceeds the high-temperature threshold, the boost converter 8 turns off and power generation by MG1 begins. In this embodiment, the non-high-temperature threshold is set to the same value as the high-temperature threshold; therefore, both the high-temperature threshold and the non-high-temperature threshold are labeled as thresholds in the figure.

[0050] At time t2, the boost converter 8 turns off, and after a certain amount of time has passed, the boost converter temperature begins to decrease. Even when the boost converter 8 turns off, the MG1 starts generating power and the power generated by the MG1 is supplied to the MG2, so the driving conditions of the hybrid vehicle 1, such as vehicle speed, are not affected.

[0051] At time t3, when the boost converter temperature falls below the non-high temperature threshold, the boost converter 8 turns on, and power generation by MG1 stops. Because the boost converter 8 turns on at time t3, the boost converter temperature begins to rise after a certain amount of time has elapsed. Even if power generation by MG1 stops, the driving conditions of the hybrid vehicle 1, such as vehicle speed, are not affected because power is supplied from the battery 3 to MG2 via the boost converter 8.

[0052] Similarly, at time t4, if the boost converter temperature exceeds the high-temperature threshold, the boost converter 8 turns off and MG1 starts generating power. At time t5, if the boost converter temperature falls below the non-high-temperature threshold, the boost converter 8 turns on and MG1 stops generating power.

[0053] At time t6, if the boost converter temperature exceeds the high-temperature threshold, the boost converter 8 turns off and MG1 starts generating power. At time t7, if the boost converter temperature falls below the non-high-temperature threshold, the boost converter 8 turns on and MG1 stops generating power.

[0054] At time t8, if the boost converter temperature exceeds the high-temperature threshold, the boost converter 8 turns off and MG1 starts generating power. At time t9, if the boost converter temperature falls below the non-high-temperature threshold, the boost converter 8 turns on and MG1 stops generating power.

[0055] At time t10, if the boost converter temperature exceeds the high-temperature threshold, the boost converter 8 turns off and MG1 starts generating power. At time t11, if the boost converter temperature falls below the non-high-temperature threshold, the boost converter 8 turns on and MG1 stops generating power.

[0056] In this way, the on / off state of the boost converter 8 is switched according to the boost converter temperature, and the operating state of the MG1 is switched in conjunction with the on / off state of the boost converter 8. This controls the boost converter temperature so that it does not exceed the allowable temperature without affecting the driving conditions of the hybrid vehicle 1, such as vehicle speed.

[0057] As described above, the control device for the hybrid vehicle according to this embodiment, when power is supplied from the battery 3 to the MG2 via the boost converter 8, limits the power supplied from the battery 3 to the MG1 via the boost converter 8 if the boost converter temperature exceeds a high-temperature threshold, and supplies the power generated by the MG1 to the MG2, thereby preventing the temperature of the components of the boost converter 8 from exceeding the allowable temperature.

[0058] In particular, the control device for the hybrid vehicle according to this embodiment can prevent the temperature of the components of the boost converter 8 from exceeding the allowable temperature without affecting the driving state of the hybrid vehicle 1.

[0059] Furthermore, in the hybrid vehicle control device according to this embodiment, when the temperature of the components of the boost converter 8 exceeds a high-temperature threshold, the device controls the supply of power generated by the MG1 to the MG2, and if the engine 2 is stopped, it controls the engine 2 to start. This reduces the impact on the driving state of the hybrid vehicle 1 caused by suppressing the temperature of the components of the boost converter 8 from exceeding the allowable temperature.

[0060] Furthermore, in the hybrid vehicle control device according to this embodiment, when the boost converter temperature exceeds a high-temperature threshold and the power supplied to the MG1 via the boost converter 8 from the battery 3 is limited, if the boost converter temperature falls below the non-high-temperature threshold, the power generation by the MG1 is stopped and the limitation on the power supplied to the MG2 via the boost converter 8 from the battery 3 is released, thereby preventing unnecessary power generation by the MG1 and improving fuel efficiency.

[0061] In this embodiment, an example in which an IGBT is used as the switching element constituting the boost converter 8 has been described. However, other switching elements such as a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) or a bipolar transistor may be used as the switching element constituting the boost converter 8.

[0062] Furthermore, although this embodiment describes an example where the high-temperature threshold is set to a constant value lower than the allowable temperature of the components of the boost converter 8, it may also be set to a value that fluctuates depending on whether or not the engine 2 is running.

[0063] In other words, taking into account the time required to start engine 2, the HCU 10 may set the high temperature threshold to a smaller value when engine 2 is stopped than when engine 2 is running.

[0064] Furthermore, in this embodiment, an example was described in which the HCU 10 controls the boost converter 8 so that power is not supplied from the battery 3 to the MG2 when the boost converter temperature exceeds a high-temperature threshold, thereby limiting the power supplied from the battery 3 to the MG2 via the boost converter 8.

[0065] In contrast, if the boost converter temperature exceeds a high-temperature threshold, the HCU 10 may control the boost converter 8 to reduce the power supplied from the battery 3 to the MG2 via the boost converter 8.

[0066] Furthermore, although this embodiment describes an example where the non-high temperature determination threshold is set to the same value as the high temperature determination threshold, it may also be set to a value smaller than the high temperature determination threshold. By configuring it in this way, as shown in Figure 8, it is possible to suppress excessive switching between the operating state of the boost converter and the operating state of MG1.

[0067] In Figure 8, at time t21, the hybrid vehicle 1 begins to move. That is, at time t21, the boost converter 8 turns on, the vehicle speed increases, and the boost converter temperature begins to rise.

[0068] At time t22, if the boost converter temperature exceeds the high-temperature threshold, the boost converter 8 turns off and MG1 starts generating power. Because the boost converter 8 turns off at time t22, the boost converter temperature begins to decrease after a certain amount of time has passed. Even when the boost converter 8 turns off, MG1 starts generating power and the power generated by MG1 is supplied to MG2, so the driving conditions of the hybrid vehicle 1, such as vehicle speed, are not affected.

[0069] At time t23, when the boost converter temperature falls below the non-high temperature threshold, the boost converter 8 turns on, and power generation by MG1 stops. Because the boost converter 8 turns on at time t23, the boost converter temperature begins to rise after a certain amount of time has elapsed. Even if power generation by MG1 stops, power is supplied from battery 3 to MG2 via boost converter 8, so the driving conditions of the hybrid vehicle 1, such as vehicle speed, are not affected.

[0070] Similarly, at time t24, if the boost converter temperature exceeds the high-temperature threshold, the boost converter 8 turns off and MG1 starts generating power. At time t25, if the boost converter temperature falls below the non-high-temperature threshold, the boost converter 8 turns on and MG1 stops generating power.

[0071] As can be seen by comparing the timing diagrams shown in Figure 7 and Figure 8, setting the non-high temperature threshold to a value smaller than the high temperature threshold suppresses excessive switching between the operating state of the boost converter and the operating state of MG1.

[0072] Although embodiments of the present invention have been disclosed above, it is clear that modifications can be made to these embodiments without departing from the scope of the present invention. The embodiments of the present invention are disclosed on the premise that equivalents with such modifications are included in the invention described in the claims. [Explanation of Symbols]

[0073] 1. Hybrid vehicle 2 engines 3 Batteries 4. First motor (generator) 6. Second motor (electric motor) 8. Boost Converter 9 Drive wheels 40 Control Unit

Claims

1. The engine and A generator that generates electricity using the driving force of the aforementioned engine, A battery that is charged with electricity generated by the aforementioned generator, An electric motor that drives the drive wheels using the power generated by the generator and the power charged in the battery, A control device for a hybrid vehicle, comprising a boost converter for boosting the voltage of the power supplied from the battery to the electric motor, A control device for a hybrid vehicle, characterized in that, while power is being supplied from the battery to the motor via the boost converter, if the temperature of the components of the boost converter exceeds a high-temperature threshold, the control unit limits the power supplied from the battery to the motor via the boost converter and controls the supply of power generated by the generator to the motor.

2. The control unit, The control device for a hybrid vehicle according to claim 1, characterized in that, when the temperature of the components of the boost converter exceeds the high temperature determination threshold, the control device controls the supply of power generated by the generator to the electric motor, and if the engine is stopped, it controls the engine to start.

3. The control unit, The control device for a hybrid vehicle according to claim 1, wherein, while the power supplied from the battery to the electric motor via the boost converter is limited due to the temperature of the components of the boost converter exceeding the high-temperature determination threshold, when the temperature of the components of the boost converter falls below the non-high-temperature determination threshold, the power generation by the generator is stopped and the limitation on the power supplied from the battery to the electric motor via the boost converter is released.

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