Hybrid vehicle control device

Abstract

To provide a hybrid vehicle control device that can protect a step-up converter from overheat without decreasing braking force.SOLUTION: When required regenerative electric power obtained by converting braking power required for decelerating a vehicle into MG2 exceeds allowable power of a step-up converter (S2), a part of the required regenerative electric power is consumed by driving MG1 so that the required regenerative electric power does not exceed the allowable power (S3).SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] Conventionally, Patent Document 1 proposes a technology that includes a motor, a power storage device, a boost converter that boosts the power on the power storage device side, and a temperature sensor that can detect the temperature of the boost converter, and that controls the motor to operate within a discharge power range that is more restricted when the temperature detected by the temperature sensor is equal to or higher than a predetermined temperature than when the temperature is below the predetermined temperature. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6589929 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the conventional technology described above, when the temperature of the boost converter is equal to or higher than a predetermined temperature, it is necessary to limit the amount of regeneration of the motor during deceleration. Therefore, the conventional technology has a problem that the braking force by the regeneration of the motor may be reduced in order to protect the boost converter from overheating.

[0005] The present invention has been made to solve the above-mentioned problems, and aims to provide a control device for a hybrid vehicle that can protect the boost converter from overheating without reducing the braking force. [Means for solving the problem]

[0006] The control device for a hybrid vehicle according to the present invention is provided on a vehicle having an internal combustion engine, a first motor linked to the internal combustion engine and generating electricity using the driving force of the internal combustion engine, a battery in which the electricity generated by the first motor is stored, a second motor driven by the electricity stored in the battery and the electricity generated by the first motor, drive wheels driven by driving the second motor, and a boost converter that increases the voltage of the electricity supplied from the battery to the first motor and the second motor and decreases the voltage of the electricity supplied from the first motor and the second motor to the battery, and during a period in which the vehicle is decelerating, the control device for a hybrid vehicle brakes the drive wheels by converting the rotational force of the drive wheels by the second motor into regenerative power that is charged to the battery, and has a configuration in which, when the required regenerative power obtained by converting the braking force required to decelerate the vehicle into the second motor exceeds the allowable power of the boost converter, a portion of the required regenerative power is consumed by driving the first motor so that the required regenerative power does not exceed the allowable power. Effect of the Invention

[0007] The present invention can provide a control device for a hybrid vehicle that can protect a boost converter from overheating without reducing braking force. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of a vehicle equipped with a hybrid vehicle control device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a flowchart showing the operation during deceleration of the hybrid vehicle control device according to the embodiment of the present invention. [Diagram 3] FIG. 3 is a timing diagram showing the state of each part when the deceleration operation of the hybrid vehicle control device according to the embodiment of the present invention is executed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] A hybrid vehicle control device according to an embodiment of the present invention is provided in a vehicle including an internal combustion engine, a first motor that is linked to the internal combustion engine and generates electricity using the driving force of the internal combustion engine, a battery that stores the electricity generated by the first motor, a second motor that is driven by the electricity stored in the battery and the electricity generated by the first motor, drive wheels that are driven by driving the second motor, and a boost converter that boosts the voltage of the electricity supplied from the battery to the first motor and the second motor and lowers the voltage of the electricity supplied from the first motor and the second motor to the battery, and brakes the drive wheels by converting the rotational force of the drive wheels by the second motor into regenerative electricity that is charged in the battery during a period in which the vehicle is decelerated. When the required regenerative electricity obtained by converting the braking force required to decelerate the vehicle into the second motor exceeds the allowable power of the boost converter, the first motor is driven to consume a part of the required regenerative electricity so that the required regenerative electricity does not exceed the allowable power. As a result, the hybrid vehicle control device according to the embodiment of the present invention can protect the boost converter from overheating without reducing the braking force. EXAMPLES

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A vehicle equipped with a hybrid vehicle control device according to an embodiment of the present invention will now be described with reference to the drawings.

[0011] As shown in FIG. 1, the vehicle 1 is configured to include an internal combustion 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.

[0012] A plurality of cylinders are formed in the engine 2. In this embodiment, the engine 2 generates power by performing a series of four strokes, which are an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke, for each cylinder.

[0013] The battery 3 is configured by a rechargeable secondary battery, for example, a lithium ion battery capable of generating an output voltage of 48 V. The battery 3 accumulates the power generated by MG1 and MG2, and supplies the power to drive MG1 and MG2.

[0014] The MG1 is provided to be interlocked with the crankshaft of the engine 2. The MG1 is connected to the battery 3 via a first inverter 5 and a boost converter 8. The 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.

[0015] The MG2 is provided so as to move in conjunction with drive wheels 9 via a power transmission member such as a gear mechanism. The MG2 is connected to the battery 3 via a second inverter 7 and a boost converter 8.

[0016] The MG2 has a function of an electric motor that rotates the drive wheels 9 by being supplied with electric power from the battery 3 and the MG1, and a function of a generator that converts the rotational force of the drive wheels 9 into electric power.

[0017] The boost converter 8 is provided between the battery 3 and the first inverter 5 and second inverter 7, and boosts the voltage of the power supplied from the battery 3 to the first inverter 5 and second inverter 7, and lowers the voltage of the power supplied from the first inverter 5 and second inverter 7 to the battery 3.

[0018] The HCU10 is composed of a computer unit equipped with a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory for storing backup data, etc., an input port, and an output port.

[0019] The ROM of this computer unit stores various constants, various maps, and the like, as well as a program for causing the computer unit to function as the HCU 10. That is, the CPU executes the program stored in the ROM using the RAM as a working area, causing the computer unit to function as the HCU 10 in this embodiment.

[0020] An input port of the HCU 10 is connected to various sensors including an accelerator pedal depression sensor 21 that detects the amount of accelerator pedal depression (hereinafter also referred to as "accelerator depression") and a vehicle speed sensor 22 that detects the vehicle speed.

[0021] The output port of the HCU 10 is connected to various control objects including a first inverter 5, a second inverter 7, a boost converter 8, and a throttle valve actuator 31 that adjusts the opening of a throttle valve that regulates the amount of intake air of the engine 2.

[0022] The HCU 10 controls various control targets connected to the output port based on information obtained from various sensors connected to the input port. During the period in which the vehicle 1 is decelerating, the HCU 10 controls the second inverter 7 so as to brake the drive wheels 9 by converting the rotational force of the drive wheels 9 into regenerative power that is charged in the battery 3 by the MG 2.

[0023] The HCU 10 calculates the required regenerative power by converting the braking force required for decelerating the vehicle 1 into the second motor during the period in which the vehicle 1 is decelerated. In this embodiment, the ROM of the HCU 10 stores a required regenerative power map in which the vehicle speed and the required regenerative power are associated with each other.

[0024] The HCU 10 refers to the required regenerative power map and calculates the required regenerative power corresponding to the vehicle speed detected by the vehicle speed sensor 22. Note that the required regenerative power map may associate the amount of change in accelerator opening, the vehicle speed, and the required regenerative power.

[0025] When the required regenerative power is calculated, if the required regenerative power exceeds the allowable power of the boost converter 8, the HCU 10 performs overheat protection control to protect the boost converter 8 from overheating by controlling the first inverter 5 to consume part of the required regenerative power by driving the MG1 so that the required regenerative power does not exceed the allowable power.

[0026] The allowable power of boost converter 8 is set to an upper limit value that does not cause boost converter 8 to overheat, taking into consideration the expected ambient temperature of boost converter 8, and is stored in the ROM of HCU 10.

[0027] When vehicle 1 is decelerated from a state in which it is traveling at a high vehicle speed, the required regenerative power may exceed the allowable power, but when vehicle 1 is decelerated from a state in which it is traveling at a low vehicle speed, the required regenerative power does not exceed the allowable power.

[0028] For this reason, the HCU 10 in this embodiment reduces the processing load on the CPU of the HCU 10 by executing overheat protection control on the condition that the vehicle speed detected by the vehicle speed sensor 22 is equal to or higher than a predetermined high vehicle speed judgment value. The high vehicle speed judgment value is set to a lower limit value at which the required regenerative power may exceed the allowable power when the vehicle 1 is decelerated, and is stored in the ROM of the HCU 10.

[0029] The deceleration operation of the HCU 10 configured as above will be described with reference to Fig. 2. The deceleration operation described below is repeatedly executed over the period during which the vehicle 1 is decelerating.

[0030] First, in S1, the HCU 10 judges whether or not the vehicle speed detected by the vehicle speed sensor 22 is equal to or higher than the high vehicle speed judgment value. If it is judged in S1 that the vehicle speed is equal to or higher than the high vehicle speed judgment value, the HCU 10 executes the process of S2. If it is judged in S1 that the vehicle speed is not equal to or higher than the high vehicle speed judgment value, the HCU 10 ends the deceleration operation.

[0031] In S2, the HCU 10 determines whether the required regenerative power exceeds the allowable power of the boost converter 8. If it is determined in S2 that the required regenerative power exceeds the allowable power of the boost converter 8, the HCU 10 executes the process of S3. If it is determined in S2 that the required regenerative power does not exceed the allowable power of the boost converter 8, the HCU 10 ends the deceleration operation.

[0032] In S3, the HCU 10 controls the first inverter 5 to consume a part of the necessary regenerative power by driving the MG 1 so that the necessary regenerative power does not exceed the allowable power. After executing the process of S3, the HCU 10 ends the deceleration operation.

[0033] In addition, in S3, the HCU 10 may increase the load of the engine 2 on the MG1 during the period in which the first inverter 5 is controlled to consume part of the required regenerative power by driving the MG1 so that the required regenerative power does not exceed the allowable power.

[0034] For example, during the period in which the HCU 10 controls the first inverter 5 to consume part of the required regenerative power by driving the MG 1 so that the required regenerative power does not exceed the allowable power, the HCU 10 may control the throttle valve actuator 31 to place the throttle valve in a fully closed state.

[0035] In this way, when MG1 is driven to consume a portion of the necessary regenerative power, the load of engine 2 on MG1 can be increased, thereby increasing the power that can be consumed by MG1.

[0036] The state of each part when the HCU 10 performs a deceleration operation will be described below with reference to FIG.

[0037] Figure 3 shows, from top to bottom, the changes in vehicle speed, accelerator opening, output of boost converter 8 (labeled "boost converter output" in the figure), temperature of boost converter 8 (labeled "boost converter temperature" in the figure), output of MG2 (labeled "MG2 output" in the figure), and engine speed of engine 2 (labeled "engine speed" in the figure).

[0038] At time t1, when the accelerator opening increases, the output of MG2 starts to increase. As the output of MG2 increases, the vehicle speed and the output of boost converter 8 increase. As the output of boost converter 8 increases, the temperature of boost converter 8 rises.

[0039] When the accelerator opening becomes 0 at time t2, the vehicle speed starts to decrease, and the output of the boost converter 8 and the output of MG2 start to decrease. Therefore, the deceleration operation shown in Fig. 2 starts at time t2.

[0040] At time t3, when HCU 10 determines that the required regenerative power exceeds the allowable power of boost converter 8, MG1 is driven to increase the engine speed of engine 2, thereby suppressing the output of boost converter 8 to the boost converter output limit value and suppressing the rate of increase in temperature of boost converter 8.

[0041] At time t4, when the HCU 10 determines that the required regenerative power does not exceed the allowable power of the boost converter 8, the driving of the MG1 is stopped, and the engine speed of the engine 2 starts to decrease.

[0042] In this way, during the period from time t3 to time t4, when HCU10 determines that the required regenerative power exceeds the allowable power of boost converter 8, the regenerative power by MG2 is consumed by the driving power of MG1, thereby suppressing the output of boost converter 8, and preventing the temperature of boost converter 8 from rising above the overheat temperature Tov without limiting the braking force by MG2.

[0043] As described above, the hybrid vehicle control device of this embodiment drives MG1 to consume part of the regenerative power of MG2 when the required regenerative power exceeds the allowable power of boost converter 8 during the period in which the vehicle is decelerating, thereby protecting boost converter 8 from overheating without reducing the braking force provided by MG2.

[0044] While the present invention has been disclosed by way of example, it will be apparent that modifications may be made to the present invention without departing from the spirit and scope of the present invention, and the present invention is disclosed with the understanding that equivalents of such modifications are intended to be included within the scope of the appended claims. [Explanation of symbols]

[0045] 1 vehicle 2. Engine (internal combustion engine) 3 Battery 4 First motor 6 Second motor 8 Boost Converter 9 Drive wheels

Claims

1. An internal combustion engine; a first motor that is linked to the internal combustion engine and generates electric power using a driving force of the internal combustion engine; a battery for storing electric power generated by the first motor; a second motor that is driven by the electric power stored in the battery and the electric power generated by the first motor; a driving wheel driven by driving the second motor; a boost converter that boosts a voltage of the electric power supplied from the battery to the first motor and the second motor and that reduces a voltage of the electric power supplied from the first motor and the second motor to the battery, a control device for a hybrid vehicle, the control device braking the drive wheels by converting a rotational force of the drive wheels by the second motor into regenerative power that is charged to the battery during a period in which the vehicle is decelerating, A control device for a hybrid vehicle, characterized in that when the required regenerative power obtained by converting the braking force required to decelerate the vehicle into the second motor exceeds the allowable power of the boost converter, a portion of the required regenerative power is consumed by driving the first motor so that the required regenerative power does not exceed the allowable power.

2. 2. The control device for a hybrid vehicle as described in claim 1, characterized in that when the required regenerative power exceeds the allowable power when the vehicle speed is equal to or higher than a predetermined high vehicle speed judgment value, a portion of the required regenerative power is consumed by driving the first motor so that the required regenerative power does not exceed the allowable power.

3. 3. The control device for a hybrid vehicle according to claim 1, wherein, when a portion of the regenerative power is consumed by driving the first motor, the load of the internal combustion engine on the first motor is increased.

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