Vehicle control device

Abstract

To provide a vehicle control device which can avoid a situation that allowable input power Win of a battery is limited.SOLUTION: On a condition that a SOC of a battery is equal to or greater than a prescribed value (YES determination in a step ST1), and a temperature of the battery is equal to or lower than a prescribed value (YES determination in a step ST2), processing for operating a water heating heater (step ST4), and processing for making water which is raised in a temperature by the heater operation processing circulate in a battery circuit (step ST6) are performed. By this constitution, a situation that allowable input power Win of the battery is limited, and a regeneration brake is not limited. As a result, it is suppressed that an ON-requirement of an engine may arise in order to secure deceleration of the vehicle, and traveling at a BEV mode becomes possible.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a vehicle control device, and more particularly to an improvement in the control of a vehicle equipped with an internal combustion engine and an electric motor as sources of driving power for traveling. [Background technology]

[0002] Conventionally, in vehicles equipped with an internal combustion engine (hereinafter sometimes referred to as an engine) and an electric motor (hereinafter sometimes referred to as a traction motor) as a driving force source for driving, such as hybrid vehicles and plug-in hybrid vehicles, when coasting, braking is performed using regenerative braking, and the traction motor is made to function as a generator to generate electricity and charge the battery (for example, Patent Document 1).

[0003] Also, as disclosed in Patent Document 1, it is known that a lithium ion secondary battery is generally used as a drive battery (hereinafter, may be simply referred to as a battery) that supplies power to a driving motor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-151258 A Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, when the battery is a lithium-ion secondary battery, in a situation where the SOC (State Of Charge) of the battery is high and the battery temperature is low, there is a risk that deterioration will progress due to precipitation of lithium metal in the negative electrode, so the allowable input power Win of the battery is limited in order to suppress this precipitation of lithium metal.

[0006] If the allowable input power Win of the battery is limited in this way, braking by regenerative braking is significantly restricted, and a request to turn the engine on is generated to ensure the deceleration of the vehicle. As a result, there is a problem that it becomes impossible to run in BEV mode, which stops the engine and uses only the driving motor as a driving power source for running.

[0007] The present invention has been made in consideration of the above-mentioned points, and an object of the present invention is to provide a vehicle control device that can avoid the situation in which the allowable input power Win of the battery described above is limited. [Means for solving the problem]

[0008] The solution of the present invention for achieving the above object is based on a vehicle control device mounted on a vehicle that includes an electric motor and an internal combustion engine that receive power from a battery as a driving force source for traveling, a battery warming circuit that allows a refrigerant that receives heat from a water heater to circulate and that enables the battery to be heated by the circulating refrigerant, and that performs braking by regenerative braking using the electric motor during coasting. This vehicle control device is characterized in that, on the condition that the SOC of the battery is equal to or higher than a predetermined value and the temperature of the battery is equal to or lower than a predetermined value, it executes a process of activating the water heater and a process of circulating the refrigerant heated by the process in the battery warming circuit.

[0009] With this specification, when the SOC of the battery is equal to or higher than a predetermined value and the temperature of the battery is equal to or lower than a predetermined value, the water heater is operated and the refrigerant heated by the above process is circulated in the battery heating circuit, thereby raising the temperature of the battery and avoiding the precipitation of lithium metal. This makes it unnecessary to limit the allowable input power Win of the battery in order to suppress the precipitation of lithium metal, and the regenerative brake is not restricted. As a result, the occurrence of a request to turn on the internal combustion engine in order to ensure the deceleration of the vehicle is suppressed, and driving in BEV mode is possible. Effect of the Invention

[0010] In the present invention, under the condition that the SOC of the battery is equal to or higher than a predetermined value and the temperature of the battery is equal to or lower than a predetermined value, a process of operating the water heater and a process of circulating the refrigerant heated by the process in the battery heating circuit are executed. This avoids a situation in which the allowable input power Win of the battery is limited, and the regenerative brake is not limited. As a result, a request to turn on the internal combustion engine in order to ensure the deceleration of the vehicle is suppressed, and running in BEV mode is possible. [Brief description of the drawings]

[0011] [Figure 1] 1 is a diagram showing an outline of a control system for a vehicle according to an embodiment; [Diagram 2] 1 is a diagram showing an outline of a coolant circuit mounted on a vehicle according to an embodiment; [Diagram 3] FIG. 4 is a flowchart showing a procedure of battery temperature increase control. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In this embodiment, the present invention will be described as being applied to a plug-in hybrid vehicle (PHEV).

[0013] Fig. 1 is a diagram showing an outline of a control system of a vehicle according to this embodiment. As shown in Fig. 1, the control system of the vehicle according to this embodiment includes an engine ECU 1, a motor ECU 2, a battery ECU 3, an air conditioner ECU 4, and an HEV_ECU (vehicle control device) 5. These ECUs 1 to 5 are configured as microprocessors centered around a CPU, and in addition to the CPU, include a ROM for storing processing programs, a RAM for temporarily storing data, an input / output port, a communication port, etc.

[0014] The engine ECU 1 controls the operation of an engine (internal combustion engine) 11 as a driving power source for traveling. Specifically, the engine ECU 1 receives signals from various sensors that detect the operating state of the engine 11 (e.g., a crank position signal from a crank position sensor 12, an engine coolant temperature signal from a water temperature sensor 13, an outside air temperature signal from an outside air temperature sensor 14, etc.) via an input port, and outputs various control signals for driving the engine 11 from the engine ECU 1 via an output port. The engine ECU 1 also communicates with an HEV_ECU 5, controls the operation of the engine 11 according to control signals from the HEV_ECU 5, and outputs data related to the operating state of the engine 11 to the HEV_ECU 5 as necessary.

[0015] The motor ECU 2 controls two motor generators (electric motors) MG1, MG2 (a first motor generator MG1 that mainly functions as a generator, and a second motor generator MG2 that mainly functions as an electric motor) by switching control of an inverter (not shown). Specifically, signals required to control the motor generators MG1, MG2 are input to the motor ECU 2 via an input port, and switching control signals and the like to switching elements (not shown) of the inverter are output from the motor ECU 2 via an output port. The motor ECU 2 also communicates with the HEV_ECU 5, and controls the motor generators MG1, MG2 by control signals from the HEV_ECU 5, and outputs data relating to the operating states of the motor generators MG1, MG2 to the HEV_ECU 5 as necessary.

[0016] The battery ECU 3 manages the battery 31, which is configured as, for example, a lithium-ion secondary battery. The battery 31 exchanges power with the motor generators MG1 and MG2 via an inverter. Specifically, the battery ECU 3 receives signals necessary for managing the battery 31, such as a terminal voltage signal from a voltage sensor 32 installed between the terminals of the battery 31, a charge / discharge current signal from a current sensor 33 attached to a power line connected to an output terminal of the battery 31, and a battery temperature signal from a temperature sensor 34 attached to the battery 31, and transmits data on the state of the battery 31 to the HEV_ECU 5 by communication as necessary. In addition, in order to manage the battery 31, the battery ECU 3 calculates a power storage ratio SOC, which is a ratio of the capacity of power that can be discharged from the battery 31 at that time to the total capacity, based on an integrated value of the charge / discharge current detected by the current sensor 33, and calculates input / output limits Win and Wout, which are allowable input / output power that may be charged / discharged from the battery 31, based on the calculated power storage ratio SOC and the battery temperature. In addition, in a situation where the SOC (storage ratio SOC) is high and the battery temperature is low, the lithium ion secondary battery constituting the battery 31 may deteriorate due to deposition of lithium metal in the negative electrode. For this reason, in the conventional technology, in such a situation, the allowable input power Win of the battery 31 is limited to suppress the deposition of lithium metal.

[0017] The air conditioner ECU 4 controls an air conditioner (not shown). Specifically, as is well known, the air conditioner ECU 4 controls a compressor and an expansion valve in a heat pump circuit of the air conditioner, a blower motor 41, an inside / outside air switching door, an air outlet switching door, and an air mix door in response to a request for cooling, heating, or dehumidification in the vehicle cabin.

[0018] The air conditioner ECU 4 also receives switch signals from various switches on an air conditioner operation panel 42 provided on the front of the vehicle interior (instrument panel) and sensor signals from various sensors. The various switches provided on the air conditioner operation panel 42 include an AUTO switch for automatically controlling the air conditioner, an air conditioner (A / C) switch for forcibly operating the compressor, an air inlet changeover switch for changing over the air inlet mode, a temperature setting switch for setting the temperature in the vehicle interior to a desired temperature (vehicle interior set temperature), an air volume changeover switch for setting the air volume of the blower motor 41 in manual mode, and an air outlet changeover switch for changing over the air outlet mode. The air conditioner operation panel 42 also has a defroster switch, which can be manually operated to set the defroster mode (mode for removing fog from windows).

[0019] The air conditioner ECU 4 also controls each device provided in a coolant circuit 6 shown in Fig. 2. The coolant circuit 6 will be described below. Fig. 2 is a diagram showing an outline of the coolant circuit 6. The coolant circuit 6 in this embodiment includes a heater unit circuit 61 provided with a heater unit 61a of the air conditioner device, and a battery circuit (referred to as a battery warming circuit in the present invention) 62 provided with a battery 31, and is configured such that a heat exchanger 63 enables heat exchange between the refrigerants (coolant) circulating through these circuits 61, 62.

[0020] The heater unit circuit 61 generally includes a water pump 61b, the engine 11, a water heater (electric heater) 61c, a flow rate control valve 61d, a heater unit 61a, and a heat exchanger 63. The heater unit 61a is disposed in a duct of an air conditioner (not shown) and exchanges heat between the coolant (engine coolant: warm water circulating through the heater unit circuit 61) and air (air supplied to the passenger compartment through the duct) to heat the air and contribute to heating the passenger compartment. The water heater 61c is an electric heater for heating the engine coolant flowing through the heater unit circuit 61, and is turned on to heat the engine coolant when the engine coolant temperature drops to a predetermined value when heating is required in the passenger compartment. In the heater unit circuit 61, the flow rate of the engine coolant flowing through the heater unit 61a and the flow rate of the engine coolant flowing through the heat exchanger 63 can be adjusted by adjusting the flow rate using the flow rate control valve 61d. Additionally, the heater unit circuit 61 has a water temperature sensor 13 disposed downstream of the water heater 61c. The location of the water temperature sensor 13 is not limited thereto, and the water temperature sensor 13 may be disposed at a plurality of locations. Additionally, while FIG. 2 shows the water heater 61c and the engine 11 connected in series, the present invention is not limited thereto. For example, they may be connected in parallel.

[0021] The battery circuit 62 is a circuit for adjusting the temperature of the battery 31, and includes a water pump 62a. The battery circuit 62 is connected to a heat exchanger 63, and is capable of receiving heat from the heater unit circuit 61 by heat exchange in the heat exchanger 63.

[0022] By providing such a coolant circuit 6, for example, when a request for heating the vehicle interior occurs, the air conditioner ECU 4 calculates the amount of heat required (requested amount of heat) in response to the heating request, and calculates the amount of heat received by the engine coolant from the engine 11. Based on this, the water pump 61b, the water heating heater 61c, etc. are controlled so that heating is performed in accordance with the requested amount of heat.

[0023] The HEV_ECU 5 controls the entire vehicle. Specifically, the HEV_ECU 5 receives, via its input ports, a connection detection signal for detecting connection of a power plug of a charger (a device connected to an external power source such as a household power source to charge the battery 31) (not shown) to an external power source, an ON / OFF signal from a start switch, a shift position signal from a shift position sensor, an accelerator opening signal from an accelerator pedal position sensor, a brake pedal position signal from a brake pedal position sensor, a vehicle speed signal from a vehicle speed sensor, and the like.

[0024] The HEV_ECU 5 also controls the driving mode of the vehicle. Specifically, the vehicle according to this embodiment is capable of driving in a hybrid mode (HEV mode) or an electric mode (BEV mode) as the driving mode. The HEV mode is a driving mode in which the vehicle runs using at least the engine 11 as a driving power source for driving. The BEV mode is a driving mode in which the engine 11 is stopped and the vehicle runs using only the second motor generator (driving motor) MG2 as a driving power source for driving. The switching control between the HEV mode and the BEV mode is well known, and therefore will not be described here.

[0025] Furthermore, when the SOC (electricity storage rate SOC) of the battery 31 drops to a predetermined value, the HEV_ECU 5 transmits an engine operation command signal to the engine ECU 1 to operate the engine 11 under that condition. As a result, the first motor generator MG1 generates power using the power of the engine 11, and the battery 31 is charged.

[0026] Furthermore, when the vehicle is coasting, the HEV_ECU 5 performs braking by regenerative braking and causes the second motor generator MG2 to function as a generator to charge the battery 31 by generating electricity.

[0027] A characteristic function of the HEV_ECU 5 in this embodiment is to execute a process of operating the water heater 61c (a process of sending a water heater operation command signal to the air conditioner ECU 4) and a process of circulating the water heated by the process through the battery circuit 62 (a process of sending a pump operation command signal to the air conditioner ECU 4) on the condition that the SOC of the battery 31 is equal to or higher than a predetermined value and the temperature of the battery 31 is equal to or lower than a predetermined value (hereinafter, these processes will be referred to as battery temperature rise control). The SOC of the battery 31 is obtained from the battery ECU 3. The temperature of the battery 31 is detected by the temperature sensor 34 and obtained from the battery ECU 3.

[0028] In addition, the HEV_ECU 5 has a function of stopping the water pump 62a of the battery circuit 62 (stopping the circulation of water in the battery circuit 62) until the coolant temperature in the heater unit circuit 61 reaches a predetermined value when the water heater 61c is operated under the condition that the SOC of the battery 31 is equal to or higher than a predetermined value and the temperature of the battery 31 is equal to or lower than a predetermined value, and operating the water pump 62a at the point when the coolant temperature in the heater unit circuit 61 reaches the predetermined value. This prevents the water pump 62a from being operated unnecessarily when the temperature difference between the water in each circuit 61, 62 is small. In addition, in this case, in the heater unit circuit 61, the flow rate of the engine coolant flowing through the heat exchanger 63 is increased by flow rate adjustment using the flow rate adjustment valve 61d, so that the amount of coolant flowing into the heater unit 61a is reduced. In this case, the upper limit value of the rotation speed of the blower motor 41 is limited to prevent the temperature of the air-conditioned air blown into the vehicle cabin from becoming low. The battery temperature rise control is executed on the condition that the operation mode of the air conditioner is not in the defroster mode. This is to maintain the amount of heat obtained by the heater unit 61a when the air conditioner is in the defroster mode, and to ensure the anti-fogging performance (performance to suppress fogging of windows).

[0029] The procedure for the battery temperature increase control will be described below with reference to the flowchart in Fig. 3. This flowchart is repeated at predetermined time intervals while the start switch of the vehicle is turned on.

[0030] First, in step ST1, it is determined whether or not the SOC of the battery 31 acquired from the battery ECU 3 is equal to or higher than a predetermined value A1.

[0031] If the SOC of the battery 31 is less than the predetermined value A1 and the determination in step ST1 is NO, the process ends. On the other hand, if the SOC of the battery 31 is equal to or greater than the predetermined value A1 and the determination in step ST1 is YES, the process proceeds to step ST2, where it is determined whether the temperature of the battery 31 acquired from the battery ECU 3 is equal to or less than a predetermined value.

[0032] If the temperature of the battery 31 exceeds the predetermined value and the determination in step ST2 is NO, the process ends. On the other hand, if the temperature of the battery 31 is equal to or lower than the predetermined value and the determination in step ST2 is YES, the process proceeds to step ST3, where it is determined whether the current operation mode of the air conditioner is a mode other than the defroster mode.

[0033] If the current operating mode of the air conditioner is the defroster mode and the determination in step ST3 is NO, the process ends. On the other hand, if the current operating mode of the air conditioner is a mode other than the defroster mode and the determination in step ST3 is YES, the process proceeds to step ST4, where the battery temperature increase control described above is started. That is, the water heater 61c is operated, and the water pump 62a of the battery circuit 62 is stopped until the temperature of the coolant circulating through the heater unit circuit 61 reaches a predetermined value. At this time, the upper limit of the rotation speed of the blower motor 41 is limited to prevent the temperature of the conditioned air blown into the vehicle cabin from becoming too low.

[0034] Then, the process proceeds to step ST5, and the process waits until the coolant temperature in the heater unit circuit 61 becomes equal to or higher than a predetermined value Te2. The above-mentioned predetermined values ​​(threshold values) A1, Te1, and Te2 are preset by experiments or simulations. The upper limit of the rotation speed of the blower motor 41 may be a preset fixed value, or may be adjusted according to the temperature and flow rate of the coolant circulating through the heater unit circuit 61.

[0035] If the coolant temperature in the heater unit circuit 61 becomes equal to or higher than a predetermined value Te2 and a YES judgment is made in step ST5, the process proceeds to step ST6, in which the water pump 62a of the battery circuit 62 is operated to circulate water in the battery circuit 62, thereby warming the battery 31 by the heat received from the coolant in the heater unit circuit 61 in the heat exchanger 63.

[0036] As described above, in this embodiment, under the condition that the SOC of the battery 31 is equal to or higher than a predetermined value and the temperature of the battery 31 is equal to or lower than a predetermined value, the process of operating the water heater 61c and the process of circulating the water heated by the process in the battery circuit 62 are executed. This avoids a situation in which the allowable input power Win of the battery 31 is limited (a situation in which the allowable input power Win of the battery 31 is limited to suppress the deposition of lithium metal), and the regenerative brake is not restricted. As a result, the occurrence of a request to turn on the engine 11 in order to ensure the deceleration of the vehicle is suppressed, and running in the BEV mode is possible.

[0037] The present invention is not limited to the above-described embodiment, and all modifications and applications within the scope of the claims and equivalents thereto are possible.

[0038] For example, in the above embodiment, the present invention has been described as being applied to a plug-in hybrid vehicle, but the present invention is not limited to this and can also be applied to a hybrid vehicle (HEV).

[0039] In the above embodiment, when the water heater 61c is operated in the battery temperature increase control, the water pump 62a of the battery circuit 62 is stopped until the coolant temperature in the heater unit circuit 61 reaches a predetermined value. However, the present invention is not limited to this, and the water pump 62a of the battery circuit 62 may be operated after a predetermined time has elapsed since the water heater 61c started to operate. [Industrial Applicability]

[0040] INDUSTRIAL APPLICABILITY The present invention is applicable as a measure for avoiding a situation in which the allowable input power Win of a battery in a vehicle that has an engine and a driving motor as a driving power source for driving the vehicle is limited. [Explanation of symbols]

[0041] 5...HEV_ECU (vehicle control device) 11...Engine (internal combustion engine) 31... battery (cell) 61c... water heater 62... battery circuit (battery heating circuit) MG1, MG2...Motor generators (electric motors)

Claims

[Claim 1] A vehicle control device is mounted on a vehicle that includes an electric motor and an internal combustion engine that receive power from a battery as a driving force source for traveling, and a battery heating circuit that allows a coolant that receives heat from a water heater to circulate and that enables the temperature of the battery to be raised by the circulating coolant, and that performs braking by regenerative braking using the electric motor during coasting, A vehicle control device characterized by executing a process of activating the water heating heater and a process of circulating the refrigerant heated by the process in the battery heating circuit, under the condition that the SOC of the battery is equal to or higher than a predetermined value and the temperature of the battery is equal to or lower than a predetermined value.

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