Control device

Abstract

To provide a control device capable of extending an execution time of an idling stop.SOLUTION: A control device mounted on a vehicle comprises: a motor for restarting an engine in an idling stop state; a first battery for supplying electric power to the motor; and a second battery for receiving a supply of charging electric power from the first battery. The control device has: a derivation section for deriving reduced electric power of the first battery during an idling stop; a first determination section for determining whether or not the first battery can supply electric power required to restart the engine to the motor based on the reduced electric power of the first battery; a second determination section for determining whether or not the second battery requires charging when the first determination section determines that the first battery can supply the electric power required to restart the engine; and a control section for preventing the charging electric power from being supplied from the first battery to the second battery when the second determination section determines that the second battery does not require the charging electric power.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a control device for controlling the restart of a vehicle engine. [Background technology]

[0002] Patent Document 1 discloses a control device that estimates the minimum voltage of a storage element during engine restart based on the amount of voltage drop of the storage element estimated during idling stop, and restarts the engine when the estimated minimum voltage falls below a threshold value. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-190347 Summary of the Invention [Problem to be solved by the invention]

[0004] The technology described in Patent Document 1 restarts the engine when the minimum voltage of the storage element falls below the value required to restart the engine, which shortens the time that idling stop is performed, thereby reducing the benefits obtained by idling stop (improved fuel efficiency and reduced exhaust gas emissions).

[0005] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a control device that can extend the execution time of idling stop. [Means for solving the problem]

[0006] In order to solve the above problem, one aspect of the disclosed technology is a control device mounted on a vehicle that has a motor that restarts an engine that has been idling stopped, a first battery that supplies power to the motor, and a second battery that receives charging power from the first battery, the control device comprising: a derivation unit that derives the reduced power of the first battery during idling stop; a first judgment unit that determines whether the first battery can supply the motor with the power necessary to restart the engine based on the reduced power of the first battery; a second judgment unit that determines whether charging of the second battery is necessary if the first judgment unit determines that the first battery cannot supply the motor with the power necessary to restart the engine; and a control unit that limits the supply of charging power from the first battery to the second battery if the second judgment unit determines that charging of the second battery is not necessary. [Effects of the Invention]

[0007] According to the control device of the present disclosure, the execution time of idling stop can be extended. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a functional block diagram of a control device and its peripheral components according to an embodiment of the present disclosure; [Figure 2] A flowchart of the engine restart control executed by the control device DETAILED DESCRIPTION OF THE INVENTION

[0009] When the power of the first battery is insufficient to restart the engine after idling stop is restored, the control device of the present disclosure extends the execution time of idling stop by eliminating the power reduction caused by polarization resistance in the first battery based on the state of the second battery that receives charging power from the first battery. Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings.

[0010] [Embodiment] <Configuration> Fig. 1 is a functional block diagram of a control device 100 and its peripheral units according to an embodiment of the present disclosure. The functional block illustrated in Fig. 1 includes an engine 10, a starter 20, a motor generator (MG) 30, an electronic load 40, a DC-DC converter (DDC) 50, a first battery 60, a second battery 70, and the control device 100. The control device 100 according to this embodiment is mounted on a vehicle or the like powered by the engine 10.

[0011] The engine 10 is a power source for the vehicle and is started by a starter 20 or a motor generator 30 .

[0012] The starter 20 is a starting device that cranks and starts the engine 10 when the vehicle's ignition switch is turned on (IG-ON). The starter 20 also starts the engine 10 when restarting after idling stop is not possible using the motor generator 30. The starter 20 operates on power supplied from the second battery 70.

[0013] The motor generator (MG) 30 is an electric motor that cranks and starts the engine 10 when the vehicle returns to a normal state from a state in which the engine 10 has been stopped due to idling stop control and the engine 10 is restarted. The motor generator 30, which functions as an electric motor, operates on power supplied from the first battery 60. The motor generator 30 also functions as a generator that generates electricity by being driven by the power (or regenerative operation) of the engine 10, and can output the generated electricity to the first battery 60.

[0014] The electronic load 40 is a variety of devices and systems mounted on the vehicle that consume electric power. The electronic load 40 is configured to operate on electric power supplied from the first battery 60 via the DC-DC converter 50 and / or electric power stored in the second battery 70. Examples of the electronic load 40 connected to the second battery 70 include auxiliary devices other than those used to drive the vehicle.

[0015] The DC-DC converter (DDC) 50 is arranged between the first battery 60 and the second battery 70, and is a voltage converter that converts the power of the first battery 60, which is the input side, to a predetermined voltage and outputs it to the second battery 70, which is the output side.

[0016] The first battery 60 is, for example, a rechargeable secondary battery such as a lithium-ion battery. The first battery 60 stores the power output by the motor generator 30 and outputs its own stored power to the DC-DC converter 50. An example of this first battery 60 is a battery with a rated voltage of 48V used in a so-called mild hybrid system.

[0017] The second battery 70 is a secondary battery configured to be rechargeable, such as a lead-acid battery or a lithium-ion battery. The second battery 70 stores (charges) the power of the first battery 60 via the DC-DC converter 50, and supplies (discharges) its stored power to the electronic load 40, etc. An example of this second battery 70 is an auxiliary battery with a rated voltage of 12 V that supplies the power required for the auxiliary electronic load 40.

[0018] The control device 100 is configured to control the operation of the idling stop function and the DC-DC converter 50. The control device 100 is communicably connected to each of the components, namely the starter 20, the motor generator 30, the DC-DC converter 50, the first battery 60, and the second battery 70, via signal lines (not shown), and can issue various instructions (start instructions, voltage value instructions) to each component, and monitor, detect, and acquire the state of each component (voltage, current, temperature, and amount of charge (SOC: State Of Charge)).

[0019] The control device 100 according to this embodiment includes a derivation unit 110, a determination unit 120, and a control unit .

[0020] The derivation unit 110 derives the power drop of the first battery 60 during idling stop. This power drop of the first battery 60 is derived based on the voltage drop caused by polarization resistance that occurs in the first battery 60 while idling stop is being performed (while the engine 10 is stopped) and the average value of the current (average current) output from the first battery 60 to the second battery 70 and the electronic load 40. Details of this derivation method will be described later.

[0021] The determination unit 120 determines whether the first battery 60 can supply the motor generator 30 with the power required to restart the engine 10 during idling stop, based on the reduced power of the first battery 60 during idling stop derived by the derivation unit 110 (first determination unit). Furthermore, if the first battery 60 cannot supply the motor generator 30 with the power required to restart the engine 10, the determination unit 120 determines whether the second battery 70 is in a state requiring charging (second determination unit). Details of these determination methods will be described later.

[0022] When the determination unit 120 determines that charging of the second battery 70 is not necessary, the control unit 130 limits the supply of charging power from the first battery 60 to the second battery 70. Furthermore, when the determination unit 120 determines that charging of the second battery 70 is necessary, the control unit 130 restarts the engine 10 using the starter 20. Furthermore, when the determination unit 120 determines that the first battery 60 can supply the motor generator 30 with the power necessary to restart the engine 10, the control unit 130 cancels the currently implemented restriction on the supply of charging power from the first battery 60 to the second battery 70.

[0023] A part or all of the above-described control device 100 may be configured by an electronic control unit (ECU) that typically includes a processor such as a microcomputer, a memory, an input / output interface, etc. This electronic control device can realize a part or all of the functions performed by the above-described derivation unit 110, determination unit 120, and control unit 130 by having the processor read and execute a program stored in the memory.

[0024] <Control> Next, the control performed by the control device 100 according to this embodiment will be described with further reference to Fig. 2. Fig. 2 is a flowchart illustrating the procedure for restart control of the engine 10 performed by each component of the control device 100.

[0025] The restart control of the engine 10 illustrated in FIG. 2 is initiated when the engine 10 is temporarily stopped by the idling stop control and a discharge current is flowing from the first battery 60 to the second battery 70.

[0026] (Step S201) The derivation unit 110 of the control device 100 derives the power that is reduced due to the polarization resistance of the first battery 60 during idling stop (hereinafter referred to as "polarization drop power"). This polarization drop power can be derived as follows.

[0027] First, the current discharged from the first battery 60 during idling stop is integrated, and the polarization resistance is estimated based on this discharge current and the voltage and temperature of the first battery 60. Next, the voltage ΔV that drops due to the polarization resistance that occurs during idling stop is calculated from the following equation [1] using the voltage Vcurrent of the first battery 60 before discharging to the DC-DC converter 50, the voltage Vdischarge of the first battery 60 after discharging to the DC-DC converter 50 starts, and a fluctuation voltage ΔVsoc calculated based on the OCV-SOC characteristics of the first battery 60 from the fluctuation storage amount ΔSOC calculated by current integration. ΔV = Vcurrent - Vdischarge - ΔVsoc … [1]

[0028] Then, the polarization drop power ΔWpola-drop is calculated from the following equation [2] based on the voltage ΔV that drops due to the polarization resistance calculated from the above equation [1] and the average current value Iaverage flowing from the first battery 60 while discharging from the first battery 60 to the DC-DC converter 50. ΔWpola-drop = ΔV × Iaverage … [2]

[0029] Once the derivation unit 110 has derived the polarization decrease power of the first battery 60 during idling stop, the process proceeds to step S202.

[0030] (Step S202) The determination unit 120 of the control device 100 determines whether the power of the first battery 60 is equal to or greater than the power required to start the engine 10. The power Wout of the first battery 60 is calculated by subtracting the polarization drop power ΔWpola-drop calculated in step S201 above from the power Wpossible that can actually be output from the first battery 60, as shown in the following equation [3]. The power Wpossible that the first battery 60 can output is appropriately determined based on the state of charge (SOC) of the first battery 60, a power map with a predetermined battery temperature axis, and the guaranteed battery output power that takes into account deterioration until the battery's warranty period. Wout = Wpossible - ΔWpola-drop … [3]

[0031] If the determination unit 120 determines that the power of the first battery 60 is equal to or greater than the power required to start the engine 10 (step S202, Yes), the process proceeds to step S205. On the other hand, if the determination unit 120 determines that the power of the first battery 60 is less than the power required to start the engine 10 (step S202, No), the process proceeds to step S203.

[0032] (Step S203) The determination unit 120 of the control device 100 determines whether or not charging of the second battery 70 is necessary. This determination is made based on whether or not the voltage of the second battery 70 exceeds a predetermined voltage required for charging. The voltage required for charging is the voltage at which the second battery 70 needs to be charged, and is set appropriately based on the performance and capacity of the second battery 70.

[0033] If the determination unit 120 determines that the second battery 70 needs to be charged (step S203, Yes), the process proceeds to step S207. On the other hand, if the determination unit 120 determines that the second battery 70 does not need to be charged (step S203, No), the process proceeds to step S204.

[0034] (Step S204) The control unit 130 of the control device 100 limits the step-down operation of the DC-DC converter 50. Specifically, the step-down operation, which is currently being performed to convert the 48V power of the first battery 60 into 12V power and supply (charge) it to the second battery 70 and the electronic load 40, is limited by reducing the amount of discharge current from the first battery 60 or by stopping the step-down operation itself. In this way, by limiting the step-down operation of the DC-DC converter 50, the polarization resistance occurring in the first battery 60 is eliminated. Therefore, the polarization drop power is smaller than that at the time of the judgment in step S202. Power of the first battery 60 (See Equation [3]) Ensures more than the power required to start engine 10 can be When the control unit 130 restricts the step-down operation of the DC-DC converter 50, the process proceeds to step S208.

[0035] (Step S205) The control unit 130 of the control device 100 determines whether or not the step-down operation of the DC-DC converter 50 is being restricted. That is, it determines whether or not the restriction on the step-down operation of the DC-DC converter 50 has already been performed in step S204.

[0036] If the control unit 130 determines that the step-down operation of the DC-DC converter 50 is being limited (step S205, Yes), the process proceeds to step S206. On the other hand, if the control unit 130 determines that the step-down operation of the DC-DC converter 50 is not being limited (step S205, No), the process proceeds to step S208.

[0037] (Step S206) The control unit 130 of the control device 100 removes the restriction on the step-down operation imposed on the DC-DC converter 50. When the control unit 130 removes the restriction on the step-down operation of the DC-DC converter 50, the process proceeds to step S208.

[0038] (Step S207) The control unit 130 of the control device 100 immediately starts the engine 10 using the starter 20. This allows the power generated by the engine 10 to be charged into the second battery 70 via the DC-DC converter 50. When the control unit 130 starts the engine 10 using the starter 20, the restart control of the engine 10 ends.

[0039] (Step S208) The control unit 130 of the control device 100 waits for the idling stop to end and for normal control to resume, The power supply from the first battery 60, which has more than the power required to start the engine 10, The engine 10 is started using the motor generator 30. When the control unit 130 starts the engine 10 using the motor generator 30, the restart control of the engine 10 ends.

[0040] [Actions and Effects] As described above, according to the control device 100 of one embodiment of the present disclosure, even if the first battery 60 is unable to supply the motor generator 30 with the power necessary to restart the engine 10, if charging of the second battery 70 is not required, the supply of power (charging current) from the first battery 60 to the second battery 70 is limited.

[0041] This process controls the first battery 60 to eliminate the polarization resistance that occurs as the first battery 60 discharges, so that the first battery 60 can secure the power necessary to restart the engine 10 while continuing the idling stop state. This allows the idling stop execution time to be extended.

[0042] The above describes one embodiment of the present disclosure, but the present disclosure can be understood as not only a control device, but also a method executed by a control device equipped with a processor, memory, etc., a program for executing this method, a computer-readable non-transitory storage medium storing the program, and a vehicle equipped with the control device. [Industrial Applicability]

[0043] The control device of the present disclosure can be used in a vehicle equipped with an engine idling stop function. [Explanation of symbols]

[0044] 10 Engine 20 Starter 30 Motor Generator (MG) 40 electronic load 60 DC-DC converter (DDC) 60 First Battery 70 Second Battery 100 control device 110 Derivation part 120 Judgment section 130 Control Unit

Claims

1. A control device mounted on a vehicle including a motor that restarts an engine that has been stopped while idling, a first battery that supplies power to the motor, and a second battery that is supplied with charging power from the first battery, a derivation unit that derives a power decrease in the first battery during the idling stop; a first determination unit that determines whether the first battery can supply the motor with the electric power required to restart the engine based on the reduced electric power of the first battery; a second determination unit that determines whether or not charging of the second battery is necessary when the first determination unit determines that the first battery cannot supply the motor with the electric power necessary to restart the engine; and A control device comprising: a control unit that, when the second determination unit determines that charging of the second battery is unnecessary, limits the supply of charging power from the first battery to the second battery.

2. 2. The control device according to claim 1, wherein the derivation unit derives the reduced power of the first battery based on a voltage drop due to polarization resistance that occurs during the idling stop and an average current output from the first battery to the second battery.

3. 2. The control device according to claim 1, wherein the first determination unit determines whether the power required to restart the engine can be supplied to the motor, the power obtained by subtracting the reduced power of the first battery from the power that the first battery can output.

4. The control device according to claim 1 , wherein the second determination unit determines whether charging of the second battery is required based on whether the voltage of the second battery exceeds a predetermined threshold value indicating the need for charging.

5. The control device according to claim 1 , wherein the control unit restarts the engine using a starter when the second determination unit determines that charging of the second battery is required.

6. 2. The control device according to claim 1, wherein the control unit releases the current restriction on the supply of charging power from the first battery to the second battery when the first determination unit determines that the first battery is capable of supplying the motor with the power necessary to restart the engine.

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