Control device for hybrid vehicle

Abstract

The invention provides a control device for a hybrid vehicle. Provided is a technique for ensuring both prevention of lithium deposition in a battery and suppression of discomfort to a driver. A control device for a hybrid vehicle calculates a reference power for increasing the speed of an engine in the total amount of power generated by deceleration when the vehicle is in a brake range and the required power is zero or less, calculates a power for preventing lithium deposition in a battery, and controls the vehicle when the reference power is lower than the power for preventing lithium deposition. The speed of the engine is controlled by the motor so as to consume acceleration power that is equal to or greater than the reference power in the total amount of the generated power, the battery is charged with the charging power, and the speed of the engine is controlled by the motor so as to consume acceleration power when the reference power exceeds the power for preventing lithium deposition, and the speed of the engine is controlled by the motor so as to consume acceleration power when the reference power exceeds the power for preventing lithium deposition. The storage battery is charged with power obtained by removing power exceeding the electric power for preventing lithium deposition from the charging power, the exceeded power is converted into deceleration torque, and the converted deceleration torque is generated by hydraulic braking.

Description

Technical Field

[0001] This disclosure relates to a control device for hybrid vehicles. Background Technology

[0002] Patent Document 1 discloses a hybrid vehicle. When the gear is in braking mode and acceleration is off, this vehicle charges the battery within the battery's input limits by regenerative braking and using an engine that operates with the motor running and fuel injection stopped, while simultaneously applying braking force to the vehicle. At this time, when the battery temperature is below a threshold, the required charge / discharge power is increased (the value on the charging side decreases) compared to when it is above the threshold, resulting in higher target charge / discharge power, higher target starting power, and higher target engine speed. This reduces driver discomfort caused by the hybrid vehicle.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2017-047820 Summary of the Invention

[0006] Patent Document 1 describes a hybrid vehicle where, under conditions varying with battery temperature, the input limit of the battery changes, potentially causing discomfort to the driver due to unintended engine speeds. This disclosure provides technology that ensures both preventing lithium deposition from the battery and suppressing discomfort to the driver.

[0007] One aspect of this disclosure relates to a control device for a hybrid vehicle that controls a hybrid vehicle capable of driving by one or both of the driving forces of an engine and a motor, and capable of converting the vehicle's kinetic energy into electrical energy to charge a lithium-ion battery. The control device includes: a gear shift sensor for detecting driving gears and braking gears that provide a stronger deceleration force compared to driving gears; an accelerator pedal sensor for detecting the amount of accelerator pedal operation; and a control unit connected to the gear shift sensor and the accelerator pedal sensor. The control unit calculates a reference power when the gear detected by the gear shift sensor is a braking gear and the required power corresponding to the amount of operation detected by the accelerator pedal sensor is 0 or less. Based on the power consumed by accelerating the engine within the total power generated during deceleration, the power required to prevent lithium deposition in the lithium-ion battery is calculated. If the reference power is lower than the power required to prevent lithium deposition, the engine speed is controlled by a motor to consume acceleration power exceeding the reference power in the total power generated. The charging power, after deducting the acceleration power from the total power generated, is then used to charge the lithium-ion battery. If the reference power exceeds the power required to prevent lithium deposition, the engine speed is controlled by a motor to consume acceleration power exceeding the reference power in the total power generated. The charging power, after deducting the power exceeding the power required to prevent lithium deposition, is then used to charge the lithium-ion battery. The excess power is converted into deceleration torque, which is then generated through hydraulic braking.

[0008] According to this disclosure, technologies are provided to ensure both the prevention of lithium deposition from the battery and the suppression of discomfort to the driver. Attached Figure Description

[0009] Figure 1 This is a block diagram illustrating an example of the structure of a hybrid vehicle equipped with a control device according to one embodiment.

[0010] Figure 2 This is a flowchart illustrating the operation of the control device.

[0011] Figure 3 It is a timing diagram illustrating the operation of the control device. Detailed Implementation

[0012] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0013] [Vehicle Structure]

[0014] Figure 1 This is a block diagram illustrating an example of the structure of a hybrid vehicle equipped with a control device according to one embodiment. Figure 1As shown, control device 1 is installed in hybrid vehicle 2 as an example. Hybrid vehicle 2 can be either a driver-driven vehicle or an autonomous vehicle.

[0015] The hybrid vehicle 2 includes an accelerator pedal sensor 11, a gear shift sensor 12, a control unit 13, an engine 14, a motor 15, a battery 16 (an example of a lithium-ion battery), and a hydraulic braking system 17. The control unit 1 is configured to include the accelerator pedal sensor 11, the gear shift sensor 12, and the control unit 13.

[0016] The accelerator pedal sensor 11 is a detector that detects the amount of operation (acceleration opening) of the accelerator pedal operated by the driver. The accelerator pedal sensor 11 outputs the detected operation amount to the control unit 13.

[0017] The gear shift sensor 12 is a detector that detects the gear shift positions of the hybrid vehicle 2. The gear shift sensor 12 detects the drive gear (D) for forward driving and the braking gear (B or S) that provides stronger deceleration compared to the drive gear. The gear shift sensor 12 can also detect other gears such as the parking gear (P), the reverse gear (R), and the neutral gear (N) used when parking.

[0018] The control unit 13 is the device that controls the hybrid vehicle 2 overall, and as an example, it consists of an ECU (Electronic Control Unit). An ECU is an electronic control unit that includes a processor such as a CPU (Central Processing Unit), storage devices such as ROM (Read Only Memory) and RAM (Random-Access Memory), storage devices such as CAN (Controller Area Network) communication circuits, and input / output circuits. The control unit 13 is connected to the accelerator pedal sensor 11 and the gear shift sensor 12 to control the hybrid vehicle 2. The control unit 13 can also be composed of multiple ECUs.

[0019] Engine 14 is an internal combustion engine that uses gasoline, light oil, or other fuels to output power. Control unit 13 acquires the crankshaft crank angle and throttle opening of engine 14, and sends control signals to the throttle motor (which adjusts the throttle position), the fuel injection valve, and the ignition coil to control engine 14. Based on the crank angle, control unit 13 calculates the crankshaft speed, i.e., the engine speed Ne of engine 14.

[0020] Motor 15 is, for example, a synchronous generator motor. Two motors 15 are prepared as both electric motors and generators, and are connected to the drive shaft of the hybrid vehicle 2 via a power splitting mechanism. The control unit 13 obtains the rotational position of the rotor of motor 15, the phase current flowing in each phase of motor 15, etc. The control unit 13 calculates the rotational speed of motor 15 based on the rotational position.

[0021] The battery 16 is configured as a lithium-ion secondary battery. The battery 16 is connected to the motor 15 via an inverter. The battery 16 is managed by the control unit 13. The control unit 13 acquires the battery voltage Vb from a voltage sensor installed between the terminals of the battery 16, the battery current Ib from a current sensor installed at the output terminal of the battery 16 (a positive value when discharging from the battery 16), etc. The control unit 13 calculates the state of charge (SOC) based on the cumulative value of the battery current Ib from the current sensor. The SOC is the ratio of the capacity of electricity that can be discharged from the battery 16 to the total capacity of the battery 16. The control unit 13 calculates the input limit power Win and the output limit power Wout of the battery 16. The input limit power Win is the permissible charging power that can also charge the battery 16, and the output limit power Wout is the permissible discharging power that can also discharge from the battery 16.

[0022] The hydraulic braking system 17 is a system for braking the hybrid vehicle 2, and includes a hydraulically driven hydraulic brake. The hydraulic braking system 17 is operated by the control unit 13.

[0023] The control unit 13 controls the engine 14 and the motor 15, and drives the hybrid vehicle 2 by the driving force of one or both of the engine 14 and the motor 15. The control unit 13 converts the kinetic energy of the hybrid vehicle 2 into electrical energy and charges the battery 16.

[0024] As a specific example, the control unit 13 sets the required torque (required in the drive shaft) for driving based on the gear position, acceleration opening, and vehicle speed. Furthermore, it controls the engine 14 and motor 15 to operate or stop the engine 14, and to ensure that the charging / discharging power Pb (=Vb·Ib) of the battery 16 is within the range of the limiting power Win, Wout, which serves as input / output limits, and outputs torque based on the required torque to the drive shaft.

[0025] When the hybrid vehicle 2 decelerates, the battery 16 remains continuously charged, which increases the risk of lithium deposition and battery degradation. To prevent lithium deposition, the control unit 13 performs Iwin control (a control that narrows the power limit Win) to reduce the amount of charge supplied to the battery 16. Furthermore, to ensure deceleration, the control unit 13 and Iwin control simultaneously increase the engine speed Ne of the engine 14 using the motor 15 (acceleration), consuming the remaining power through Iwin control. This suppresses lithium deposition, but on the other hand, the increased engine speed Ne during Iwin control may lead to deterioration in noise and vibration characteristics.

[0026] To prevent deterioration of noise and vibration characteristics, the frequency of Iwin control intervention is considered. Therefore, in scenarios where the charge level increases, such as when shifting to B or S gear while driving forward, Winp control is pre-emptively applied to narrow the power limit Win. This increases the engine speed Ne of the motor 14 based on the driver's operation of the motor 15, thus reducing discomfort. However, even if the charge level is reduced during Winp control but charging continues, the time until Iwin control intervention can only be extended. Therefore, the control unit 13 compares the intervention levels of Winp control and Iwin control. If a difference occurs, the hydraulic braking system 17 ensures deceleration, controlling each structure to reduce the charge level.

[0027] Figure 2 This is a flowchart illustrating the operation of the control device. Figure 2 The flowchart shown, for example, begins at the timing of ignition activation in hybrid vehicle 2. Refer as appropriate. Figure 3 ,illustrate Figure 2 The flowchart shown. Figure 3 It is a timing diagram illustrating the operation of the control device.

[0028] like Figure 2 As shown, in step S10, the control unit 13 of the control device 1 determines whether the current gear detected by the gear shift sensor 12 is B gear or S gear. If the current gear is B gear or S gear (step S10: "Yes"), the control unit 13 determines in step S12 whether the user's requested power is 0 or less. The control unit 13 calculates the user's requested power based on the operation amount detected by the accelerator pedal sensor 11. For example, when the accelerator pedal is released, the user's requested power becomes 0 or less.

[0029] If it is determined that the user's requested power is 0 or less (step S12: "Yes"), the control unit 13 calculates the reference power Win for engine acceleration in step S14. The reference power Win is defined as the power consumed by accelerating the engine 14 based on the total power generated during deceleration.

[0030] like Figure 3 As shown in (A) and (B), when the current gear is B or S (time t1) and acceleration is off (time t2), as Figure 3 The deceleration begins as shown in (C). Regarding Figure 3 The user power (total power generation) shown in (D) is not entirely charged. Power within a range smaller than the reference power Win used for engine acceleration is charged, while the acceleration power Ne exceeding the reference power Win used for engine acceleration is consumed by controlling the speed Ne of engine 14 using motor 15. Figure 3 (F) indicates the engine speed Ne of engine 14, and the acceleration power is controlled according to Ne.

[0031] If the user's requested power is determined to be 0 or less (step S12: "Yes"), the control unit 13 further calculates the lithium deposition prevention power Win of the battery 16 in step S16. The lithium deposition prevention power Win is a limiting power, set to prevent charging beyond the lithium deposition prevention power Win. Figure 3 As shown in (E), as an example, the power Win used to prevent lithium deposition decreases monotonically from the timing (time t2) of the accelerated shutdown.

[0032] Next, in step S18, the control unit 13 subtracts the power Win used to prevent lithium deposition from the reference power Win used for engine acceleration, and determines whether it is within a predetermined value. The control unit 13 determines whether the reference power Win calculated in step S14 is lower than the power Win used to prevent lithium deposition calculated in step S16.

[0033] If the reference power Win is determined to be lower than the power Win used to prevent lithium deposition (step S18: "Yes"), the control unit 13 performs normal control. Specifically, the control unit 13 controls the speed Ne of the engine 14 using the motor 15 to charge the battery 16 with the charging power obtained by deducting the acceleration power from the total generated power. This normal control is performed between time t2 and time t3.

[0034] If the reference power Win is determined to be lower than the power Win used to prevent lithium deposition (step S18: "No"), that is, if the reference power Win exceeds the power Win used to prevent lithium deposition (after time t3), it is necessary to consume power at some point that falls within the range of power Win used to prevent lithium deposition and power Win below the reference power Win. For example, although it is also possible to adjust the charge and discharge balance as a power consumption for speed-up, but... Figure 3 The dashed line (F) indicates that the change in engine speed of engine 14 is an unintentional acceleration by the driver.

[0035] Therefore, in step S20, the control unit 13 converts the excess power into deceleration, and in step S22, it requests hydraulic braking. For example... Figure 3 As shown in (G), from time t3 onwards, the hydraulic braking system 17 is instructed to apply braking hydraulic pressure to achieve a deceleration equivalent to the charging power Win used to prevent lithium deposition. By utilizing hydraulic braking to ensure deceleration, the engine speed also progresses after time t3 as shown by the solid line, preventing unintentional acceleration by the driver. In this way, the control unit 13 controls the engine speed Ne of the engine 14 with the motor 15 in a manner that consumes acceleration power exceeding the reference power Win of the total generated power, charging the battery 16 with the power remaining after deducting the power Win used to prevent lithium deposition from the charging power, converting the excess power into deceleration torque, which is then converted into deceleration torque through hydraulic braking.

[0036] If the current gear is not in B or S gear (step S10: "No"), if the user's requested power is not below 0 (step S12: "No"), if normal control ends after step S18, or if control using hydraulic braking ends after step S22, Figure 2 The flowchart shown ends here. The process continues repeatedly from the beginning. Figure 2 The flowchart shown continues until the termination condition is met.

[0037] [Summary of Implementation Methods]

[0038] According to the control unit 13 of the control device 1, by using an actuator other than the battery 16, engine 14, and motor 15, namely a hydraulic brake, hydraulic braking can replace the charging power consumed by accelerating the engine 14. Therefore, the engine speed Ne of the engine 14 can be reduced, suppressing unintentional increases in engine speed by the driver, thereby suppressing discomfort to the driver. In addition, the control device 1 can reduce the engine speed Ne of the engine 14, thus preventing the deterioration of noise and vibration characteristics, and achieving a balance between fuel consumption rate, noise and vibration characteristics, and driving performance. In summary, the control device 1 can ensure both preventing lithium deposition in the battery 16 and suppressing discomfort to the driver.

[0039] The above describes an exemplary implementation method, but it is not limited to the exemplary implementation method described above. Various omissions, substitutions, and changes can be made.

[0040] (Symbol Explanation)

[0041] 1: Control unit; 2: Hybrid vehicle; 11: Accelerator pedal sensor; 12: Gear shift sensor; 13: Control unit; 14: Engine; 15: Motor; 16: Battery; 17: Hydraulic braking system.

Claims

1. A control device for a hybrid vehicle, Controlling a hybrid vehicle that can be driven by one or both of its engine and motor, and can convert the vehicle's kinetic energy into electrical energy to charge a lithium-ion battery. The control device for the hybrid vehicle includes: A gear shift sensor detects the drive gear and the braking gear that exerts a stronger deceleration force compared to the drive gear; Accelerator pedal sensor detects the amount of accelerator pedal operation; and The control unit is connected to the gear shift sensor and the accelerator pedal sensor. The control unit: When the gear detected by the gear shift sensor is the braking gear, and the required power corresponding to the operation amount detected by the accelerator pedal sensor is 0 or less. Calculate the baseline power, which is defined as the power consumed by accelerating the engine, based on the total generated power during deceleration. Calculate the power required to prevent lithium deposition from the lithium-ion battery. When the reference power is lower than the power used to prevent lithium deposition, the motor controls the engine speed in such a way that it consumes an acceleration power greater than the reference power from the total power generation, and charges the lithium-ion battery with the charging power remaining after deducting the acceleration power from the total power generation. When the reference power exceeds the power used to prevent lithium deposition, the motor controls the engine speed in such a way that it consumes more than the reference power in the total power generation. The power after deducting the power exceeding the power used to prevent lithium deposition from the charging power is charged to the lithium-ion battery. The excess power is converted into deceleration torque, and the converted deceleration torque is generated by hydraulic braking.

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