Bus energy management method and system considering power and charging current rationality

Abstract

The present invention belongs to the field of electronic control technology for fuel cell buses, and provides a bus energy management method and system that considers the rationality of power and charging current. According to different states of charge of power batteries, different reasonable powers are determined to be emitted by the fuel cell system; the power battery SOC is controlled to be maintained at a higher point and maintained in a small range of fluctuations near the higher point by considering the reasonable power point of the fuel cell; the electricity emitted by the fuel cell system is directly used for driving the whole vehicle, avoiding the problem of excessive power battery SOC and frequent shutdown of the fuel cell system, and improving the economy of the whole vehicle and the life of the fuel cell system. At the same time, when the whole vehicle brakes and recovers energy, the charging current is controlled to be always less than the charging current allowed by the power battery by considering the operating power of the fuel cell system, so as to promote the optimal energy recovery of the power battery, and prevent the overcharging of the power battery during the braking process of the whole vehicle, thereby improving the service life of the power battery.

Description

Technical Field

[0001] The present invention belongs to the technical field of electronic control of fuel cell buses, and in particular relates to a bus energy management method and system that considers the rationality of power and charging current. Background Art

[0002] For fuel cell vehicles, the power of the fuel cell system responds to the power request of the vehicle, and the economy and life of the fuel cell system are closely related to the power request strategy of the vehicle. In the actual operation of the vehicle, customers have two main concerns about fuel cell vehicles. One is power anxiety. The power of the power battery and the output power of the fuel cell cannot be balanced, and it is difficult to adapt to the changes in various operating conditions of the vehicle. The second is vehicle economy. The purchase price and operating price of the vehicle are high, so it is imperative to increase the life of the fuel cell system and reduce the hydrogen consumption of the vehicle.

[0003] The inventors found that during the driving process of the whole vehicle, the state of charge (SOC) of the power battery is too high and the fuel cell system shuts down frequently, which affects the economy of the whole vehicle and the life of the fuel cell system; at the same time, during the braking process of the whole vehicle, the power battery is prone to overcharging, affecting the service life of the power battery. Summary of the invention

[0004] In order to solve the above problems, the present invention proposes a bus energy management method and system that considers the rationality of power and charging current. When the whole vehicle makes a power request to the fuel cell system according to the power battery SOC, the whole vehicle considers a reasonable fuel cell power point to control the power battery SOC to remain at a higher point and maintain a small range of fluctuations near the higher point; in addition, when the whole vehicle recovers braking energy, the whole vehicle considers the fuel cell operating power to control the recovery current to always be less than the charging current allowed by the power battery, thereby promoting the optimal energy recovery of the power battery.

[0005] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0006] In a first aspect, the present invention provides a bus energy management method considering the rationality of power and charging current, comprising:

[0007] The vehicle makes a power request to the fuel cell system based on the power battery’s state of charge;

[0008] According to different states of charge of the power battery, determine the different reasonable powers emitted by the fuel cell system;

[0009] When the vehicle brakes to recover energy, the charging current is always smaller than the charging current allowed by the power battery, taking into account the operating power of the fuel cell system.

[0010] Further, when the state of charge is within the range of a preset first state of charge and a second state of charge, the power requested by the whole vehicle from the fuel cell system is the preset first power; when the state of charge is within the range of a preset second state of charge and a third state of charge, the power requested by the whole vehicle from the fuel cell system is the preset second power; when the state of charge is within the range of a preset third state of charge and a fourth state of charge, the power requested by the whole vehicle from the fuel cell system is the preset third power; when the state of charge is within the range of a preset third state of charge and a fourth state of charge, the power requested by the whole vehicle from the fuel cell system is 0; wherein, the first state of charge is less than the second state of charge, the second state of charge is less than the third state of charge, and the third state of charge is less than the fourth state of charge.

[0011] Furthermore, the first power is the rated power of the fuel cell system; the second power is the average power required for the whole vehicle under the vehicle operating condition of the fuel cell system; and the third power is the power corresponding to the maximum efficiency point of the fuel cell system.

[0012] Further, when the state of charge is within a preset range of a first state of charge and a second state of charge, it is a hysteresis interval.

[0013] Furthermore, the maximum value of the charging current is determined according to different braking durations.

[0014] Furthermore, when the duration of braking is less than a preset time, the charging current does not exceed the braking feedback current allowed by the power battery; otherwise, the charging current does not exceed the continuous charging current allowed by the power battery.

[0015] Furthermore, the brake pedal switch signal is obtained to determine whether the vehicle is in a braking state. If it is not in a braking state, the braking feedback torque value sent by the vehicle controller to the motor is 0. If it is in a braking state, the timing is started to determine the duration of braking.

[0016] In a second aspect, the present invention further provides a bus energy management system that takes into account the rationality of power and charging current, including:

[0017] The power request module is configured to: request the vehicle to make a power request to the fuel cell system according to the state of charge of the power battery;

[0018] The power request module is configured to: determine different reasonable powers emitted by the fuel cell system according to different states of charge of the power battery;

[0019] The current control module is configured to: when the vehicle brakes and recovers energy, the charging current is controlled to be always smaller than the charging current allowed by the power battery by taking into account the operating power of the fuel cell system.

[0020] In a third aspect, the present invention further provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the bus energy management method considering the rationality of power and charging current as described in the first aspect.

[0021] In a fourth aspect, the present invention further provides an electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the steps of the bus energy management method considering the rationality of power and charging current as described in the first aspect are implemented.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] In the present invention, when the vehicle makes a power request to the fuel cell system according to the power battery state of charge SOC, the fuel cell system is determined to emit different reasonable powers according to different power battery states of charge; the power battery SOC is controlled to be kept at a higher point and maintained in a small range of fluctuations near the higher point by considering the reasonable fuel cell power point; the electricity emitted by the fuel cell system is directly used for driving the vehicle, reducing energy conversion losses, and greatly improving the high-efficiency working time of the fuel cell system. At the same time, the problems of excessive power battery SOC and frequent shutdown of the fuel cell system are avoided, and the economy of the vehicle and the life of the fuel cell system are improved. At the same time, when the vehicle brakes and recovers energy, the charging current is always controlled to be less than the charging current allowed by the power battery by considering the operating power of the fuel cell system, so as to promote the optimal energy recovery of the power battery, prevent the overcharging of the power battery during the braking process of the vehicle, and improve the service life of the power battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings in the specification that constitute a part of this embodiment are used to provide a further understanding of this embodiment. The schematic embodiments of this embodiment and their descriptions are used to explain this embodiment and do not constitute improper limitations on this embodiment.

[0025] Figure 1 A power request strategy diagram for a fuel cell system of a vehicle according to Embodiment 1 of the present invention;

[0026] Figure 2 This is a flow chart of the braking feedback torque of the whole vehicle controlling motor according to Embodiment 1 of the present invention. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0028] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0029] Embodiment 1:

[0030] This embodiment provides a bus energy management method that considers the rationality of power and charging current. When the whole vehicle makes a power request to the fuel cell system according to the power battery state of charge SOC, the fuel cell system is determined to emit different reasonable powers according to different power battery states of charge; the power battery SOC is controlled to be kept at a higher point and maintained in a small range near the higher point by considering the reasonable fuel cell power point; the electricity generated by the fuel cell system is directly used for the whole vehicle driving, reducing energy conversion loss, and greatly improving the high-efficiency working time of the fuel cell system. At the same time, the problem of excessive power battery SOC and frequent shutdown of the fuel cell system is avoided, and the economy of the whole vehicle and the life of the fuel cell system are improved. At the same time, when the whole vehicle brakes and recovers energy, the charging current is controlled to be always less than the charging current allowed by the power battery by considering the operating power of the fuel cell system, so as to promote the optimal energy recovery of the power battery. During the braking process of the whole vehicle, the overcharging of the power battery is prevented, and the service life of the power battery is improved.

[0031] Optionally, the method of this implementation includes the following contents:

[0032] S1. Turn on the fuel cell bus key to the ON position, and the vehicle controller, fuel cell system controller and battery management system are awakened;

[0033] The key electrical signal is divided into three signals: OFF, ON and Start. When in the ON position, the vehicle controller, fuel cell system controller and battery management system are awakened and can send and receive messages normally. The vehicle controller, fuel cell system controller and battery management system can realize signal interaction through the CAN network architecture.

[0034] S2, the vehicle controller receives the power battery SOC value and sends the target power value to the fuel cell system controller; the key turns on the start signal, the vehicle is high voltage, and the instrument displays ready. Turn on the fuel cell system switch button, and the vehicle controller receives the SOC value sent by the power battery system through the CAN line. When the state of charge is within the range of a preset first state of charge SOC1 and a second state of charge SOC2, the power requested by the whole vehicle to the fuel cell system is the preset first power P1; when the state of charge is within the range of a preset second state of charge SOC2 and a third state of charge SOC3, the power requested by the whole vehicle to the fuel cell system is the preset second power P2; when the state of charge is within the range of a preset third state of charge SOC3 and a fourth state of charge SOC4, the power requested by the whole vehicle to the fuel cell system is the preset third power P3; when the state of charge is within the range of a preset third state of charge SOC3 and a fourth state of charge SOC4, the power requested by the whole vehicle to the fuel cell system is 0; wherein, the first state of charge SOC1 is less than the second state of charge SOC2, the second state of charge SOC2 is less than the third state of charge SOC3, and the third state of charge SOC3 is less than the fourth state of charge SOC4. The first power P1 is the rated power of the fuel cell system; the second power P2 is the average power required for the vehicle under the vehicle operating condition of the fuel cell system; and the third power P3 is the power corresponding to the maximum efficiency point of the fuel cell system.

[0035] Specifically, Figure 1As shown in the figure, when SOC≤SOC2, the power requested by the vehicle to the fuel cell system is P1, P1 is the rated power of the fuel cell system, the rated power value depends on the fuel cell system model equipped with the vehicle, and the rated power of different fuel cell system models is different. When SOC>SOC2, the power requested by the vehicle to the fuel cell system is P2, P2 is the average power demand of the vehicle under the operating condition of the fuel cell vehicle, and the P2 value is a survey parameter. The average demand of the vehicle under each vehicle operating condition is different, and the vehicle purchaser needs to provide data with a small error. When SOC≥SOC3, the power requested by the vehicle to the fuel cell system is P3, P3 is the power corresponding to the maximum efficiency point of the fuel cell system. The power corresponding to the maximum efficiency point of different fuel cell systems is different, and the power corresponding to the maximum efficiency point is between 10% and 15% of its rated power. When SOC≥SOC4, the power requested by the vehicle to the fuel cell system is 0, that is, the vehicle controls the fuel cell system to shut down. The SOC interval SOC1~SOC2 is a hysteresis interval, that is, when the fuel cell operating power P1 is greater than the average power demand of the vehicle, the power battery SOC rises. When the SOC rises to the SOC2 inflection point and further exceeds SOC2, the vehicle's request for power from the fuel cell system drops from P1 to P2. When the fuel cell operating power P2 is less than the average power demand of the vehicle, the power battery SOC drops. When the power battery SOC drops to the SOC2 inflection point and further less than SOC2, the vehicle's request for power from the fuel cell system continues to remain at point P2. When the power battery SOC continues to drop to the SOC1 inflection point and further less than SOC1, the vehicle's request for power from the fuel cell system changes from P2 to P1. Since P2 is the average power demand of the fuel cell vehicle under the operating conditions, during the operation of the fuel cell vehicle, the power battery SOC value is bound to fluctuate around SOC2. Increasing the SOC1-SOC2 hysteresis interval can prevent the vehicle's request for power from the fuel cell system from fluctuating back and forth between P1 and P2.

[0036] S3, the vehicle controller receives relevant parameters such as the brake pedal status, the fuel cell system, the battery management system, and the motor controller, and sends the brake feedback torque value to the motor controller;

[0037] The maximum value of the charging current is determined according to the duration of braking. When the duration of braking is less than the preset time, the charging current does not exceed the braking feedback current allowed by the power battery, otherwise, the charging current does not exceed the continuous charging current allowed by the power battery.

[0038] Specifically, Figure 2As shown, it is a flow chart of the braking feedback torque of the vehicle motor. The vehicle controller receives the brake pedal switch signal to determine whether the vehicle is in a braking state. If it is not in a braking state, the braking feedback torque value sent by the vehicle controller to the motor is 0. If it is in a braking state, the vehicle controller starts timing. If the continuous braking time is ≥30s, the vehicle controller receives the continuous charging current and power battery voltage value allowed by the power battery issued by the battery management system, the fuel cell operating power value issued by the fuel cell system controller, and the motor speed value issued by the motor controller through the CAN network, and calculates the braking feedback torque value T of the motor through formula 1 and controls the braking feedback torque value of the motor not to exceed T. If the continuous braking time is <30s, the vehicle controller receives the braking feedback current and power battery voltage value allowed by the power battery issued by the battery management system, the fuel cell operating power value issued by the fuel cell system controller, and the motor speed value issued by the motor controller through the CAN network, and calculates the braking feedback torque value T1 of the motor through formula 2 and controls the braking feedback torque value of the motor not to exceed T1.

[0039] The calculation method of motor braking feedback torque is:

[0040] If the brake time is ≥30s,

[0041] If the braking time is less than 30 seconds,

[0042] Among them, T and T1 are the motor braking feedback torque, N·m; U is the power battery voltage, V; I is the continuous charging current allowed by the power battery, A; I1 is the braking feedback current allowed by the power battery, A; P is the operating power of the fuel cell / W; N is the speed of the motor, rpm.

[0043] This embodiment can ensure that the vehicle has sufficient power to the greatest extent possible, so that the electricity generated by the fuel cell is directly used to drive the vehicle, reduce energy conversion losses, maximize the efficient working time of the fuel cell system, avoid excessive SOC of the power battery and frequent shutdown of the fuel cell system, and improve the economy of the vehicle and the life of the fuel cell system; in addition, during the braking process of the vehicle, the power battery is prevented from overcharging, thereby increasing the service life of the power battery.

[0044] Embodiment 2:

[0045] This embodiment provides a bus energy management system that considers the rationality of power and charging current, including:

[0046] The power request module is configured to: request the vehicle to make a power request to the fuel cell system according to the state of charge of the power battery;

[0047] The power request module is configured to: determine different reasonable powers emitted by the fuel cell system according to different states of charge of the power battery;

[0048] The current control module is configured to: when the vehicle brakes and recovers energy, the charging current is controlled to be always smaller than the charging current allowed by the power battery by taking into account the operating power of the fuel cell system.

[0049] The working method of the system is the same as the bus energy management method considering the rationality of power and charging current in Example 1, and will not be repeated here.

[0050] Embodiment 3:

[0051] This embodiment provides a computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, the steps of the bus energy management method considering the rationality of power and charging current described in Example 1 are implemented.

[0052] Embodiment 4:

[0053] This embodiment provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, the steps of the bus energy management method considering the rationality of power and charging current described in Example 1 are implemented.

[0054] The above description is only a preferred embodiment of the present embodiment and is not intended to limit the present embodiment. For those skilled in the art, the present embodiment may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present embodiment shall be included in the protection scope of the present embodiment.

Claims

1. A bus energy management method considering the rationality of power and charging current, characterized in that: include: The vehicle makes a power request to the fuel cell system based on the power battery’s state of charge; According to different states of charge of the power battery, determine the different reasonable powers emitted by the fuel cell system; When the vehicle brakes to recover energy, the charging current is always smaller than the charging current allowed by the power battery, taking into account the operating power of the fuel cell system; Determine the maximum value of the charging current according to the duration of braking; when the duration of braking is less than the preset time, the charging current does not exceed the braking feedback current allowed by the power battery, otherwise, the charging current does not exceed the continuous charging current allowed by the power battery; obtain the brake pedal switch signal to determine whether the vehicle is in a braking state, if it is not in a braking state, the braking feedback torque value sent by the vehicle controller to the motor is 0, if it is in a braking state, start timing to determine the duration of braking; If the continuous braking time is ≥30s, the vehicle controller receives the allowable continuous charging current and power battery voltage value of the power battery sent by the battery management system, the fuel cell operating power value sent by the fuel cell system controller, and the motor speed value sent by the motor controller through the CAN network, calculates the braking feedback torque value T of the motor and controls the braking feedback torque value of the motor not to exceed T; if the continuous braking time is <30s, the vehicle controller receives the allowable braking feedback current and power battery voltage value of the power battery sent by the battery management system, the fuel cell operating power value sent by the fuel cell system controller, and the motor speed value sent by the motor controller through the CAN network, calculates the braking feedback torque value T1 of the motor and controls the braking feedback torque value of the motor not to exceed T1; The calculation method of motor braking feedback torque is: If the brake time is ≥30s, ; If the braking time is less than 30 seconds, ; Among them, T and T1 are the motor braking feedback torque; U is the power battery voltage; I is the continuous charging current allowed by the power battery; I1 is the braking feedback current allowed by the power battery; P is the operating power of the fuel cell; N is the speed of the motor.

2. The bus energy management method considering the rationality of power and charging current as claimed in claim 1, characterized in that: When the state of charge is within the range of a preset first state of charge and a second state of charge, the power requested by the whole vehicle to the fuel cell system is the preset first power; when the state of charge is within the range of a preset second state of charge and a third state of charge, the power requested by the whole vehicle to the fuel cell system is the preset second power; when the state of charge is within the range of a preset third state of charge and a fourth state of charge, the power requested by the whole vehicle to the fuel cell system is the preset third power; when the state of charge is within the range of a preset third state of charge and a fourth state of charge, the power requested by the whole vehicle to the fuel cell system is 0; wherein, the first state of charge is less than the second state of charge, the second state of charge is less than the third state of charge, and the third state of charge is less than the fourth state of charge.

3. The bus energy management method considering the rationality of power and charging current as claimed in claim 2, characterized in that: The first power is the rated power of the fuel cell system; the second power is the average power required for the whole vehicle under the vehicle operating condition of the fuel cell system; and the third power is the power corresponding to the maximum efficiency point of the fuel cell system.

4. The bus energy management method considering the rationality of power and charging current as claimed in claim 1, characterized in that: When the state of charge is within a preset range of a first state of charge and a second state of charge, it is a hysteresis interval.

5. A bus energy management system that takes into account the rationality of power and charging current, characterized in that: include: The power request module is configured to: request the vehicle to make a power request to the fuel cell system according to the state of charge of the power battery; The power request module is configured to: determine different reasonable powers emitted by the fuel cell system according to different states of charge of the power battery; The current control module is configured to: when the vehicle brakes and recovers energy, the charging current is controlled to be always smaller than the charging current allowed by the power battery by taking into account the operating power of the fuel cell system; Determine the maximum value of the charging current according to the duration of braking; when the duration of braking is less than the preset time, the charging current does not exceed the braking feedback current allowed by the power battery, otherwise, the charging current does not exceed the continuous charging current allowed by the power battery; obtain the brake pedal switch signal to determine whether the vehicle is in a braking state, if it is not in a braking state, the braking feedback torque value sent by the vehicle controller to the motor is 0, if it is in a braking state, start timing to determine the duration of braking; If the continuous braking time is ≥30s, the vehicle controller receives the allowable continuous charging current and power battery voltage value of the power battery sent by the battery management system, the fuel cell operating power value sent by the fuel cell system controller, and the motor speed value sent by the motor controller through the CAN network, calculates the braking feedback torque value T of the motor and controls the braking feedback torque value of the motor not to exceed T; if the continuous braking time is <30s, the vehicle controller receives the allowable braking feedback current and power battery voltage value of the power battery sent by the battery management system, the fuel cell operating power value sent by the fuel cell system controller, and the motor speed value sent by the motor controller through the CAN network, calculates the braking feedback torque value T1 of the motor and controls the braking feedback torque value of the motor not to exceed T1; The calculation method of motor braking feedback torque is: If the brake time is ≥30s, ; If the braking time is less than 30 seconds, ; Among them, T and T1 are the motor braking feedback torque; U is the power battery voltage; I is the continuous charging current allowed by the power battery; I1 is the braking feedback current allowed by the power battery; P is the operating power of the fuel cell; N is the speed of the motor.

6. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps of the bus energy management method considering the rationality of power and charging current as described in any one of claims 1-4 are implemented.

7. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the steps of the bus energy management method considering the rationality of power and charging current as described in any one of claims 1-4 are implemented.

Images