Braking energy recovery method, system and engineering vehicle

Abstract

The present invention discloses a brake energy recovery method, system, and engineering vehicle. The brake energy recovery method utilizes dual pedals for brake energy recovery. In pure electric braking mode, the method monitors the maximum allowable battery recharge power and integrates the current motor speed to determine the current maximum recharge braking torque. Based on the pedal depth, the current braking torque is output in proportion to the maximum recharge braking torque, achieving the most efficient energy recovery. In mechanical braking mode, the brake pressure of the mechanical brake hydraulic circuit is monitored and the recharge braking torque is output in proportion. In both pure electric and mechanical combined braking modes, the electric brake pedal is prioritized, and the brake pressure signal is shielded. This method achieves higher brake energy recovery efficiency and a better handling experience.

Description

Technical Field

[0001] The present invention belongs to the technical field of vehicle driving control, and relates to a braking energy recovery method, system and engineering vehicle. Background Art

[0002] The braking system of new energy electric products generally has a brake energy recovery function. The component that conventionally triggers brake energy recovery in the industry is a brake pedal with a potentiometer. For example, in a specific application, the brake pedal travel is 0° to 15°, of which 0° to 6° is the potentiometer trigger signal for pure electric braking; when it is greater than 6°, pure electric braking and mechanical braking act simultaneously.

[0003] The use of a brake pedal with a potentiometer to trigger regenerative braking is mainly divided into three stages:

[0004] (1) Light braking: When the brake pedal is depressed, pure electric braking is triggered first. Since the pure electric braking stroke is small, it is a light braking situation. To ensure the control experience, the maximum recovery power is not considered. According to the pedal stroke (the greater the pedal stroke, the greater the electric braking torque), combined with actual vehicle control, different braking torques are calibrated, and the electric braking control characteristic curve under light braking is fitted.

[0005] (2) Moderate-intensity braking: When the brake pedal is depressed, the electric brake enters the combined action range of pure electric braking and mechanical braking. To avoid over-rapid braking, the electric brake is generally set to a pedal opening limit. Only below the limit will the electric brake take effect. During this process, the electric brake torque needs to be calibrated based on the controllability. The electric brake control characteristic curve under moderate-intensity braking is fitted based on the calibration points.

[0006] (3) High-intensity braking: When the pedal opening is greater than the set value, high-intensity braking is initiated. At this time, the braking intensity is high and the motor speed drops rapidly. Further energy recovery will cause excessive braking, resulting in locking, sudden braking, and poor controllability. At the same time, the action time is short, the energy absorbed is small, and energy recovery is of little significance. Therefore, energy recovery is no longer performed.

[0007] The existing solution of using a brake pedal with a potentiometer for brake energy recovery has the following technical problems:

[0008] Pure electric braking is a light braking method with a small pedal stroke. If energy recovery is performed at maximum recovery power, the braking torque will be too large, the braking will be too sudden, and the handling will be poor. When entering the pedal stroke area where pure electric braking and mechanical braking act at the same time, the mechanical braking itself will quickly reduce the motor speed. If energy recovery is performed at maximum recovery power or the recovery power is set to a constant value, the electric braking torque will increase rapidly. If both act at the same time, the braking will be too sudden and the handling will be poor.

[0009] In practice, in order to coordinate the handling experience, the entire energy recovery process actually reduces the power of braking energy recovery, and less energy is recovered. Summary of the Invention

[0010] Purpose of the invention: The first purpose of the present invention is to provide a braking energy recovery method that can take into account both controllability and maximum energy recovery; the second purpose of the present invention is to provide a braking energy recovery system; the third purpose of the present invention is to provide an engineering vehicle that uses the braking energy recovery system.

[0011] Technical solution: The braking energy recovery method of the present invention utilizes dual pedals for braking energy recovery, and the dual pedals include an electric brake pedal and a mechanical brake pedal. When the electric brake pedal is stepped on, the braking mode is pure electric; when the mechanical brake pedal is stepped on, the braking mode is mechanical; when the electric brake pedal and the mechanical brake pedal are stepped on at the same time, the braking mode is pure electric and mechanical combined.

[0012] (1) Pure electric braking mode:

[0013] Get the maximum recharge power currently allowed by the battery management system BMS;

[0014] Get the current motor speed;

[0015] According to the current maximum allowable regenerative braking power and the current motor speed, the current maximum allowable regenerative braking torque is obtained;

[0016] The maximum allowable regenerative braking torque corresponds to a 100% opening of the electric brake pedal. The regenerative braking torque signal used to control the motor is proportionally output according to the percentage of the electric brake pedal's pedal stroke to achieve braking.

[0017] (2) Mechanical brake mode

[0018] Calibrate the maximum brake pressure P and recharge power W of pure electric and mechanical combined braking;

[0019] Obtain the brake pressure of the mechanical brake hydraulic circuit;

[0020] Get the current motor speed;

[0021] Based on the recharge power W and the current motor speed, the maximum allowable recharge braking torque is obtained;

[0022] The maximum brake pressure P corresponds to the currently allowed maximum regenerative braking torque. The regenerative braking torque signal for controlling the motor is output according to the formula: brake pressure × currently allowed maximum regenerative braking torque / P, to achieve braking.

[0023] (3) Pure electric and mechanical combined braking mode

[0024] Give priority to responding to the electric brake pedal and shielding the brake pressure signal.

[0025] Furthermore, obtaining the maximum recharge power currently allowed by the battery management system BMS includes: obtaining the maximum recharge current allowed and the current system voltage output by the battery management system BMS, and the maximum recharge power currently allowed is the product of the maximum recharge current allowed and the current system voltage.

[0026] Furthermore, obtaining the currently allowed maximum recharge braking torque according to the currently allowed maximum recharge power and the current motor speed includes:

[0027] T=9550P / n

[0028] Where T represents the current maximum allowable regenerative braking torque, P represents the current maximum allowable regenerative power, and n represents the current motor speed.

[0029] Furthermore, the calibration of the maximum braking pressure P and recharging power W of the combined pure electric and mechanical braking includes:

[0030] The maximum braking pressure P and recharging power W are determined through experiments. The maximum braking pressure P and recharging power W are based on the fact that when braking, the vehicle will not lock or brake suddenly, and the braking operation will be smooth.

[0031] Furthermore, when the electric brake pedal is triggered, or there is a brake pressure signal, the throttle signal no longer responds.

[0032] The braking energy recovery system of the present invention is used to implement the above-mentioned braking energy recovery method, and the braking energy recovery system includes:

[0033] Dual pedals, including an electric brake pedal and a mechanical brake pedal; when the electric brake pedal is stepped on, it is in pure electric braking mode; when the mechanical brake pedal is stepped on, it is in mechanical braking mode; when the electric brake pedal and the mechanical brake pedal are stepped on at the same time, it is in pure electric and mechanical combined braking mode; the electric brake pedal uses a foot controller, and the mechanical brake pedal uses a conventional brake valve;

[0034] A motor controller, configured to control the motor to output a regenerative braking torque according to the regenerative braking torque signal, wherein the motor controller is integrated with a speed sensor for detecting the current motor speed;

[0035] A pressure sensor is used to detect the brake pressure of the mechanical brake hydraulic circuit;

[0036] The vehicle controller is used to enter the corresponding braking mode according to the double-pedal depression situation, obtain the parameters used to calculate the current maximum allowable recharge braking torque, calculate the current maximum allowable recharge braking torque and output the recharge braking torque signal to the motor controller according to the proportional relationship.

[0037] Furthermore, when the pressure sensor adopts a pressure switch, the detected brake pressure is a constant value, and the output recharge brake torque signal is a torque signal corresponding to the brake pressure constant value.

[0038] Furthermore, the electric brake pedal is reused with other pedals of the braking system, including the rotary brake pedal.

[0039] Furthermore, when the electric brake pedal is an electric brake pedal that outputs a switch signal, the output regenerative braking torque signal is a torque signal corresponding to a percentage of the switch stroke.

[0040] The engineering vehicle of the present invention includes the above-mentioned braking energy recovery system.

[0041] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0042] The present invention utilizes dual pedals for brake energy recovery, with a dedicated electric brake pedal offering a greater travel than existing brake pedals with potentiometers. This system is capable of achieving maximum recharge power brake energy recovery: by monitoring the battery's maximum allowable recharge power and integrating the current motor speed to determine the current maximum recharge braking torque, the current braking torque is output proportionally to the maximum recharge braking torque based on the pedal depth, achieving maximum energy recovery efficiency. The current braking torque increases proportionally with the pedal depth, providing excellent controllability. The original mechanical brake pedal is retained, and the brake pressure of the mechanical brake hydraulic circuit is monitored, with the recharge braking torque output proportionally, achieving combined control of electric and mechanical braking.

[0043] The braking energy recovery efficiency of the present invention is higher, which can effectively improve the driving range and provide a better control experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a flow chart of the pure electric braking energy recovery method;

[0045] Figure 2 This is the relationship between pedal depth and recharge braking torque under pure electric braking;

[0046] Figure 3 This is a flowchart of a method for simultaneous pure electric and mechanical braking energy recovery;

[0047] Figure 4 This is a diagram showing the relationship between brake pressure and recharge brake torque under simultaneous pure electric and mechanical braking. DETAILED DESCRIPTION

[0048] The present invention will be further described below with reference to the accompanying drawings.

[0049] An embodiment of the present application provides a braking energy recovery method, which uses a dual pedal to recover braking energy, and the dual pedal includes an electric brake pedal and a mechanical brake pedal; when the electric brake pedal is stepped on, it is a pure electric braking mode; when the mechanical brake pedal is stepped on, it is a mechanical braking mode; when the electric brake pedal and the mechanical brake pedal are stepped on at the same time, it is a pure electric and mechanical combined braking mode.

[0050] (1) Pure electric braking mode:

[0051] Combine Figure 1 , obtain the maximum allowable recharge current and current system voltage output by the battery management system (BMS), and calculate the current maximum allowable recharge power based on the maximum allowable recharge current and the current system voltage. The current maximum allowable recharge power is the product of the maximum allowable recharge current and the current system voltage.

[0052] Get the current motor speed;

[0053] Based on the current maximum allowable regenerative power and the current motor speed, the current maximum allowable regenerative braking torque is obtained; this includes:

[0054] T=9550P / n

[0055] Where T represents the current maximum allowable regenerative braking torque, P represents the current maximum allowable regenerative power, and n represents the current motor speed.

[0056] The 100% opening of the electric brake pedal corresponds to the current maximum allowable regenerative braking torque. According to the percentage of the electric brake pedal pedal stroke (i.e., the pedaling depth), the regenerative braking torque signal used to control the motor is proportionally output to achieve braking, such as Figure 2 As shown;

[0057] When the electric brake pedal is triggered, the throttle signal no longer responds.

[0058] (2) Mechanical brake mode

[0059] Combine Figure 3 The maximum brake pressure P and regenerative power W for combined electric and mechanical braking are calibrated. This calibration is based on the consideration that increased brake pressure rapidly decreases motor speed, while constant regenerative power rapidly increases negative torque from regenerative braking. The combined effects of these two factors can cause locking and poor handling. The maximum brake pressure P and regenerative power W are determined through testing. These maximum brake pressure P and regenerative power W are designed to ensure smooth braking without locking or sudden braking during braking.

[0060] Obtain the brake pressure of the mechanical brake hydraulic circuit;

[0061] Get the current motor speed;

[0062] Based on the recharge power W and the current motor speed, the maximum allowable recharge braking torque is obtained;

[0063] The maximum braking pressure P corresponds to the current maximum allowable recharge braking torque. The recharge braking torque signal used to control the motor is proportionally output according to the braking pressure × the current maximum allowable recharge braking torque / P to achieve braking, such as Figure 4 As shown;

[0064] The deeper the mechanical brake pedal is depressed, the greater the brake pressure becomes, which is a linear relationship. When the driver depresses the mechanical brake pedal, the brake pressure can be detected.

[0065] When there is a brake pressure signal, the throttle signal no longer responds.

[0066] (3) Pure electric and mechanical combined braking mode

[0067] When the electric brake pedal and the mechanical brake pedal act at the same time, in order to ensure maximum recovery efficiency, the electric brake pedal is responded to first, and the throttle signal and brake pressure signal are shielded.

[0068] The present application also provides a braking energy recovery system for implementing the above-mentioned braking energy recovery method. The braking energy recovery system includes:

[0069] The dual-pedal system includes an electric brake pedal and a mechanical brake pedal. When the electric brake pedal is pressed, the braking mode is purely electric; when the mechanical brake pedal is pressed, the braking mode is mechanical; and when both the electric and mechanical brake pedals are pressed simultaneously, the braking mode is a combination of pure electric and mechanical. The electric brake pedal uses a foot controller that outputs a proportional electrical signal based on the pedal stroke. This is widely used in construction machinery, such as cranes, where electric throttle and slew brakes are commonly used. The mechanical brake pedal uses a conventional brake valve. The electric brake pedal can be located on the left side of the driver's cab, while the mechanical brake pedal can be located on the right side.

[0070] A motor controller, configured to control the motor to output a regenerative braking torque according to the regenerative braking torque signal, wherein the motor controller is integrated with a speed sensor for detecting the current motor speed;

[0071] A pressure sensor is used to detect the brake pressure of the mechanical brake hydraulic circuit;

[0072] The vehicle controller is used to enter the corresponding braking mode according to the double pedal pressing situation, obtain the parameters used to calculate the current maximum allowable recharge braking torque, calculate the current maximum allowable recharge braking torque and output the recharge braking torque signal to the motor controller according to the proportional relationship. Specifically,

[0073] When entering pure electric braking mode, the vehicle controller obtains the maximum allowable recharge current and current system voltage output by the battery management system (BMS) to calculate the current maximum allowable recharge power. It then obtains the current motor speed output by the motor controller and, combined with the current maximum allowable recharge power, calculates the current maximum allowable recharge braking torque. Finally, it obtains the percentage of pedal stroke feedback from the electric brake pedal and proportionally outputs the recharge braking torque signal to the motor controller.

[0074] When mechanical braking mode is entered, the vehicle controller obtains the brake pressure of the mechanical brake hydraulic circuit as detected by the pressure sensor and the current motor speed output by the motor controller. It then calculates the maximum allowable regenerative braking torque based on the regenerative power W and the current motor speed. Finally, based on the maximum brake pressure P, the vehicle controller outputs a regenerative braking torque signal proportional to the formula: brake pressure multiplied by the current maximum allowable regenerative braking torque / P. The maximum brake pressure P and regenerative power W are pre-calibrated and stored.

[0075] The aforementioned pressure sensor is capable of continuous pressure detection. In some embodiments, the pressure sensor can also be a pressure switch that performs fixed-value detection. For example, the pressure switch's detection value can be set to 80% of the maximum brake pressure P. When the driver depresses the mechanical brake pedal, the brake pressure in the mechanical brake hydraulic circuit reaches 80% of the maximum brake pressure P. This is detected and fed back to the vehicle controller, which then outputs a corresponding proportional regenerative braking torque signal to the motor controller for braking. A disadvantage of this embodiment is that it can only output point values, not continuous output.

[0076] Similarly, the aforementioned electric brake pedal uses a foot controller capable of outputting a continuous proportional signal. In some embodiments, the electric brake pedal can also be configured to output a switching signal. For example, when the electric brake pedal reaches 60% of its travel, the vehicle controller outputs a corresponding proportional regenerative braking torque signal to the motor controller for braking. This embodiment also suffers from the disadvantage of only being able to output point values, rather than a continuous output.

[0077] In some embodiments, the electric brake pedal does not need to be specially arranged, but can reuse other pedals already in the braking system. For example, for a crane, the electric brake pedal and the slewing brake pedal can be reused. When stepped on, the functions of electric braking and slewing braking are realized simultaneously.

[0078] An embodiment of the present application also provides an engineering vehicle, comprising the above-mentioned braking energy recovery system.

Claims

1. A braking energy recovery method, characterized in that: The dual-pedal system uses electric and mechanical brake pedals for braking energy recovery. When the electric brake pedal is pressed, the vehicle is in pure electric braking mode; when the mechanical brake pedal is pressed, the vehicle is in mechanical braking mode; when both the electric and mechanical brake pedals are pressed at the same time, the vehicle is in a combined electric and mechanical braking mode. (1) Pure electric braking mode: Get the maximum recharge power currently allowed by the battery management system BMS; Get the current motor speed; According to the current maximum allowable regenerative braking power and the current motor speed, the current maximum allowable regenerative braking torque is obtained; The maximum allowable regenerative braking torque corresponds to a 100% opening of the electric brake pedal. The regenerative braking torque signal used to control the motor is proportionally output according to the percentage of the electric brake pedal's pedal stroke to achieve braking. (2) Mechanical brake mode Calibrate the maximum brake pressure P and recharge power W of pure electric and mechanical combined braking; Obtain the brake pressure of the mechanical brake hydraulic circuit; Get the current motor speed; Based on the recharge power W and the current motor speed, the maximum allowable recharge braking torque is obtained; The maximum brake pressure P corresponds to the currently allowed maximum regenerative braking torque. The regenerative braking torque signal for controlling the motor is output according to the formula: brake pressure × currently allowed maximum regenerative braking torque / P, to achieve braking. (3) Pure electric and mechanical combined braking mode Give priority to responding to the electric brake pedal and shielding the brake pressure signal.

2. The braking energy recovery method according to claim 1, characterized in that: The obtaining of the maximum recharge power currently allowed by the battery management system BMS includes obtaining the maximum recharge current allowed and the current system voltage output by the battery management system BMS, wherein the maximum recharge power currently allowed is the product of the maximum recharge current allowed and the current system voltage.

3. The braking energy recovery method according to claim 1, characterized in that: Obtaining the currently allowed maximum recharge braking torque according to the currently allowed maximum recharge power and the current motor speed includes: T=9550P / n Where T represents the current maximum allowable regenerative braking torque, P represents the current maximum allowable regenerative power, and n represents the current motor speed.

4. The braking energy recovery method according to claim 1, characterized in that: The calibration of the maximum brake pressure P and recharge power W of the electric and mechanical combined braking includes: The maximum braking pressure P and recharging power W are determined through experiments. The maximum braking pressure P and recharging power W are based on the fact that when braking, the vehicle will not lock or brake suddenly, and the braking operation will be smooth.

5. The braking energy recovery method according to claim 1, characterized in that: When the electric brake pedal is triggered, or there is a brake pressure signal, the throttle signal no longer responds.

6. A braking energy recovery system, used to implement the braking energy recovery method according to any one of claims 1 to 5, characterized in that: The braking energy recovery system comprises: Dual pedals, including an electric brake pedal and a mechanical brake pedal; when the electric brake pedal is stepped on, it is in pure electric braking mode; when the mechanical brake pedal is stepped on, it is in mechanical braking mode; when the electric brake pedal and the mechanical brake pedal are stepped on at the same time, it is in pure electric and mechanical combined braking mode; the electric brake pedal uses a foot controller, and the mechanical brake pedal uses a conventional brake valve; A motor controller, configured to control the motor to output a regenerative braking torque according to the regenerative braking torque signal, wherein the motor controller is integrated with a speed sensor for detecting the current motor speed; A pressure sensor is used to detect the brake pressure of the mechanical brake hydraulic circuit; The vehicle controller is used to enter the corresponding braking mode according to the double-pedal depression situation, obtain the parameters used to calculate the current maximum allowable recharge braking torque, calculate the current maximum allowable recharge braking torque and output the recharge braking torque signal to the motor controller according to the proportional relationship.

7. The braking energy recovery system according to claim 6, characterized in that: When the pressure sensor adopts a pressure switch, the detected brake pressure is a fixed value, and the output recharge brake torque signal is a torque signal corresponding to the fixed brake pressure value.

8. The braking energy recovery system according to claim 6, characterized in that: The electric brake pedal is reused with other pedals in the braking system, including the swing brake pedal.

9. The braking energy recovery system according to claim 6, characterized in that: When the electric brake pedal is an electric brake pedal that outputs a switch signal, the output regenerative braking torque signal is a torque signal corresponding to the percentage of the switch stroke.

10. An engineering vehicle, characterized in that: A brake energy recovery system comprising the brake energy recovery system according to any one of claims 6 to 9.

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