Travel brake energy recovery system for electric forklift, control method and medium thereof

Abstract

The travel brake energy recovery system of an electric forklift, its control method and medium, relate to the technical field of electric forklifts. The signal output end of the whole machine controller is electrically connected to the low-voltage system, high-voltage system, drive system, and signal input end of the brake system through a CAN line. The high-voltage power output end of the high-voltage system is electrically connected to the drive system, the brake system, and the power input end of the low-voltage system. The low-voltage power output end of the low-voltage system is electrically connected to the low-voltage power input end of the whole machine controller and various auxiliary components of the vehicle. The signal output end of each auxiliary component of the electric forklift is electrically connected to the signal input end of the whole machine controller through a CAN line. The controller is configured to calculate the required braking force in real time based on the current vehicle status information before the electric forklift receives the braking signal. When the electric forklift receives the braking signal, the braking force required for the whole vehicle is distributed, and the travel motor and mechanical brake of the braking system are controlled to operate.

Description

Technical Field

[0001] The present invention relates to the technical field of electric forklifts, and in particular to a travel braking energy recovery system of an electric forklift, a control method thereof, and a medium. Background Art

[0002] In the widespread use of electric forklifts, the performance of brake energy recovery systems is crucial for improving vehicle range and reducing operating costs. Currently, most electric forklifts have low brake energy recovery efficiency, failing to fully utilize the energy generated during braking for reuse. This results in a significant amount of energy being wasted during braking, impacting the vehicle's range and energy efficiency. Furthermore, existing systems are relatively crude in their distribution and management of braking force, unable to accurately distribute braking force based on varying operating conditions and vehicle status. This not only limits the efficiency of energy recovery but can also impact the vehicle's braking performance and safety.

[0003] The shortcomings of electric forklifts' brake energy recovery systems are particularly evident under frequent braking conditions. Due to the lack of an effective energy recovery mechanism, the vehicle's kinetic energy cannot be effectively converted into electrical energy and stored in the battery during braking, thus failing to provide additional power for subsequent driving. This inefficient energy recovery significantly limits the range of electric forklifts under frequent braking conditions, increasing charging frequency and operating costs.

[0004] At the same time, the driving experience of the existing system during braking also has a lot of room for improvement. Due to the inaccurate assessment of braking force, the braking process is not smooth enough, which brings an uncomfortable operating experience to the operator and affects work efficiency. Summary of the Invention

[0005] The present invention provides a travel brake energy recovery system for an electric forklift, a control method thereof, and a medium thereof, aiming to solve the problem of low brake energy recovery efficiency of existing electric forklifts and thereby improve endurance.

[0006] In a first aspect, the present invention provides a travel brake energy recovery system for an electric forklift, which includes: a whole machine controller, a low-voltage system, a high-voltage system, a drive system, and a braking system.

[0007] The signal output end of the whole machine controller is electrically connected to the signal input end of the low-voltage system, the high-voltage system, the drive system, and the brake system through a CAN line.

[0008] The high-voltage power output end of the high-voltage system is electrically connected to the driving system, the braking system, and the power input end of the low-voltage system.

[0009] The low-voltage electrical output end of the low-voltage system is electrically connected to the low-voltage electrical input ends of the whole machine controller and various auxiliary components of the vehicle.

[0010] The signal output terminals of the auxiliary components of the electric forklift are electrically connected to the signal input terminals of the whole machine controller via CAN lines.

[0011] The whole machine controller is configured to calculate the required braking force in real time based on the current vehicle status information before the electric forklift receives a brake signal. When the electric forklift receives the brake signal, it distributes the braking force required for the entire vehicle and controls the operation of the travel motor and mechanical brake of the braking system.

[0012] Preferably, the electrical system of the travel brake energy recovery system includes: a power battery, a battery management system, a high-voltage management unit, a motor controller, a DC / DC converter, a travel motor, a mechanical brake, a whole machine controller, other auxiliary components, a brake pedal, and a low-voltage battery.

[0013] The high-voltage power output of the power battery is electrically connected to the high-voltage power input of the battery management system. The high-voltage power output of the battery management system is electrically connected to the high-voltage power input of the high-voltage management unit. The high-voltage power output of the high-voltage management unit is divided into two paths, which are electrically connected to the DC / DC converter and the high-voltage power input of the motor controller respectively. The high-voltage power output of the motor controller is electrically connected to the high-voltage power input of the travel motor, and the motor controller converts the high-voltage direct current into three-phase high-voltage alternating current.

[0014] The DC / DC converter is adapted to convert high-voltage direct current into low-voltage direct current for powering the low-voltage system. The low-voltage output of the DC / DC converter is divided into four paths, which are electrically connected to the whole machine controller, the other auxiliary components, the brake pedal, and the low-voltage input of the low-voltage battery.

[0015] The low-voltage power output of the low-voltage battery is divided into three paths, which are electrically connected to the low-voltage power input of the vehicle controller, the brake pedal, and other auxiliary components. The low-voltage battery is suitable for powering other auxiliary components when the vehicle is powered on.

[0016] Preferably, the drive system includes the motor controller and the travel motor. The braking system comprises the travel motor and a mechanical brake. The travel motor is used for both driving the vehicle forward and braking, and thus belongs to both the drive system and the braking system. When braking is performed by the travel motor, the travel motor generates a back electromotive force, which in turn generates a braking current.

[0017] Preferably, the signal receiving end of the whole machine controller is electrically connected to the signal output end of each auxiliary component. The control signal sending end of the whole machine controller is electrically connected to the control signal receiving end of each auxiliary component.

[0018] The signal terminal of the battery management system is electrically connected to the signal terminal of the high-voltage management unit through a CAN line.

[0019] Preferably, the whole machine controller is provided with a state detection unit, a braking control unit and a braking force distribution unit.

[0020] Each auxiliary component of an electric forklift sends detection signals to the information receiving end of the whole vehicle controller and receives control commands from the transmitting end of the whole vehicle controller. The status signals sent by each auxiliary component and the driving signals obtained by collating these status signals form the whole vehicle information.

[0021] The vehicle information includes the working status information of each auxiliary component during the operation of the electric forklift, load information, electric forklift actuator posture information, current vehicle speed information, current acceleration information, slope information, pedal opening change information, first judgment information of the emergency braking judgment unit, and second judgment information of the motor braking and power generation judgment unit.

[0022] Preferably, the status detection unit is adapted to determine whether each auxiliary component is currently operating normally based on status signals received from each auxiliary component via the CAN line in real time. If a fault occurs, the fault information is directly displayed on the vehicle display screen. If no fault occurs, partial status information is processed and split into two paths, which are sent to the brake control unit and the brake force distribution unit for processing, calculation, and judgment.

[0023] The braking control unit is used to calculate the real-time required braking force information and the real-time motor braking power generation status information and send them to the braking force distribution unit. The braking control unit includes a braking force estimation unit, a unit for determining whether emergency braking is required, a unit for determining whether the motor braking power generation status is available, and a braking force calculation unit.

[0024] After receiving the status information sent by the status detection unit, the braking force estimation unit is used to identify the current driving condition of the entire vehicle. Based on different combinations of driving speed, load mass, and fork posture, the required braking force is preliminarily calculated based on the maximum braking intensity value within different braking intensity ranges, and this is used as the maximum braking force threshold under non-emergency braking conditions. When in the low braking intensity or medium braking intensity range, under no-load conditions, the braking intensity is the actual value. Under loaded conditions, the braking intensity needs to be optimized based on the detected load mass, and the optimization coefficient k is inversely proportional to the load mass. When in emergency braking intensity, the braking intensity is the actual value.

[0025] The emergency braking determination unit is used to identify the braking intensity based on the fuzzy controller based on the brake pedal opening change information and the vehicle speed in the initial braking stage, so as to determine whether emergency braking is required. , For braking strength, For speed, For time, is the gravity coefficient, Denotes differential. Definition For low braking strength, For the medium braking intensity range, It is the emergency braking intensity.

[0026] The required braking force calculated by the braking force calculation unit The motor efficiency and battery efficiency detected by the state detection unit in the braking phase are dynamically optimized by the particle swarm optimization algorithm to optimize the braking force output by the motor, so that the motor can output the maximum braking torque under the premise of meeting high efficiency. The maximum braking force that the motor can currently provide By comparing and setting the threshold, the distribution mode is divided into two categories: motor braking and motor braking plus mechanical braking. Less than or equal to the maximum braking force that the motor can currently provide , then choose to rely on the motor for braking. If the required braking force Greater than the maximum braking force that the motor can currently provide , then select motor braking plus mechanical braking. The proportion weight of motor braking force and mechanical braking force is allocated by different braking modes, and the braking force proportion weight control signal is sent to the motor controller and mechanical brake to control the vehicle to brake according to the braking demand. For quality.

[0027] Preferably, the braking force distribution unit is used to distribute the proportional weights of the electric braking force and the mechanical braking force based on the data calculated by the braking force calculation unit, through conditional judgment and sorting calculation, and send the braking force proportional weight control signal to the motor controller and the mechanical brake to control the entire vehicle to brake according to the braking demand.

[0028] Preferably, the whole-machine controller also includes a brake stability closed-loop control. When distributing braking force, the whole-machine controller uses a state detection unit to monitor the vehicle's braking state information, transmitted by various auxiliary components during the braking process, in real time. Combined with the operator's braking experience and control signals, the state detection unit monitors and transmits the operator's braking demand in real time. The sliding membrane controller then optimizes the braking demand force to reduce braking shock and achieve smoother braking.

[0029] In a second aspect, the present invention provides a control method for a travel brake energy recovery system of an electric forklift, which includes steps S1 to S5.

[0030] S1. Obtain the status signals sent by each auxiliary component via the CAN line in real time and determine whether each auxiliary component is currently in normal working condition. If a fault occurs, the fault information is directly displayed on the vehicle display.

[0031] S2. If there are no faults, after receiving the status information from the status detection unit, the current vehicle driving condition is identified. Based on the different combinations of driving speed, load mass, and fork posture, the required braking force is preliminarily calculated based on the maximum braking intensity value within different braking intensity ranges. This is used as the maximum braking force threshold for non-emergency braking conditions. When in the low or medium braking intensity range, under no-load conditions, the braking intensity is the actual value. Under loaded conditions, the braking intensity needs to be optimized based on the detected load mass, and the optimization coefficient k is inversely proportional to the load mass. When in emergency braking intensity, the braking intensity is the actual value.

[0032] S3, based on the fuzzy controller, the brake pedal opening change information and the vehicle speed at the initial stage of braking are used to identify the braking intensity, thereby determining whether emergency braking is required. , For braking strength, For speed, For time, is the gravity coefficient, Denotes differential. Definition For low braking strength, For the medium braking intensity range, It is the emergency braking intensity.

[0033] S4, when emergency braking is not required, the energy storage recovery state judgment unit and the information of the battery and motor temperature judgment unit are used to make conditional judgments, thereby selecting the motor braking state. The energy storage recovery state judgment unit is used to judge the capacity of the battery SOC and set the energy recovery threshold according to the battery charge and discharge characteristics, so that the recoverable energy range is within the minimum recovery capacity. With maximum recycling capacity The battery and motor temperature determination unit is used to monitor the temperature rise of the battery and motor, and by setting a temperature threshold, the battery and motor operate within a preset operating efficiency range. The motor force comparison and determination unit is used to compare the braking force estimation information sent by the braking control unit.

[0034] S5. Required braking force calculated The motor efficiency and battery efficiency during the braking phase are dynamically optimized using a particle swarm optimization algorithm to ensure that the motor outputs the maximum braking torque while meeting high efficiency. The maximum braking force that the motor can currently provide By comparing and setting the threshold, the distribution mode is divided into two categories: motor braking and motor braking plus mechanical braking. Less than or equal to the maximum braking force that the motor can currently provide , then choose to rely on the motor for braking. If the required braking force Greater than the maximum braking force that the motor can currently provide , then select motor braking plus mechanical braking. The proportion weight of motor braking force and mechanical braking force is allocated by different braking modes, and the braking force proportion weight control signal is sent to the motor controller and mechanical brake to control the vehicle to brake according to the braking demand. For quality.

[0035] In a third aspect, the present invention provides a computer-readable storage medium, which includes a stored computer program, wherein when the computer program is running, the device where the computer-readable storage medium is located is controlled to execute the control method of the travel brake energy recovery system of an electric forklift.

[0036] By adopting the above technical solution, the present invention can achieve the following technical effects:

[0037] The electric forklift's travel brake energy recovery system of the present invention achieves significant performance improvements and economic benefits through innovative design and optimized control strategies. The system is capable of real-time monitoring and analysis of the vehicle's status under different driving conditions, thereby accurately estimating and rationally allocating braking force. In this way, the electric forklift can maximize the use of motor braking energy recovery during braking, significantly improving the vehicle's endurance. In addition, the system can respond quickly during emergency braking to ensure braking safety. At the same time, through optimized control algorithms, the braking response speed and stability are improved, providing the operator with a smoother and more comfortable driving experience.

[0038] The system also uses a closed-loop control mechanism to combine vehicle braking status information with operator feedback based on braking experience, enabling intelligent adjustment of required braking force during the braking process. This design results in smoother braking, further enhancing the driving experience while reducing operator workload. Through rational braking force distribution and efficient energy recovery, the system not only improves the energy efficiency of electric forklifts but also strongly supports their sustainable development, resulting in significant economic and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solution of the present invention, the following is a brief introduction to the drawings required for use in the specific implementation methods of the present invention. It should be understood that the following drawings only show certain specific implementation methods of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0040] Figure 1 This is a schematic diagram of the electric forklift's travel brake energy recovery system.

[0041] Figure 2 This is a schematic diagram of the travel brake system of an electric forklift.

[0042] Figure 3 This is the signal transmission flow chart of the electric forklift's travel brake energy recovery system.

[0043] Markings in the figure: 1-power battery 1, 2-battery management system 2, 3-high voltage management unit 3, 4-motor controller 4, 5-DC / DC converter 5, 6-travel motor 6, 7-mechanical brake, 8-machine controller 8, 9-other auxiliary components 9, 10-brake pedal 10, 11-low voltage battery 11. DETAILED DESCRIPTION

[0044] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings. Obviously, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0045] Example 1, please refer to Figures 1 to 3 The first embodiment of the present invention provides a travel brake energy recovery system for an electric forklift, which includes a whole machine controller 8, a low-voltage system, a high-voltage system, a drive system, and a braking system.

[0046] The signal output end of the whole machine controller 8 is electrically connected to the signal input end of the low-voltage system, the high-voltage system, the drive system, and the brake system through a CAN line. The high-voltage electrical output end of the high-voltage system is electrically connected to the drive system, the brake system, and the power input end of the low-voltage system. The low-voltage electrical output end of the low-voltage system is electrically connected to the low-voltage electrical input end of the whole machine controller 8 and each auxiliary component 9 of the vehicle. The signal output end of each auxiliary component of the electric forklift is electrically connected to the signal input end of the whole machine controller 8 through a CAN line. Among them, each auxiliary component 9 includes auxiliary control equipment installed in existing electric forklifts, such as the vehicle display screen, accelerator pedal, and brake pedal. Each auxiliary component also includes various detection sensors installed in existing electric forklifts. For example, the temperature sensor, level sensor, speed sensor, and acceleration sensor of the motor.

[0047] Preferably, the whole vehicle controller 8 is configured to estimate the maximum braking force thresholds under different combinations of non-emergency braking conditions in real time based on the current vehicle status information before the electric forklift receives a braking signal. When the electric forklift receives a braking signal, it calculates and distributes the braking force required for the entire vehicle, and controls the operation of the travel motor 6 and mechanical brake of the braking system.

[0048] On the basis of the above embodiment, in an optional embodiment of the present invention, as Figure 1 As shown, the electrical system of the travel brake energy recovery system includes: a power battery 1, a battery management system 2, a high-voltage management unit 3, a motor controller 4, a DC / DC converter 5, a travel motor 6, a mechanical brake, a whole machine controller 8, other auxiliary components 9, a brake pedal 10, and a low-voltage battery 11. The low-voltage battery 11 is a 24V battery.

[0049] The electrical connection relationship between the power battery 1 and the power supply circuit of the DC / DC converter 5 is as follows: Figure 1As shown by the red solid line in . The high-voltage output terminal of the power battery 1 is electrically connected to the high-voltage input terminal of the battery management system 2. The high-voltage output terminal of the battery management system 2 is electrically connected to the high-voltage input terminal of the high-voltage management unit 3. The high-voltage output terminal of the high-voltage management unit 3 is divided into two paths, which are electrically connected to the DC / DC converter 5 and the high-voltage input terminal of the motor controller 4 respectively. The high-voltage output terminal of the motor controller 4 is electrically connected to the high-voltage input terminal of the travel motor 6, and the motor controller 4 converts the high-voltage direct current into three-phase high-voltage alternating current.

[0050] The DC / DC converter 5 is adapted to convert high-voltage DC power into low-voltage DC power for powering the low-voltage system. The low-voltage output of the DC / DC converter 5 is divided into four paths, which are electrically connected to the low-voltage input of the whole machine controller 8, the other auxiliary components 9, the brake pedal 10, and the low-voltage battery 11, respectively.

[0051] The electrical connection relationship of the power supply circuit of the low-voltage battery 11 is as follows Figure 1 As shown by the solid black line, the low-voltage output terminal of the low-voltage battery 11 is divided into three paths, which are respectively electrically connected to the low-voltage input terminals of the vehicle controller 8, the brake pedal 10, and the other auxiliary components 9. The low-voltage battery 11 is suitable for powering the other auxiliary components 9 when the vehicle is powered on.

[0052] like Figure 1 As shown, the drive system includes the motor controller 4 and the travel motor 6. The braking system consists of the travel motor 6 and a mechanical brake. The travel motor 6 is used for both driving the vehicle forward and braking, and therefore belongs to both the drive system and the braking system. Specifically, when braking is performed by the travel motor 6, the travel motor 6 generates a back electromotive force, which in turn generates a braking current.

[0053] The signal circuit of the whole machine controller 8 is as follows Figure 1 As shown by the black dotted lines in FIG. The signal receiving end of the whole machine controller 8 is electrically connected to the signal output end of the other auxiliary components 9. The control signal sending end of the whole machine controller 8 is electrically connected to the control signal receiving end of the other auxiliary components 9. The signal end of the battery management system 2 is electrically connected to the signal end of the high-voltage management unit 3 via a CAN line.

[0054] On the basis of the above embodiment, in an optional embodiment of the present invention, as Figure 1 and 3 As shown, the whole machine controller 8 is provided with a state detection unit, a braking control unit and a braking force distribution unit.

[0055] Each auxiliary component of the electric forklift sends a detection signal to the information receiving end of the whole machine controller 8, and receives a control command from the sending end of the whole machine controller 8. Among them, the status signal sent by each auxiliary component is analyzed to form the whole vehicle information.

[0056] The vehicle information includes the working status information of each auxiliary component during the operation of the electric forklift, load information, electric forklift actuator posture information, current vehicle speed information, current acceleration information, slope information, pedal opening change information, first judgment information of the emergency braking judgment unit, and second judgment information of the motor braking and power generation judgment unit.

[0057] The status detection unit is adapted to determine whether each auxiliary component is currently functioning properly based on status signals received from each auxiliary component via the CAN line. If a fault occurs, the fault information is displayed directly on the vehicle's display screen. If no fault occurs, partial status information is processed and split into two paths, which are then sent to the brake control unit and brake force distribution unit for processing, calculation, and judgment.

[0058] The braking control unit is used to calculate the real-time required braking force information and the real-time motor braking power generation status information and send them to the braking force distribution unit. The braking control unit includes a braking force estimation unit, a unit for determining whether emergency braking is required, a unit for determining whether the motor braking power generation status is available, and a braking force calculation unit.

[0059] After receiving status information from the status detection unit, the braking force estimation unit identifies the current vehicle driving condition. Based on different combinations of driving speed, load mass, and fork posture, the maximum braking force within different braking intensity ranges is used to make a preliminary estimate of the required braking force. This estimate serves as the maximum braking force threshold for non-emergency braking conditions. When operating in the low or medium braking intensity range, the braking force is used as the actual value under unloaded conditions. Under loaded conditions, the braking force is optimized based on the detected load mass, with the optimization coefficient k being inversely proportional to the load mass. When operating in emergency braking intensity, the braking force is used as the actual value.

[0060] The emergency braking determination unit is used to identify the braking intensity based on the opening change information of the brake pedal 10 and the vehicle speed in the initial stage of braking according to the designed fuzzy controller, so as to determine whether emergency braking is required. , For braking strength, For speed, For time, is the gravity coefficient, Represents differential; definition For low braking strength, For the medium braking intensity range, is the emergency braking intensity;

[0061] The unit for judging whether the state is capable of motor braking and power generation is used to make conditional judgment based on the information of the energy storage recovery state judgment unit, the battery and motor temperature judgment unit and the motor power comparison judgment unit, so as to select the state capable of motor braking. The energy storage recovery state judgment unit is used to judge the capacity of the battery SOC and set the energy recovery threshold according to the battery charge and discharge characteristics, so that the recoverable energy range is within the minimum recovery capacity. With maximum recycling capacity The battery and motor temperature determination unit is used to monitor the temperature rise of the battery and the motor, and to set a temperature threshold so that the battery and the motor operate within a preset working efficiency range.

[0062] The braking force distribution unit is used to calculate the required braking force according to the received braking force calculation unit. The motor efficiency and battery efficiency detected by the state detection unit in the braking phase are dynamically optimized by the designed particle swarm optimization algorithm to optimize the braking force output by the motor, so that the motor can output the maximum braking torque under the premise of meeting high efficiency. For quality.

[0063] The required braking force The maximum braking force that the motor can currently provide By comparing and setting the threshold, the distribution mode is divided into two categories: motor braking and motor braking plus mechanical braking; if the required braking force Less than or equal to the maximum braking force that the motor can currently provide , then choose to rely on the motor for braking; if the required braking force Greater than the maximum braking force that the motor can currently provide , then motor braking plus mechanical braking is selected. Different braking modes are used to allocate the proportional weights of motor braking force and mechanical braking force. A braking force proportional weight control signal is sent to the motor controller 4 and the mechanical brake, controlling the vehicle to brake according to braking requirements. This maximizes the use of motor braking for reverse power generation, thereby recovering more energy and improving endurance.

[0064] Specifically, when hybrid braking is required, the real-time braking force required is decoupled, and the appropriate braking mode is selected based on the braking conditions. The actuator is then controlled by sending an operating signal via the CAN line. Preferably, during emergency braking, the braking force ratio is adjusted so that the required braking force for the entire vehicle is provided by the mechanical brake. During hybrid braking, the total braking force requirement is first calculated, and then the motor output braking force is dynamically optimized. The remaining braking force requirement is provided by the mechanical brake.

[0065] On the basis of the above embodiment, in an optional embodiment of the present invention, as Figure 3 As shown, the whole machine controller 8 also includes a braking stability unit.

[0066] When the vehicle controller 8 distributes braking force and applies it to the braking system, the state detection unit monitors brake feedback signals, such as braking impact, in real time and transmits the braking demand adjusted by the operator, ensuring smoother braking. This improves the driving experience. Specifically, the braking force distribution unit controls the travel motor 6 and mechanical brake in the braking system. When braking according to different braking states, the state detection unit monitors the vehicle's braking state information transmitted by various auxiliary components in real time. Combined with the operator's control signals after experiencing the braking, the designed sliding membrane controller optimizes the braking demand force, thereby reducing braking impact, achieving smoother braking, and improving the driving experience.

[0067] The electric forklift of the present invention is described in detail below.

[0068] During normal operation, the status detection unit in the vehicle controller 8 receives real-time status information from various auxiliary components. It first determines whether each auxiliary component is operating normally. If a fault occurs, the fault information is displayed directly on the vehicle display. If no fault occurs, the status information is processed and split into two paths, which are then sent to the brake control unit and the brake force distribution unit for processing, calculation, and judgment.

[0069] The braking force estimation unit in the brake control unit estimates the maximum braking force threshold for non-emergency braking conditions based on the received status information and sends it to the motor braking and power generation determination unit. The motor braking and power generation determination unit then uses the received status information to determine whether the vehicle is currently in a state capable of motor braking and power generation, preparing for subsequent braking signals.

[0070] When the operator has a braking demand, the emergency braking judgment unit first receives the pedal opening change signal and the vehicle speed signal in the initial braking stage sent by the state detection unit, and judges whether emergency braking is needed based on the designed fuzzy controller.

[0071] If emergency braking is required, the braking force calculation unit calculates the current required braking force and then sends the current required braking force signal to the braking force distribution unit, which distributes the braking force weight entirely to the mechanical brake.

[0072] If emergency braking is not required, the braking demand signal is passed to the motor braking and power generation determination unit. Based on the determination made during normal driving, the motor braking and power generation determination unit passes the braking demand information to the braking force calculation unit to accurately calculate the currently required braking force. The braking force is then optimized based on the braking impact feedback from the braking stability unit.

[0073] If the motor braking and power generation is not possible, the currently required braking force signal is sent to the braking force distribution unit, and the braking force distribution unit allocates all the braking force weights to the mechanical brake.

[0074] If the motor is currently in a state where it can generate electricity through braking, the current required braking force signal is sent to the braking force distribution unit, which then dynamically optimizes the braking force output by the motor based on the particle swarm optimization algorithm. The maximum braking force that the motor can currently provide By comparing and setting the threshold, the distribution mode is divided into two categories: motor braking and motor braking plus mechanical braking; if the required braking force Less than or equal to the maximum braking force that the motor can currently provide , then choose to rely on the motor for braking; if the required braking force Greater than the maximum braking force that the motor can currently provide , then select motor braking plus mechanical braking. Based on the selected braking mode, the braking force distribution weight is reasonably distributed.

[0075] If the braking mode is selected to rely solely on motor braking, the braking force distribution weight is entirely allocated to motor braking.

[0076] If the braking mode is motor + mechanical combined braking, the motor braking force is controlled to maintain the maximum braking force that can be provided at present. , the other braking force is met by mechanical braking.

[0077] Finally, the above-mentioned status detection unit monitors the vehicle braking status information sent by various auxiliary components during the braking process in real time, combines the control signals obtained by the operator after the braking driving experience, and optimizes the braking demand force through the designed sliding membrane controller, thereby reducing the braking impact, making braking smoother and improving the driving experience.

[0078] A travel brake energy recovery system for an electric forklift in an embodiment of the present invention sends status signals to the whole machine controller 8 through various auxiliary components. The whole machine controller 8 sends control signals to each actuator after sorting, calculating and judging. The above-mentioned status detection unit monitors the whole vehicle braking status information sent by various auxiliary components during the braking process in real time. Combined with the control signal obtained by the operator after the braking driving experience, the designed sliding membrane controller optimizes the braking demand braking force, thereby reducing the braking impact, making braking smoother, and improving the driving experience. It aims to solve the problems of low braking energy recovery efficiency and poor driving experience of existing electric forklifts and improve battery life.

[0079] It has the following technical effects. 1. The braking system of the electric forklift is jointly controlled by the travel motor 6 and the mechanical brake, which can provide more braking force at the same time and reduce the cost of using the mechanical brake. 2. The electric forklift can make a preliminary estimate of the maximum braking force threshold under non-emergency braking conditions before braking under different driving conditions, thereby improving the safety and driving experience under load conditions during braking. 3. When braking, the electric forklift can reasonably allocate the required braking force ratio weight according to the current vehicle status information and the motor braking conditions judged in advance, and make the maximum use of the motor braking to recover the braking energy while ensuring safety, thereby improving the endurance. 4. When braking, the electric forklift can monitor the vehicle braking status information sent by each auxiliary component during the braking process in real time based on the status detection unit, and optimize the braking required braking force based on the control signal obtained by the operator after the braking driving experience, thereby reducing the braking impact, making the braking smoother, and improving the driving experience.

[0080] Embodiment 2: The present invention provides a control method for a travel brake energy recovery system of an electric forklift, which includes steps S1 to S5.

[0081] S1. Obtain the status signals sent by each auxiliary component in real time through the CAN line, and determine whether each auxiliary component is currently in normal working condition; if a fault occurs, the fault information is directly displayed on the vehicle display;

[0082] S2. If there is no fault, after receiving the status information sent by the status detection unit, the current vehicle driving condition is identified. Based on different combinations of driving speed, load mass, and fork posture, the required braking force is preliminarily estimated according to the maximum braking intensity value in different braking intensity ranges. This is used as the maximum braking force threshold under non-emergency braking conditions. When in the low braking intensity or medium braking intensity range, under no-load conditions, the braking intensity is the actual value. Under loaded conditions, the braking intensity needs to be optimized based on the detected load mass, and the optimization coefficient k is inversely proportional to the load mass. When in emergency braking intensity, the braking intensity is the actual value.

[0083] S3, based on the fuzzy controller, the brake pedal opening change information and the vehicle speed at the initial stage of braking are used to identify the braking intensity, thereby determining whether emergency braking is required; wherein, , For braking strength, For speed, For time, is the gravity coefficient, Represents differential; definition For low braking strength, For the medium braking intensity range, is the emergency braking intensity;

[0084] S4. When emergency braking is not required, the energy storage recovery state judgment unit and the information of the battery and motor temperature judgment unit are used to make conditional judgments, thereby selecting the motor braking state; wherein, the energy storage recovery state judgment unit is used to judge the capacity of the battery SOC and set the energy recovery threshold according to the battery charge and discharge characteristics, so that the recoverable energy range is within the minimum recovery capacity. With maximum recycling capacity The battery and motor temperature judgment unit is used to monitor the temperature rise of the battery and the motor, and by setting the temperature threshold, the battery and the motor work in a preset working efficiency range; the motor force comparison judgment unit is used to compare the braking force estimation information sent by the braking control unit;

[0085] S5. Required braking force calculated The motor efficiency and battery efficiency in the braking phase are dynamically optimized by the particle swarm optimization algorithm to make the motor output the maximum braking torque while meeting the high efficiency requirement. The maximum braking force that the motor can currently provide By comparing and setting the threshold, the distribution mode is divided into two categories: motor braking and motor braking plus mechanical braking; if the required braking force Less than or equal to the maximum braking force that the motor can currently provide , then choose to rely on the motor for braking; if the required braking force Greater than the maximum braking force that the motor can currently provide , then select motor braking plus mechanical braking; through different braking modes to allocate the proportional weight of motor braking force and mechanical braking force, and send the braking force proportional weight control signal to the motor controller and mechanical brake to control the vehicle to brake according to the braking demand; Among them, For quality.

[0086] Embodiment 3. The present invention provides a computer-readable storage medium, which includes a stored computer program, wherein when the computer program is running, the device where the computer-readable storage medium is located is controlled to execute a control method for a travel brake energy recovery system of an electric forklift as described in Embodiment 2.

[0087] In the several embodiments provided in the embodiments of the present invention, it should be understood that the disclosed devices and methods can also be implemented in other ways. The device and method embodiments described above are merely illustrative. For example, the flowcharts and block diagrams in the accompanying drawings show the possible architectures, functions, and operations of the devices, methods, and computer program products according to multiple embodiments of the present invention. In this regard, each box in the flowchart or block diagram can represent a module, program segment, or part of the code, which contains one or more executable instructions for implementing the specified logical functions. It should also be noted that in some alternative implementations, the functions marked in the boxes can also occur in an order different from that marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flowchart, as well as the combination of boxes in the block diagram and / or flowchart, can be implemented using a dedicated hardware-based system that performs the specified functions or actions, or can be implemented using a combination of dedicated hardware and computer instructions.

[0088] In addition, the functional modules in the various embodiments of the present invention may be integrated together to form an independent part, or each module may exist independently, or two or more modules may be integrated to form an independent part.

[0089] If the functions are implemented in the form of software modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the portion that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, electronic device, or network device, etc.) to perform all or part of the steps of the methods described in various embodiments of the present invention. The aforementioned storage media include various media that can store program code, such as USB flash drives, mobile hard drives, read-only memories (ROMs), random access memories (RAMs), magnetic disks, or optical disks. It should be noted that, in this document, the terms "comprise," "include," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or device that includes a series of elements includes not only those elements but also other elements not explicitly listed, or also includes elements inherent to such process, method, article, or device. Without further constraints, an element defined by the phrase "comprises a..." does not preclude the existence of additional identical elements in the process, method, article or apparatus that includes the element.

[0090] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The singular forms "a", "an", "the" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise.

[0091] It should be understood that the term "and / or" as used herein is merely a description of the relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, or B exists alone. Furthermore, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0092] The word "if," as used herein, may be interpreted as "at the time of" or "when" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrases "if it is determined" or "if (stated condition or event) is detected" may be interpreted as "when it is determined" or "in response to the determination" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)," depending on the context.

[0093] The references to "first" and "second" in the embodiments merely distinguish similar objects and do not represent a specific ordering of the objects. It is understood that the specific order or precedence of "first" and "second" can be interchanged where appropriate. It should be understood that the objects distinguished by "first" and "second" can be interchanged where appropriate, so that the embodiments described herein can be implemented in an order other than that illustrated or described herein.

[0094] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A travel braking energy recovery system for an electric forklift, characterized in that: include: Machine controller, low-voltage system, high-voltage system, drive system, and brake system; The signal output terminal of the whole machine controller is electrically connected to the signal input terminals of the low-voltage system, the high-voltage system, the drive system, and the brake system through a CAN line; The high-voltage power output terminal of the high-voltage system is electrically connected to the drive system, the brake system, and the power input terminal of the low-voltage system; The low-voltage electrical output end of the low-voltage system is electrically connected to the low-voltage electrical input ends of the whole machine controller and various auxiliary components of the vehicle; The signal output terminals of the auxiliary components of the electric forklift are electrically connected to the signal input terminals of the whole machine controller via CAN lines; The whole machine controller is configured to calculate the required braking force in real time based on the current vehicle state information before the electric forklift receives the braking signal; when the electric forklift receives the braking signal, the braking force is distributed to the braking force required for the whole vehicle, and the operation of the travel motor and mechanical brake of the braking system is controlled; The whole machine controller is provided with a state detection unit, a brake control unit and a brake force distribution unit; Each auxiliary component of the electric forklift sends detection signals to the information receiving end of the whole machine controller, and receives control commands from the sending end of the whole machine controller. Among them, the status signals sent by each auxiliary component and the driving signals obtained based on the status signals form the whole vehicle information; The vehicle information includes the working status information of each auxiliary component during the operation of the electric forklift, load information, electric forklift actuator posture information, current vehicle speed information, current acceleration information, slope information, pedal opening change information, first judgment information of the emergency braking judgment unit, and second judgment information of the motor braking and power generation judgment unit; The state detection unit is adapted to determine whether each auxiliary component is currently in normal working condition based on the state signals received from each auxiliary component sent in real time via the CAN line; if a fault occurs, the fault information is directly displayed on the vehicle display screen; if there is no fault, part of the state information is divided into two paths through information processing and sent to the brake control unit and the brake force distribution unit for sorting, calculation and judgment respectively; The braking control unit is used to calculate the real-time required braking force information and the real-time motor braking power generation state information and send them to the braking force distribution unit; the braking control unit includes a braking force estimation unit, a unit for determining whether emergency braking is required, a unit for determining whether the motor braking power generation state is available, and a braking force calculation unit; The braking force estimation unit is used to identify the current driving condition of the vehicle after receiving the status information sent by the status detection unit, and preliminarily calculate the required braking force according to the maximum braking intensity value in different braking intensity ranges based on different combinations of driving speed, load mass and fork posture, and use this as the maximum braking force threshold under non-emergency braking conditions; when in the low braking intensity or medium braking intensity range, under no-load conditions, the braking intensity is the actual value; under loaded conditions, the braking intensity needs to be optimized according to the detected load mass, and the optimization coefficient k is inversely proportional to the load mass; when in emergency braking intensity, the braking intensity is the actual value; The emergency braking determination unit is used to identify the braking intensity based on the brake pedal opening change information and the vehicle speed in the initial braking stage according to the fuzzy controller, so as to determine whether emergency braking is required; The required braking force calculated by the braking force calculation unit and the motor efficiency and battery efficiency detected by the state detection unit in the braking phase are dynamically optimized by the particle swarm optimization algorithm to enable the motor to output the maximum braking torque under the premise of meeting high efficiency; the required braking force is converted into The maximum braking force that the motor can currently provide By comparing and setting the threshold, the distribution mode is divided into two categories: motor braking and motor braking plus mechanical braking; if the required braking force Less than or equal to the maximum braking force that the motor can currently provide , then choose to rely on the motor for braking; if the required braking force Greater than the maximum braking force that the motor can currently provide , then select motor braking plus mechanical braking; through different braking modes, the proportional weight of motor braking force and mechanical braking force is allocated, and the braking force proportional weight control signal is sent to the motor controller and mechanical brake to control the vehicle to brake according to the braking demand; The whole machine controller also includes a brake stability closed-loop control. When distributing braking force, the whole machine controller monitors the vehicle's braking state information sent by various auxiliary components during the braking process in real time based on the state detection unit. Combined with the operator's control signal after the braking driving experience, the state detection unit monitors and transmits the operator's adjusted braking demand in real time, and optimizes the braking demand force through the sliding membrane controller to reduce braking shock and achieve smoother braking. The braking force distribution unit is used to distribute the proportional weights of the electric braking force and the mechanical braking force based on the data calculated by the braking force calculation unit, through conditional judgment and sorting calculation, and send a braking force proportional weight control signal to the motor controller and the mechanical brake to control the vehicle to brake according to the braking demand; in, Where, For braking strength, For speed, For time, is the gravity coefficient, Represents differential; definition For low braking strength, For the medium braking intensity range, is the emergency braking intensity; in, Where, Braking force for demand, For quality.

2. The electric forklift travel brake energy recovery system according to claim 1, characterized in that: The electrical system of the travel brake energy recovery system includes: a power battery, a battery management system, a high-voltage management unit, a motor controller, a DC / DC converter, a travel motor, a mechanical brake, a whole machine controller, other auxiliary components, a brake pedal, and a low-voltage battery; The high-voltage power output terminal of the power battery is electrically connected to the high-voltage power input terminal of the battery management system; the high-voltage power output terminal of the battery management system is electrically connected to the high-voltage power input terminal of the high-voltage management unit; the high-voltage power output terminal of the high-voltage management unit is divided into two paths, which are electrically connected to the DC / DC converter and the high-voltage power input terminal of the motor controller respectively; the high-voltage power output terminal of the motor controller is electrically connected to the high-voltage power input terminal of the travel motor, and the motor controller converts the high-voltage direct current into three-phase high-voltage alternating current; The DC / DC converter is suitable for converting high-voltage direct current into low-voltage direct current for powering the low-voltage system; the low-voltage power output end of the DC / DC converter is divided into four paths, which are respectively electrically connected to the whole machine controller, the other auxiliary components, the brake pedal, and the low-voltage power input end of the low-voltage battery; The low-voltage electrical output end of the low-voltage battery is divided into three paths, which are electrically connected to the low-voltage electrical input ends of the whole machine controller, the brake pedal, and the other auxiliary components respectively; the low-voltage battery is suitable for powering other auxiliary components when the whole vehicle is powered on.

3. The travel braking energy recovery system of an electric forklift according to claim 2, characterized in that: The drive system includes the motor controller and the travel motor; the braking system includes the travel motor and a mechanical brake; wherein the travel motor is used for both driving when moving forward and braking when braking, and therefore belongs to both the drive system and the braking system as two virtual systems; when braking is performed by the travel motor, the travel motor will generate back electromotive force, thereby generating a braking current.

4. The travel braking energy recovery system of an electric forklift according to claim 2, characterized in that: The signal receiving end of the whole machine controller is electrically connected to the signal output end of each auxiliary component respectively; the control signal sending end of the whole machine controller is electrically connected to the control signal receiving end of each auxiliary component respectively; The signal terminal of the battery management system is electrically connected to the signal terminal of the high-voltage management unit through a CAN line.

5. A control method for a travel brake energy recovery system of an electric forklift, configured to be executed by the travel brake energy recovery system of an electric forklift according to any one of claims 1 to 4, characterized in that: Include: Obtain the status signals sent by each auxiliary component in real time through the CAN line, and determine whether each auxiliary component is currently in normal working condition; if a fault occurs, the fault information will be directly displayed on the vehicle display screen; If there is no fault, after receiving the status information sent by the status detection unit, the current driving condition of the vehicle is identified. According to the different combinations of driving speed, load mass and fork posture, the required braking force is preliminarily calculated based on the maximum braking intensity value in different braking intensity ranges, and this is used as the maximum braking force threshold under non-emergency braking conditions; when in the low braking intensity or medium braking intensity range, under no-load conditions, the braking intensity is the actual value; under loaded conditions, the braking intensity needs to be optimized according to the detected load mass, and the optimization coefficient k is inversely proportional to the load mass; when in emergency braking intensity, the braking intensity is the actual value; The fuzzy controller identifies the braking intensity based on the brake pedal opening change information and the vehicle speed at the initial stage of braking to determine whether emergency braking is required; , For braking strength, For speed, For time, is the gravity coefficient, Represents differential; definition For low braking strength, For the medium braking intensity range, is the emergency braking intensity; When emergency braking is not required, the condition is judged according to the information of the energy storage recovery state judgment unit and the battery and motor temperature judgment unit, so as to select the motor braking state; wherein, the energy storage recovery state judgment unit is used to judge the capacity of the battery SOC and set the energy recovery threshold according to the battery charge and discharge characteristics, so that the recoverable energy range is within the minimum recovery capacity. With maximum recycling capacity The battery and motor temperature judgment unit is used to monitor the temperature rise of the battery and the motor, and by setting the temperature threshold, the battery and the motor work in a preset working efficiency range; the motor force comparison judgment unit is used to compare the braking force estimation information sent by the braking control unit; According to the calculated required braking force The motor efficiency and battery efficiency in the braking phase are dynamically optimized by the particle swarm optimization algorithm to make the motor output the maximum braking torque while meeting the high efficiency requirement. The maximum braking force that the motor can currently provide By comparing and setting the threshold, the distribution mode is divided into two categories: motor braking and motor braking plus mechanical braking; if the required braking force Less than or equal to the maximum braking force that the motor can currently provide , then choose to rely on the motor for braking; if the required braking force Greater than the maximum braking force that the motor can currently provide , then select motor braking plus mechanical braking; through different braking modes to allocate the proportional weight of motor braking force and mechanical braking force, and send the braking force proportional weight control signal to the motor controller and mechanical brake to control the vehicle to brake according to the braking demand; Among them, For quality.

6. A computer-readable storage medium, characterized in that The computer-readable storage medium includes a stored computer program, wherein when the computer program is executed, the device where the computer-readable storage medium is located is controlled to execute the control method of the travel brake energy recovery system of the electric forklift according to claim 5.

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