Walking braking energy recovery system of electric forklift, control method of walking braking energy recovery system and medium

Abstract

The invention discloses a walking braking energy recovery system of an electric forklift and a control method and a medium thereof, and relates to the technical field of electric forklifts. The signal output end of the whole machine controller is electrically connected to the signal input ends of the low-voltage system, the high-voltage system, the driving system and the braking system through CAN lines. The high-voltage 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. The low-voltage output end of the low-voltage system is electrically connected with the whole machine controller and the low-voltage input end of each auxiliary component of the vehicle. The signal output end of each auxiliary component of the electric forklift is electrically connected with the signal input end of the whole machine controller through a CAN line. And the controller is configured to calculate the required braking force in real time based on the current whole vehicle state information before the electric forklift receives the braking signal. When the electric forklift receives the braking signal, braking force needed by braking of the whole forklift is distributed, and a walking motor and a mechanical brake of the braking system are controlled to act.

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 and a control method and medium thereof. Background Art

[0002] In the wide application of electric forklifts, the performance of the brake energy recovery system is of great significance for improving vehicle endurance and reducing operating costs. At present, the brake energy recovery efficiency of most electric forklifts is low, and the energy generated during braking cannot be fully utilized for reuse, resulting in a large amount of energy being wasted during braking, affecting the vehicle's endurance energy efficiency performance. In addition, the existing system is relatively rough in the distribution and management of braking force, and cannot accurately distribute braking force according to different working conditions and vehicle status. This not only limits the efficiency of energy recovery, but may also affect the braking performance and safety of the vehicle.

[0003] The shortcomings of the brake energy recovery system of electric forklifts are particularly obvious under conditions of frequent braking. Due to the lack of an effective energy recovery mechanism, the vehicle cannot effectively convert kinetic energy into electrical energy and store it in the battery during braking, thus failing to provide additional power support for subsequent driving. This problem of low energy recovery efficiency greatly limits the range of electric forklifts under conditions of frequent braking, increasing the charging frequency and operating costs of the vehicle.

[0004] At the same time, there is still much room for improvement in the driving experience of the existing system during braking. Due to the inaccurate assessment of the 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 of an electric forklift and a control method and medium thereof, aiming to solve the problem of low brake energy recovery efficiency of the existing electric forklift and improve the driving range.

[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 brake 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 electrical 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 state 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.

[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 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.

[0014] 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.

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

[0016] Preferably, the drive system includes the motor controller and the travel motor. The braking system includes the travel motor and a mechanical brake. 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, which are two virtual systems. When braking is performed by the travel motor, the travel motor generates a back electromotive force, and then 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 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.

[0018] The signal end of the battery management system is electrically connected to the signal end 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 the electric forklift sends a detection signal to the information receiving end of the whole machine controller, and receives a control command from the sending end of the whole machine controller. Among them, the status signal sent by each auxiliary component and the driving signal obtained by sorting out the status signal 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 state detection unit is suitable for judging whether each auxiliary component is in a normal working state according to the state signal received from each auxiliary component in real time through the CAN line. If a fault occurs, the fault information is directly presented 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.

[0023] 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.

[0024] The braking force estimation unit is used to identify the current vehicle driving condition 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 according to 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.

[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 stage of braking, so as to determine whether emergency braking is required. , For braking strength, For speed, For time, is the gravity coefficient, Denotes a 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 used to dynamically optimize the braking force output by the motor through a particle swarm optimization algorithm, 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 comparison and setting a 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 brake only by the motor. 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 the mechanical brake to control the vehicle to brake according to the braking demand. Among them, For quality.

[0027] Preferably, the braking force distribution unit is used to distribute the proportional weight 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 sends the braking force proportional weight control signal to the motor controller and the mechanical brake to control the whole vehicle to brake according to the braking demand.

[0028] Preferably, the whole machine controller also includes a braking stability closed-loop control. When distributing the braking force, the whole machine controller monitors the vehicle braking state information sent by each auxiliary component in the braking process in real time based on the state detection unit, and combines the control signal after the operator's braking driving experience. The state detection unit monitors and transmits the braking demand adjusted by the operator in real time, and optimizes the braking demand braking force through the sliding membrane controller to reduce the braking impact and make the braking more stable.

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

[0030] 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.

[0031] S2. If there is no fault, after receiving the status information sent by the status detection unit, the current driving condition of the whole vehicle is identified, and the required braking force is preliminarily calculated according to the maximum braking intensity value in different braking intensity ranges according to the different combinations of driving speed, load mass and fork posture, 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, the braking intensity is the actual value under no-load conditions. 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.

[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, so as to determine whether emergency braking is required. , For braking strength, For speed, For time, is the gravity coefficient, Denotes a 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 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 battery SOC capacity and set the energy recovery threshold according to the battery charge and discharge characteristics, so that the recoverable energy interval 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.

[0034] S5. Required braking force calculated The motor efficiency and battery efficiency during the braking phase are calculated and the braking force output by the motor is dynamically optimized through the particle swarm optimization algorithm, so that the motor can output the maximum braking torque while meeting the high efficiency requirement. The maximum braking force that the motor can currently provide By comparison and setting a 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 brake only by the motor. 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 the mechanical brake to control the vehicle to brake according to the braking demand. Among them, For quality.

[0035] In a third aspect, the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium 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 braking energy recovery system of an electric forklift.

[0036] By adopting the above technical solution, the present invention can achieve the following technical effects: The travel brake energy recovery system of the electric forklift of the present invention achieves significant performance improvement and economic benefits through innovative design and optimized control strategy. The system can monitor and analyze the status of the entire vehicle in real time under different driving conditions, so as to accurately estimate and reasonably distribute the 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 the optimized control algorithm, the response speed and stability of the brake are improved, providing the operator with a smoother and more comfortable driving experience.

[0037] The system also combines the vehicle's braking status information with the operator's control signal after the braking driving experience through a closed-loop control mechanism, realizing intelligent adjustment of the required braking force during the braking process. This design makes braking smoother, further improves the driving experience, and reduces the operator's labor intensity. Through reasonable braking force distribution and efficient energy recovery, the system not only improves the energy efficiency of electric forklifts, but also provides strong support for the sustainable development of electric forklifts, with significant economic and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces 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 related drawings can be obtained based on these drawings without paying creative work.

[0039] Figure 1 This is a schematic diagram of the electric forklift's travel brake energy recovery system.

[0040] Figure 2 This is a schematic diagram of the travel brake system of an electric forklift.

[0041] Figure 3 It is a signal transmission flow chart of the electric forklift's travel brake energy recovery system.

[0042] 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

[0043] The technical solutions in the embodiments of the present invention will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] 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 brake system.

[0045] 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 a vehicle display screen, an accelerator pedal, and a brake pedal. Each auxiliary component also includes various detection sensors installed in existing electric forklifts. For example, a temperature sensor, a level sensor, a speed sensor, and an acceleration sensor of a motor.

[0046] Preferably, the whole machine controller 8 is configured to estimate the maximum braking force threshold under different combinations of non-emergency braking conditions 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 required for the whole vehicle is calculated and distributed, and the travel motor 6 and the mechanical brake of the braking system are controlled to operate.

[0047] Based on the above embodiments, 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. Among them, the low-voltage battery 11 is a 24V battery.

[0048] 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 power output terminal of the power battery 1 is electrically connected to the high-voltage power input terminal of the battery management system 2. The high-voltage power output terminal of the battery management system 2 is electrically connected to the high-voltage power input terminal of the high-voltage management unit 3. The high-voltage power 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 power input terminal of the motor controller 4 respectively. The high-voltage power output terminal of the motor controller 4 is electrically connected to the high-voltage power 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.

[0049] The DC / DC converter 5 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 5 is divided into four paths, which are electrically connected to the low-voltage power input end of the whole machine controller 8, the other auxiliary components 9, the brake pedal 10, and the low-voltage battery 11 respectively.

[0050] The electrical connection relationship of the power supply circuit of the low-voltage battery 11 is as follows Figure 1 The low-voltage electrical output end of the low-voltage battery 11 is divided into three paths, which are respectively electrically connected to the whole machine controller 8, the brake pedal 10, and the low-voltage electrical input ends of the other auxiliary components 9. The low-voltage battery 11 is suitable for supplying power to other auxiliary components 9 when the whole vehicle is powered on.

[0051] like Figure 1 As shown, the driving system includes the motor controller 4 and the travel motor 6. The braking system includes the travel motor 6 and a mechanical brake. The travel motor 6 is used for both driving when moving forward and braking when braking, and therefore belongs to both the driving system and the braking system, which are two virtual systems. Specifically, when braking is performed by the travel motor 6, the travel motor 6 generates a back electromotive force, and then generates a braking current.

[0052] 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 through the CAN line.

[0053] Based on the above embodiments, 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.

[0054] 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. The status signal sent by each auxiliary component is analyzed to form the whole vehicle information.

[0055] 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.

[0056] The state detection unit is suitable for judging whether each auxiliary component is in a normal working state according to the state signal received from each auxiliary component in real time through the CAN line. If a fault occurs, the fault information is directly presented 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.

[0057] 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.

[0058] The braking force estimation unit is used to identify the current vehicle driving condition after receiving the status information sent by the status detection unit, and make a preliminary estimate of the required braking force according to the maximum braking intensity value in different braking intensity ranges according to 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, the braking intensity is the actual value under no-load conditions; 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.

[0059] 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; 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 interval 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.

[0060] The braking force distribution unit is used to calculate the required braking force calculated by the braking force calculation unit according to the received braking force. 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 for 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.

[0061] The required braking force The maximum braking force that the motor can currently provide By comparison, a threshold is set to divide the distribution mode 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 brake only by the motor; 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 4 and the mechanical brake to control the whole vehicle to brake according to the braking demand, so as to maximize the use of motor braking for reverse power generation to recover more energy and improve the endurance.

[0062] Specifically, when hybrid braking is required, the real-time required braking force is decoupled, and according to different braking conditions, the appropriate braking mode is selected and the operating signal is sent through the CAN line to control the actuator. Preferably, during emergency braking, the braking force ratio weight is adjusted so that the required braking force of the entire vehicle is output by mechanical braking. During hybrid braking, the total braking force requirement is calculated first, and then the braking force output by the motor is dynamically optimized, and the remaining braking force requirements are provided by mechanical braking.

[0063] Based on the above embodiments, in an optional embodiment of the present invention, as Figure 3 As shown, the whole machine controller 8 also includes a braking stability unit.

[0064] When the whole machine controller 8 distributes the braking force and acts on the braking system, the state detection unit monitors the braking feedback signals such as the braking impact degree in real time and transmits the braking demand adjusted by the operator to make the braking smoother. Thereby improving the driving experience. Specifically, the braking force distribution unit controls the travel motor 6 and the mechanical brake in the braking system. When braking according to different braking states, the above-mentioned state detection unit monitors the whole vehicle braking state information sent by each auxiliary component during the braking process in real time, and combines the control signal obtained by the operator after the braking driving experience, and optimizes the braking demand braking force through the designed sliding membrane controller, thereby reducing the braking impact degree, making the braking smoother and improving the driving experience.

[0065] The electric forklift of the present invention is described in detail below.

[0066] During the normal driving of the electric forklift, the state detection unit in the whole machine controller 8 receives the state information sent by each auxiliary component in real time. First, it is determined whether each auxiliary component is in a normal working state. If a fault occurs, the fault information is directly presented on the whole 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.

[0067] The braking force estimation unit in the brake control unit estimates the maximum braking force threshold under non-emergency braking conditions based on the received status information, and sends it to the motor braking and power generation state judgment unit. The motor braking and power generation state judgment unit combines the received status information to determine whether the current vehicle state is in the motor braking and power generation state. Prepare for receiving the brake signal later.

[0068] 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.

[0069] If emergency braking is required, the braking force calculation unit calculates the currently required braking force, and then sends the currently required braking force signal to the braking force distribution unit. The braking force distribution unit allocates all braking force distribution weights to the mechanical brake.

[0070] If emergency braking is not required, the braking demand signal is further transmitted to the motor braking and power generation state judgment unit. The motor braking and power generation state judgment unit transmits the braking demand information to the braking force calculation unit to accurately calculate the currently required braking force based on the judgment made during normal driving, and optimizes the currently required braking force based on the braking impact feedback from the braking stability unit.

[0071] If the motor braking and power generation are not possible at present, the currently required braking force signal is sent to the braking force distribution unit, and the braking force distribution unit distributes all the braking force distribution weights to the mechanical brake.

[0072] If the motor is currently in a state where it can generate electricity through braking, the currently 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 comparison, a threshold is set to divide the distribution mode 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 brake only by the motor; 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.

[0073] If the braking mode is selected to rely only on motor braking, the braking force distribution weight is entirely allocated to motor braking.

[0074] If the braking mode is selected as 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.

[0075] Finally, the above-mentioned state detection unit monitors the vehicle braking state information sent by various auxiliary components during the braking process in real time, and combines the control signal 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.

[0076] A travel brake energy recovery system for an electric forklift in an embodiment of the present invention sends status signals to a whole machine controller 8 through various auxiliary components. The whole machine controller 8 sends control signals to various actuators 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, and optimizes the braking demand braking force through the designed sliding membrane controller in combination with the control signal obtained after the braking driving experience obtained by the operator, thereby reducing the braking impact degree, making the braking smoother and improving the driving experience. The purpose is to solve the problems of low braking energy recovery efficiency and poor driving experience of existing electric forklifts and improve the endurance.

[0077] 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 maximize the use of motor braking to recover braking energy while ensuring safety, thereby improving endurance. 4. When braking, the electric forklift can monitor the vehicle braking status information sent by various auxiliary components during the braking process in real time based on the status detection unit, and optimize the braking demand 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.

[0078] Embodiment 2: The present invention provides a control method for a travel brake energy recovery system of an electric forklift, which comprises steps S1 to S5.

[0079] 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 a normal working state; if a fault occurs, the fault information is directly displayed on the vehicle display screen; S2. If there is no fault, after receiving the status information sent by the status detection unit, the current vehicle driving condition is identified, and the required braking force is preliminarily estimated according to the maximum braking intensity value in different braking intensity ranges according to different combinations of driving speed, load mass and fork posture, 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; S3, based on the fuzzy controller, the brake pedal opening change information and the vehicle speed in the initial stage of braking are used to identify the braking intensity, so as to determine 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; S4. When emergency braking is not required, conditional judgment is performed based on 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 value according to the battery charge and discharge characteristics, so that the recoverable energy interval 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 estimate the braking force sent by the braking control unit; S5. Required braking force calculated The motor efficiency and battery efficiency in the braking phase are dynamically optimized through the particle swarm optimization algorithm, so that the motor can output the maximum braking torque under the premise of high efficiency. The maximum braking force that the motor can currently provide By comparison, a threshold is set to divide the distribution mode 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 brake only by the motor; 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 the mechanical brake to control the vehicle to brake according to the braking demand; wherein, For quality.

[0080] Embodiment 3: The present invention provides a computer-readable storage medium, wherein the computer-readable storage medium 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 braking energy recovery system of an electric forklift as described in Embodiment 2.

[0081] In several embodiments provided in the embodiments of the present invention, it should be understood that the disclosed apparatus and method can also be implemented in other ways. The apparatus and method embodiments described above are merely schematic. For example, the flowcharts and block diagrams in the accompanying drawings show the possible architecture, functions and operations of the apparatus, method and computer program product according to multiple embodiments of the present invention. In this regard, each box in the flowchart or block diagram can represent a module, a program segment or a part of a code, and the module, program segment or a part of the code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in a different order from the order 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, and the combination of boxes in the block diagram and / or flowchart can be implemented with a dedicated hardware-based system that performs a specified function or action, or can be implemented with a combination of dedicated hardware and computer instructions.

[0082] 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.

[0083] If the function is implemented in the form of a software function module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art or the part of the technical solution can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions to enable a computer device (which can be a personal computer, an electronic device, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program code. It should be noted that in this article, the term "include", "include" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements includes not only those elements, but also includes other elements that are not explicitly listed, or also includes elements inherent to such process, method, article or device. Without more constraints, an element defined by the phrase "comprising a..." does not exclude the existence of other identical elements in the process, method, article or apparatus comprising the element.

[0084] 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", "said" 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 other meanings.

[0085] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0086] 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 determining" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)", depending on the context.

[0087] The "first\second" mentioned in the embodiments is only to distinguish similar objects, and does not represent a specific order for the objects. It is understandable that the "first\second" can be interchanged with the specific order or sequence where permitted. It should be understood that the objects distinguished by "first\second" can be interchanged where appropriate, so that the embodiments described herein can be implemented in an order other than those illustrated or described herein.

[0088] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A travel braking energy recovery system for an electric forklift, characterized in that: include: The whole 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 terminal 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 driving system, the braking 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 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 a CAN line; 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 the braking signal; when the electric forklift receives the braking signal, the braking force required for braking the whole vehicle is distributed, and the travel motor and mechanical brake of the braking system are controlled.

2. The travel braking energy recovery system of an electric forklift 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 other auxiliary components respectively; the low-voltage battery is suitable for supplying power to 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 driving 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 driving system and the braking system, which are two virtual systems; when braking is performed by the travel motor, the travel motor will generate back electromotive force, and then generate 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 end of the battery management system is electrically connected to the signal end of the high voltage management unit through a CAN line.

5. The travel braking energy recovery system of an electric forklift according to claim 1, characterized in that: 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 a detection signal to the information receiving end of the whole machine controller, and receives a control command from the sending end of the whole machine controller; wherein the state signal sent by each auxiliary component and the driving signal obtained by sorting out the state signal 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.

6. The travel braking energy recovery system of an electric forklift according to claim 5, characterized in that: The state detection unit is suitable for judging whether each auxiliary component is in a normal working state according to the state signal received from each auxiliary component in real time through 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 status 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; 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 judging whether emergency braking is required, a unit for judging 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 vehicle driving condition 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 intervals according to different combined conditions 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 interval, under the no-load condition, the braking intensity is the actual value; under the loaded condition, 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 the 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 fuzzy controller based on the brake pedal opening change information and the vehicle speed in the initial stage of braking, so as to determine 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; The required braking force calculated by the braking force calculation unit The motor efficiency and battery efficiency in the braking phase detected by the state detection unit are dynamically optimized by a 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 required braking force The maximum braking force that the motor can currently provide By comparison, a threshold is set to divide the distribution mode 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 brake only by the motor; 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 the mechanical brake to control the vehicle to brake according to the braking demand; wherein, For quality.

7. The travel braking energy recovery system of an electric forklift according to claim 6, characterized in that: The braking force distribution unit is used to distribute the proportional weight 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 whole vehicle to brake according to the braking demand.

8. The travel braking energy recovery system of an electric forklift according to claim 1, characterized in that: The whole machine controller also includes a braking stability closed-loop control; when distributing braking force, the whole machine controller monitors the vehicle braking state information sent by various auxiliary components during the braking process in real time based on the state detection unit, and combines the control signal obtained by the operator after the braking driving experience. The state detection unit monitors and transmits the braking demand adjusted by the operator in real time, and optimizes the braking demand braking force through the sliding membrane controller to reduce the braking impact and make the braking smoother.

9. A control method for a travel braking energy recovery system of an electric forklift, 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 whole vehicle is identified, and the required braking force is preliminarily calculated according to the maximum braking intensity value in different braking intensity ranges according to different combinations of driving speed, load mass and fork posture, 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 charging and discharging characteristics, so that the recoverable energy interval 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 estimate the braking force sent by the braking control unit; The required braking force calculated The motor efficiency and battery efficiency in the braking phase are dynamically optimized through the particle swarm optimization algorithm, so that the motor can output the maximum braking torque under the premise of high efficiency. The maximum braking force that the motor can currently provide By comparison, a threshold is set to divide the distribution mode 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 brake only by the motor; 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 the mechanical brake to control the vehicle to brake according to the braking demand; wherein, For quality.

10. 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 braking energy recovery system of the electric forklift according to claim 9.

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