An electrically driven construction vehicle energy management system and control method

Abstract

The application provides an electric transmission type engineering vehicle energy management system, which comprises a power balance module, a generator set control module and a drive control module.The power balance module resolves the output electric power of the generator by using a fixed electric quantity power following control strategy according to the current state of a battery pack and power demand information of the drive control module.The generator set control module performs real-time hydraulic system power estimation, limits the output electric power of the generator if the power provided by a prime mover reaches an upper limit, and performs speed control on the prime mover and torque control on the generator.The drive control module determines drive motor running control and receives the electric power for charging and discharging sent by the power balance module through a CAN bus as the power limit of the drive motor.The application limits the output power of the generator by performing real-time hydraulic system power estimation, thereby avoiding speed drop or flameout of the prime mover caused by excessive load.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of vehicle energy control, in particular to an electric drive type engineering vehicle energy management system. The present application also relates to an electric drive type engineering vehicle energy management control method. BACKGROUND

[0002] For medium and high power level engineering vehicles, a dual energy source technical solution with hydrogen fuel cell, methanol engine or diesel engine as the main energy source and battery pack as the auxiliary energy source is favored. Compared with electric vehicles, the electric drive engineering vehicle of this solution has a working condition in which the transmission system and the hydraulic system work at the same time. If the total power requested by the generator and the hydraulic system reaches the upper limit of the power provided by the prime mover, the prime mover is prone to speed drop or flameout due to excessive load.

[0003] Due to the high price of batteries, each host factory seeks to match a small capacity battery, and meets the use demand by continuously optimizing the power balance control strategy. The control of the prime mover is mostly obtained by the best fuel economy curve calculation method or the multi-point speed switching control of the prime mover according to the power load matching interval. However, as a large inertia and large delay prime mover system, the prime mover cannot completely follow the dynamically changing speed demand. At the same time, due to the large instantaneous change of the working load of the engineering vehicle, the speed of the prime mover is frequently switched, which is more detrimental to the energy saving of the whole machine. SUMMARY

[0004] The purpose of the present application is to overcome the defects in the prior art and provide an electric drive type engineering vehicle energy management system. The present application also relates to an electric drive type engineering vehicle energy management control method.

[0005] The present application provides an electric drive type engineering vehicle energy management system, comprising: a power balance module, a generator set control module and a drive control module.

[0006] The power balance module is used to analyze the output electric power of the generator by adopting a fixed electric quantity power following control strategy according to the current state of the battery pack and the power demand information of the drive control module.

[0007] The generator set control module is used to perform real-time hydraulic system power estimation. If the power provided by the prime mover reaches the upper limit, the output electric power of the generator is limited, and the speed of the prime mover is controlled, and the torque of the generator is controlled.

[0008] The drive control module is used to determine the drive motor running control, and receives the electric power using charging and discharging sent by the power balance module through the CAN bus as the power limit of the drive motor.

[0009] Optionally, the analyzing the generator output power comprises:

[0010] The power generation mode after the vehicle is started up and parked: the expected output power is the maximum continuous charging power allowed by the battery pack.

[0011] Optionally, the analyzing the generator output power further comprises:

[0012] The fixed power following control strategy mode: when the current battery power is greater than the first preset value of the battery power, and the demand power is greater than the minimum demand power, the first preset value of the battery power is reduced to the minimum set value, and the expected output power is obtained according to the fixed power following control strategy.

[0013] Optionally, the analyzing the generator output power further comprises:

[0014] The forced discharge mode: when the current battery power is greater than the preset maximum value of the battery, and the demand power is less than the maximum continuous discharging power allowed by the battery pack, the expected output power is zero.

[0015] Optionally, the fixed power following control strategy mode comprises:

[0016] The fuzzy controller is adopted, the current battery power and the demand power are taken as the inputs of the fuzzy controller, the charging and discharging coefficient of the battery pack is taken as the output of the controller, the charging and discharging coefficient ∈[-1,1];

[0017] The battery power is limited in a preset range;

[0018] When the battery power reaches the minimum value of the preset range, and the demand power reaches the minimum demand threshold, the charging and discharging coefficient is controlled to be-1 and the battery pack is charged at the maximum capacity; when the battery power reaches the maximum value of the preset range, and the demand power reaches the maximum demand threshold, the charging and discharging coefficient is controlled to be 1, and the battery pack is discharged at the maximum capacity; when the battery power reaches the preset range, and the demand power reaches the demand intermediate threshold, the charging and discharging coefficient is controlled to be 0.

[0019] The expression of the generator output power is as follows:

[0020]

[0021]

[0022]

[0023] wherein, is the generator output power; is the demand power; is the expected power. desired current for the battery pack; current bus voltage; battery pack charge-discharge coefficient; C is the battery pack charge-discharge rate; rated capacity.

[0024] The electric power output of the generator 6, the electric drive engineering vehicle energy management system according to claim 1, characterized in that the generator set control module control strategy comprises:

[0025] Collecting the generator DC bus voltage and current signals, the actual speed signal of the prime mover, the utilization torque percentage of the prime mover and the hydraulic system pressure signal;

[0026] When the prime mover energy first flows through the hydraulic system and then reaches the generator, if the hydraulic system does not work, the desired electric power is the final generator set control electric power; if the hydraulic system works, real-time hydraulic system power estimation is performed, and if the sum of the power requested by the generator and the hydraulic system reaches the upper limit of the power provided by the prime mover, the generator output power is limited;

[0027] According to the power provided by the prime mover minus the hydraulic system estimated power and multiplied by the generator system efficiency, the utilization electric power of the generator is obtained, and the smaller value between the utilization electric power and the desired electric power is taken as the final generator set control electric power.

[0028] Optionally, the power provided by the prime mover is obtained through the utilization torque percentage of the prime mover, the maximum reference torque and the actual speed; the hydraulic system estimated power is obtained by estimating the hydraulic equivalent estimated torque according to the hydraulic system pressure signal, combined with the actual speed of the prime mover.

[0029] Optionally, when the low temperature or the energy management system component fails, the drive control module utilizes the discharge electric power obtained by the sum of the current electric power of the generator and the peak discharge power allowed by the battery pack, the current electric power of the generator is obtained through the generator DC bus voltage and current; the drive control module utilizes the charging electric power as the peak charging electric power allowed by the battery pack.

[0030] Optionally, according to the generator set control electric power The different power intervals, the preset hysteresis band power, the allowable reduced speed flag, the hydraulic system pressure signal, the thumb wheel speed regulation and the FNR direction signal determine the working mode and speed instruction of the prime mover, and the speed control of the prime mover is adopted, and the speed reduction switching control strategy is as follows:

[0031] Idle speed working mode, the energy management controller adjusts the prime mover to the first preset speed;

[0032] The controller obtains the second preset speed of the prime mover according to a preset characteristic data table to realize dynamic adjustment of the output flow of the hydraulic system in the parking mode, wherein the characteristic data table is a one-dimensional data table of the thumb wheel speed regulation and the speed of the prime mover.

[0033] The energy management controller adjusts the prime mover to the third preset speed in the non-parking hydraulic system mode.

[0034] In the non-parking hydraulic system mode, the prime mover operates at a constant speed in each power interval according to the different power intervals of the generator set control electric power, and the speeds of the prime mover corresponding to n power intervals are the fourth preset speed to the (n+3)th preset speed. The speed switching condition is that the initial speed is the fourth preset speed, when the actual power is greater than the first preset power, the speed of the prime mover is increased from the fourth preset speed to the fifth preset speed; when the actual power is less than the first preset power minus the preset hysteresis power, the speed of the prime mover is decreased from the fifth preset speed to the fourth preset speed, otherwise, the prime mover continues to operate at the fifth preset speed; when the actual power is greater than the second preset power, the speed of the prime mover is increased from the fifth preset speed to the sixth preset speed; according to the feedback actual speed of the prime mover, the torque instruction of the generator is determined according to the generator control electric power, and the torque of the generator is controlled. The average value is less than , the speed of the prime mover is decreased from the fifth preset speed to the fourth preset speed, otherwise, the prime mover continues to operate at the fifth preset speed; when the actual power is greater than the second preset power, the speed of the prime mover is increased from the fifth preset speed to the sixth preset speed; according to the feedback actual speed of the prime mover, the torque instruction of the generator is determined according to the generator control electric power, and the torque of the generator is controlled.

[0035] The application also provides an energy management control method of an electric transmission type engineering vehicle, comprising:

[0036] According to the current state of the battery pack and the power demand information of the drive control module, the output electric power of the generator is analyzed by adopting a fixed electric quantity power following control strategy;

[0037] The hydraulic system power is estimated in real time, if the power provided by the prime mover reaches the upper limit, the output electric power of the generator is limited, the speed of the prime mover is controlled, and the torque of the generator is controlled;

[0038] The driving motor running control is determined, and the electric power used for charging and discharging is received through the CAN bus as the power limit of the driving motor.

[0039] The application has the following advantages and beneficial effects:

[0040] ​​​​The application provides an electric transmission type engineering vehicle energy management system, comprising: a power balance module, a generator set control module and a drive control module; the power balance module is used for analyzing generator output electric power by adopting a fixed electric quantity power following control strategy according to the current state of a battery pack and power demand information of the drive control module; the generator set control module is used for real-time hydraulic system power estimation, if the power provided by a prime mover reaches an upper limit, the generator output electric power is limited, and the prime mover is controlled in speed and the generator is controlled in torque; the drive control module is used for determining drive motor travel control, and receiving electric power by charging and discharging sent by the power balance module through a CAN bus as power limitation of the drive motor. Through whole machine power flow analysis, the electric transmission type engineering vehicle has a working condition that the transmission system and the hydraulic system work at the same time, real-time hydraulic system power estimation is performed, if the sum of power requested by the generator and the hydraulic system reaches the upper limit of the power provided by the prime mover, the generator output power is limited, so that the prime mover is prevented from dropping speed or stalling due to excessive load, and a prime mover speed reduction frequency switching control strategy is adopted to meet the power demand of the rear power chain and effectively avoid frequent speed switching, so that the energy saving and emission reduction of the bulldozer are realized. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 Fig. 1 is a schematic diagram of an electric transmission type engineering vehicle energy management system in the application.

[0042] Figure 2 Fig. 5 is a schematic diagram of fixed electric quantity power following fuzzy control input and output membership function in the application.

[0043] Figure 3 Fig. 7 is a schematic diagram of prime mover speed reduction frequency switching control and prototype machine working point comparison in the application. DETAILED DESCRIPTION

[0044] The application will be further described below in combination with the drawings and specific embodiments, so that those skilled in the art can better understand the application and implement it.

[0045] The following are examples of specific implementation processes provided for detailed description of the technical scheme to be protected by the application, but the application can also be implemented in other ways different from the description, and those skilled in the art can implement the application by using different technical means under the guidance of the concept of the application, so the application is not limited by the following specific embodiments.

[0046] The application provides an electric transmission type engineering vehicle energy management system, which comprises a generator set control module, a power balance module and a drive control module; the generator set control module is used for real-time hydraulic system power estimation, and if the power provided by a prime mover reaches an upper limit, the output electric power of a generator is limited, and the prime mover is controlled in speed and the generator is controlled in torque; the power balance module is used for analyzing the output electric power of the generator by using a fixed electric quantity power following control strategy according to the current state of a battery pack and power demand information of the drive control module; and the drive control module is used for determining drive motor travel control and receiving the electric power for charging and discharging sent by the power balance module through a CAN bus as power limitation of the drive motor. Through whole machine power flow analysis, the electric transmission type engineering vehicle has a working condition that the transmission system and the hydraulic system work at the same time, real-time hydraulic system power estimation is performed, if the sum of the power requested by the generator and the hydraulic system reaches the upper limit of the power provided by the prime mover, the output power of the generator is limited, so that the prime mover is prevented from dropping in speed or stalling due to excessive load.

[0047] Figure 1 Figure 1 is a schematic diagram of an electric transmission type engineering vehicle energy management system in the application.

[0048] Please refer to Figure 1 Figure 1, which comprises that the electric transmission type engineering vehicle energy management system is composed of a power balance module 102, a generator set control module 101 and a drive control module 103.

[0049] The power balance module 102 analyzes the output electric power of the generator by using a fixed electric quantity power following control strategy according to the current state of the battery pack collected through the CAN bus and the power demand information of the drive control module 103, so as to realize front and rear power balance control of the electric transmission type engineering vehicle.

[0050] The generator set control module 101 comprises a prime mover and a controller thereof, a generator controller and a controller thereof, and a battery pack, the generator controller is connected with the battery pack, the prime mover is rigidly connected with a hydraulic pump through a PTO and provides energy for the hydraulic system. Preferably, the prime mover is a diesel engine in the embodiment.

[0051] In order to prevent the prime mover from dropping in speed or stalling due to excessive load, real-time hydraulic system power estimation is performed, if the power provided by the prime mover reaches an upper limit, the output electric power of the generator is limited, the prime mover is controlled in speed and the generator is controlled in torque, so as to realize accurate control of the output electric power of the generator and calculation of the charging and discharging electric power by the drive control module 103.

[0052] The drive control module 103 includes a plurality of drive motors and their controllers, which drive the left and right side tracks respectively. The drive control module 103 realizes the driver's driving intention determination and drive motor driving control, and receives the charging and discharging electric power sent by the power balance module 102 through the CAN bus as the power limit of the drive motor.

[0053] The power balance module 102 controls the generator output electric power Pgen according to the current battery pack current capacity, bus voltage, and its allowed pulsed and continuous charging and discharging power, the demand power of the drive control module 103 The process includes three modes:

[0054] The first mode is the parking power generation mode after power-on and starting, and the expected output electric power Pego is the maximum continuous charging power of the battery pack. The first mode is the parking power generation mode after power-on and starting, and the expected output electric power Pego is the maximum continuous charging power of the battery pack.

[0055] The second mode is the fixed capacity power following control mode, which is entered from the first mode when the current battery pack current capacity is greater than the first preset value of the battery pack capacity; at the same time, the driver's driving demand is considered, and once the demand power Pdem is greater than the minimum demand power Pdemmin, the first preset value of the capacity is appropriately reduced to the minimum set value socmin, and S2 is entered. The expected output electric power Pego is obtained according to the fixed capacity power following control strategy. The second mode is the fixed capacity power following control mode, which is entered from the first mode when the current battery pack current capacity is greater than the first preset value of the battery pack capacity; at the same time, the driver's driving demand is considered, and once the demand power Pdem is greater than the minimum demand power Pdemmin, the first preset value of the capacity is appropriately reduced to the minimum set value socmin, and S2 is entered. The expected output electric power Pego is obtained according to the fixed capacity power following control strategy.

[0056] The third mode is the forced discharging working mode, which is entered from the second mode when the current battery capacity is greater than the preset maximum battery socmax and the demand power is less than the maximum continuous discharging power of the battery pack, and the expected output electric power Pego is zero.

[0057] Figure 2 The figure is a schematic diagram of the input and output membership functions of the fixed capacity power following fuzzy control in the present application.

[0058] Please refer to Figure 2 The fixed capacity power following control strategy in the present application includes:

[0059] M1: The strategy adopts a fuzzy controller, taking the current battery capacity and the demand power as the inputs of the fuzzy controller, and taking the charging and discharging coefficient of the battery pack as the output of the controller, M2: In order to ensure that the battery pack has good charging and discharging characteristics and efficient operation, the current battery capacity is limited to a reasonable range around 0.6; the current battery capacity and the demand power are taken as the inputs of the fuzzy controller, and the charging and discharging coefficient of the battery pack is taken as the output of the controller, ∈[-1,1].

[0060] M2: In order to ensure that the battery pack has good charging and discharging characteristics and efficient operation, the current battery capacity is limited to a reasonable range around 0.6; the current battery capacity and the demand power are taken as the inputs of the fuzzy controller, and the charging and discharging coefficient of the battery pack is taken as the output of the controller,

[0061] ​​M3: Fuzzy control rule: when the battery power is very low close to socmin and the demand power is very small, control -1, charge the battery pack to the maximum capacity; when the battery power is very high close to socmax and the demand power is very large, control 1, discharge the battery pack to the maximum capacity; when the battery power is close to 0.6 and the demand power is moderate, control 0.

[0062] M4: The generator output electric power is expressed as follows:

[0063]

[0064]

[0065]

[0066] wherein, is the generator output electric power; is the demand power; is the expected electric power; is the expected current of the battery pack; is the current bus voltage; is the battery pack charge-discharge coefficient; C is the battery pack charge-discharge rate; is the rated capacity. The generator output electric power

[0067] The generator set control module 101 control strategy according to the acquisition generator DC bus voltage and current signal, prime mover actual speed signal, prime mover utilization torque percentage, hydraulic system pressure signal;

[0068] As a preferred mode, the transmission system and the hydraulic system of the bulldozer have a working condition of working at the same time, at this time the total power requested by the generator and the hydraulic system may exceed the power upper limit of the prime mover, therefore the above various mode output front power chain expected electric power enter the generator utilization electric power limiting module, the calculation formula is as follows:

[0069]

[0070]

[0071]

[0072]

[0073]

[0074] ​​​In the above formula, is the final diesel-electric unit expected output electric power; is the generator utilization electric power; is the power provided for the prime mover; is the hydraulic system estimated power; is the generator system efficiency; is the prime mover actual speed, is the prime mover utilization torque percentage; is the maximum reference torque is the hydraulic equivalent estimated torque; is the hydraulic system pressure; q1 is the working pump displacement, is the hydraulic system mechanical efficiency.

[0075] When the low-temperature, energy management system components fail, the power provided is limited, and the drive control module 103 needs to respond in time to the power limitation, the drive control module 103 utilizes the discharge electric power through the sum of the generator current electric power and the battery pack allowed peak discharge electric power, the generator current electric power is obtained through the generator DC bus voltage and current; the drive control module 103 utilizes the charging electric power as the battery pack allowed peak charging electric power.

[0076] According to the different power intervals of the generator set control electric power, the preset hysteresis band power, the allowable reduced speed flag, the hydraulic system pressure signal, the thumb wheel speed regulation, and the FNR direction signal, the prime mover working mode and speed instruction are determined, and the speed control of the prime mover is carried out, and the speed reduction switching control strategy is as follows:

[0077] Idle speed working mode, the energy management controller adjusts the prime mover to the first preset speed 750 r / min.

[0078] Neutral hydraulic system working mode, the controller obtains the second preset speed of the prime mover according to the pre-set characteristic data table, and realizes the dynamic adjustment of the hydraulic system output flow when parking. The characteristic data table is a one-dimensional data table of thumb wheel speed regulation and prime mover speed; the data points in the data table include the lowest opening degree and the highest opening degree value of the thumb wheel speed regulation, and the lowest value 750 r / min and the highest value 1700 r / min of the prime mover speed corresponding to the speed of the hydraulic system action.

[0079] Non-neutral hydraulic system working mode, in order to ensure that the hydraulic system can output enough power during driving, the energy management controller adjusts the prime mover to the third preset speed 1700 r / min.

[0080] Non-neutral hydraulic system non-working mode, according to the diesel-electric unit expected output electric power Different power intervals, each interval prime mover with constant speed, for example: 3 power interval corresponding prime mover speed is 1200r / min, 1400r / min, 1700r / min, the speed switching mode: the initial speed is the fourth preset speed 1200rpm, when Greater than the first preset power 140kW, the prime mover speed from the fourth preset speed to the fifth preset speed 1400r / min; when Less than the first preset power minus the preset hysteresis band power 110kW, start timing 20 seconds, the average value is less than 110kW, allow to reduce the speed flag position 1, the prime mover speed from the fifth preset speed to the fourth preset speed 1200r / min, otherwise continue to run at the fifth preset speed.

[0081] When Greater than the second preset power 180kW, the prime mover speed from the fifth preset speed to the sixth preset speed 1700r / min. Meet the power chain power demand while effectively avoid frequent switching speed, realize the energy saving and emission reduction of bulldozer. Other power intervals are not described.

[0082] Finally, combined with the actual prime mover speed value of feedback, according to the generator set control electric power, determine the generator torque instruction, torque control of the generator. In this application, the fixed electric power following control strategy is adopted, which improves the efficiency of battery pack and meets the power demand of the rear power chain; The charge-discharge coefficient is used as the output of the fuzzy controller to make the battery expected power control more accurate. Due to power balance and fixed electric power following fuzzy control, the power demand can be provided by the generator and the battery, and the system can meet the use demand by matching relatively smaller capacity battery, effectively reducing the cost.

[0083] To verify the effectiveness of the control strategy, based on Matlab / Simulink, the current battery power and demand power simulation tool is established to simulate the simulation model of the tracked hydraulic mechanical transmission bulldozer and the electric transmission bulldozer for engineering application, and the continuous 10 times cycle operation condition simulation comparison is carried out, such as Figure 3 ​As shown, the speed switches between 1200rpm, 1400rpm and 1700rpm with the change of load demand power, while the prime mover speed of the prototype basically works in the speed range of about 2000rpm, it can be seen that the energy management control strategy of the electric transmission bulldozer makes the prime mover work in the better economic range, which plays a certain role in improving the fuel economy of the whole machine. The prototype machine completes 40m earthmoving in 75.4s and consumes 1.18L of fuel, while the electric transmission machine type single cycle takes 68 seconds and consumes 0.97L of fuel; it can be seen that under the working condition, the oil saving rate of the electric transmission relative to the prototype machine is 19.5%, and the work efficiency is improved by 6.1%.

[0084] The application also provides an energy management control method of an electric transmission engineering vehicle, which is executed based on the hardware provided by the above system, and comprises the following steps of:

[0085] The hydraulic system power is estimated in real time, if the power provided by the prime mover reaches the upper limit, the generator output power is limited, and the speed of the prime mover is controlled, and the torque of the generator is controlled;

[0086] According to the current state of the battery pack and the power demand information of the drive control module 103, the generator output power is analyzed by adopting a fixed electric quantity power following control strategy.

[0087] The driving motor running control is determined, and the electric power obtained by charging and discharging is received through the CAN bus as the power limit of the driving motor.

[0088] The above examples of the application are described in detail, but the content is only the preferred embodiment of the application, and cannot be considered as limiting the scope of the application. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, it is not necessary and impossible to exhaust all the embodiments. The obvious changes or variations derived therefrom are still within the protection scope of the application.

Claims

1. An electrically powered construction vehicle energy management system characterized by, The application relates to a power balance module, a generator set control module and a drive control module. The power balance module is used for resolving the expected output electric power of a generator by adopting a fixed electric quantity power following control strategy according to the current state of a battery and the required power of the drive control module. The generator set control module is used for real-time hydraulic system power estimation, limiting the expected output electric power of the generator and controlling the rotating speed of the prime mover and the torque of the generator if the power provided by the prime mover reaches the upper limit. The drive control module is used for judging the drive motor running control and receiving the electric power for charging and discharging sent by the power balance module through a CAN bus as the power limit of the drive motor. The drive control module collects the generator DC bus voltage and current signals, the actual rotating speed signal of the prime mover, the utilization torque percentage of the prime mover and the hydraulic system pressure signal; when the energy of the prime mover flows through the hydraulic system and then reaches the generator, if the hydraulic system does not work, the expected output electric power of the generator is the final generator set control electric power; if the hydraulic system works, real-time hydraulic system power estimation is carried out, if the sum of the powers required by the generator and the hydraulic system reaches the upper limit of the power provided by the prime mover, the expected output electric power of the generator is limited; the utilization electric power of the generator is obtained by multiplying the power provided by the prime mover by the generator system efficiency after the power provided by the prime mover is reduced by the estimated power of the hydraulic system, and the smaller value between the utilization electric power of the generator and the expected output electric power of the generator is taken as the final generator set control electric power. The expected output electric power of the generator is resolved by adopting the fixed electric quantity power following control strategy, which comprises the following steps: According to the final generator set control electric power The different power intervals, the preset hysteresis band power, the allowable reduced speed flag, the hydraulic system pressure signal, the thumb wheel speed regulation and the FNR direction signal determine the prime mover working mode and the speed instruction, and the speed control of the prime mover is performed. The speed reduction frequency switching control strategy is as follows: the idle speed working mode, the energy management controller adjusts the prime mover to the first preset speed; the neutral hydraulic system working mode, the controller obtains the second preset speed of the prime mover according to the pre-set characteristic data table to realize the dynamic adjustment of the hydraulic system output flow when parking, wherein the characteristic data table is a one-dimensional data table of the thumb wheel speed regulation and the prime mover speed; the non-neutral hydraulic system working mode, the energy management controller adjusts the prime mover to the third preset speed; the non-neutral hydraulic system non-working mode, according to the different power intervals of the final generator set control electric power, the prime mover runs at a constant speed in each interval, and the prime mover speeds corresponding to the three power intervals are the fourth preset speed to the sixth preset speed. The speed switching condition is: the initial speed is the fourth preset speed, when the first preset power is greater than the first preset power, the prime mover speed is increased from the fourth preset speed to the fifth preset speed; when the first preset power minus the preset hysteresis band power is less than the first preset power minus the preset hysteresis band power , the average value is less than , the allowable reduced speed flag is 1, the prime mover speed is reduced from the fifth preset speed to the fourth preset speed, otherwise the prime mover runs at the fifth preset speed; when the second preset power is greater than the second preset power, the prime mover speed is increased from the fifth preset speed to the sixth preset speed; according to the feedback actual prime mover speed value, the generator torque instruction is determined according to the final generator set control electric power, and the torque control of the generator is performed.

2. The electrically driven works vehicle energy management system of claim 1, characterized by, After power-on starting and parking power generation mode: the expected output electric power of the generator is taken as the maximum continuous charging power allowed by the battery. The expected output electric power of the generator is resolved by adopting the fixed electric quantity power following control strategy, which further comprises the following steps:

3. The electrically driven works vehicle energy management system of claim 2, characterized by, The fixed electric quantity power following control strategy: when the current electric quantity of the battery is greater than the first preset value of the battery electric quantity, if the required power is greater than the minimum required power, the first preset value of the electric quantity is reduced to the minimum set value, and the expected output electric power of the generator is obtained according to the fixed electric quantity power following control strategy. The expected output electric power of the generator is resolved by adopting the fixed electric quantity power following control strategy, which further comprises the following steps:

4. The electrically driven works vehicle energy management system of claim 3, characterized by, Forced discharging mode: when the current electric quantity of the battery is greater than the preset maximum value of the battery, and the required power is less than the maximum continuous discharging power allowed by the battery, the expected output electric power of the generator is zero. The fixed electric quantity power following control strategy comprises the following steps:

5. The electrically powered construction vehicle energy management system of claim 3, wherein, The electric quantity of the battery is limited in a preset range; Adopting the fuzzy controller to take the current power of the battery and the demand power as the input of the fuzzy controller, taking the charge-discharge coefficient of the battery as the output of the controller ∈[-1,1] When the electric quantity of the battery reaches the minimum value of the preset range and the required power reaches the minimum required threshold, the charging and discharging coefficient is controlled to be -1 and the battery is charged at the maximum capacity; when the electric quantity of the battery reaches the maximum value of the preset range and the required power reaches the maximum required threshold, the charging and discharging coefficient is controlled to be 1 and the battery is discharged at the maximum capacity; when the electric quantity of the battery reaches the preset range and the required power reaches the required intermediate threshold, the charging and discharging coefficient is controlled to be 0. ​ The generator expected output power expression is as follows: ； ； ； wherein, is the desired output electric power for the generator; is the demanded power; is the desired electric power for the battery; is the desired electric current for the battery; is the current bus voltage; is the battery charge-discharge coefficient; C is the battery charge-discharge rate; is the battery rated capacity.

6. The electrically powered construction vehicle energy management system of claim 1, wherein, The power provided by the prime mover is obtained by using the torque percentage, the maximum reference torque and the actual speed of the prime mover; the hydraulic system estimated power is obtained by estimating the hydraulic equivalent estimated torque according to the hydraulic system pressure signal and combining the actual speed of the prime mover.

7. An electrically driven work vehicle energy management control method characterized by, Applied to the system of claim 1, comprising: According to the current state of the battery and the required power of the drive control module, the expected output power of the generator is analyzed by using a fixed electric quantity power following control strategy; Real-time hydraulic system power estimation, if the power provided by the prime mover reaches the upper limit, the expected output power of the generator is limited, and the speed control of the prime mover and the torque control of the generator are performed; Determine the driving motor running control, and receive the electric power used for charging and discharging through the CAN bus as the power limit of the driving motor.

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