Patent Publication Number: US-2023151830-A1

Title: Hydraulic-electric coupling driven multi-actuator system and control method

Description:
TECHNICAL FIELD 
     The present disclosure relates to technical field of hydraulic transmission and electro-mechanical transmission, and in particular to a hydraulic-electric coupling driven multi-actuator system and control method. 
     BACKGROUND 
     Hydraulic systems are widely applied in various non-road mobile equipment such as aerospace, deep-sea equipment, construction machinery, road construction machinery, mining machinery, forestry machinery and agricultural machinery due to their advantages such as high power density. At present, centralized power supply and multi-way valve power distribution modes are generally adopted in most of multi-actuator hydraulic systems. An output pressure of a pump is matched with a maximum load association, and the other associations compensate for influence of load difference through the respective pressure compensators, which results in large throttling losses on the pressure compensators and control valves of the low-load associations and low overall energy efficiency of the system. In addition, there is a serious problem of kinetic and potential energy waste in the equipment with a lifting device. 
     In an electro-mechanical actuator driven system, the rotary motion of the motor is converted into the linear motion through mechanical transmission. Compared with hydraulic driving, electro-mechanical actuator driving has advantages of energy saving, environmental protection, easy control, high control accuracy and the like, but the electro-mechanical actuator has low power density and poor carrying capacity. Moreover, at present, driving systems of single electro-mechanical actuators are simply superposed to form the driving system of multiple electro-mechanical actuators, and the overall installed power of the system is large. 
     Based on the above-mentioned problem, a novel multi-actuator control system is urgently needed to reduce throttling loss and installed power. 
     SUMMARY 
     An objective of the present disclosure is to provide a hydraulic-electric coupling driven multi-actuator system and control method, which may reduce throttling loss and installed power. 
     In order to achieve the above objective, the present disclosure provides the following solution. 
     A hydraulic-electric coupling driven multi-actuator system includes: 
     one or more hydraulic-electric hybrid driven actuators;   first inverters, control valves and pressure sensor groups; wherein the number of the first inverters, the number of the control valves and the number of the pressure sensor groups are the same as the number of hydraulic-electric hybrid driven actuators, respectively;   each hydraulic-electric hybrid driven actuator is correspondingly connected with one first inverter, one control valve and one pressure sensor group; the pressure sensor group is configured to detect pressure information of a corresponding hydraulic-electric hybrid driven actuator;   centralized hydraulic units connected with the control valves and configured to supply oil for the hydraulic-electric hybrid driven actuators and to perform power compensation; and   control units respectively connected with the hydraulic-electric hybrid driven actuators and the pressure sensor groups, where each control unit is configured to control output torque of a first motor of the corresponding hydraulic-electric hybrid driven actuator based on pressure information of the hydraulic-electric hybrid driven actuator, such that pressure of the driving cavities of the hydraulic-electric hybrid driven actuators is equal.   

     In an embodiment, the hydraulic-electric hybrid driven actuator may include: 
     the first motor;   a speed reducer connected with the first motor;   a cylinder barrel fixedly connected with the speed reducer;   a push rod arranged in the cylinder barrel and movably connected with the cylinder barrel;   a lead screw arranged in the cylinder barrel; wherein one end of the lead screw is connected with the speed reducer, and another end of the lead screw is connected with the push rod through a screw transmission pair; and the lead screw performs rotary motion under the control of the first motor and the speed reducer, and further drives the push rod to perform linear motion through the screw transmission pair;   a sealing member arranged between the push rod and the cylinder barrel; wherein the cylinder barrel is divided into two cavities by the sealing member, i.e., a rodless cavity close to the speed reducer and a rod cavity close to the push rod;   wherein working oil ports of each control valve respectively communicate with two cavities of the corresponding hydraulic-electric hybrid driven actuator; the control valve is configured to provide power compensation for the corresponding hydraulic-electric hybrid driven actuator through the working oil ports based on torque information output by the first motor of the corresponding hydraulic-electric hybrid driven actuator; and an oil return port of the control valve communicates with an oil tank.   

     In an embodiment, the pressure sensor group may include: 
     a first pressure sensor connected with the rodless cavity of the corresponding hydraulic-electric hybrid driven actuator and configured to detect pressure information of the rodless cavity of the corresponding hydraulic-electric hybrid driven actuator; and   a second pressure sensor connected with the rod cavity of the corresponding hydraulic-electric hybrid driven actuator and configured to detect pressure information of the rod cavity of the corresponding hydraulic-electric hybrid driven actuator.   

     In an embodiment, the centralized hydraulic unit may include a second inverter, a second motor, a hydraulic pump, an oil tank, an oil supply pipeline, an overflow valve, a bypass proportional valve and a shuttle valve; wherein 
     the second motor is connected with the second inverter;   the hydraulic pump is coaxially connected with the second motor, an oil suction port of the hydraulic pump communicates with the oil tank, and an oil outlet of the hydraulic pump communicates with the oil supply pipeline;   the overflow valve respectively communicates with the oil supply pipeline and the oil tank;   the shuttle valve is connected with a load detection end of a control valve corresponding to each hydraulic-electric hybrid driven actuator and configured to detect a maximum load pressure of the hydraulic-electric hybrid driven actuator; and   the bypass proportional valve is provided with a first working oil port, a second working oil port, a third working oil port, a spring end and a pressure detection end; wherein   the first working oil port of the bypass proportional valve communicates with the oil tank; the second working oil port of the bypass proportional valve communicates with an energy accumulator; the third working oil port of the bypass proportional valve communicates with the oil supply pipeline; and the spring end of the bypass proportional valve is connected with the shuttle valve and configured to detect maximum load feedback pressure of each hydraulic-electric hybrid driven actuator;   the pressure detection end of the bypass proportional valve is connected with the oil supply pipeline and configured to detect outlet pressure of the hydraulic pump; and   the bypass proportional valve is controlled by the outlet pressure of the hydraulic pump, load feedback pressure and spring force, such that the outlet pressure of the hydraulic pump is always higher than load pressure by a fixed value.   

     In an embodiment, the hydraulic-electric coupling driven multi-actuator system may further include: 
     a direct-current bus respectively connected with the first inverter and the second inverter and configured to perform energy distribution and energy sharing on each hydraulic-electric hybrid driven actuator. 
     In an embodiment, the hydraulic-electric coupling driven multi-actuator system may further include a power switch, a rectifier, a direct current-direct current (DC-DC) converter and a super-capacitor group sequentially connected on the direct-current bus. 
     In order to achieve the above objective, the present disclosure further provides the following solution. 
     A hydraulic-electric coupling driven multi-actuator control method includes: 
     controlling operating speed of each hydraulic-electric hybrid driven actuator by the respective associated first motor when a plurality of hydraulic-electric hybrid driven actuators under load difference co-operate;   performing power compensation on electric driving of each hydraulic-electric hybrid driven actuator by centralized hydraulic units in a unified mode; and   adjusting output torque of the first motor of each hydraulic-electric hybrid driven actuator, and controlling pressure of a driving cavity of the hydraulic-electric hybrid driven actuator based on pressure information of the hydraulic-electric hybrid driven actuator, such that the pressure of the driving cavities of the hydraulic-electric hybrid driven actuators is equal.   

     In an embodiment, the hydraulic-electric coupling driven multi-actuator control method may further include: 
     controlling a bypass proportional valve, such that outlet pressure of a hydraulic pump is higher than a maximum load pressure by a fixed value and the openings of the associated control valves are the biggest. 
     In an embodiment, the hydraulic-electric coupling driven multi-actuator control method may further include: 
     calculating demand flow of each associated hydraulic-electric hybrid driven actuator based on flow matching principle; and   adjusting a swash plate swing angle of a hydraulic pump based on the demand flow to control output flow of the hydraulic pump to be consistent with the demand flow.   

     According to specific embodiments provided in the present disclosure, the present disclosure has the following technical effects: pressure information of each hydraulic-electric hybrid driven actuator is detected by a pressure sensor, and based on the pressure information, the output torque of a motor of the corresponding hydraulic-electric hybrid driven actuator is controlled, so that pressure of the driving cavities of the hydraulic-electric hybrid driven actuators is equal, which greatly reduces the throttling loss caused by load differences among hydraulic-electric hybrid driven actuators. In addition, power of the hydraulic-electric hybrid driven actuators is supplemented by arranging the control valves and the centralized hydraulic units, which may realize that a low-power motor driving and pull high-power actuators, significantly reducing total installed power of the multi-actuator system, especially for multi-actuator engineering equipment. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order to illustrate the embodiments of the present disclosure or the technical solutions of the conventional art more clearly, the accompanying drawing used in the embodiments will be briefly described below. Apparently, the accompanying drawing described below show merely some embodiments of the present disclosure. For those of ordinary skill in the art, other drawings can be obtained according to the accompanying drawings without creative efforts. 
         FIG.  1    is a structural schematic diagram of a hydraulic-electric coupling driven multi-actuator system of the present disclosure; 
         FIG.  2    is a flow chart of a hydraulic-electric coupling driven multi-actuator control method of the present disclosure; 
         FIG.  3    is a mechanical structure schematic diagram of a hydraulic-electric coupling driven excavator; and 
         FIG.  4    is a schematic circuit diagram of a hydraulic-electric coupling driven multi-actuator system applied to the complete excavator machine according to the present disclosure. 
     
    
    
     Reference Numerals 
       1 , power switch;  2 , rectifier;  3 , direct-current bus;  4 , filter capacitor;  5 , direct current-direct current (DC-DC) converter;  6 , super-capacitor group; 
       7 , first inverter;  7 - 1 ,  7 - 2 , movable arm associated inverter;  7 - 3 ,  7 - 4 , bucket rod associated inverter;  7 - 5 , rotation associated inverter; 
       8 , hydraulic-electric hybrid driven actuator;  8 - 1 ,  8 - 2 , movable arm associated hydraulic-electric hybrid driven actuator;  8 - 3 ,  8 - 4 , bucket rod associated hydraulic-electric hybrid driven actuator; 
       9 , first motor;  10 , speed reducer;  11 , lead screw;  12 , push rod;  13 , cylinder barrel;  14 , sealing member; 
       15 ,  15 - 1 ,  15 - 2 ,  15 - 3 ,  15 - 4 , first pressure sensor;  16 ,  16 - 1 ,  16 - 2 ,  16 - 3 ,  16 - 4 , second pressure sensor; 
       17 , control valve;  17 - 1 , movable arm associated control valve;  17 - 2 , bucket associated control valve;  17 - 3 , bucket rod associated control valve;  17 - 4 , rotation associated control valve; 
       18 ,  18 - 1 ,  18 - 2 , third pressure sensor;  19 ,  19 - 1 ,  19 - 2 , second inverter;  20 ,  20 - 1 ,  20 - 2 , second motor;  21 ,  21 - 1 ,  21 - 2 , hydraulic pump;  22 , oil tank;  23 ,  23 - 1 ,  23 - 2 , overflow valve;  24 , bypass proportional valve;  25 , energy accumulator;  26 , shuttle valve;  27 , pressure difference compensator;  28 , valve core displacement sensor;  29 , switch valve; 
       30 , walking device;  31 , rotary motor;  32 , rotary platform;  33 , movable arm;  34 , bucket rod;  35 , bucket;  36 , bucket hydraulic cylinder;  37 , rotation motor; 
     A, first working oil port of control valve; B, second working oil port of control valve; P, oil inlet of control valve; T, oil return port of control valve; LS, load pressure detection end of control valve; L, oil supply pipeline; E, first working oil port of bypass proportional valve; F, second working oil port of bypass proportional valve; and C, third working oil port of bypass proportional valve. 
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     The technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present disclosure. Apparently, the described embodiments are merely a part of the embodiments of the present disclosure, rather than all of the embodiments. All other embodiments obtained by the ordinary skilled in the art based on the embodiment of the present disclosure without creative efforts shall fall within the scope of protection of the present disclosure. 
     The present disclosure aims to provide a hydraulic-electric coupling driven multi-actuator system and control method. Pressure information of each hydraulic-electric hybrid driven actuator is detected by a pressure sensor, and based on the pressure information, output torque of a motor of a corresponding hydraulic-electric hybrid driven actuator is controlled, so that pressure of the driving cavities of the hydraulic-electric hybrid driven actuators is equal, which greatly reduces throttling loss caused by load differences among hydraulic-electric hybrid driven actuators. In addition, power of the hydraulic-electric hybrid driven actuators is supplemented by arranging control valves and centralized hydraulic units, which may realize that a low-power motor driving and pull high-power actuators, significantly reducing total installed power of the multi-actuator system, especially for multi-actuator engineering equipment. 
     To make the foregoing objectives, features and advantages of the present disclosure clearer and more comprehensible, the present disclosure is described in further detail below in conjunction with the accompanying drawings and specific implementations. 
     As shown in  FIG.  1   , the hydraulic-electric coupling driven multi-actuator system of the present disclosure includes: one or more hydraulic-electric hybrid driven actuators  8 ; first inverters  7 , control valves  17  and pressure sensor groups; centralized hydraulic units; and control units. 
     The number of the first inverters  7 , the number of the control valves  17  and the number of the pressure sensor groups are the same as that of the hydraulic-electric hybrid driven actuators  8  respectively. Preferably, the control valve  17  is a three-position four-way control valve with a load pressure feedback function. 
     Each hydraulic-electric hybrid driven actuator  8  is correspondingly connected with one first inverter  7 , one control valve  17  and one pressure sensor group. The pressure sensor group is configured to detect pressure information of a corresponding hydraulic-electric hybrid driven actuator  8 . 
     The centralized hydraulic units are connected with the control valves  17  and configured to supply oil for the hydraulic-electric hybrid driven actuators  8  and perform power compensation. 
     The control units are respectively connected with the hydraulic-electric hybrid driven actuators  8  and the pressure sensor groups, where each control unit is configured to, based on the pressure information of a corresponding hydraulic-electric hybrid driven actuator  8 , control output torque of the first motor of the corresponding hydraulic-electric hybrid driven actuator  8 , such that pressure of the driving cavities of the hydraulic-electric hybrid driven actuators  8  is equal. Without throttling loss, influence of the load differences of respective actuators is eliminated which greatly reduces the throttling loss caused by the difference pressure of the driving cavities of the hydraulic-electric hybrid driven actuators  8 . 
     In the present disclosure, power of all the first motors is supplemented by arranging the control valves  17  and the centralized hydraulic units, which may realize that the low-power motor can drive and pull the high-power actuators, significantly reducing the total installed power of the multi-actuator system, especially for the multi-actuator engineering equipment. 
     Further, the hydraulic-electric hybrid driven actuator  8  includes the first motor  9 , a speed reducer  10 , a cylinder barrel  13 , a push rod  12  and a lead screw  11 . 
     Where, the speed reducer  10  is connected with the first motor  9 . 
     The cylinder barrel  13  is fixedly connected with the speed reducer  10 . 
     The push rod  12  is arranged in the cylinder barrel  13  and movably connected with the cylinder barrel  13 . 
     The lead screw  11  is arranged in the cylinder barrel  13 . One end of the lead screw  11  is connected with the speed reducer  10 , and the other end of the lead screw  11  is connected with the push rod  12  through a screw transmission pair. The lead screw  11  performs rotary motion under the control of the first motor  9  and the speed reducer, and further drives the push rod  12  to perform linear motion through the screw transmission pair. Due to mechanical transmission, the hydraulic-electric hybrid driven actuator has better control performance. 
     A sealing member  14  is arranged between the push rod  12  and the cylinder barrel  14 . The cylinder barrel  13  is divided into two cavities by the sealing member  14 , i.e., a rodless cavity close to the speed reducer and a rod cavity close to the push rod  12 . 
     The working oil ports of each control valve  17  respectively communicate with two cavities of the corresponding hydraulic-electric hybrid driven actuator  8 . The control valve  17  is configured to provide power compensation for the corresponding hydraulic-electric hybrid driven actuator  8  through the working oil ports based on the pressure information of the driving cavity of the corresponding hydraulic-electric hybrid driven actuator  8 . An oil return port of the control valve  17  communicates with an oil tank  22 . 
     On the basis of ensuring the flow distribution accuracy of the system, opening of an valve port of each associated control valve  17  is increased, the throttling loss of the valve ports is reduced maximumly, thereby minimizing the throttling loss of the control valves  17 , and further the throttling loss of the whole system. 
     Furthermore, the pressure sensor group includes a first pressure sensor  15  and a second pressure sensor  16 . 
     Wherein, the first pressure sensor  15  is connected with the rodless cavity of the corresponding hydraulic-electric hybrid driven actuator  8  and configured for detecting the pressure information of the rodless cavity of the corresponding hydraulic-electric hybrid driven actuator  8 . 
     The second pressure sensor  16  is connected with the rod cavity of the corresponding hydraulic-electric hybrid driven actuator  8  and configured for detecting the pressure information of the rod cavity of the corresponding hydraulic-electric hybrid driven actuator  8 . 
     Specifically, the centralized hydraulic unit includes a second inverter  19 , a second motor  20 , a hydraulic pump  21 , an oil tank  22 , an oil supply pipeline L, an overflow valve  23 , a bypass proportional valve  24 , an energy accumulator  25  and a shuttle valve  26 . 
     The second motor  20  is connected with the second inverter  19 . 
     The hydraulic pump  21  is coaxially connected with the second motor  20 , an oil suction port of the hydraulic pump  21  communicates with the oil tank  22 , and an oil outlet of the hydraulic pump  21  communicates with the oil supply pipeline L. 
     The overflow valve  23  respectively communicates with the oil supply pipeline L and the oil tank  22 . 
     The shuttle valve  26  is connected with a load detection end of the control valve  17  corresponding to each hydraulic-electric hybrid driven actuator  8  and configured to detect the maximum load pressure of the hydraulic-electric hybrid driven actuator  8 . 
     The bypass proportional valve  24  is provided with a first working oil port E, a second working oil port F, a third working oil port C, a spring end and a pressure detection end. 
     The first working oil port E of the bypass proportional valve  24  communicates with the oil tank  22 . The second working oil port F of the bypass proportional valve  24  communicates with the energy accumulator  25 . The third working oil port C of the bypass proportional valve  24  communicates with the oil supply pipeline. The spring end of the bypass proportional valve  24  is connected with the shuttle valve  26 , and the spring end of the bypass proportional valve  24  is configured to detect the maximum load feedback pressure of each hydraulic-electric hybrid driven actuator  8 . 
     The pressure detection end of the bypass proportional valve  24  is connected with the oil supply pipeline L, and configured to detect the outlet pressure of the hydraulic pump  21 . 
     The bypass proportional valve  24  is controlled by the outlet pressure of the hydraulic pump  21 , load feedback pressure and spring force, such that the outlet pressure of the hydraulic pump  21  is always higher than a load pressure by a fixed value. 
     In an embodiment, the centralized hydraulic unit further includes a third pressure sensor  18 . The third pressure sensor  18  communicates with the oil supply pipeline L, and the third pressure sensor  18  is configured to detect the pressure of the oil supply pipeline L in real time. 
     In an embodiment, the hydraulic-electric coupling driven multi-actuator system further includes a direct-current bus  3 . The direct-current bus  3  is respectively connected with the first inverter  7  and the second inverter  19 , and configured to perform energy distribution and energy sharing on each hydraulic-electric hybrid driven actuator  8 . 
     Further, the hydraulic-electric coupling driven multi-actuator system further includes a power switch  1 , a rectifier  2 , a direct current-direct current (DC-DC) converter  5  and a super-capacitor group  6  sequentially connected over the direct-current bus  3 . 
     Through the direct-current bus  3  and the super-capacitor group  6 , kinetic and potential energy recycling may be achieved. When the hydraulic-electric hybrid driven actuator  8  is in an overload working condition, the kinetic and potential energy of the actuator is converted into electric energy by the first motor  9 , and the electric energy is stored in the super-capacitor group  6  by the direct-current bus  3 . The kinetic and potential energy generated by the system may also be directly utilized by the direct-current bus  3  to realize energy sharing. The excess energy may be further converted into hydraulic energy by the second motor  20  and the hydraulic pump  21  of the centralized hydraulic unit, and the hydraulic energy is stored in the energy accumulator  25 . The energy utilization process is opposite to the recovery process. 
     In the embodiment, the energy accumulator  25  is one of an air bag energy accumulator, a piston energy accumulator and a spring energy accumulator. The second motor  20  is electrically connected with the direct-current bus  3  through the second inverter  19  to obtain power. 
     As shown in  FIG.  2   , a hydraulic-electric coupling driven multi-actuator control method in the present disclosure includes steps S 1 , S 2  and S 3 . 
     S 1 : The operating speed of each hydraulic-electric hybrid driven actuator  8  is controlled by the respective associated first motor when a plurality of hydraulic-electric hybrid driven actuators  8  under load difference co-operate. 
     S 2 : Power compensation is performed on electric driving of each hydraulic-electric hybrid driven actuator  8  by the centralized hydraulic units in a unified mode. 
     S 3 : According to the pressure information of the hydraulic-electric hybrid driven actuator  8 , the output torque of the first motor of the hydraulic-electric hybrid driven actuator  8  is adjusted, to control the pressure of the driving cavity of the hydraulic-electric hybrid driven actuator  8 , such that the pressure of the driving cavities of the hydraulic-electric hybrid driven actuators  8  is equal. 
     Further, the hydraulic-electric coupling driven multi-actuator control method further includes step S 4 . 
     S 4 : A bypass proportional valve is controlled, such that outlet pressure of the hydraulic pump  21  is higher than the maximum load pressure by a fixed value and the openings of the associated control valves  17  are the biggest. 
     Furthermore, the hydraulic-electric coupling driven multi-actuator control method further includes steps S 5  and S 6 . 
     S 5 : Demand flow of each associated hydraulic-electric hybrid driven actuator  8  is calculated based on flow matching principle. 
     S 6 : A swash plate swing angle of a hydraulic pump  21  is adjusted based on the demand flow to control output flow of the hydraulic pump  21  to be consistent with the demand flow. 
     One embodiment of the hydraulic-electric coupling driven multi-actuator system and control method of the present disclosure applied to an excavator is described as follows. 
       FIG.  3    is a mechanical structure schematic diagram of a hydraulic-electric coupling driven excavator in the present disclosure. As widely applied typical multi-actuator mechanical equipment, the excavator mainly includes a walking device  30 , a rotary platform  32  arranged on the walking device  30 , a rotary motor  31  for driving the rotary platform  32  to rotate, a movable arm  33  which is connected with the rotary platform  32  and relatively rotates in the up-and-down direction, movable arm associated hydraulic-electric hybrid driven actuators  8 - 1 ,  8 - 2  for driving the movable arm  33  to lift up and down, a bucket rod  34  which is mounted at the front end of the movable arm  33  and may relatively rotate, a bucket rod associated hydraulic-electric hybrid driven actuator  8 - 3  for driving the bucket rod  34  to move, a bucket  35  which is mounted at the front end of the bucket rod  34  and may relatively rotate, and a bucket hydraulic cylinder  36  for driving the bucket  35  to move. 
       FIG.  4    is a schematic circuit diagram of a hydraulic-electric coupling driven multi-actuator system applied to the complete excavator machine according to the present disclosure. As shown in  FIG.  4   , the circuit of the electrically driven excavator includes: 
     a direct-current bus  3 ;   one or two movable arm associated hydraulic-electric hybrid driven actuators  8 - 1 ,  8 - 2 , one or two movable arm associated inverters  7 - 1 ,  7 - 2  and a movable arm associated control valve  17 - 1 ;   one or two bucket rod associated hydraulic-electric hybrid driven actuators  8 - 3 ,  8 - 4 , one or two bucket rod associated inverters  7 - 3 ,  7 - 4  and a bucket rod associated control valve  17 - 3 ;   a bucket hydraulic cylinder  36  and a bucket associated control valve  17 - 2 ;   a rotary motor  31 , a rotation motor  37 , a rotation associated inverter  7 - 5  and a rotation associated control valve  17 - 4 ; and   two centralized hydraulic units and control units. Each centralized hydraulic unit includes the second inverter  19 , the second motor  20 , the hydraulic pump, the oil tank  22  and the overflow valve  23 .   

     The direct-current bus  3  is connected with the power switch  1 , the rectifier  2 , the filter capacitor  4 , the DC-DC converter  5  and the super-capacitor group  6 . 
     The movable arm associated inverters  7 - 1 ,  7 - 2 , the bucket rod associated inverters  7 - 3 ,  7 - 4 , the rotation associated inverter  7 - 5 , and the second inverters  19 - 1 ,  19 - 2  are electrically connected with the direct-current bus  3 . 
     The direct-current bus  3  distributes power and shares energy for each actuator through each inverter, and stores excess energy into the super-capacitor group  6 . 
     The movable arm associated hydraulic-electric hybrid driven actuators  8 - 1 ,  8 - 2  are hydraulic-electric hybrid driven actuators of the hydraulic-electric coupling driven multi-actuator system in the present disclosure. The movable arm associated hydraulic-electric hybrid driven actuators  8 - 1 ,  8 - 2  are respectively connected with the movable arm associated inverters  7 - 1 ,  7 - 2 . The two cavities of the movable arm associated hydraulic-electric hybrid driven actuator respectively communicate with the working oil ports A, B of the movable arm associated control valve  17 - 1 . 
     The bucket rod associated hydraulic-electric hybrid driven actuators  8 - 3 ,  8 - 4  are hydraulic-electric hybrid driven actuators of the hydraulic-electric coupling driven multi-actuator system in the present disclosure. The bucket rod associated hydraulic-electric hybrid driven actuators  8 - 3 ,  8 - 4  are respectively connected with the bucket rod associated inverters  7 - 3 ,  7 - 4 . The two cavities of the bucket rod associated hydraulic-electric hybrid driven actuator respectively communicate with the working oil ports A, B of the bucket rod associated control valve  17 - 3 . 
     The rotary motor  31  is coaxially connected with the rotation motor  37 . The rotation motor  37  is connected with the rotation associated inverter  7 - 5 . The two cavities of the rotary motor respectively communicate with the working oil ports A, B of the rotation associated control valve  17 - 4 . 
     The two cavities of the bucket hydraulic cylinder  36  respectively communicate with the working oil ports A, B of the bucket associated control valve  17 - 2 , and the bucket association is further provided with a pressure difference compensator  27  and a valve core displacement sensor  28 . The oil outlet of the pressure difference compensator communicates with the oil inlet of the bucket associated control valve  17 - 2 . The bucket associated control valve  17 - 2  is a three-position four-way control valve with a load pressure detection function. The spring end of the pressure difference compensator  17 - 2  communicates with the load pressure detection port LS, and the other end of the pressure difference compensator  17 - 2  communicates with the oil inlet P of the control valve. 
     The centralized hydraulic unit is the centralized hydraulic unit of the hydraulic-electric coupling driven multi-actuator system in the present disclosure. A first centralized hydraulic unit is connected with the movable arm associated control valve  17 - 1  and the bucket associated control valve  17 - 2 , and a second centralized hydraulic unit is connected with the bucket rod associated control valve  17 - 3  and the rotation associated control valve  17 - 4 . The centralized hydraulic units are configured to supply oil for the movable arm associated hydraulic-electric hybrid driven actuator, the bucket rod associated hydraulic-electric hybrid driven actuator, the rotary motor and the bucket hydraulic cylinder to perform power compensation. 
     The first centralized hydraulic unit and the second centralized hydraulic unit are connected through the switch valve  29 . When a single centralized hydraulic unit does not provide enough flow, the control unit controls the switch valve  29  to communicate the two centralized hydraulic units for confluence to supply oil for the actuators. 
     The control unit is respectively connected with each hydraulic-electric hybrid driven actuator, the rotation motor, the control valve, the switch valve, the second motor and the hydraulic pump. 
     The control unit controls the motor output torques of the corresponding movable arm associated hydraulic-electric hybrid driven actuators  8 - 1 ,  8 - 2 , the motor output torques of the bucket rod associated hydraulic-electric hybrid driven actuators  8 - 3 ,  8 - 4  and the output torque of the rotation motor  37  according to the movable arm associated hydraulic-electric hybrid driven actuators  8 - 1 ,  8 - 2 , the bucket rod associated hydraulic-electric hybrid driven actuators  8 - 3 ,  8 - 4 , and the rotary motor  31 , the bucket hydraulic cylinder  36  and the maximum load pressure information of multiple actuators detected by the pressure sensors, to compensate the load differences among the multiple actuators, such that the pressure of the driving cavities of the actuators under coordination actions is equal as much as possible, and the throttling loss at the control valve ports caused by the load difference of multiple actuators is reduced. 
     The specific control method of the excavator system is the same as the hydraulic-electric coupling driven multi-actuator control method of the present disclosure. 
     In this specification, several specific examples are used for illustration of the principles and implementations of the present disclosure. The descriptions of the foregoing embodiments are used to help understanding the method of the present disclosure and the core ideas thereof. In addition, for those of ordinary skill in the art, there will be changes in the specific embodiments and the scope of application in accordance with the teachings of the present disclosure. In conclusion, the content of this specification shall not be construed as a limitation to the present disclosure.