Electric excavator system and control method

Abstract

An electric excavator system and a control method. The control method comprises: acquiring a pump body pressure and a pilot pressure of each plunger pump (1); determining a required flow rate of each plunger pump (1) on the basis of the pump body pressure and the pilot pressure; determining an initial calculated rotation speed of an electric motor (2) on the basis of the required flow rate of each plunger pump; determining a calculated rotation speed of the electric motor (2) on the basis of the initial calculated rotation speed; determining a rotation speed adjustment policy for the electric motor (2) on the basis of the calculated rotation speed, and on the basis of the rotation speed adjustment policy, controlling the electric motor (2) to adjust a rotation speed; and on the basis of the calculated rotation speed, and the required flow rate of each plunger pump (1), determining a displacement adjustment policy for each plunger pump (1), and on the basis of each displacement adjustment policy, controlling a corresponding plunger pump (1) to adjust displacement. When flow rates of plunger pumps (1) remain unchanged, the comprehensive efficiency of the plunger pumps (1) and an electric motor (2) is made optimal, thereby achieving lower energy consumption and longer endurance time in the same operation.

Description

Electric excavator system and control method

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the China Patent Office on November 24, 2023, with application number 202311586626.0 and invention name “Electric Excavator System and Control Method”, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to the technical field of excavators, and in particular to an electric excavator system and a control method. Background Art

[0004] As society pays more attention to environmental protection, traditional excavators are no longer suitable for new environmental requirements; among them, electric excavators are gradually becoming a new development direction.

[0005] Current pure electric excavators suffer from short battery life due to the heavy weight and high cost of their power batteries. Existing technologies mostly rely on the control strategies of traditional diesel engines, maintaining a constant speed during operation and adjusting power solely through adjustments to the main pump displacement. This significantly limits the efficiency of electric excavator powertrains, resulting in energy waste and increased vehicle energy consumption.

[0006] Summary of the Invention

[0007] The main purpose of this application is to provide an electric excavator system and a control method, aiming to solve the problem of large efficiency limitations of the electric excavator power system.

[0008] To achieve the above-mentioned object, the present application provides a control method for an electric excavator system, wherein the electric excavator system includes a motor and a plurality of plunger pumps drivingly connected to the motor;

[0009] The control method includes:

[0010] Obtaining the pump body pressure and pilot pressure of each plunger pump;

[0011] determining the required flow rate of each plunger pump according to the pump body pressure and the pilot pressure;

[0012] Determining the initial calculated speed of the motor according to the required flow of each plunger pump;

[0013] Determining a calculated speed of the motor according to the initially calculated speed;

[0014] Determining a speed adjustment strategy for the motor according to the calculated speed, and controlling the motor to adjust the speed according to the speed adjustment strategy;

[0015] According to the calculated rotational speed and the required flow of each plunger pump, a displacement adjustment strategy of each plunger pump is determined, and the corresponding plunger pump is controlled to adjust the displacement according to each displacement adjustment strategy.

[0016] Optionally, determining the initial calculated rotation speed of the motor according to the required flow rate of each plunger pump includes:

[0017] selecting a maximum value among the plurality of required flow rates as a reference flow rate;

[0018] The initial rotational speed is calculated based on the reference flow rate.

[0019] Optionally, calculating the initial rotational speed according to the reference flow rate includes:

[0020] Obtaining a set displacement of the plunger pump corresponding to the reference flow rate;

[0021] Selecting the maximum value among the set displacements as the reference displacement;

[0022] The initial rotational speed is calculated based on the reference flow rate and the reference displacement.

[0023] Optionally, determining the calculated speed of the motor according to the initially calculated speed includes:

[0024] Determine the weight adjustment coefficient;

[0025] Obtaining limiting parameters of the motor;

[0026] The calculated speed of the motor is determined according to the initially calculated speed, the weight adjustment coefficient and the limit parameter.

[0027] Optionally, determining the weight adjustment coefficient includes:

[0028] Obtaining the starting pressure and maximum pressure of a system composed of a plurality of plunger pumps;

[0029] Determining the average pressure of each plunger pump according to the pump body pressure of each plunger pump;

[0030] A weight adjustment coefficient is determined according to the average pressure and the starting pressure.

[0031] Optionally, determining a weight adjustment coefficient according to the average pressure and the starting pressure includes:

[0032] When the average pressure is greater than the starting pressure, determining the weight adjustment coefficient to be a first fixed value;

[0033] When the average pressure is less than the starting pressure, the weight adjustment coefficient is calculated and determined according to the average pressure, the starting pressure, and the maximum pressure.

[0034] Optionally, the limiting parameters include a limited torque and a limited power of the motor.

[0035] Optionally, determining a speed adjustment strategy for the motor according to the calculated speed, and controlling the motor to adjust the speed according to the speed adjustment strategy includes:

[0036] Obtaining the current speed of the motor;

[0037] At the current speed, the preset speed step values ​​are progressively increased in sequence to obtain a plurality of process target speeds between the current speed and the calculated speed;

[0038] According to the plurality of process target speeds, the motor speed is controlled to change step by step from the current speed to the calculated speed.

[0039] Optionally, determining a displacement adjustment strategy for each plunger pump according to the calculated rotational speed and the required flow rate of each plunger pump, and controlling each corresponding plunger pump to adjust its displacement according to each displacement adjustment strategy includes:

[0040] Determine and obtain the calculated displacement and multiple process target displacements corresponding to the plunger pump according to the calculated rotational speed, the multiple process target rotational speeds, and the corresponding required flow rates of the plunger pump;

[0041] Determining and calculating a calculated current and a plurality of target currents of a solenoid valve of the plunger pump according to the calculated displacement and the plurality of process target displacements;

[0042] According to the plurality of target currents, the current of the solenoid valve of the plunger pump is controlled to be transformed step by step to the calculated current.

[0043] The present application also provides an electric excavator system, comprising:

[0044] A plurality of plunger pumps, each of which is provided with a solenoid valve;

[0045] a motor for controlling the rotational speed of the plurality of plunger pumps; and

[0046] A control device electrically connects the plurality of plunger pumps and the motor, the control device comprising a memory and a processor and a control program for the electric excavator system stored in the memory and executable on the processor, the control program for the electric excavator system being configured to implement the steps of the control method for the electric excavator system according to any one of claims 1 to 9.

[0047] In the control method of the electric excavator system provided in the present application, multiple plunger pumps are connected in series and controlled by the same motor, wherein the initial speed is obtained by comprehensively considering the required flow rates of the multiple plunger pumps, and the calculated speed is obtained by adjusting the initial speed, so that the calculated speed can not only meet the efficient operation of the motor, but also make each plunger pump in an efficient working range with a larger displacement, so that the comprehensive efficiency of the plunger pump and the motor is optimized by controlling the speed and solenoid valve under the condition that the flow rate of each plunger pump remains unchanged, and under the same working conditions, the energy consumption is lower and the endurance time is longer. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] FIG1 is a schematic structural diagram of an electric excavator system provided in an embodiment of the present application;

[0049] FIG2 is a flowchart of an electric excavator system control method provided by an embodiment of the present application;

[0050] FIG3 is a flowchart of an embodiment of a control method for the electric excavator system in FIG2 .

[0051] Description of Figure Numbers:

[0052] The realization of the objectives, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0053] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0054] It should be noted that if the embodiments of the present application involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.

[0055] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present application, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the meaning of "and / or" appearing throughout the text includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme in which A and B are satisfied at the same time. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement it. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0056] As society pays more attention to environmental protection, traditional excavators are no longer suitable for new environmental requirements; among them, electric excavators are gradually becoming a new development direction.

[0057] Most of the current pure electric excavators directly use the control strategy of traditional diesel engines. The speed remains unchanged during operation, and the power adjustment relies solely on the adjustment of the main pump displacement. This makes the efficiency adjustment of the electric excavator power system very limited, resulting in partial energy waste, increasing the energy consumption of the entire vehicle, and shortening the vehicle's cruising time. In order to ensure the normal use of the pure electric excavator, the weight of the battery has to be increased, resulting in a further increase in the weight and cost of the entire vehicle.

[0058] Please refer to FIG. 1 . The present application provides an electric excavator system 100 , comprising a plurality of plunger pumps 1 and a motor 2 . Each plunger pump 1 is provided with a solenoid valve. The motor 2 is used to control the rotation speed of the plurality of plunger pumps 1 .

[0059] In the electric excavator system 100 provided in the present application, a single motor 2 is used to control multiple plunger pumps 1 in series, wherein the multiple plunger pumps 1 supply oil to different actuators respectively. Since different actuators have different working states, their required flow rates are inconsistent. By comprehensively considering the working efficiency of the motor 2 and the multiple plunger pumps 1, it is convenient to control the working efficiency of the entire system.

[0060] It should be noted that during the operation of the plunger pump, when the required flow rate is constant, the displacement of the plunger pump and the speed of the motor are set inversely proportional, and the displacement and speed respectively affect the working efficiency of the motor 2 and the plunger pump 1. When the displacement increases, the efficiency of the plunger pump 1 increases, and when the speed increases, the efficiency of the motor 2 increases. Therefore, it is necessary to simultaneously meet the requirements that the motor 2 is in the largest speed range and the displacement of multiple plunger pumps 1 are in a larger range, so that the working efficiency of the entire system can be maximized.

[0061] It should be noted that, in this embodiment, the motor 2 drives and controls the rotation speeds of the plurality of plunger pumps 1 simultaneously, so that the plunger pumps generate corresponding flow rates and displacements.

[0062] Furthermore, the electric excavator system 100 further includes a plurality of pressure sensors 3 , which are respectively provided corresponding to the plurality of plunger pumps 1 , so as to detect the pressure of the plunger pumps.

[0063] On the other hand, the electric excavator system 100 further includes a control device, which electrically connects the plurality of plunger pumps 1 and the motor 2 to control the switching of the solenoid valves of the plunger pumps 1 and the rotation of the motor 2 .

[0064] Optionally, the control device includes a memory, a processor, and a control program of the electric excavator system stored in the memory, and the processor executes the control program of the electric excavator system to implement the following control method of the electric excavator system:

[0065] Obtaining the pump body pressure and pilot pressure of each plunger pump;

[0066] determining the required flow rate of each plunger pump according to the pump body pressure and the pilot pressure;

[0067] Determining the initial calculated speed of the motor according to the required flow of each plunger pump;

[0068] Determining a calculated speed of the motor according to the initially calculated speed;

[0069] Determining a speed adjustment strategy for the motor according to the calculated speed, and controlling the motor to adjust the speed according to the speed adjustment strategy;

[0070] According to the calculated rotational speed and the required flow of each plunger pump, a displacement adjustment strategy of each plunger pump is determined, and the corresponding plunger pump is controlled to adjust the displacement according to each displacement adjustment strategy.

[0071] Optionally, determining the initial calculated rotation speed of the motor according to the required flow rate of each plunger pump includes:

[0072] selecting a maximum value among the plurality of required flow rates as a reference flow rate;

[0073] The initial rotational speed is calculated based on the reference flow rate.

[0074] Optionally, calculating the initial rotational speed according to the reference flow rate includes:

[0075] Obtaining a set displacement of the plunger pump corresponding to the reference flow rate;

[0076] Selecting the maximum value among the set displacements as the reference displacement;

[0077] The initial rotational speed is calculated based on the reference flow rate and the reference displacement.

[0078] Optionally, determining the calculated speed of the motor according to the initially calculated speed includes:

[0079] Determine the weight adjustment coefficient;

[0080] Obtaining limiting parameters of the motor;

[0081] The calculated speed of the motor is determined according to the initially calculated speed, the weight adjustment coefficient and the limit parameter.

[0082] Optionally, determining the weight adjustment coefficient includes:

[0083] Obtaining the starting pressure and maximum pressure of a system composed of a plurality of plunger pumps;

[0084] Determining the average pressure of each plunger pump according to the pump body pressure of each plunger pump;

[0085] A weight adjustment coefficient is determined according to the average pressure and the starting pressure.

[0086] Optionally, determining a weight adjustment coefficient according to the average pressure and the starting pressure includes:

[0087] When the average pressure is greater than the starting pressure, determining the weight adjustment coefficient to be a first fixed value;

[0088] When the average pressure is less than the starting pressure, the weight adjustment coefficient is calculated and determined according to the average pressure, the starting pressure, and the maximum pressure.

[0089] Optionally, the limiting parameters include a limited torque and a limited power of the motor.

[0090] Optionally, determining a speed adjustment strategy for the motor according to the calculated speed, and controlling the motor to adjust the speed according to the speed adjustment strategy includes:

[0091] Obtaining the current speed of the motor;

[0092] At the current speed, the preset speed step values ​​are progressively increased in sequence to obtain a plurality of process target speeds between the current speed and the calculated speed;

[0093] According to the plurality of process target speeds, the motor speed is controlled to change step by step from the current speed to the calculated speed.

[0094] Optionally, determining a displacement adjustment strategy for each plunger pump according to the calculated rotational speed and the required flow rate of each plunger pump, and controlling each corresponding plunger pump to adjust its displacement according to each displacement adjustment strategy includes:

[0095] Determine and obtain the calculated displacement and multiple process target displacements corresponding to the plunger pump according to the calculated rotational speed, the multiple process target rotational speeds, and the corresponding required flow rates of the plunger pump;

[0096] Determining and calculating a calculated current and a plurality of target currents of a solenoid valve of the plunger pump according to the calculated displacement and the plurality of process target displacements;

[0097] According to the plurality of target currents, the current of the solenoid valve of the plunger pump is controlled to be transformed step by step to the calculated current.

[0098] In the control method of the electric excavator system provided in the present application, multiple plunger pumps 1 are connected in series and controlled by the same motor 2, wherein the initial speed is obtained by comprehensively considering the required flow of multiple plunger pumps 1, and the initial speed is adjusted so that the initial speed can not only meet the efficient operation of the motor, but also make each plunger pump 1 in an efficient working range with a larger displacement, so that the comprehensive efficiency of the plunger pump 1 and the motor 2 is optimized by controlling the speed and solenoid valve while keeping the flow of each plunger pump 1 unchanged, and under the same working conditions, the energy consumption is lower and the endurance time is longer.

[0099] Referring to FIG. 2 and FIG. 3 , the present application further provides a control method for an electric excavator system, the control method comprising:

[0100] S10, obtaining the pump body pressure and pilot pressure of each plunger pump;

[0101] Among them, the multiple plunger pumps 1 supply oil to different actuators respectively, so that the pump body pressures on the multiple plunger pumps 1 are different, and thus the working states required on different plunger pumps 1 are different. Therefore, when controlling the electric excavator system, it is necessary to first obtain the working conditions of each of the plunger pumps 1 at this time, and judge the state of each of the plunger pumps 1 at this time based on the actual pump body pressure and pilot pressure.

[0102] It should be noted that the pump body pressure is obtained through a pressure sensor; and the pilot pressure is a preset reference value for each of the plunger pumps 1. When the electric excavator is working, different actuators generate different pressure values, which makes the pump body pressure generated on each of the plunger pumps 1 different. The pilot pressure is combined to facilitate the subsequent accurate control of the state of the plunger pump 1.

[0103] S20, determining the required flow rate of each plunger pump according to the pump body pressure and the pilot pressure;

[0104] After obtaining the pump body pressure and the pilot pressure, the required flow rate of the plunger pump 1 required to complete a series of action requirements can be determined to ensure that the required flow rate can respond according to the change of the pump body pressure.

[0105] It should be noted that, in this embodiment, the required flow rate can be matched with the pump body pressure and the pilot pressure according to actual test results, as long as the required flow rate on each plunger pump 1 can be determined according to the pump body pressure.

[0106] S30, determining the initial calculated speed of the motor according to the required flow of each plunger pump;

[0107] After the required flow rates of the plunger pumps 1 are obtained, the initial calculated speed of the motor 2 can be determined according to the multiple required flow rates, so as to control the motor 2 according to the initial calculated speed.

[0108] It should be noted that the flow rate and speed satisfy the following relationship: n=Q / q

[0109] Among them, n is the speed, Q is the flow rate, and q is the displacement.

[0110] S40, determining a calculated speed of the motor according to the initially calculated speed;

[0111] Among them, since the required flow rates among the multiple plunger pumps 1 are different, the actual required speeds are different. In order to improve the control efficiency of the motor 2 over the multiple plunger pumps 1, it is necessary to adjust the initial calculated speed so that the motor 2 can not only meet the efficiency of the multiple plunger pumps 1, but also be in a speed range with higher working efficiency.

[0112] It should be noted that for a motor, the efficiency of the motor is related to both the speed and the torque. In the working range where the torque is large and the speed is small, the working efficiency is higher.

[0113] S50, determining a speed adjustment strategy for the motor according to the calculated speed, and controlling the motor to adjust the speed according to the speed adjustment strategy;

[0114] Among them, after obtaining the adjusted calculated speed, the control target that the motor 2 ultimately needs to achieve can be obtained based on the calculated speed, and the motor can be controlled according to the preset adjustment strategy, so that the motor 2 can still be in a high working efficiency area when controlling multiple plunger pumps 1 at the same time.

[0115] S60 , determining a displacement adjustment strategy for each of the plunger pumps based on the calculated rotational speed and the required flow rate of each of the plunger pumps, and controlling the corresponding plunger pump to adjust the displacement according to each of the displacement adjustment strategies.

[0116] Among them, for each of the plunger pumps 1, the rotational speed has been obtained, and at the same time, the required flow rate under the corresponding working conditions has also been determined. Based on this, the displacement of each of the plunger pumps 1 can be obtained, and then according to the different displacement requirements of each of the plunger pumps 1, the plunger pump 1 can be controlled to adjust the solenoid valve therein, and then corresponding adjustments can be made, so that each of the plunger pumps 1 is also in the working range with the highest working efficiency.

[0117] It should be noted that, for a plunger pump, the greater the pressure and the higher the displacement, the higher the pump's working efficiency; therefore, when the pressure of each plunger pump is determined, the displacement is controlled to achieve the highest overall efficiency of the plurality of plunger pumps 1.

[0118] In the control method of the electric excavator system provided in the present application, multiple plunger pumps 1 are connected in series and controlled by the same motor 2, wherein the initial speed is obtained by comprehensively considering the required flow of multiple plunger pumps 1, and the initial speed is adjusted so that the initial speed can not only meet the efficient operation of the motor, but also make each plunger pump 1 in an efficient working range with a larger displacement, so that the comprehensive efficiency of the plunger pump 1 and the motor 2 is optimized by controlling the speed and solenoid valve while keeping the flow of each plunger pump 1 unchanged, and under the same working conditions, the energy consumption is lower and the endurance time is longer.

[0119] Optionally, step S30 includes:

[0120] S31, selecting a maximum value among the plurality of required flow rates as a reference flow rate;

[0121] In this embodiment, without considering the displacement, the greater the required flow rate, the faster the speed. According to the relationship between the flow rate, displacement, and speed, a higher calculated speed can be achieved. On this basis, the working efficiency of the motor 2 can be improved while meeting the needs of the pump body.

[0122] S32. Calculate an initial rotational speed based on the reference flow rate.

[0123] After obtaining the maximum value as the reference flow rate, calculation is performed using the maximum value to obtain the initial speed.

[0124] Specifically, step S32 includes:

[0125] S321, obtaining a set displacement of the plunger pump corresponding to the reference flow rate;

[0126] After obtaining the reference flow rate, the corresponding plunger pump 1 has a set displacement. In order to facilitate the calculation of the speed required by the plunger pump 1 at this time, it is necessary to obtain the set displacement of the plunger pump 1.

[0127] S322, selecting the maximum value among the set displacements as a reference displacement;

[0128] Since the larger the displacement, the higher the working efficiency of the plunger pump 1, and at the same time, the variation range of the pump efficiency is much greater than that of the motor efficiency, it is believed that the system efficiency can be improved by making the pump work under a large displacement condition by comprehensively considering the highest system efficiency. Therefore, it is necessary to use the maximum value of the set displacement as the reference displacement for calculating the speed.

[0129] S323. Calculate an initial rotational speed based on the reference flow rate and the reference displacement.

[0130] Taking the maximum value of the reference flow rate can ensure that the motor speed is as high as possible to ensure that the motor 2 has a higher working efficiency. At the same time, taking the maximum displacement as the reference displacement can ensure that the pump has a higher working efficiency, thereby improving the working efficiency of the entire system.

[0131] On the other hand, step S40 includes:

[0132] S41. Determine a weight adjustment coefficient;

[0133] After obtaining the initial speed, directly controlling the motor to rotate according to the initial speed may cause damage to the motor and fail to meet the normal operation of the motor. Therefore, weighted control of the motor is required to ensure the normal operation of the motor.

[0134] S42, obtaining limiting parameters of the motor;

[0135] The limiting parameters of the motor 2 are obtained to determine the basic value of subsequent weighting.

[0136] S43. Determine the calculated speed of the motor according to the initially calculated speed, the weight adjustment coefficient, and the limit parameter.

[0137] According to the limiting parameter and the initially calculated speed, the initially calculated speed is weighted to the basic value brought by the limiting parameter in a weighted manner, which can ensure the efficient operation of the motor 2 and the safety of the motor 2 at the same time.

[0138] Specifically, step S41 includes:

[0139] S411, obtaining the starting pressure and maximum pressure of the system composed of multiple plunger pumps;

[0140] The system composed of the plunger pump 1 ensures the normal operation of the entire system by adjusting the starting pressure and the maximum pressure. Therefore, before controlling the motor, the weight needs to be determined according to the pressure conditions on the plunger pump 1.

[0141] S412, determining an average pressure of each plunger pump according to the pump body pressure of each plunger pump;

[0142] The weight of the initially calculated rotational speed is determined according to the average pressure on each plunger pump 1 , thereby ensuring that the initially calculated rotational speed can adapt to the average pressure on the plunger pump 1 .

[0143] S413: Determine a weight adjustment coefficient according to the average pressure and the starting pressure.

[0144] In this embodiment, the weight of the initial calculated speed of the motor 2 is determined based on the relationship between the average pressure and the starting pressure to ensure that the normal operation of the plurality of plunger pumps is guaranteed while ensuring the efficient operation of the motor.

[0145] Specifically, step S413 includes:

[0146] S4131: When the average pressure is greater than the starting pressure, determine the weight adjustment coefficient to be a first fixed value;

[0147] S4132: When the average pressure is less than the starting pressure, determine the weight adjustment coefficient based on the average pressure, the starting pressure, and the maximum pressure.

[0148] Specifically, the weight adjustment coefficient is determined by calculating the average pressure, the starting pressure, and the maximum pressure to satisfy the following relationship: k=(p avg -p sta ) / (p max -p sta )

[0149] Wherein, k is the weight adjustment coefficient, p avg is the average pressure, the p sta is the starting pressure, the p max is the maximum pressure.

[0150] Optionally, the starting pressure satisfies the following relationship: sta =tor / (2q max )

[0151] Among them, the q max is the reference displacement, that is, the maximum value of the set drift of the plunger pump 1 corresponding to the reference flow.

[0152] In addition, the limiting parameters include the limited torque and limited power of the motor.

[0153] Specifically, in this embodiment, step S43 satisfies the following relationship: c =k*(pow / tor)+(1-k)n c '

[0154] Among them, the n c is the calculated speed, k is the weight adjustment coefficient, pow is the limited power, tor is the limited torque, and n c’ is the initial speed.

[0155] In addition, in this embodiment, when the average pressure is less than the starting pressure, k is determined according to the average pressure;

[0156] When the average pressure is greater than the starting pressure, k is zero, so that the calculated speed is equal to the initially calculated speed.

[0157] On the other hand, step S50 includes:

[0158] S51, obtaining the current rotation speed of the motor;

[0159] S52, at the current speed, sequentially incrementing preset speed step values ​​to obtain a plurality of process target speeds between the current speed and the calculated speed;

[0160] S53. According to the plurality of process target speeds, control the motor speed to change step by step from the current speed to the calculated speed.

[0161] In this embodiment, the motor 2 is controlled to change from the current speed to the calculated speed in a step-by-step manner, and the speed change rate of the motor 2 is controlled to ensure the change efficiency of the motor 2 and avoid increased energy consumption caused by direct adjustment.

[0162] Optionally, step S60 includes:

[0163] S61, determining and obtaining a calculated displacement and a plurality of process target displacements corresponding to the plunger pump according to the calculated rotational speed, the plurality of process target rotational speeds, and the corresponding required flow rates of the plunger pump;

[0164] According to the calculated speed and the plurality of target speeds, a target displacement corresponding to each speed can be obtained.

[0165] S62, determining and calculating a calculated current and a plurality of target currents of the solenoid valve of the plunger pump according to the calculated displacement and the plurality of process target displacements;

[0166] The solenoid valve of the plunger pump 1 can be controlled according to the target displacement, thereby obtaining a corresponding target current so that the plunger pump 1 adjusts the displacement to the target displacement.

[0167] S63. According to the plurality of target currents, control the current of the solenoid valve of the plunger pump to be transformed step by step to the calculated current.

[0168] In this embodiment, the rotation speed of the motor 2 is adjusted step by step, and the corresponding solenoid valve of the plunger pump 1 is also adjusted step by step synchronously, so that the two are adjusted together to meet the required flow rate and at the same time ensure the overall working efficiency of the entire system.

[0169] It should be noted that the target current and the target displacement satisfy the following relationship: I = I min +(q 1r -q min )(I max -I min ) / (q max -q min )

[0170] Wherein, I is the target current, I min is the minimum current of the solenoid valve, I max is the maximum current of the solenoid valve, q min is the minimum displacement of the corresponding plunger pump, q max is the reference displacement, q 1r is the target displacement.

[0171] The above are only preferred embodiments of the present application and do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A control method for an electric excavator system, characterized in that: The electric excavator system includes a motor and a plurality of plunger pumps drivingly connected to the motor; The control method comprises: Obtaining the pump body pressure and pilot pressure of each plunger pump; Determining the required flow rate of each plunger pump according to the pump body pressure and the pilot pressure; Determining the initial speed of the motor according to the required flow of each plunger pump; Determining a calculated speed of the motor according to the initially calculated speed; Determining a speed adjustment strategy for the motor according to the calculated speed, and controlling the motor to adjust the speed according to the speed adjustment strategy; According to the calculated rotation speed and the required flow rate of each plunger pump, the displacement adjustment strategy of each plunger pump is determined, and the corresponding plunger pump is controlled to adjust the displacement according to each displacement adjustment strategy.

2. The control method of the electric excavator system according to claim 1, characterized in that: The step of determining the initial speed of the motor according to the required flow of each plunger pump comprises: Selecting a maximum value among the plurality of required flow rates as a reference flow rate; The initial rotation speed is calculated based on the reference flow rate.

3. The control method of the electric excavator system according to claim 2, characterized in that: The step of calculating the initial speed according to the reference flow rate includes: Obtaining a set displacement of the plunger pump corresponding to the reference flow rate; Selecting the maximum value among the set displacements as the reference displacement; The initial rotational speed is calculated based on the reference flow rate and the reference displacement.

4. The control method of the electric excavator system according to claim 1, characterized in that: Determining the calculated speed of the motor according to the initially calculated speed includes: Determine the weight adjustment factor; Obtaining limiting parameters of the motor; The motor speed is determined according to the initial calculated speed, the weight adjustment coefficient and the limiting parameter. Calculate the speed.

5. The control method of the electric excavator system according to claim 4, characterized in that: The determining of the weight adjustment coefficient comprises: Obtaining the starting pressure and the maximum pressure of the system composed of a plurality of the plunger pumps; Determine the average pressure of each plunger pump according to the pump body pressure of each plunger pump; A weight adjustment coefficient is determined according to the average pressure and the starting pressure.

6. The control method of the electric excavator system according to claim 5, characterized in that: The determining of the weight adjustment coefficient according to the average pressure and the starting pressure includes: When the average pressure is greater than the starting pressure, determining the weight adjustment coefficient to be a first fixed value; When the average pressure is less than the starting pressure, the weight adjustment coefficient is calculated and determined according to the average pressure, the starting pressure and the maximum pressure.

7. The control method of the electric excavator system according to claim 4, characterized in that: The limiting parameters include a limited torque and a limited power of the motor.

8. The control method of the electric excavator system according to claim 1, characterized in that: The step of determining a speed adjustment strategy for the motor according to the calculated speed, and controlling the motor to adjust the speed according to the speed adjustment strategy includes: Obtaining the current speed of the motor; At the current speed, the preset speed step values ​​are progressively increased in sequence to obtain a plurality of process target speeds between the current speed and the calculated speed; According to the plurality of process target speeds, the motor speed is controlled to change step by step from the current speed to the calculated speed.

9. The control method of the electric excavator system according to claim 8, characterized in that: Determining the displacement adjustment strategy of each plunger pump according to the calculated rotation speed and the required flow rate of each plunger pump, and controlling the corresponding plunger pumps to adjust their respective displacements according to each displacement adjustment strategy, includes: According to the calculated rotation speed, the plurality of process target rotation speeds and the corresponding required flow rate of the plunger pump, determining and obtaining the calculated displacement corresponding to the plunger pump and the plurality of process target displacements; Determine and calculate a calculated current and a plurality of target currents of the solenoid valve of the plunger pump according to the calculated displacement and the plurality of process target displacements; According to the plurality of target currents, the current of the solenoid valve of the plunger pump is controlled to be transformed step by step to the calculated current.

10. An electric excavator system, characterized in that: include: A plurality of plunger pumps, each of which is provided with a solenoid valve; A motor, used to control the rotation speed of the plurality of plunger pumps; as well as, A control device electrically connects the plurality of plunger pumps and the motor, the control device comprising a memory and a processor and a control program for the electric excavator system stored in the memory and executable on the processor, the control program for the electric excavator system being configured to implement the steps of a control method for the electric excavator system as described in any one of claims 1 to 9.

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