Double-variable control method and device for rotating speed and displacement of electric drive pump

Abstract

The invention discloses an electric drive pump rotating speed and displacement double-variable control method and device. The method comprises the steps that whole vehicle working state information is obtained; according to the whole vehicle working state information, a double-variable control strategy under the corresponding working state is executed, and the double-variable control strategy under the corresponding working state comprises the steps that the rotating speed and the displacement value of an electric drive pump meeting the target flow request and the optimal electric drive pump system comprehensive efficiency under the current load pressure are determined; the optimal rotating speed and the optimal displacement of the electric drive pump are determined based on a displacement difference threshold value and the difference relation between the rotating speed and the displacement value of the electric drive pump meeting the target flow request and the optimal comprehensive efficiency of the electric drive pump system under the current load pressure and the current actual rotating speed and the displacement of the electric drive pump; and the electric drive pump is adjusted according to the optimal rotating speed and the optimal displacement of the electric drive pump. The system has the advantages that on the basis that the system flow requirement is met, the motor rotating speed and the pump displacement are adjusted to the optimal working state, and high system efficiency is obtained.

Description

Technical Field

[0001] The invention relates to a method and device for controlling the speed and displacement of an electric drive pump, and belongs to the technical field of new energy engineering machinery. Background Art

[0002] As the new energy source that has received the most attention at present, the application and value of new energy in the field of engineering machinery are gradually becoming prominent. It provides more efficient, environmentally friendly and energy-saving solutions for engineering construction, and promotes the electrification and intelligent development of engineering machinery. Excavators play an important role in engineering construction and maintain a growth trend. The electrification development of excavators continues to accelerate. At present, the configuration commonly used by electric excavators is the oil-to-electric method, that is, the electric motor replaces the engine as the power source, and the traditional hydraulic system remains unchanged. Although the efficiency of the whole machine has been improved on the basis of the fuel model, the overall energy efficiency is low, the cost is high, and the competitiveness is weaker than the traditional model. It is urgent to upgrade the technical architecture.

[0003] The electrification of excavators has promoted the application of electric drive pump technology in excavators. Compared with the traditional engine-driven hydraulic system, the electric drive pump increases the speed and efficiency of the pump, thereby greatly improving the energy utilization efficiency of the excavator, and can achieve a greater workload under the same energy consumption. Moreover, by driving the high-speed pump with a motor, the response speed is faster, the control is more precise, and more precise operation can be achieved. Dual variable control of the electric drive pump system can greatly reduce the size of the motor, make the structure more compact, help save space, reduce the weight of the whole machine, and further reduce energy consumption.

[0004] In view of the electrification of the hydraulic drive system of the excavator, the existing technology has realized the application of motor-driven pumps and control methods on the excavator. However, the electric drive pump system only controls a single variable of speed or displacement, and does not realize dual variable control of flow and displacement. The overall efficiency of the system is limited compared with traditional fuel excavators. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a method and device for dual-variable control of the speed and displacement of an electric drive pump.

[0006] In order to solve the above technical problems, the present invention is implemented by adopting the following technical solutions.

[0007] On the one hand, the present invention discloses a method for controlling the speed and displacement of an electric drive pump, comprising: Obtain vehicle working status information; The dual-variable control strategy under the corresponding working state is executed according to the vehicle working state information, and the dual-variable control strategy under the corresponding working state includes: Determine the electric pump speed and displacement values ​​that meet the target flow request and the optimal electric pump system comprehensive efficiency under the current load pressure; determine the optimal speed and optimal displacement of the electric pump based on a preset displacement difference threshold value based on the current load pressure and the difference between the electric pump speed and displacement values ​​that meet the target flow request and the optimal electric pump system comprehensive efficiency under the current load pressure and the current actual electric pump speed and displacement; The electric drive pump is adjusted according to the optimal rotation speed and optimal displacement of the electric drive pump.

[0008] Furthermore, it also includes determining a corresponding control current according to the optimal displacement, calculating a difference between the control current corresponding to the optimal displacement and the control current corresponding to the current actual displacement, and using a segmented PID algorithm in a closed loop to calculate a final output displacement; The formula for calculating the final output displacement using the segmented PID algorithm closed loop is: ; Where: n for the current moment; V ( n ) is the output displacement at the current moment, which is used as the final output displacement output; Δ I ( n ), Δ I ( n -1) are the differences between the target current value and the actual current value at the current moment and the previous moment respectively; Δ I ( i ) is the i The difference between the target current value and the actual current value at the moment, i ∈[0, n ]; P , I , D are respectively a proportional parameter, an integral parameter, and a differential parameter; the target current value is the control current determined by the optimal displacement at the corresponding moment, and the actual current value is the current corresponding to the actual output flow of the electric drive pump collected at the corresponding moment.

[0009] Furthermore, the obtaining of vehicle working status information includes: Get current traffic request Q K , calculate the current traffic request value Q K The target flow value at the previous moment Q K-1 The flow difference between the changes Δ Q ; Determine the flow difference Δ Q The absolute value of the lower threshold Q minThe relationship between the flow difference Δ Q The absolute value is greater than the set threshold low point Q min , send target traffic Q Equal to the current traffic request value Q K ; Such as flow difference Δ Q The absolute value is not greater than the set threshold low point Q min , then the target flow Q Equal to the target flow value at the previous moment Q K-1 ; Determine the flow difference Δ Q Set the acceleration threshold high Q max The relationship between the flow difference Δ Q Greater than the acceleration threshold high point Q max , output the vehicle working status information as acceleration state; Determine the flow difference Δ Q With the deceleration threshold set high - Q max The relationship between the flow difference Δ Q Less than deceleration threshold high - Q max , output the vehicle working state information as deceleration state; If the flow difference Δ Q Located at the high point of the set acceleration threshold Q max With the deceleration threshold set high - Q max The output vehicle working status information is in a stable state; If the target flow value at the previous moment Q K-1 Not 0, current traffic request value Q K If it is 0 and the current action handle opening is 0, the output vehicle working status information is the loaded state; If the target flow value at the previous moment Q K-1 0, current traffic request value Q K If the value is 0 and the opening of the action handle is 0 and it lasts for a preset time, the output vehicle working status information is the shutdown state.

[0010] Furthermore, the dual variable control strategy includes: The maximum allowable speed is calculated based on the target flow and the allowable range of the current displacement opening. Speed maxand the minimum allowable speed Speed min ; Based on speed interval Speed Intal Set N speed selection points at equal intervals within the speed allowable range; Calculate the comprehensive efficiency of the electric-driven pump system at each speed selection point, and rank the comprehensive efficiency of the electric-driven pump system at each speed selection point from high to low; According to the sorting results, the differences between the speed and displacement of the speed selection point corresponding to the comprehensive efficiency of the electric drive pump system and the current actual speed and displacement are calculated in sequence from high to low, until the calculated differences are all less than the corresponding set thresholds, and the speed and displacement of the speed selection point corresponding to the comprehensive efficiency of the electric drive pump system at this time are taken as the optimal speed and optimal displacement of the electric drive pump.

[0011] Furthermore, the calculation process of the comprehensive efficiency of the electric drive pump system includes: The displacement value is determined according to the target flow and speed selection point, the required torque is determined according to the displacement value and the current load pressure, and the motor efficiency of each speed selection point is obtained by looking up the motor efficiency MAP diagram according to the speed selection point and the required torque value; the pump efficiency of each speed selection point is obtained by looking up the pump efficiency MAP diagram according to the current load pressure, speed selection point and displacement value; the comprehensive efficiency of the electric drive pump system is obtained by multiplying the motor efficiency by the pump efficiency.

[0012] Further, the adjusting the electric drive pump according to the optimal speed and optimal displacement of the electric drive pump includes: When the working status information of the whole vehicle is the acceleration state, the current speed value of the electric drive pump is fixed unchanged, the optimal displacement is taken as the target displacement to adjust the displacement of the electric drive pump, and the electric drive pump displacement adjustment value is monitored in real time. When it is monitored that the electric drive pump displacement adjustment value reaches a set percentage of the target displacement, the optimal speed is taken as the target speed to adjust the speed of the electric drive pump, so that the displacement and speed of the electric drive pump are adjusted to the optimal speed and optimal displacement at the same time.

[0013] Further, the adjusting the electric drive pump according to the optimal speed and optimal displacement of the electric drive pump includes: When the vehicle working state information is a deceleration state, the current displacement value of the fixed electric drive pump remains unchanged, and the speed of the electric drive pump is adjusted individually according to the target flow demand and the current displacement value; After adjusting individually to meet the target flow requirement, the current speed value of the electric drive pump is fixed unchanged, the optimal displacement is used as the target displacement to adjust the displacement of the electric drive pump, and the electric drive pump displacement adjustment value is monitored in real time. When it is monitored that the electric drive pump displacement adjustment value reaches a set percentage of the target displacement, the optimal speed is used as the target speed to adjust the speed of the electric drive pump, so that the displacement and speed of the electric drive pump are simultaneously adjusted to the optimal speed and optimal displacement.

[0014] Further, the adjusting the electric drive pump according to the optimal speed and optimal displacement of the electric drive pump includes: When the vehicle working state information is in a stable state, the opening allowable range of the current displacement is set to be not less than 50%, and the dual variable control strategy is used to determine the optimal speed and optimal displacement of the electric drive pump that meets the opening allowable range of not less than 50%; The current speed value of the electric drive pump is fixed unchanged, the optimal displacement of the electric drive pump that meets the allowable opening range of not less than 50% is used as the target displacement to adjust the displacement of the electric drive pump, and the electric drive pump displacement adjustment value is monitored in real time. When it is monitored that the electric drive pump displacement adjustment value reaches the set percentage of the target displacement, the optimal speed of the electric drive pump that meets the allowable opening range of not less than 50% is used as the target speed to adjust the speed of the electric drive pump, so that the displacement and speed of the electric drive pump are simultaneously adjusted to the optimal speed and optimal displacement.

[0015] Furthermore, the percentage is calculated as follows: ; Where: E is a percentage; T P is the pump displacement response time of the electric drive pump; T M is the motor speed response time of the electric drive pump.

[0016] Further, the adjusting the electric drive pump according to the optimal speed and optimal displacement of the electric drive pump includes: When the vehicle working status information is a loaded state, the opening of the electric drive pump is reduced to a preset opening value and remains unchanged, and the speed of the motor of the electric drive pump is reduced to a preset speed value and remains unchanged.

[0017] Further, the adjusting the electric drive pump according to the optimal speed and optimal displacement of the electric drive pump includes: When the vehicle working status information is a shutdown state, the opening of the electric drive pump is reduced to a preset opening value and remains unchanged, and the speed of the motor of the electric drive pump is reduced to 0.

[0018] In a second aspect, the present invention discloses a speed and displacement dual-variable control device for an electric drive pump, comprising: The acquisition module is used to obtain the working status information of the whole vehicle; The strategy control module is used to execute the dual-variable control strategy in the corresponding working state according to the vehicle working state information, and the dual-variable control strategy in the corresponding working state includes: Determine the electric pump speed and displacement values ​​that meet the target flow request and the optimal electric pump system comprehensive efficiency under the current load pressure; determine the optimal speed and optimal displacement of the electric pump based on a preset displacement difference threshold value based on the current load pressure and the difference between the electric pump speed and displacement values ​​that meet the target flow request and the optimal electric pump system comprehensive efficiency under the current load pressure and the current actual electric pump speed and displacement; The regulating module is used to regulate the electric drive pump according to the optimal rotation speed and optimal displacement of the electric drive pump.

[0019] The beneficial effects achieved by the present invention are: According to the flow request and load pressure, the comprehensive efficiency of the motor speed and pump displacement is traversed and optimized, and the optimal speed and displacement combination that can be executed under the current flow demand is output. On the basis of meeting the system flow demand, the motor speed and pump displacement are adjusted to the best working state to obtain higher system efficiency; the speed and displacement are controlled differently according to different operating conditions, and the system efficiency is maintained at a high level comprehensively considered, while ensuring the system responsiveness and stability; the speed and displacement corresponding to the optimal value of the system comprehensive efficiency traversed and screened are limited to ensure that the output values ​​of the speed and displacement are within a reasonable range with the current actual values, avoiding system oscillations. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is the structure diagram of the parallel high-speed electric drive pump system for excavators; Figure 2 It is a flow chart for judging the working status; Figure 3 This is the double variable control flow chart. DETAILED DESCRIPTION

[0021] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0022] Embodiment 1: This embodiment introduces a method for controlling the speed and displacement of an electric drive pump. According to the flow request and the load pressure, the motor speed and pump displacement are optimized for comprehensive efficiency, and the optimal speed and displacement combination that can be executed under the current flow demand is output. On the basis of meeting the system flow demand, the motor speed and pump displacement are adjusted to the optimal working state to obtain higher system efficiency. The steps include: Obtain vehicle working status information; The dual-variable control strategy under the corresponding working state is executed according to the vehicle working state information, and the dual-variable control strategy under the corresponding working state includes: Determine the electric pump speed and displacement values ​​that meet the target flow request and the optimal electric pump system comprehensive efficiency under the current load pressure; determine the optimal speed and optimal displacement of the electric pump based on a preset displacement difference threshold value based on the current load pressure and the difference between the electric pump speed and displacement values ​​that meet the target flow request and the optimal electric pump system comprehensive efficiency under the current load pressure and the current actual electric pump speed and displacement; The electric drive pump is adjusted according to the optimal rotation speed and optimal displacement of the electric drive pump.

[0023] The method further includes determining a corresponding control current according to the optimal displacement, calculating a difference between the control current corresponding to the optimal displacement and the control current corresponding to the current actual displacement, and using a segmented PID algorithm in a closed loop to calculate a final output displacement; The formula for calculating the final output displacement using the segmented PID algorithm closed loop is: ; Where: n for the current moment; V ( n ) is the output displacement at the current moment, which is used as the final output displacement output; Δ I ( n ), Δ I ( n -1) are the differences between the target current value and the actual current value at the current moment and the previous moment respectively; Δ I ( i ) is the i The difference between the target current value and the actual current value at the moment, i ∈[0, n ]; P , I , D are respectively a proportional parameter, an integral parameter, and a differential parameter; the target current value is the control current determined by the optimal displacement at the corresponding moment, and the actual current value is the current corresponding to the actual output flow of the electric drive pump collected at the corresponding moment.

[0024] The obtaining of vehicle working status information includes: Get current traffic request Q K , calculate the current traffic request value Q K The target flow value at the previous moment Q K-1 The flow difference between the changes Δ Q ; Determine the flow difference Δ Q The absolute value of the lower threshold Q min The relationship between the flow difference ΔQ The absolute value is greater than the set threshold low point Q min , send target traffic Q Equal to the current traffic request value Q K ; Such as flow difference Δ Q The absolute value is not greater than the set threshold low point Q min , then the target flow Q Equal to the target flow value at the previous moment Q K-1 ; Determine the flow difference Δ Q Set the acceleration threshold high Q max The relationship between the flow difference Δ Q Greater than the acceleration threshold high point Q max , output the vehicle working status information as acceleration state; Determine the flow difference Δ Q With the deceleration threshold set high - Q max The relationship between the flow difference Δ Q Less than deceleration threshold high - Q max , output the vehicle working state information as deceleration state; If the flow difference Δ Q Located at the high point of the set acceleration threshold Q max With the deceleration threshold set high - Q max The output vehicle working status information is in a stable state; If the target flow value at the previous moment Q K-1 Not 0, current traffic request value Q K If it is 0 and the current action handle opening is 0, the output vehicle working status information is the loaded state; If the target flow value at the previous moment Q K-1 0, current traffic request value Q K If the value is 0 and the opening of the action handle is 0 and it lasts for a preset time, the output vehicle working status information is the shutdown state.

[0025] The dual variable control strategy includes: The maximum allowable speed is calculated based on the target flow and the allowable range of the current displacement opening. Speed max and the minimum allowable speed Speedmin ; Based on speed interval Speed Intal Set N speed selection points at equal intervals within the speed allowable range; Calculate the comprehensive efficiency of the electric-driven pump system at each speed selection point, and rank the comprehensive efficiency of the electric-driven pump system at each speed selection point from high to low; According to the sorting results, the differences between the speed and displacement of the speed selection point corresponding to the comprehensive efficiency of the electric drive pump system and the current actual speed and displacement are calculated in sequence from high to low, until the calculated differences are all less than the corresponding set thresholds, and the speed and displacement of the speed selection point corresponding to the comprehensive efficiency of the electric drive pump system at this time are taken as the optimal speed and optimal displacement of the electric drive pump.

[0026] The calculation process of the comprehensive efficiency of the electric drive pump system includes: The displacement value is determined according to the target flow and speed selection point, the required torque is determined according to the displacement value and the current load pressure, and the motor efficiency of each speed selection point is obtained by looking up the motor efficiency MAP diagram according to the speed selection point and the required torque value; the pump efficiency of each speed selection point is obtained by looking up the pump efficiency MAP diagram according to the current load pressure, speed selection point and displacement value; the comprehensive efficiency of the electric drive pump system is obtained by multiplying the motor efficiency by the pump efficiency.

[0027] The step of adjusting the electric drive pump according to the optimal speed and optimal displacement of the electric drive pump comprises: When the working status information of the whole vehicle is the acceleration state, the current speed value of the electric drive pump is fixed unchanged, the optimal displacement is taken as the target displacement to adjust the displacement of the electric drive pump, and the electric drive pump displacement adjustment value is monitored in real time. When it is monitored that the electric drive pump displacement adjustment value reaches a set percentage of the target displacement, the optimal speed is taken as the target speed to adjust the speed of the electric drive pump, so that the displacement and speed of the electric drive pump are adjusted to the optimal speed and optimal displacement at the same time.

[0028] The step of adjusting the electric drive pump according to the optimal speed and optimal displacement of the electric drive pump comprises: When the vehicle working state information is a deceleration state, the current displacement value of the fixed electric drive pump remains unchanged, and the speed of the electric drive pump is adjusted individually according to the target flow demand and the current displacement value; After adjusting individually to meet the target flow requirement, the current speed value of the electric drive pump is fixed unchanged, the optimal displacement is used as the target displacement to adjust the displacement of the electric drive pump, and the electric drive pump displacement adjustment value is monitored in real time. When it is monitored that the electric drive pump displacement adjustment value reaches a set percentage of the target displacement, the optimal speed is used as the target speed to adjust the speed of the electric drive pump, so that the displacement and speed of the electric drive pump are simultaneously adjusted to the optimal speed and optimal displacement.

[0029] The step of adjusting the electric drive pump according to the optimal speed and optimal displacement of the electric drive pump comprises: When the vehicle working state information is in a stable state, the opening allowable range of the current displacement is set to be not less than 50%, and the dual variable control strategy is used to determine the optimal speed and optimal displacement of the electric drive pump that meets the opening allowable range of not less than 50%; The current speed value of the electric drive pump is fixed unchanged, the optimal displacement is used as the target displacement to adjust the displacement of the electric drive pump, and the electric drive pump displacement adjustment value is monitored in real time. When it is monitored that the electric drive pump displacement adjustment value reaches a set percentage of the target displacement, the optimal speed is used as the target speed to adjust the speed of the electric drive pump, so that the displacement and speed of the electric drive pump are simultaneously adjusted to the optimal speed and optimal displacement.

[0030] The percentage is calculated as follows: ; Where: E is a percentage; T P is the pump displacement response time of the electric drive pump; T M is the motor speed response time of the electric drive pump.

[0031] The step of adjusting the electric drive pump according to the optimal speed and optimal displacement of the electric drive pump comprises: When the vehicle working status information is a loaded state, the opening of the electric drive pump is reduced to a preset opening value and remains unchanged, and the speed of the motor of the electric drive pump is reduced to a preset speed value and remains unchanged.

[0032] The step of adjusting the electric drive pump according to the optimal speed and optimal displacement of the electric drive pump comprises: When the vehicle working status information is a shutdown state, the opening of the electric drive pump is reduced to a preset opening value and remains unchanged, and the speed of the motor of the electric drive pump is reduced to 0.

[0033] Example 2 is based on the same inventive concept as Example 1. This example introduces a method for controlling the speed and displacement of an electric drive pump, which is applied to a high-speed electric drive pump system for a pure electric excavator. The system adopts a three-motor distributed drive, and the system structure is as shown in the attached figure. Figure 1As shown, it includes batteries, electric drive pump assemblies, distributed main valves, controllers, action handles, load sensors, etc. The battery is the power source of the system; the electric drive pump assembly is a component assembly that integrates the motor, motor controller, and high-speed pump; three high-speed electric drive pump assemblies are connected together in parallel to jointly provide the required flow for the entire hydraulic system; the action handle is divided into three opening ranges: neutral, forward extension, and backward pull. The handle opening corresponds to the target flow request size. The corresponding flow request is 0 when in the neutral position. The larger the opening in the forward extension or backward pull range, the larger the corresponding target flow; the controller receives the flow request value of the handle and the pressure information fed back by the load sensor, and after calculation, sends the required speed and displacement to the high-speed electric drive pump assembly to achieve the target flow requirement; This method performs dual-variable control on the speed and displacement output by the electric drive pump system. The specific execution process includes the following steps: vehicle working state judgment, electric drive pump speed, displacement dual-variable control, system optimal comprehensive efficiency limitation, and demand displacement control, as shown below: S1. Vehicle working status judgment: According to the current flow request, the target flow value at the last moment, the set threshold low point, the set acceleration (deceleration) threshold high point, and the opening of the action handle, the target flow value and the current working state are determined. The state determination flow chart is as shown in the attached figure. Figure 2 shown.

[0034] The hydraulic controller collects the current flow request based on the handle signal Q K , the current traffic request Q K Sent to the vehicle controller, the vehicle controller program calculates the current traffic request value Q K The target flow value at the previous moment Q K-1 The difference between the changes Δ Q ; Determine the flow difference Δ Q The absolute value of the lower threshold Q min If the flow difference is greater than the set threshold low point, the target flow is sent. Q Equal to the current traffic request value Q K If the flow difference is less than the set threshold value, the target flow remains unchanged. Q K-1 .

[0035] Determine the flow difference Δ Q Set the acceleration threshold high Q max If the flow difference is greater than the set threshold high point, the system determines that it has entered the acceleration state; Determine the flow difference ΔQ With the deceleration threshold set high - Q max If the flow difference is less than the set threshold high point, the system will judge to enter the deceleration state; If the flow difference Δ Q Located at the high point of the set acceleration threshold Q max With the deceleration threshold set high - Q max The system determines that it has entered a stable operating state.

[0036] If the system's target flow value at the last moment Q K-1 Not 0, the current traffic request value Q K is 0, and the current action handle opening is 0, the system determines that it has entered the loaded state.

[0037] If the current system traffic request value Q K When the value is 0 and the opening of the action handle is 0, the system will enter the shutdown state when it determines that this state lasts for 5 seconds.

[0038] Q min , Q max The selection of usually needs to be calibrated based on actual vehicle testing. The following is a set of reference values ​​during the implementation process: Q min =10; Q max =50.

[0039] S2, electric drive pump speed and displacement dual variable control: The controller program receives the working status information sent by the vehicle, executes the dual-variable control strategy under the corresponding working status, and outputs the speed and displacement values ​​that meet the target flow request.

[0040] 1. Acceleration state: When the system judges that it has entered the acceleration state, the target flow demand increases rapidly. Because the response speeds of speed and displacement are inconsistent, the motor speed response speed is higher than the pump displacement response speed. If the speed and displacement are adjusted at the same time, the system is prone to jitter, affecting the working stability; and simply adjusting the displacement or speed is difficult to respond quickly to system needs, and the system efficiency cannot be guaranteed at a high level. At this time, the speed and displacement are screened at the same time according to the target flow demand, and the speed and displacement values ​​that meet the change gradient and have higher comprehensive efficiency are screened. First, the target speed value is fixed unchanged, the screened target displacement value is output, the pump displacement is adjusted, and the real-time displacement change value is detected. When it is detected that the displacement value is adjusted to the corresponding percentage of the target displacement value, the target speed output is executed at the same time, and the motor speed is adjusted to achieve the purpose of smooth system regulation. The control logic flow chart is as attached. Figure 3 As shown, the specific implementation is as follows: (1) Speed ​​selection point determination: The controller program calculates the maximum allowable speed based on the target flow and the allowable range of the current displacement (the minimum allowable displacement is limited to 50%, and the maximum allowable displacement is the maximum displacement supported by the hardware). Speed max and the minimum allowable speed Speed min . (The maximum displacement usually needs to be given in combination with the high-speed pump design parameters).

[0041] The allowable speed range is { Speed max , Speed min}; Within the permissible speed range, N Determine the speed interval by the principle of equal division and equal interval Speed Intal .

[0042] N is calibrated according to different test conditions. N =100; Set the value at equal intervals within the speed range N Speed ​​operating point: Speed 1= Speed min ; Speed 2= Speed min + Speed Intal* 1; Speed 3= Speed min + Speed Intal* 2; ……………… Speed N = Speed min + Speed Intal* ( N -1); (2) Determination of the optimal value of system comprehensive efficiency: According to the current target flow rate, the speed selection points and displacement values ​​that can meet the target flow rate request are traversed and optimized, and the speed and displacement values ​​that meet the flow request and have the highest system overall efficiency are calculated, and the motor speed and pump displacement at the next moment are output.

[0043] Comprehensive efficiency calculation module: The calculation module takes the target flow, system pressure, and speed selection point as input. The displacement value is determined by the target flow and speed selection point, and the required torque is determined by the displacement value and system pressure. The motor efficiency of each speed selection point can be obtained by looking up the speed selection point and the required torque value in the motor efficiency MAP diagram; the pump efficiency of each speed selection point can be obtained by looking up the system pressure, speed selection point, and displacement value in the pump efficiency MAP diagram; the product of the motor efficiency and the pump efficiency is the comprehensive efficiency of the electric drive pump system.

[0044] The specific mathematical formula is as follows: V = Q / n ´; T = VP * s ; Where: V is the target displacement; Q Request for target traffic; n ´ is the speed selection point; T is the required torque value; P is the system load pressure; s is the calculation coefficient; 2) Bring the first speed selection point into the comprehensive efficiency calculation module to calculate the system comprehensive efficiency of the first speed selection point η 1, and the efficiency value η 1 and the corresponding speed n 1´, Displacement V 1 is temporarily stored in the controller program efficiency position 1. Bring the second speed selection point into the comprehensive efficiency calculation module to calculate the comprehensive efficiency η 2. η 2 and temporarily stored in the controller program efficiency position 1 η If the values ​​are compared, η 2 is greater than η , then η 2. n 2´、 V 2 is temporarily stored in efficiency position 1, and the data in efficiency position 1 is replaced in efficiency position 2; if η 2 is less than the efficiency position 1 η , then η 2. n 2´、 V 2 is temporarily stored in efficiency position 2. The third speed selection point is brought into the comprehensive efficiency calculation module to calculate the comprehensive efficiency η 3. η 3 and the current stored in the controller program efficiency position 1 and efficiency position 2 in sequence η If the values ​​are compared, η 3 is greater than η value, then η 3. n 3´、 V 3 is temporarily stored in the corresponding efficiency position, and the data of the corresponding efficiency position is replaced by the next efficiency position in turn; if η 3 is less than η value, then η 3. n 3´、 V 3 is temporarily stored in efficiency position 3. The eleventh speed selection point is brought into the comprehensive efficiency calculation module to calculate the comprehensive efficiency η 11 ,Will η 11 Sequentially with the temporary controller program efficiency position 1 to 10 η If the values ​​are compared, η 11 Greater than η value, then η 11 , n 11 ´、 V 11 Temporarily stored in the corresponding efficiency position, the data of the corresponding efficiency position is replaced by the next efficiency position in turn; if η 11 Less than η value, then η 11 , n 11 ´、 V 11 Abandon. The program sets 10 efficiency positions in total, which are N The speed selection points are brought into the comprehensive efficiency calculation module to calculate the system comprehensive efficiency. According to the above traversal method, the N The top 10 speeds and displacements in terms of comprehensive efficiency among the speed selection points.

[0045] 3) Speed ​​and displacement interval adjustment: First, the target speed value is fixed, and the displacement value corresponding to the optimal value of the system's overall efficiency is screened out as the target displacement for output, and the pump displacement adjustment value is monitored in real time. When the pump displacement is monitored to be adjusted to the target displacement setting percentage, the target speed output is executed at the same time, and the motor speed is adjusted to ensure that the displacement and speed are adjusted to the value corresponding to the optimal value of the system's overall efficiency at the same time, ensuring the stability of the system adjustment. The target displacement percentage is usually calibrated according to the actual values ​​of the motor speed and pump displacement response speed, and the calculation formula is as follows: ; Where: E is a percentage; T P is the pump displacement response time of the electric drive pump; T M is the motor speed response time of the electric drive pump.

[0046] 2. Deceleration state: When the system judges that it has entered the deceleration state, the target flow demand decreases rapidly. At this time, in order to meet the operational safety requirements, the flow needs to be reduced as soon as possible. Because the response speed of the speed and displacement are inconsistent, if the speed and displacement are adjusted at the same time, it is difficult to quickly respond to the system flow demand. At this time, the fixed target displacement value remains unchanged from the previous moment, and the speed is controlled separately according to the target flow and the displacement value at the previous moment. The speed output value is used to adjust the motor speed to quickly reach the target flow demand, ensuring the timely response of the system flow. After the system target flow demand is reached, the aforementioned speed selection point is selected, and the speed and displacement are traversed and optimized according to the target flow allocation method to perform dual-variable control, so that the system efficiency remains at a high level. The specific implementation method is the same as that in the acceleration state.

[0047] 3. Steady state: When the system judges that it has entered a stable operation state, the change rate of the target flow is small. In order to improve the overall efficiency of the system, the speed and displacement are controlled in a dual variable manner. Due to the influence of the characteristics of the high-speed pump itself, the pump efficiency is greater when the displacement is larger, so the displacement value range is limited to more than 50%. At this time, the speed and displacement are controlled in a dual variable manner by selecting the above-mentioned speed point and traversing and optimizing according to the target flow distribution displacement. The specific implementation method is the same as that in the acceleration state.

[0048] 4. Load state: When the system determines that it has entered the loaded state, the target flow rate is reduced to 0. In order to be ready to respond to the next flow request at any time, combined with the characteristics of the electric drive pump's slow displacement response and fast speed response, the displacement value is reduced to 50% and remains unchanged, and the speed is reduced to 500r, and the system maintains a low flow output.

[0049] 5. Shutdown state: When the system judges that it has entered the shutdown state, the displacement is reduced to 50% and remains unchanged, the speed is reduced to 0, and the system output flow is 0.

[0050] S3, system optimal comprehensive efficiency limit: According to the relationship between the speed and displacement corresponding to the efficiency position and the current actual speed and displacement, the output value of the speed and displacement is judged. The logic judgment flow chart includes:

[0051] Determine the relationship between the speed and displacement corresponding to efficiency position 1 in the control program and the current actual speed and displacement, and take their differences respectively. If the differences in speed and displacement are both less than the set threshold, take the speed and displacement corresponding to efficiency position 1 as the output value.

[0052] If any difference is greater than the set threshold, the difference between the speed and displacement corresponding to efficiency position 2 and the current actual speed and displacement is calculated. If the difference between the speed and displacement is less than the set threshold, the speed and displacement corresponding to efficiency position 2 are taken as the output value.

[0053] If any of the speed and displacement differences corresponding to efficiency position 2 is greater than the set threshold, the efficiency positions 3 to 10 are traversed in sequence until the speed and displacement differences are both less than the set threshold, and the speed and displacement corresponding to the current efficiency position are output as the target speed and displacement.

[0054] In order to balance the requirements of response speed and stability under different load conditions, different threshold settings are used under different load pressures. When the load pressure is small, a smaller threshold is selected to ensure the stability of the system. When the load pressure is large, a larger threshold is selected to ensure that the system responds to flow requirements in a timely manner. The set threshold changes with the load pressure, and the set threshold under different load pressures is obtained by linear fitting through table lookup. The relationship between the threshold and load pressure usually needs to be calibrated based on actual vehicle tests. Table 1 gives a set of reference values ​​during the implementation process: Table 1 Pressure (bar) Speed ​​threshold (r / min) Displacement threshold (cc) 50 140 1.3 100 150 1.4 150 160 1.5 200 180 1.7 250 200 1.9 S4. Demand displacement control: According to the difference between the control current corresponding to the target displacement and the actual displacement, the segmented PID algorithm is used to calculate the PWM duty cycle of the current regulation in a closed loop.

[0055] S4. Demand displacement control: According to the difference between the control current corresponding to the target displacement and the actual displacement, the segmented PID algorithm is used to calculate the PWM duty cycle of the current regulation in a closed loop.

[0056] The selection of PID parameters depends on the load pressure and speed. The PID parameters are divided into 25 intervals in combination with the load pressure and speed. Each interval corresponds to a set of proportional parameters P, integral parameters I, and differential parameters D, so that when the load pressure and speed are greater, the output value of the target displacement is greater, and when the load pressure and speed are smaller, the output value of the target displacement is smaller, thereby improving the accuracy of displacement control and further improving the accuracy of flow control. The specific calculation method is as follows: ; Where: n for the current moment; V ( n ) is the output displacement at the current moment, which is used as the final output displacement output; Δ I ( n ), Δ I ( n -1) are the differences between the target current value and the actual current value at the current moment and the previous moment respectively; Δ I ( i ) is the i The difference between the target current value and the actual current value at the moment, i ∈[0, n ]; P , I , D are proportional parameter, integral parameter and differential parameter respectively; the target current value is the control current determined by the optimal displacement at the corresponding moment, and the actual current value is the current corresponding to the actual output flow of the electric drive pump collected at the corresponding moment; P , I , D The parameters are selected based on actual vehicle test calibration. Table 2 gives a set of reference values ​​during the implementation process.

[0057] Table 2 PID speed 0~50 50~100 100~150 150~200 200~250 0~1000 7 / 1.3 / 1 8 / 1.4 / 1 9 / 1.5 / 1 10 / 1.6 / 1 11 / 1.7 / 1 1000~2000 8 / 1.4 / 1 9 / 1.5 / 1 10 / 1.6 / 1 11 / 1.7 / 1 12 / 1.8 / 1 2000~3000 9 / 1.5 / 1 10 / 1.6 / 1 11 / 1.7 / 1 12 / 1.8 / 1 13 / 1.9 / 1 3000~4000 10 / 1.6 / 1 11 / 1.7 / 1 12 / 1.8 / 1 13 / 1.9 / 1 14 / 2 / 1 4000~5000 11 / 1.7 / 1 12 / 1.8 / 1 13 / 1.9 / 1 14 / 2 / 1 15 / 2.1 / 1

[0058] Embodiment 3 is based on the same inventive concept as Embodiment 1. This embodiment introduces a speed and displacement dual-variable control device for an electric drive pump, comprising: The acquisition module is used to obtain the working status information of the whole vehicle; The strategy control module is used to execute the dual-variable control strategy in the corresponding working state according to the vehicle working state information, and the dual-variable control strategy in the corresponding working state includes: Determine the electric pump speed and displacement values ​​that meet the target flow request and the optimal electric pump system comprehensive efficiency under the current load pressure; determine the optimal speed and optimal displacement of the electric pump based on a preset displacement difference threshold value based on the current load pressure and the difference between the electric pump speed and displacement values ​​that meet the target flow request and the optimal electric pump system comprehensive efficiency under the current load pressure and the current actual electric pump speed and displacement; The regulating module is used to regulate the electric drive pump according to the optimal rotation speed and optimal displacement of the electric drive pump.

[0059] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0060] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0061] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0062] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1The steps for the functions specified in one or more boxes.

[0063] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for controlling the speed and displacement of an electric pump, characterized in that: include: Get the working status information of the whole vehicle; The dual-variable control strategy under the corresponding working state is executed according to the vehicle working state information, and the dual-variable control strategy under the corresponding working state includes: Determine the electric pump speed and displacement values ​​that meet the target flow request and the optimal electric pump system comprehensive efficiency under the current load pressure; determine the optimal speed and optimal displacement of the electric pump based on a preset displacement difference threshold value based on the current load pressure and the difference between the electric pump speed and displacement values ​​that meet the target flow request and the optimal electric pump system comprehensive efficiency under the current load pressure and the current actual electric pump speed and displacement; The electric drive pump is adjusted according to the optimal rotation speed and optimal displacement of the electric drive pump.

2. The electric drive pump speed and displacement dual variable control method according to claim 1 is characterized in that: The method further includes determining a corresponding control current according to the optimal displacement, calculating a difference between the control current corresponding to the optimal displacement and the control current corresponding to the current actual displacement, and using a segmented PID algorithm in a closed loop to calculate a final output displacement; The formula for calculating the final output displacement using the segmented PID algorithm closed loop is: ； Where: n for the current moment; V ( n ) is the output displacement at the current moment, which is used as the final output displacement output; Δ I ( n ), Δ I ( n -1) are the differences between the target current value and the actual current value at the current moment and the previous moment respectively; Δ I ( i ) is the i The difference between the target current value and the actual current value at the moment, i ∈[0, n ]; P , I , D are respectively a proportional parameter, an integral parameter, and a differential parameter; the target current value is the control current determined by the optimal displacement at the corresponding moment, and the actual current value is the current corresponding to the actual output flow of the electric drive pump collected at the corresponding moment.

3. The electric drive pump speed and displacement dual variable control method according to claim 1 is characterized in that: The obtaining of vehicle working status information includes: Get current traffic request Q K , calculate the current traffic request value Q K The target flow value at the previous moment Q K-1 The flow difference between the changes Δ Q ; Determine the flow difference Δ Q The absolute value of the lower threshold Q min The relationship between the flow difference Δ Q The absolute value is greater than the set threshold low point Q min , send target traffic Q Equal to the current traffic request value Q K ; Such as flow difference Δ Q The absolute value is not greater than the set threshold low point Q min , then the target flow Q Equal to the target flow value at the previous moment Q K-1 ; Determine the flow difference Δ Q Set the acceleration threshold high point Q max The relationship between the flow difference Δ Q Greater than the acceleration threshold high point Q max , output the vehicle working status information as acceleration state; Determine the flow difference Δ Q With the deceleration threshold set high - Q max The relationship between the flow difference Δ Q Less than deceleration threshold high - Q max , output the vehicle working state information as deceleration state; If the flow difference Δ Q At the high point of the set acceleration threshold Q max With the deceleration threshold set high - Q max The output vehicle working status information is in a stable state; If the target flow value at the previous moment Q K-1 Not 0, current traffic request value Q K If it is 0 and the current action handle opening is 0, the output vehicle working status information is the loaded state; If the target flow value at the previous moment Q K-1 0, current traffic request value Q K If the value is 0 and the opening of the action handle is 0 and it lasts for a preset time, the output vehicle working status information is the shutdown state.

4. The electric drive pump speed and displacement dual variable control method according to claim 3 is characterized in that: The dual variable control strategy includes: The maximum allowable speed is calculated based on the target flow and the allowable range of the current displacement opening. Speed max and the minimum allowable speed Speed min ; Based on speed interval Speed Intal Set N speed selection points at equal intervals within the speed allowable range; Calculate the comprehensive efficiency of the electric-driven pump system at each speed selection point, and rank the comprehensive efficiency of the electric-driven pump system at each speed selection point from high to low; According to the sorting results, the differences between the speed and displacement of the speed selection point corresponding to the comprehensive efficiency of the electric drive pump system and the current actual speed and displacement are calculated in sequence from high to low, until the calculated differences are all less than the corresponding set thresholds, and the speed and displacement of the speed selection point corresponding to the comprehensive efficiency of the electric drive pump system at this time are taken as the optimal speed and optimal displacement of the electric drive pump.

5. The electric drive pump speed and displacement dual variable control method according to claim 4 is characterized in that: The calculation process of the comprehensive efficiency of the electric drive pump system includes: The displacement value is determined according to the target flow and speed selection point, the required torque is determined according to the displacement value and the current load pressure, and the motor efficiency of each speed selection point is obtained by looking up the motor efficiency MAP diagram according to the speed selection point and the required torque value; the pump efficiency of each speed selection point is obtained by looking up the pump efficiency MAP diagram according to the current load pressure, speed selection point and displacement value; the comprehensive efficiency of the electric drive pump system is obtained by multiplying the motor efficiency by the pump efficiency.

6. The electric drive pump speed and displacement dual variable control method according to claim 4 is characterized in that: The step of adjusting the electric drive pump according to the optimal speed and optimal displacement of the electric drive pump comprises: When the working status information of the whole vehicle is the acceleration state, the current speed value of the electric drive pump is fixed unchanged, the optimal displacement is taken as the target displacement to adjust the displacement of the electric drive pump, and the electric drive pump displacement adjustment value is monitored in real time. When it is monitored that the electric drive pump displacement adjustment value reaches a set percentage of the target displacement, the optimal speed is taken as the target speed to adjust the speed of the electric drive pump, so that the displacement and speed of the electric drive pump are adjusted to the optimal speed and optimal displacement at the same time.

7. The electric drive pump speed and displacement dual variable control method according to claim 4 is characterized in that: The step of adjusting the electric drive pump according to the optimal speed and optimal displacement of the electric drive pump comprises: When the vehicle working state information is a deceleration state, the current displacement value of the fixed electric drive pump remains unchanged, and the speed of the electric drive pump is adjusted individually according to the target flow demand and the current displacement value; After adjusting individually to meet the target flow requirement, the current speed value of the electric drive pump is fixed unchanged, the optimal displacement is used as the target displacement to adjust the displacement of the electric drive pump, and the electric drive pump displacement adjustment value is monitored in real time. When it is monitored that the electric drive pump displacement adjustment value reaches a set percentage of the target displacement, the optimal speed is used as the target speed to adjust the speed of the electric drive pump, so that the displacement and speed of the electric drive pump are simultaneously adjusted to the optimal speed and optimal displacement.

8. The electric drive pump speed and displacement dual variable control method according to claim 4 is characterized in that: The step of adjusting the electric drive pump according to the optimal speed and optimal displacement of the electric drive pump comprises: When the vehicle working state information is in a stable state, the opening allowable range of the current displacement is set to be not less than 50%, and the dual variable control strategy is used to determine the optimal speed and optimal displacement of the electric drive pump that meets the opening allowable range of not less than 50%; The current speed value of the electric drive pump is fixed unchanged, the optimal displacement of the electric drive pump that meets the allowable opening range of not less than 50% is used as the target displacement to adjust the displacement of the electric drive pump, and the electric drive pump displacement adjustment value is monitored in real time. When it is monitored that the electric drive pump displacement adjustment value reaches the set percentage of the target displacement, the optimal speed of the electric drive pump that meets the allowable opening range of not less than 50% is used as the target speed to adjust the speed of the electric drive pump, so that the displacement and speed of the electric drive pump are simultaneously adjusted to the optimal speed and optimal displacement.

9. The electric drive pump speed and displacement dual variable control method according to any one of claims 6 to 8, characterized in that: The percentage is calculated as follows: ； Where: E is a percentage; T P is the pump displacement response time of the electric drive pump; T M is the motor speed response time of the electric drive pump.

10. The electric drive pump speed and displacement dual variable control method according to claim 4, characterized in that: The step of adjusting the electric drive pump according to the optimal speed and optimal displacement of the electric drive pump comprises: When the vehicle working status information is a loaded state, the opening of the electric drive pump is reduced to a preset opening value and remains unchanged, and the speed of the motor of the electric drive pump is reduced to a preset speed value and remains unchanged.

11. The electric drive pump speed and displacement dual variable control method according to claim 4, characterized in that: The step of adjusting the electric drive pump according to the optimal speed and optimal displacement of the electric drive pump comprises: When the vehicle working status information is a shutdown state, the opening of the electric drive pump is reduced to a preset opening value and remains unchanged, and the speed of the motor of the electric drive pump is reduced to 0.

12. A dual variable control device for electric drive pump speed and displacement, characterized in that: include: The acquisition module is used to obtain the working status information of the whole vehicle; The strategy control module is used to execute the dual-variable control strategy in the corresponding working state according to the vehicle working state information, and the dual-variable control strategy in the corresponding working state includes: Determine the electric pump speed and displacement values ​​that meet the target flow request and the optimal electric pump system comprehensive efficiency under the current load pressure; determine the optimal speed and optimal displacement of the electric pump based on a preset displacement difference threshold value based on the current load pressure and the difference between the electric pump speed and displacement values ​​that meet the target flow request and the optimal electric pump system comprehensive efficiency under the current load pressure and the current actual electric pump speed and displacement; The regulating module is used to regulate the electric drive pump according to the optimal rotation speed and optimal displacement of the electric drive pump.

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