Multi-motor load distribution method

Abstract

The invention relates to the technical field of multi-motor driving, and discloses a multi-motor load distribution method, which comprises the following steps: acquiring rotating speeds and torques of a plurality of motors; calculating the average power of the plurality of motors according to the torques of the plurality of motors; calculating the load power of each motor according to the rotating speed and the torque of each motor; constructing an average power closed-loop controller according to the average power of the plurality of motors and the load power of each motor, and determining the droop adjusting quantity of each motor; and superposing the droop adjustment quantity of each motor and the rotating speed of each motor to obtain the adjusted rotating speed of each motor. According to the invention, the droop adjusting amount is calculated through the average power closed-loop control module, so that no-static-error load power distribution is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of multi-motor driving, and in particular to a multi-motor load distribution method. Background Art

[0002] In a multi-motor drive system, how to achieve a balance between the load powers of each motor has always been a hot research issue. At present, the motor load power distribution method in most commercial motor drives is droop control. The conventional droop control method is to perform proportional feedforward adjustment on the speed of each motor according to the output torque of each motor. This method will cause the speed of all motors to be lower or higher than the command speed of the system, which will cause the motor speed of the system to fluctuate greatly under low-speed operation conditions, and some motors may be blocked. In addition, since the conventional droop control method only uses proportional feedforward adjustment, it will cause static errors between the load powers of each motor, making it difficult to achieve accurate load balancing. Summary of the invention

[0003] In view of the above-mentioned deficiencies in the prior art, the present invention provides a multi-motor load distribution method, which calculates the droop adjustment amount through an average power closed-loop control module to achieve load power distribution without static error; in addition, the average speed closed-loop control module is used to calculate the feedforward torque amount to reduce the speed tracking error of each motor, and prevent the speeds of all motors from deviating from the command speed of the system in one direction. This ensures that the multi-motor drive system can achieve load power distribution without static error in the full speed range.

[0004] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is: In a first aspect, the present invention provides a multi-motor load distribution method, comprising the following steps: Get the speed and torque of multiple motors; Calculate the average power of the multiple motors according to the torques of the multiple motors; Calculate the load power of each motor according to the speed and torque of each motor; An average power closed-loop controller is constructed according to the average power of multiple motors and the load power of each motor to determine the droop adjustment amount of each motor; The droop adjustment amount of each motor is superimposed on the rotational speed of each motor to obtain the adjusted rotational speed of each motor.

[0005] Furthermore, the average power of multiple motors is calculated as follows: , Among them, P_avg is the average power of multiple motors, n is the number of motors, fei is the speed of the i-th motor, and Teci is the torque of the i-th motor.

[0006] Furthermore, the load power of each motor is calculated as follows: , Among them, P_n is the load power of the nth motor, fen is the speed of the nth motor, and Tecn is the torque of the nth motor.

[0007] Furthermore, the average power closed-loop controller is specifically: , Among them, △fcn is the droop adjustment amount of the nth motor, kpp and kip are the gain coefficients of the average power closed-loop controller, P_avg is the average power of multiple motors, P_n is the load power of the nth motor, and t is the motor running time.

[0008] Furthermore, the droop adjustment amount of each motor is superimposed with the speed of each motor to obtain the adjusted speed of each motor, specifically: , Among them, fn is the adjusted speed of the nth motor, fen is the speed of the nth motor, and △fcn is the droop adjustment amount of the nth motor.

[0009] In a second aspect, the present invention provides a multi-motor load distribution method, comprising the following steps: Get the speed, torque and command speed of multiple motors; Calculate the average speed and average power of the multiple motors according to the speed and torque of the multiple motors; Calculate the load power of each motor according to the speed and torque of each motor; An average power closed-loop controller is constructed according to the average power of multiple motors and the load power of each motor to determine the droop adjustment amount of each motor; The droop adjustment amount of each motor is superimposed with the speed of each motor to obtain the adjusted speed of each motor; Calculating the speed error of each motor according to the adjusted speed of each motor and the command speed of the multiple motors; Determine the command torque of each motor according to the speed error of each motor; An average speed closed-loop controller is constructed according to the command speeds of the plurality of motors and the average speeds of the plurality of motors to determine the feedforward torque amount of each motor; The feedforward torque of each motor is superimposed on the command torque of each motor to obtain the adjusted command torque of each motor.

[0010] Furthermore, the average speed of multiple motors is calculated as follows: , Among them, f_avg is the average speed of multiple motors, n is the number of motors, and fei is the speed of the i-th motor.

[0011] Furthermore, the speed error of each motor is calculated as follows: , Among them, fnc is the speed error of the nth motor, is the command speed of multiple motors, and fn is the adjusted speed of the nth motor.

[0012] Furthermore, the average speed closed-loop controller is specifically: , Among them, △Te is the feedforward torque of the nth motor, kpf and kif are the gain coefficients of the average speed closed-loop controller, is the command speed of multiple motors, f_avg is the average speed of multiple motors, and t is the motor running time.

[0013] Furthermore, the feedforward torque of each motor is superimposed with the command torque of each motor to obtain the adjusted command torque of each motor, which is specifically: , Among them, Tecn is the command torque after adjustment of the nth motor, is the command torque of the nth motor, and △Te is the feedforward torque of the nth motor.

[0014] The present invention has the following beneficial effects: The present invention calculates the droop adjustment amount through the average power closed-loop control module, thereby realizing load power distribution without static error; and also calculates the feedforward torque amount through the average speed closed-loop control module to reduce the speed tracking error of each motor, and prevents the speed of all motors from deviating from the command speed of the system in one direction. Thus, it is ensured that the multi-motor drive system can realize load power distribution without static error in the full speed range. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic flow chart of a multi-motor load distribution method in one embodiment of the present invention; Figure 2 It is a control block diagram of a multi-motor load distribution method; Figure 3 This is a schematic diagram of the principle of the average power closed-loop control module; Figure 4 A schematic flow chart of a multi-motor load distribution method in another embodiment of the present invention; Figure 5 This is a schematic diagram of the principle of the average speed closed-loop control module. DETAILED DESCRIPTION

[0016] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0017] like Figure 1 As shown, a multi-motor load distribution method provided by an embodiment of the present invention includes the following steps S101 to S105: S101, obtaining the rotation speed and torque of multiple motors; In an optional embodiment of the present invention, Figure 2 As shown, the command speed of the multi-motor is Here n is defined as the number of motors, that is, this method can be applied to a multi-motor control system with n motors, and n is greater than or equal to 2. Figure 2 Taking three motors as an example, the feedback speed of each motor is fe1, fe2, fe3, ..., fen, the feedback speed of each motor after adjustment is f1, f2, f3, ..., fn, the speed error of each motor after adjustment is f1c, f2c, f3c, ..., fnc, the ASR module represents the speed loop controller, its input is the speed error fnc of each motor, and its output is the command torque of each motor , , , ..., , △Te is the feedforward torque. The ACR module represents the current loop controller, whose input is the command torque Tec1, Tec2, Tec3, ..., Tecn of each motor after adjustment, the PWM module represents the pulse width modulation module, the INV module represents the inverter main circuit, and Motor1, Motor2, and Motor3 are motor 1, motor 2, and motor 3 respectively.

[0018] In step S101 , the command torque Tec1 , Tec2 , Tec3 , . . . , Tecn of each motor after adjustment is used as the torque of each motor. A load observer or other method may also be used to calculate the torque of each motor.

[0019] S102, calculating average power of the multiple motors according to the torques of the multiple motors; In an optional embodiment of the present invention, the calculation method of calculating the average power of the multiple motors according to the torques of the multiple motors in step S102 is: , Among them, P_avg is the average power of multiple motors, n is the number of motors, fei is the speed of the i-th motor, and Teci is the torque of the i-th motor.

[0020] S103, calculating the load power of each motor according to the rotation speed and torque of each motor; In an optional embodiment of the present invention, step S103 calculates the corresponding load power P_n according to the feedback speed fen and torque Tecn of the nth motor, and the calculation method is: , Among them, P_n is the load power of the nth motor, fen is the speed of the nth motor, and Tecn is the torque of the nth motor.

[0021] S104, constructing an average power closed-loop controller according to the average power of the multiple motors and the load power of each motor, and determining the droop adjustment amount of each motor; In an optional embodiment of the present invention, in step S104, an average power closed-loop controller can be constructed according to the error between the average power P_avg of the multiple motors and the load power P_n of each motor as follows: , Among them, △fcn is the droop adjustment amount of the nth motor, kpp and kip are the gain coefficients of the average power closed-loop controller, P_avg is the average power of multiple motors, P_n is the load power of the nth motor, and t is the motor running time.

[0022] Here, the proportional-integral controller is used as an example. Other closed-loop controllers can also be selected to perform average power closed-loop control of multiple motors. Figure 3 is the internal schematic diagram of the average power closed-loop control module. Figure 3 Take three motors as an example. Figure 3 In the example, each motor corresponds to an average power closed-loop controller. Figure 3 The output of each average power closed-loop controller is the droop adjustment value △fcn of the nth motor.

[0023] S105 , superimposing the droop adjustment amount of each motor with the rotation speed of each motor to obtain the adjusted rotation speed of each motor.

[0024] In an optional embodiment of the present invention, step S105 superimposes the droop adjustment amount Δfcn of the n-th motor and the feedback speed fen of the n-th motor to obtain the adjusted feedback speed fn of the n-th motor, which is specifically: , Among them, fn is the adjusted speed of the nth motor, fen is the speed of the nth motor, and △fcn is the droop adjustment amount of the nth motor.

[0025] like Figure 4 As shown, the embodiment of the present invention further provides a multi-motor load distribution method, comprising the following steps S201 to S209: S201, obtaining the speed, torque and command speed of multiple motors; In an optional embodiment of the present invention, Figure 2 As shown, the command speed of the multi-motor is Here n is defined as the number of motors, that is, this method can be applied to a multi-motor control system with n motors, and n is greater than or equal to 2. Figure 2 Taking three motors as an example, the feedback speed of each motor is fe1, fe2, fe3, ..., fen, the feedback speed of each motor after adjustment is f1, f2, f3, ..., fn, the speed error of each motor after adjustment is f1c, f2c, f3c, ..., fnc, the ASR module represents the speed loop controller, its input is the speed error fnc of each motor, and its output is the command torque of each motor , , , ..., , △Te is the feedforward torque. The ACR module represents the current loop controller, whose input is the command torque Tec1, Tec2, Tec3, ..., Tecn of each motor after adjustment, the PWM module represents the pulse width modulation module, the INV module represents the inverter main circuit, and Motor1, Motor2, and Motor3 are motor 1, motor 2, and motor 3 respectively.

[0026] In step S201, the command torque Tec1, Tec2, Tec3, ..., Tecn of each motor after adjustment is used as the torque of each motor. The torque of each motor may also be calculated by a load observer or other methods.

[0027] S202, calculating the average speed and average power of the multiple motors according to the speed and torque of the multiple motors; In an optional embodiment of the present invention, step S202 calculates the average speed and average power of the multiple motors according to the speed and torque of the multiple motors in the following manner: , , Among them, P_avg is the average power of multiple motors, f_avg is the average speed of multiple motors, n is the number of motors, fei is the speed of the i-th motor, and Teci is the torque of the i-th motor.

[0028] S203, calculating the load power of each motor according to the rotation speed and torque of each motor; In an optional embodiment of the present invention, step S203 calculates the corresponding load power P_n according to the feedback speed fen and torque Tecn of the nth motor, and the calculation method is: , Among them, P_n is the load power of the nth motor, fen is the speed of the nth motor, and Tecn is the torque of the nth motor.

[0029] S204, constructing an average power closed-loop controller according to the average power of the multiple motors and the load power of each motor, and determining the droop adjustment amount of each motor; In an optional embodiment of the present invention, in step S204, an average power closed-loop controller can be constructed according to the error between the average power P_avg of the multiple motors and the load power P_n of each motor as follows: , Among them, △fcn is the droop adjustment amount of the nth motor, kpp and kip are the gain coefficients of the average power closed-loop controller, P_avg is the average power of multiple motors, P_n is the load power of the nth motor, and t is the motor running time.

[0030] Here, the proportional-integral controller is used as an example. Other closed-loop controllers can also be selected to perform average power closed-loop control of multiple motors. Figure 3 is the internal schematic diagram of the average power closed-loop control module. Figure 3 Take three motors as an example. Figure 3 In the example, each motor corresponds to an average power closed-loop controller. Figure 3 The output of each average power closed-loop controller is the droop adjustment value △fcn of the nth motor.

[0031] S205, superimposing the droop adjustment amount of each motor with the rotation speed of each motor to obtain the adjusted rotation speed of each motor; In an optional embodiment of the present invention, step S205 superimposes the droop adjustment amount Δfcn of the n-th motor and the feedback speed fen of the n-th motor to obtain the adjusted feedback speed fn of the n-th motor, which is specifically: , Among them, fn is the adjusted speed of the nth motor, fen is the speed of the nth motor, and △fcn is the droop adjustment amount of the nth motor.

[0032] S206, calculating the speed error of each motor according to the adjusted speed of each motor and the command speeds of the multiple motors; In an optional embodiment of the present invention, step S206 combines the command speed of the system The error input signal of the speed loop controller of the nth motor can be obtained, and the calculation method is: , Among them, fnc is the speed error of the nth motor, is the command speed of multiple motors, and fn is the adjusted speed of the nth motor.

[0033] S207, determining the command torque of each motor according to the speed error of each motor; In an optional embodiment of the present invention, step S207 uses the speed error fcn of each motor as the error input signal, and outputs the command torque of each motor through the speed loop controller. , , , ..., .

[0034] S208, constructing an average speed closed-loop controller according to the command speeds of the multiple motors and the average speeds of the multiple motors, and determining the feedforward torque of each motor; In an optional embodiment of the present invention, in order to prevent the speeds of all motors from deviating from the command speed of the system in one direction, step S208 also constructs an average speed closed-loop controller to further reduce the speed tracking error of each motor. Here, the idea of ​​virtual spindle control is borrowed, and the average speed f_avg of multiple motors is used as the feedback speed of the virtual spindle to avoid the establishment of a virtual spindle model, reduce the sensitivity of the method to model parameters, and according to the command speed of the system The error between the feedback speed f_avg of the virtual spindle can be used to construct the average speed closed-loop controller as: , Among them, △Te is the feedforward torque of the nth motor, kpf and kif are the gain coefficients of the average speed closed-loop controller, is the command speed of multiple motors, f_avg is the average speed of multiple motors, and t is the motor running time.

[0035] Here, the proportional-integral controller is used as an example. Other closed-loop controllers can also be selected to perform closed-loop control of the average speed of multiple motors. Figure 5 is the internal schematic diagram of the average speed closed-loop control module. Figure 5 In the system, all motors share an average speed closed-loop controller, and the output of the average speed closed-loop controller is the feedforward torque △Te.

[0036] S209, superimposing the feedforward torque of each motor with the command torque of each motor to obtain the adjusted command torque of each motor.

[0037] In an optional embodiment of the present invention, step S209 compares the feedforward torque ΔTe with the command torque of the nth motor. The adjusted command torque Tecn of the nth motor is obtained by superposition, which is: , Among them, Tecn is the command torque after adjustment of the nth motor, is the command torque of the nth motor, and △Te is the feedforward torque of the nth motor.

[0038] Through the above steps, it can be known that the present invention calculates the droop adjustment amount △fcn of each motor through the average power closed-loop controller, and then adds the droop adjustment amount △fcn of each motor and the feedback speed fen of each motor to obtain the feedback speed fn after adjustment of each motor, and finally realizes the load power distribution without static error through the control of the speed controller of each motor; in addition, the present invention also calculates the feedforward torque amount △Te through the average speed closed-loop controller, and adds the feedforward torque amount △Te to the command torque of each motor. The adjusted command torque Tecn of each motor is obtained by adding them together to further reduce the speed tracking error of each motor and prevent the speed of all motors from deviating from the command speed of the system in one direction. This ensures that the multi-motor drive system can achieve load power distribution without static error in the full speed range.

[0039] 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.

[0040] 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 comprising 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.

[0041] 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 1 The steps for the functions specified in one or more boxes.

[0042] The present invention uses specific embodiments to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

[0043] Those skilled in the art will appreciate that the embodiments described herein are intended to help readers understand the principles of the present invention, and should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific variations and combinations that do not deviate from the essence of the present invention based on the technical revelations disclosed by the present invention, and these variations and combinations are still within the protection scope of the present invention.

Claims

1. A multi-motor load distribution method, characterized in that: The following steps are involved: Get the speed and torque of multiple motors; Calculate the average power of the multiple motors according to the torques of the multiple motors; Calculate the load power of each motor according to the speed and torque of each motor; An average power closed-loop controller is constructed according to the average power of multiple motors and the load power of each motor to determine the droop adjustment amount of each motor; The droop adjustment amount of each motor is superimposed on the rotational speed of each motor to obtain the adjusted rotational speed of each motor.

2. A multi-motor load distribution method according to claim 1, characterized in that: The average power of multiple motors is calculated as: ， Among them, P_avg is the average power of multiple motors, n is the number of motors, fei is the speed of the i-th motor, and Teci is the torque of the i-th motor.

3. A multi-motor load distribution method according to claim 1, characterized in that: The calculation method of the load power of each motor is: ， Among them, P_n is the load power of the nth motor, fen is the speed of the nth motor, and Tecn is the torque of the nth motor.

4. A multi-motor load distribution method according to claim 1, characterized in that: The average power closed-loop controller is specifically: ， Among them, △fcn is the droop adjustment amount of the nth motor, kpp and kip are the gain coefficients of the average power closed-loop controller, P_avg is the average power of multiple motors, P_n is the load power of the nth motor, and t is the motor running time.

5. A multi-motor load distribution method according to claim 1, characterized in that: The droop adjustment amount of each motor is superimposed with the speed of each motor to obtain the adjusted speed of each motor, which is specifically: ， Among them, fn is the adjusted speed of the nth motor, fen is the speed of the nth motor, and △fcn is the droop adjustment amount of the nth motor.

6. A multi-motor load distribution method, characterized in that: The following steps are involved: Get the speed, torque and command speed of multiple motors; Calculate the average speed and average power of the multiple motors according to the speed and torque of the multiple motors; Calculate the load power of each motor according to the speed and torque of each motor; An average power closed-loop controller is constructed according to the average power of multiple motors and the load power of each motor to determine the droop adjustment amount of each motor; The droop adjustment amount of each motor is superimposed with the speed of each motor to obtain the adjusted speed of each motor; Calculating the speed error of each motor according to the adjusted speed of each motor and the command speed of the multiple motors; Determine the command torque of each motor according to the speed error of each motor; An average speed closed-loop controller is constructed according to the command speeds of the plurality of motors and the average speeds of the plurality of motors to determine the feedforward torque amount of each motor; The feedforward torque of each motor is superimposed on the command torque of each motor to obtain the adjusted command torque of each motor.

7. A multi-motor load distribution method according to claim 6, characterized in that: The average speed of multiple motors is calculated as: ， Among them, f_avg is the average speed of multiple motors, n is the number of motors, and fei is the speed of the i-th motor.

8. A multi-motor load distribution method according to claim 6, characterized in that: The speed error of each motor is calculated as: ， Among them, fnc is the speed error of the nth motor, is the command speed of multiple motors, and fn is the adjusted speed of the nth motor.

9. A multi-motor load distribution method according to claim 6, characterized in that: The average speed closed-loop controller is specifically: ， Among them, △Te is the feedforward torque of the nth motor, kpf and kif are the gain coefficients of the average speed closed-loop controller, is the command speed of multiple motors, f_avg is the average speed of multiple motors, and t is the motor running time.

10. A multi-motor load distribution method according to claim 6, characterized in that: The feedforward torque of each motor is superimposed with the command torque of each motor to obtain the adjusted command torque of each motor, which is specifically: ， Among them, Tecn is the command torque after adjustment of the nth motor, is the command torque of the nth motor, and △Te is the feedforward torque of the nth motor.

Images