Motor speed regulation system

Abstract

The motor speed regulation system comprises a speed loop forming an outer loop and a current loop forming an inner loop, wherein the output of the speed loop is the input of the current loop. The speed loop is a closed loop and comprises a speed regulator, the speed regulator is a PID controller, and the PID controller has a speed loop proportionality coefficient; and the adjusting module is used for adjusting the speed ring proportionality coefficient. The adjusting module is configured to obtain the total speed change amount accumulated in each operation process by adjusting the speed ring proportionality coefficient in the multiple operation processes executed by the speed regulator for the same load parameter. And determining the speed loop proportionality coefficient corresponding to the minimum value in the total speed change amount in each operation process as the speed loop proportionality coefficient used by the speed regulator in the subsequent operation process after the multiple operation processes.

Description

Technical Field

[0001] The present application relates to a motor speed regulation system, which can realize automatic regulation of the proportional coefficient of the motor speed loop. Background Art

[0002] The motor speed control system usually includes two parts: the speed loop and the current loop. The current loop is the inner loop, which includes a current regulator. The speed loop is the outer loop, which includes a speed regulator. The input parameters of the speed regulator are the given speed and the feedback speed, and the output parameter is the current loop given value of the current loop. The open-loop transfer function of the speed regulator includes a speed loop proportional coefficient term. The speed loop proportional coefficient is related to the mechanical system parameters of the motor and its drive. However, the mechanical system parameters of the motor and its drive cannot be accurately measured under normal circumstances, so it is necessary to adjust the speed loop proportional coefficient online. On the other hand, for the motor speed control system using the speed control model, the model is an ideal model, and the speed loop proportional coefficient calculated according to the ideal model usually cannot be accurately adapted to the speed control system, and the speed loop proportional coefficient still needs to be adjusted during motor operation. Summary of the invention

[0003] The purpose of the present application is to provide a motor speed control system that can adaptively adjust the speed loop proportional coefficient of the motor speed control system.

[0004] To this end, the present application provides, in one aspect, a motor speed control system, comprising:

[0005] A speed loop constituting an outer loop and a current loop constituting an inner loop, wherein the output of the speed loop is the input of the current loop;

[0006] The speed loop is a closed loop, comprising: a speed regulator, the speed regulator is a PID controller, the PID controller has a speed loop proportional coefficient; and a regulating module for adjusting the speed loop proportional coefficient;

[0007] Wherein, the adjustment module is configured as follows:

[0008] During multiple operations performed by the speed regulator for the same load parameters, the total accumulated speed change during each operation is obtained by adjusting the speed loop proportional coefficient;

[0009] The speed loop proportional coefficient corresponding to the minimum value of the total speed change in each operation process is determined as the speed loop proportional coefficient used by the speed regulator in subsequent operation processes after the multiple operation processes.

[0010] In one embodiment, the adjustment module is configured to determine the speed loop proportional coefficient used in subsequent operation by cyclically executing the following steps:

[0011] Determine the previous total speed change during the previous run;

[0012] The speed loop proportional coefficient in the previous operation process is corrected by adjusting the step length to obtain the speed loop proportional coefficient in the current operation process;

[0013] Determine the current total speed change during the current run;

[0014] The total speed change in the current running process is subtracted from the previous speed change in the previous running process to obtain the total change difference;

[0015] The polarity of the adjustment step in the next operation process is determined based on the polarity of the total amount of change difference; wherein, if the total amount of change difference is a positive value, the adjustment step in the next operation process takes a negative sign; wherein, if the total amount of change difference is a negative value, the adjustment step in the next operation process takes a positive sign.

[0016] In one embodiment, the value of the adjustment step is the same during each operation. Alternatively, the value of the adjustment step decreases as the absolute value of the total amount difference decreases during each operation.

[0017] In one embodiment, after the polarity of the total amount difference changes, the polarity of the adjustment step is changed. Further, after the polarity of the total amount difference changes, the value of the adjustment step may be reduced.

[0018] In one implementation, the adjustment step is expressed as the product of the current total speed change and a set adjustment coefficient.

[0019] In one implementation, the value of the adjustment coefficient is set based on motor performance and application scenarios.

[0020] In one implementation, the load parameter is a load value or a load change value of the motor.

[0021] In one embodiment, the total speed change amount is the time integral of the change amplitude of the feedback speed received during the operation of the speed regulator in response to a certain load change relative to the input given speed.

[0022] According to the speed loop proportional coefficient adaptive adjustment function of the motor speed control system of the present application, the speed loop proportional coefficient can be automatically adjusted and optimized quickly and accurately, so that the motor can dynamically and intelligently realize speed regulation quickly during the loading process. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The foregoing and other aspects of the present application will be more fully understood and appreciated through the following detailed description made with reference to the accompanying drawings, in which:

[0024] Figure 1 is a schematic diagram of the control logic of the motor speed control system of the present application;

[0025] Figure 2 It is a schematic diagram of speed control of the motor speed regulation system of the present application during the loading process;

[0026] Figure 3 is a schematic curve diagram of the relationship between the speed loop proportional coefficient and the accumulated speed error of the motor speed control system of the present application;

[0027] Figure 4 is a logic block diagram of a speed regulator in the motor speed regulation system of the present application;

[0028] Figure 5 It is a schematic diagram of a feasible solution for adjusting the speed loop proportional coefficient in the motor speed control system of the present application. DETAILED DESCRIPTION

[0029] The present application generally relates to a motor speed control system, and more particularly to automatic adjustment of a speed loop proportional coefficient in a motor speed control system.

[0030] The control logic block diagram applicable to the motor speed control system of this application is as follows Figure 1 As shown. The motor speed control system consists of two parts: the speed loop and the current loop. The speed loop is the outer loop, which contains the speed regulator. The input parameter of the speed regulator is the given speed (or speed given value) ω * And the feedback speed (or speed feedback value) ω, the output parameter is the current loop given value of the current loop. The transfer function of the speed regulator is represented by G1. The current loop is an inner loop, which includes a current regulator, which is used to implement rapid control of the torque by adjusting the input current supplied to each phase winding of the motor. The current loop can be equivalent to a first-order inertia link. The input parameter of the current loop is the output parameter of the speed regulator, that is, the current loop given value. The transfer function of the current loop is represented by G2. The current loop output value is transferred to the motor item, and the transfer function of the motor item is represented by G3. The transfer function G3 can include parameters such as the motor torque coefficient, the total rotational inertia of the motor and the load, and the load torque. The output of the motor item is the output speed or the actual speed (that is, the feedback speed of the speed regulator) ω.

[0031] The above transfer functions of the motor speed control system can adopt traditional forms known in the art, and can be represented in various forms well known to those skilled in the art, which will not be described in detail here.

[0032] The speed regulator is a PID controller. Due to the presence of feedback, the speed loop is a closed-loop system, and its open-loop transfer function can be expressed as G0=G1*G2*G3.

[0033] The proportional coefficient of the proportional control term in the speed regulator is the speed loop proportional coefficient K contained in the transfer function G1. p , which is related to the total moment of inertia of the motor and load, the speed loop cutoff frequency, the motor permanent magnet flux and the number of pole pairs. Generally speaking, the speed loop proportional coefficient K p It is related to the parameters of the motor and the mechanical system it drives, but the parameters of the motor and the mechanical system it drives are generally difficult to accurately determine. On the other hand, if a physical model is used to express the speed loop proportional coefficient K p However, due to the load moment of inertia, it is difficult to accurately determine the speed loop proportional coefficient with this physical model. In view of this, the present application aims to adjust the speed loop proportional coefficient during motor operation to obtain the optimal value of the speed loop proportional coefficient and realize online adaptive adjustment of the speed loop proportional coefficient.

[0034] In order to determine the influence of the speed loop proportional coefficient on the motor speed regulation function, the applicant first examined the speed error existing during the speed regulation during the motor loading process, such as Figure 2 The schematic diagram is shown in Figure 2 In the figure, the horizontal axis represents time t, and the vertical axis represents motor speed and load. Before time t1, the load T L In the lower load area (for example, in the motor idling state). At time t1, the load T L Increase (e.g., the motor changes from an idling state to a load) and maintain the increased load.

[0035] On the other hand, within the entire time period, given the speed ω * The actual motor speed (feedback speed) ω remains equal to the given speed ω before time t1 * At time t1, due to the increase in load, the actual motor speed ω begins to decrease. Due to the action of the motor speed control system, the actual speed ω begins to increase after decreasing and returns to the given speed ω at time t2. * .

[0036] From time t1 to when the actual speed ω recovers to be equal to the given speed ω * The time period between the moment t2 is the motor load T L The response time of the motor to the load T L The response capability is reflected in the response time on the one hand, and the actual speed ω relative to the given speed ω on the other hand. * The change range of ω e , where ω e =|ω * -ω|. It should be noted here that under load T L When the actual speed ω increases, the actual speed ω is relative to the given speed ω *Reduce; at load T L When decreasing, the actual speed ω is relative to the given speed ω * To cover these two situations, this application uses the actual speed ω relative to the given speed ω * The absolute value of the change is taken as the magnitude of change ω e , that is, the amplitude of change ω e The value of is always positive.

[0037] This application uses the total amount of speed change accumulated within the response time ω ei It is a representation of the motor's ability to respond to load. The total speed change is Figure 2 The dotted area is shown in the figure. The total speed change ω ei is the change amplitude ω within the response time e The integral of time t. A feasible specific calculation method is: determine a time step, divide the response time into time points separated by the time step; accumulate the speed change amplitude ω at each time point e The product of the time step is the total speed change ω ei The total speed change ω ei The value of is always positive.

[0038] The applicant has further realized that for the same load change value ΔT L (It may be an increase or decrease), the total speed change ω ei And the speed loop proportional coefficient K p There is a quadratic relationship between them, that is, for a certain load change value ΔT L , the total speed change ω ei Can be roughly expressed as the speed loop proportional coefficient K p The quadratic function of Figure 3 Schematic representation. Figure 3 In the figure, the horizontal axis represents the speed loop proportional coefficient K p , the vertical axis represents the total speed change ω ei . Based on the speed loop proportional coefficient K p is the total speed change of the variable ω ei The quadratic curve presented is an upward-opening curve with a minimum value ω ei_min The speed loop proportional coefficient K p Less than the minimum value ω ei_min At the corresponding point, the total speed change ω ei Speed ​​loop proportional coefficient K p The speed loop proportional coefficient K p Greater than the minimum valueω ei_min At the corresponding point, the total speed change ωei Speed ​​loop proportional coefficient K p increases monotonically with the increase of .

[0039] Based on the above understanding, the present invention proposes that during the operation of the motor, based on the load change value ΔT L Dynamically adjust the speed loop proportional coefficient K p , so that the total amount of motor speed change ω ei It should be pointed out that in practice it is impossible to achieve the total motor speed change ω ei The absolute minimum value of , so in practice it is sufficient to reach the approximate minimum value.

[0040] For this reason, Figure 4 As shown, in the motor speed control system, the present application provides a speed regulator M2 with a regulating module M1 for adjusting the speed loop proportional coefficient K for the speed regulator M2. p The algorithm of the regulation module M1 performs the following functions, that is, when the motor is running, for the same load change value ΔT L The operating state is adjusted by adjusting the speed loop proportional coefficient K p , determine the total amount of motor speed change ω ei The minimum value, and the total amount of change corresponding to the motor speed ω ei Minimum speed loop proportional coefficient K p As the motor runs in the subsequent operation, the same load change value ΔT appears L The speed loop proportional coefficient K used when p .

[0041] The regulation module M1 can use a known suitable optimization algorithm to determine the total amount of motor speed change ω ei Minimum speed loop proportional coefficient K p , where the optimization variable is K p , the optimization goal is min(ω ei As an example, a K suitable for use in the adjustment module M1 p The regulation process optimization algorithm is described as follows.

[0042] For a certain load change value ΔT L The current operation process of the motor (or the current speed regulation process) is based on the following formula to adjust the speed loop proportional coefficient K p :

[0043] K p =K p '+a*ω ei '

[0044] Where K p ' is the speed loop proportional coefficient in the previous operation process (or the previous speed regulation process), Kp It is the speed loop proportional coefficient in the current operation process. ei ' is the total amount of the previous speed change, and there is the same load change value ΔT L The total amount of speed change of the motor in the previous operation process. a is the adjustment coefficient, which is a value that can be set. The size of the adjustment coefficient a affects the adjustment times (adjustment speed) of the adjustment module M1, as described later.

[0045] In the current operation process, the adjusted speed loop proportional coefficient K p Perform speed regulation and determine the total speed change during the current operation ω ei , which can be called the total amount of current speed change.

[0046] Next, determine the total change difference Δω between the current total speed change and the previous total speed change:

[0047] Δω=ω ei -ω ei '

[0048] The polarity, i.e., the sign, of the adjustment coefficient a in the next operation process is determined based on the polarity, i.e., the sign, of Δω. The sign of the adjustment coefficient a is opposite to that of Δω, i.e., if Δω is positive, a is negative, and if Δω is negative, a is positive.

[0049] Afterwards, for the subsequent occurrences of the same load change value ΔT L During each motor operation, the speed loop proportional coefficient K is adjusted repeatedly. p steps until ω ei Less than ω ei ', and the absolute value of the difference between the two |Δω|≤Δω_th, where Δω_th is the set speed change total difference threshold.

[0050] In reaching ω ei Less than ω ei ', and |Δω|≤Δω_th, the speed loop proportional coefficient K p Fixed, applied to the subsequent occurrence of the same load change value ΔT L Speed ​​regulation during motor operation.

[0051] Through the above-mentioned speed loop proportional coefficient procedure, after the motor has experienced several operation processes with the same load change value, the speed loop proportional coefficient that basically corresponds to the minimum value of the total speed change can be determined. In the subsequent operation process with the same load change value, the motor speed control system adjusts the speed of the motor with the speed loop proportional coefficient determined in this way, which can improve the motor's responsiveness to the load, wherein not only the total speed change of the motor when the load changes can be reduced, but also the motor response time can be shortened.

[0052] Regarding the adjustment coefficient a, it can be understood that it represents K p The polarity of the adjustment step, i.e. the sign, is the same as the polarity of the adjustment coefficient a. The larger the value of the adjustment coefficient a, the greater the K p The faster the value is adjusted, the faster K p However, considering that near the point where the polarity of Δω changes, a large value of the adjustment coefficient a may not easily lead to K p Therefore, if a smaller adjustment coefficient a is selected, the adjustment speed will be slower (more adjustment times), but it will be easier to obtain K near the point where the polarity of Δω changes. p Stable value, K p The regulation process is more stable. The value of the regulation coefficient a can be appropriately selected based on the motor performance and application scenario.

[0053] Furthermore, in K p During the value adjustment process, the value of the adjustment coefficient a or the adjustment step length (regardless of polarity) can be kept constant each time the adjustment is made. Alternatively, the adjustment coefficient a or the adjustment step length can be gradually reduced as |Δω| decreases. This is beneficial to K p The stability of the regulation process.

[0054] Furthermore, after the polarity of Δω changes, the value of the adjustment coefficient a or the adjustment step length can be reduced, for example, the value of the adjustment coefficient a or the adjustment step length can be reduced by half or more, which is further beneficial to K p The stability of the regulation process.

[0055] Figure 5 An exemplary process of adjusting the speed loop proportional coefficient of the present application is shown. Figure 5 In the figure, the horizontal axis represents the speed loop proportional coefficient K at a specific load change value. p , the vertical axis represents the total speed change ω ei Assume that point 0 represents the set K before the motor first experiences this load change value. p ' and the calculated ω ei '. It can be understood that for different load change values, setting K p Point 1 represents the K value determined by the adjustment when the motor first experiences this load change value. p and the calculated ω ei . K at point 1 p Relative to K at point 0 p 'Changed by an adjustment step ΔK (ΔK = a*ω ei '), where as an example, the adjustment coefficient a can take a negative sign when it is used for the first time (of course, it can also take a positive sign).ei Relative to ω at point 0 ei 'Changed by Δω. Assuming that Δω is a negative sign as shown in the figure, when this load change value occurs later, continue to adjust K p . As shown in the figure, when Δω is negative, a takes a positive sign (if Δω is positive, a takes a negative sign). The value of the adjustment coefficient a or the adjustment step ΔK may remain the same, or the value of the adjustment coefficient a or the adjustment step ΔK may be gradually reduced as |Δω| decreases, as shown in points 2, 3, and 4 in the figure. At point 4, Δω becomes positive, then when the load change value appears next time, a changes polarity, that is, it becomes negative, as shown in point 5. The value of the adjustment coefficient a or the adjustment step ΔK at point 5 can be reduced relative to the value of the adjustment coefficient a or the adjustment step ΔK at point 4, for example, reduced by half. If at point 5 ω ei Less than ω at point 4 ei , and the absolute value of the difference between the two |Δω|≤Δω_th, then terminate K p During the adjustment process, K p The value is recorded as the speed loop proportional coefficient when the load change value appears again in the future. ei Greater than point 4 ω ei , when the load change value appears later, the adjustment coefficient a or the adjustment step length ΔK can be further reduced and its polarity can be changed, and so on, until the current point ω is satisfied. ei Smaller than the previous point ω ei , and the absolute value of the difference between the two |Δω|≤Δω_th. The final K p The value is used as the speed loop proportional coefficient when the load change value appears again in the future. For different load change values, the same process is used to adjust the speed loop proportional coefficient to obtain the speed loop proportional coefficient suitable for various load change values.

[0056] It can be further understood that for many application scenarios of the motor, the motor runs idling when it is turned on, and only has its own load. At this time, the load is very small and can be ignored. Next, after the motor is connected to the load, the load change value can basically be regarded as equivalent to the value of the load itself. Therefore, using the speed loop proportional coefficient adjustment process described above, the speed loop proportional coefficient applicable to various load values ​​can also be determined. Therefore, in the present application, the load value and the load change value can be collectively referred to as load parameters, and the motor speed control system of the present application can determine the speed loop proportional coefficient applicable to various load parameters during the operation of the motor. The load value can be measured by the torque sensor of the motor, and the load change value can be calculated by the measured value of the torque sensor.

[0057] According to the motor speed control system of the present application, by automatically optimizing the speed loop proportional coefficient corresponding to the minimum value of the total speed change for different load parameters during the early operation of the motor, without manually setting the speed loop proportional coefficient during the use of the motor, not only can the total speed change during the speed control process be reduced, but also the load response time can be shortened. By selecting the adjustment coefficient, the optimized speed loop proportional coefficient can be quickly determined after the motor has run a limited number of times, so that the motor can respond quickly and smoothly when the load changes, and the amplitude and time of the motor speed change can be suppressed. The motor speed control system of the present application is suitable for various motors with speed control functions.

[0058] Although the present application is described herein with reference to specific embodiments, the scope of the present application is not limited to the details shown. Various modifications may be made to these details without departing from the basic principles of the present application.

Claims

1. A motor speed control system, comprising: A speed loop constituting an outer loop and a current loop constituting an inner loop, wherein the output of the speed loop is the input of the current loop; The speed loop is a closed loop, comprising: a speed regulator (M2), the speed regulator is a PID controller, and the PID controller has a speed loop proportional coefficient (K p ); and a regulating module (M1) for adjusting the speed loop proportional coefficient (K p ); Wherein, the adjustment module (M1) is configured as follows: During the multiple operations performed by the speed regulator (M2) for the same load parameters, by adjusting the speed loop proportional coefficient (K p ) to obtain the total accumulated speed change (ω) during each operation ei ); The total speed change (ω ei ) corresponds to the speed loop proportional coefficient (K p ) is determined as the speed loop proportional coefficient (K) used by the speed regulator (M2) in the subsequent operation process after the multiple operation processes. p ).

2. The motor speed control system according to claim 1, wherein: The regulating module (M1) is configured to determine the speed loop proportional coefficient (K) used in the subsequent operation process by cyclically executing the following steps: p ): Determine the total amount of previous speed change (ω ei '); Use the adjustment step size (ΔK) to adjust the speed loop proportional coefficient (K) in the previous operation process. p ') to correct and obtain the speed loop proportional coefficient (K p ); Determine the current total speed change (ω ei ); The total amount of current speed change (ω ei ) minus the previous speed change in the previous operation (ω ei ') to obtain the total change difference (Δω); The polarity of the adjustment step (ΔK) in the next operation process is determined based on the polarity of the total amount of change difference (Δω); wherein, if the total amount of change difference (Δω) is a positive value, the adjustment step (ΔK) in the next operation process takes a negative sign; wherein, if the total amount of change difference (Δω) is a negative value, the adjustment step (ΔK) in the next operation process takes a positive sign.

3. The motor speed control system according to claim 2, wherein: During each operation, the value of the adjustment step (ΔK) is the same.

4. The motor speed control system according to claim 2, wherein: During each operation, the value of the adjustment step (ΔK) decreases as the absolute value of the total amount difference (Δω) decreases.

5. The motor speed control system according to any one of claims 2 to 4, wherein: After the polarity of the total amount difference (Δω) changes, the polarity of the adjustment step (ΔK) is changed.

6. The motor speed control system according to claim 5, wherein: After the polarity of the total amount difference (Δω) changes, the value of the adjustment step (ΔK) is reduced.

7. The motor speed control system according to any one of claims 2 to 6, wherein: The adjustment step (ΔK) is expressed as the total amount of current speed change (ω ei ) multiplied by the set adjustment coefficient (a).

8. The motor speed control system according to claim 7, wherein: The value of the adjustment coefficient (a) is set based on motor performance and application scenarios.

9. The motor speed control system according to any one of claims 1 to 8, wherein: The load parameter is the load value or load change value of the motor.

10. The motor speed control system according to any one of claims 1 to 9, wherein: The total speed change (ω ei ) is the feedback speed (ω) received during the operation of the speed regulator (M2) in response to a load change relative to the input given speed (ω * ) changes in the range (ω e ) is the integral of .

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