阅读说明：本技术 一种基于模糊控制的永磁同步电机直流母线电压控制方法 (Permanent magnet synchronous motor direct current bus voltage control method based on fuzzy control ) 是由 宋昕昱 韩一博 韩利利 于 2020-12-03 设计创作，主要内容包括：本发明涉及一种基于模糊控制的永磁同步电机直流母线电压控制方法,包括如下步骤：S1,对电机系统进行参数标定,根据测试数据,在恒负载下,由当前给定转速确定电机相电流的目标值；S2,将电机相电流目标值与电机相电流实际值的差值、差值变化率均输入模糊控制器；S3,模糊控制器输出直流母线电压的调节值,根据功率匹配原则,通过调节直流母线电压来调整电机相电流；S4,调整电机相电流的大小到合理范围。(The invention relates to a method for controlling the voltage of a direct-current bus of a permanent magnet synchronous motor based on fuzzy control, which comprises the following steps: s1, calibrating parameters of the motor system, and determining the target value of the motor phase current according to the test data and the current given rotating speed under the constant load; s2, inputting the difference value and the change rate of the difference value between the target value of the motor phase current and the actual value of the motor phase current into a fuzzy controller; s3, the fuzzy controller outputs the adjustment value of the DC bus voltage, and adjusts the motor phase current by adjusting the DC bus voltage according to the power matching principle; and S4, adjusting the magnitude of the motor phase current to a reasonable range.)

1. A method for controlling the voltage of a direct-current bus of a permanent magnet synchronous motor based on fuzzy control is characterized by comprising the following steps:

s1, calibrating parameters of the motor system, and determining the target value of the motor phase current according to the test data and the current given rotating speed under the constant load;

s2, inputting the difference value and the change rate of the difference value between the target value of the motor phase current and the actual value of the motor phase current into a fuzzy controller;

s3, the fuzzy controller outputs the adjustment value of the DC bus voltage, and adjusts the motor phase current by adjusting the DC bus voltage according to the power matching principle;

and S4, adjusting the magnitude of the motor phase current to a reasonable range.

2. The method for controlling the direct-current bus voltage of the permanent magnet synchronous motor based on the fuzzy control as claimed in claim 1, wherein the test data comprises different output voltages, output current values and direct-current bus voltage values of the motor when the motor operates stably at different rotating speeds under the constant load torque.

3. The method as claimed in claim 2, wherein the fuzzy controller is designed according to the target motor phase current value and the target dc bus voltage value corresponding to the given current rotation speed.

4. The method as claimed in claim 3, wherein the fuzzy controller uses a dual-input single-output, and takes the difference between the target value of the motor phase current and the actual value of the motor phase current and the change rate of the difference as input, and the output is the regulated value of the DC bus voltage.

5. The method for controlling the DC bus voltage of the PMSM based on the fuzzy control as claimed in claim 4, wherein the target value of the motor phase current is I^*The difference value between the motor phase current target value and the motor phase current actual value is I_eThe rate of change of the difference is I_ecAnd recording the actual value of the motor phase current at a certain moment as I_nAnd the actual value of the motor phase current after a period of time T is recorded as I_n+1，I^*、I_ec、I_e、I_n、I_n+1And T satisfies the following relationship:

I_e1＝I_n-I^* (1)

I_e2＝I_n+1-I^* (2)

I_ec＝(I_e2-I_e1)/T (3)。

6. the method for controlling the DC bus voltage of the PMSM based on the fuzzy control as claimed in claim 5, wherein if I is_eThe value is always zero, the fuzzy controller is not started.

7. The method as claimed in claim 6, wherein the parameters of the fuzzy controller include input and output quantity, input and output discourse domain, fuzzy subset and membership function, and fuzzy solution method.

Technical Field

The invention relates to the technical field of motor control, in particular to a method for controlling the voltage of a direct-current bus of a permanent magnet synchronous motor based on fuzzy control.

Background

The permanent magnet synchronous motor is a motor with simple structure, low cost and high efficiency, and is widely applied to the industrial engineering fields such as aerospace, numerical control machine tools, electric vehicles and the like. The traditional method for controlling the permanent magnet synchronous motor uses a PI regulator, but the prior technical scheme has the technical problems that:

1. when the direct-current bus power of the permanent magnet synchronous motor is too high, the situation that the direct-current bus power is not matched with the motor power can occur, so that the motor current is continuously increased, an integral error can be accumulated when the PI regulator adjusts the increased current, the integral error is accumulated to a certain amount, the PI regulator loses the effect, the current is increased to be uncontrollable, and further the motor rotating speed is too high and out of control;

the PI regulator is a linear control system, while the permanent magnet synchronous motor is a nonlinear multivariable multi-parameter coupling system, and in the motor control process, the PI regulator is continuously influenced by parameter change and system disturbance of the permanent magnet synchronous motor, and the regulation capability and stability of the PI regulator are reduced;

3. when the integral saturation phenomenon occurs, a control variable of the control system enters a nonlinear interval, the PI regulator cannot enable a control signal to follow a given signal, the error of the control system is increased, the control response time is greatly increased, and even the motor enters an out-of-control state.

Disclosure of Invention

Aiming at the technical problems in the prior art, the invention provides a fuzzy control-based permanent magnet synchronous motor direct current bus voltage control method, which solves the problem that integral errors are accumulated by a PI regulator in a permanent magnet synchronous motor control system and a circuit thereof to cause the deviation of motor phase currents, and solves the problem that the motor is out of control due to the deviation of the motor phase currents in the permanent magnet synchronous motor control system and the circuit thereof.

To suppress or eliminate the integration error, the output of the PI regulator (i.e., the motor phase current) needs to be controlled to return to or be limited to the correct range. Because the phase current of the motor is not easy to be directly controlled, according to a power matching principle (that is, the input power of a system, the rectified direct-current bus power, the inversion power of an inversion part and the running power of the motor are equal when loss is not considered), when the system fluctuates, the phase current of the motor can deviate from a phase current target value determined by the current rotating speed, and the power can be correspondingly changed, at the moment, the direct-current bus voltage can be easily controlled, the power is adjusted, and the phase current of the motor is indirectly adjusted to return to the target value.

The invention is realized by adopting the following scheme: a permanent magnet synchronous motor direct current bus voltage control method based on fuzzy control comprises the following steps:

s1, calibrating parameters of the motor system by adopting the existing testing method, and determining the target value of the motor phase current according to the testing data and the current given rotating speed under the constant load;

s2, inputting the difference value and the change rate of the difference value between the target value of the motor phase current and the actual value of the motor phase current into a fuzzy controller;

s3, the fuzzy controller outputs the adjustment value of the DC bus voltage, and adjusts the motor phase current by adjusting the DC bus voltage according to the power matching principle, thereby indirectly reducing or even eliminating the integral error brought by the PI regulator, and reducing or eliminating the influence of the external interference on the system;

and S4, adjusting the magnitude of the motor phase current to a reasonable range, and reducing or eliminating the integral error brought by the PI regulator.

The "reasonable range" described in S4 is understood as: if the motor system continuously operates with the current relatively stable motor phase current, the integral error is accumulated by the PI regulator and the integral is finally saturated, or the phase current has large fluctuation, the PI regulator excessively responds to cause the system to be out of control, and the current phase current is out of a reasonable range; the reasonable range of motor phase current should enable the PI regulator to properly regulate static errors without generating and accumulating integral errors.

The "reasonable range" of motor phase currents is determined by testing to determine this specific range.

The invention relates to a method for controlling the voltage of a direct current bus of a permanent magnet synchronous motor based on fuzzy control, which detects the error and fluctuation of phase current in a fuzzy control mode, controls and adjusts the voltage of the direct current bus according to the detected error value, changes the power of the direct current bus, indirectly adjusts the phase current of the motor, eliminates the integral error accumulated by a PI (proportional integral) regulator, and prevents overlarge phase current and out-of-control motor caused by the saturation of the integral error.

The method is characterized in that the existing testing method is adopted to calibrate the parameters of the motor system, and the recorded testing method is a technical method which is disclosed in the prior art and is applied to detecting the parameters of the motor system. And according to the data of the motor system obtained from the test result, under the condition of constant load, determining the motor phase current value and the direct current bus voltage value under different rotating speeds, and according to the performance parameter characteristics of the motor system, designing a fuzzy controller and configuring the fuzzy controller in a motor control system.

When the permanent magnet synchronous motor operates, the target value of the current phase current is determined according to the given rotating speed, and the actual value of the motor phase current is detected. And calculating the difference value between the actual value and the target value and the change rate of the difference value, inputting the difference value into a fuzzy controller, and outputting the regulating value of the direct current bus voltage by the fuzzy controller. Adjusting direct current bus voltage can influence direct current bus power, according to the power matching principle, the phase current of motor also can corresponding change to eliminate or reduce the integral error of PI regulator output, prevent that the system from receiving external disturbance and appearing the integral saturation, and then prevent that the motor leads to phase current regulation to be out of order and then the motor is out of control because of the integral saturation.

Compared with the prior art, the invention can achieve the following beneficial effects: the control method provided by the invention eliminates or reduces the integral error output by the PI regulator, thereby preventing integral saturation of the system caused by external interference, and preventing phase current regulation abnormality of the motor due to integral saturation and further preventing the motor from being out of control.

The following description will be given with reference to specific examples.

Drawings

Fig. 1 is a schematic structural diagram of a motor system according to an embodiment of the present invention.

Fig. 2 is a schematic flow chart of a method for controlling a dc bus voltage of a permanent magnet synchronous motor based on fuzzy control according to an embodiment of the present invention.

Wherein the reference numerals are: 1. a fuzzy controller; 2. a direct current bus; 3. an inverter circuit; 4. a permanent magnet synchronous motor.

Detailed Description

To facilitate an understanding of the present invention for those skilled in the art, the present invention will be described in further detail below with reference to specific embodiments and accompanying drawings.

As shown in fig. 1, the present embodiment provides a motor system, which includes a fuzzy controller 1, a dc bus 2, an inverter circuit 3, and a permanent magnet synchronous motor 4, wherein an output end of the dc bus 2 is electrically connected to input ends of the fuzzy controller 1 and the inverter circuit 3, respectively, and an output end of the inverter circuit 3 is electrically connected to the permanent magnet synchronous motor 4.

As shown in fig. 2, the present embodiment provides a method for controlling a dc bus voltage of a permanent magnet synchronous motor based on fuzzy control, and the method is particularly suitable for a permanent magnet synchronous motor 4. The control method comprises the steps of firstly determining load torque matched with a motor system, and obtaining target motor phase current values I corresponding to the motor system under different given rotating speeds through a large number of motor system tests under the torque condition^*DC bus 2 target voltage U^* _dc. When the motor system normally operates at a given rotation speed, the difference of the actual motor phase current from the target value and the change rate of the motor phase current difference are detected and input to the fuzzy controller 1. The fuzzy controller 1 outputs the change value of the voltage of the direct current bus 2 through calculation and judgment of the phase current difference value and the difference value change rate, adjusts the voltage of the direct current bus 2, further adjusts the power of the direct current bus 2, and indirectly adjusts the phase current of the motor according to a power matching principle.

In this embodiment, the load torque matched with the motor system is determined through a motor system test, which specifically includes: the method comprises the steps that a determined motor load is required, a constant torque can be obtained by determining the unchanged motor load, according to an equation (4) and an equation (5), namely a power matching principle, the output voltage, the output current and the voltage of a direct current bus 2 of the motor are changed by changing the running rotating speed of the motor, tests mainly record different output voltage, output current values and voltage values of the direct current bus 2 of the motor when the motor runs stably at different rotating speeds under the constant load torque, and the values are used for parameter setting of the fuzzy controller 1. And setting various parameters of the fuzzy controller 1 according to the test result of the motor system, including input and output discourse domain, fuzzy subset and membership function, establishing a proper fuzzy solving mode, and completing the fuzzy controller 1. The fuzzy controller 1 adopts double-input single-output, takes the phase current difference value and the phase current difference value change rate as input, and outputs the change value of the voltage of the direct current bus 2.

Different phase current target values are set according to different given rotating speeds. The following parameters are sampled when the motor system operates: 1. real-time phase current I of the motor; 2. the motor given speed w is given by a frequency signal. According to the given rotating speed w, determining a standard value I of the motor phase current^*And DC bus 2 target voltage U^* _dc. Real-time phase current I and target phase current I^*The difference and the rate of change of the difference are used as input values for the fuzzy controller 1.

Calculating the difference value of the input phase current and the change rate of the phase current difference value and respectively recording as I_eAnd I_ec。I_ecCan be under two adjacent samples I_eOr I after a certain period of time T_eThe rate of change of (c). If calculated as I_eThe value is always zero, the subsequent fuzzy controller 1 is not turned on. The actual current value at a certain time is recorded as I_nThe actual current value after a period of time T is recorded as I_n+1。I^*、I_ec、I_e、I_n、I_n+1And T satisfies the following relationship:

I_e1＝I_n-I^* (1)

I_e2＝I_n+1-I^* (2)

I_ec＝(I_e2-I_e1)/T (3)

based on establishing fuzzy controlParameters of the system 1, judging I via the fuzzy controller 1_eAnd I_ecDetermined output (change value U of DC bus 2 voltage)_dce) The voltage of the direct current bus 2 is adjusted to the target direct current bus 2 voltage U determined by the current given rotating speed^* _dc。

For the electric machine system, its torque T_eIs fixed, the power P of the motor system varies given different speeds w, P, T_eAnd w satisfies:

meanwhile, according to the condition that the power P of the motor system is equal to the power of the direct current bus 2, the direct current bus 2 has different voltages U under different rotating speeds w_dcAnd current I_dc，P、U_dcAnd I_dcSatisfies the following conditions:

P＝U_dc×I_dc (5)

obtaining the corresponding target phase current value I under each rotating speed w under the condition of stable operation of the motor system^*Target DC bus 2 voltage U^* _dc。

According to the corresponding target phase current value I at each rotating speed w^*Target DC bus 2 voltage U^* _dcThe fuzzy controller 1 is designed, and parameters of the fuzzy controller 1 comprise a controller structure, an input/output discourse domain, a fuzzy subset, a membership function and a fuzzy solution method. Wherein the controller structure is to determine the input and output quantities of the fuzzy controller 1, wherein I is used_eAnd I_ecAs an input quantity, U_dceAs an output.

Suppose a conclusion from the test data, I_eWill generally not exceed + -1A, when T is 100ms (milliseconds), I_ecHas a value of + -5A/100 ms, U_dcThe variation of the input and output domains is determined at +/-5V, and then a proper fuzzy subset and membership function are established. In order to obtain better control effect and control precision, three fuzzy subsets of two inputs are adoptedAngular subset: { NB, NS, ZO, PS, PB }. Output U_dcThe fuzzy subset of (2) also employs a triangular subset. NB means that the actual value differs greatly from the target value, NS means that the difference is small, ZO means that there is almost no error, PS means that the difference is small, and PB means that the difference is large.

Because the value range of the input quantity is a section of continuous real number domain, and after the fuzzification, the input needs to be corresponding to a discrete fuzzy subset, and the value of the input needs to be corresponding to the fuzzy subset through a membership function. By means of I_eIllustrating the membership function:

NB＝(-0.5-x)/0.5，-1≤x＜-0.5

PB＝(x-0.5)/0.5，0.5≤x≤1

the degree of membership indicates the degree to which an element belongs to the fuzzy set. According to the above formula, if I_eThe values of the membership degree PS (0.6) and PB (0.6) are 0.8 and 0.2, respectively.

When the two inputs are fuzzified, fuzzification output can be carried out according to the fuzzy control rule. After one input quantity is fuzzified, two fuzzy subsets are corresponding to the input quantity, and then four applicable fuzzy rules can appear by matching the two fuzzy subsets in pairs after the input quantity is fuzzified by the double-input fuzzy controller. The following table shows the fuzzy rule table:

and selecting a fuzzy resolving mode according to the calculation results of the four fuzzy controls.

The output also has similar membership function, but the output is the prior fuzzy quantity, and the fuzzy is needed to be resolved to be converted into an accurate value for output.

In this embodiment, w is 50Hz, T is 100ms, and corresponds to I^*Is 1.0A, U^* _dcIs 311V. Normal operation of the motor system, I_eValue of (A) and (B)_ecAlways 0. Occurrence of disturbance such that I_eBecomes 0.2A, recorded as I_e1(ii) a After 100ms, I_eBecomes 0.9A, is marked as I_e2. Start of calculation of I_ec，I_ecIt was 0.7A/100 ms. Will I_e2And I_ecInputting the fuzzy controller 1, carrying out fuzzification into PB, PS, ZO and PS, finding out four corresponding fuzzy rules according to fuzzy control rules, and carrying out calculation.

U_dceThere will be four ranges according to the four fuzzy rules, and it is assumed that we solve the fuzzy by the maximum membership mean value method, which will obtain U_dceThe precise value of (2).

Output deblurring, I_e2The membership degree to PB is 0.8, and the membership degree to PS is 0.2; i is_ecThe degree of membership was 0.72 for ZO and 0.28 for PS. The fuzzy control algorithm can obtain the output fuzzy quantity of 0.72NS, the 0.72NS has two values, one is-3.2 and the other is-1.8, the average value of the two values is-2.5, and the output U is obtained at the moment_dceThe clear value of (A) is-2.5, indicating that U is to be added_dcAdjusted to-2.5V less than the current value. This flow is repeated, and the voltage control of the dc bus 2 is continuously performed.

The controlled voltage of the direct current bus 2 changes the power of the direct current bus 2, and the phase current of the motor also changes according to the power matching principle. Thereby reducing or eliminating the integral error introduced by the PI regulator.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.