CN112511064A

CN112511064A - Motor current loop PI controller parameter self-tuning method

Info

Publication number: CN112511064A
Application number: CN202011232941.XA
Authority: CN
Inventors: 张田飞; 王梦柯; 魏世克
Original assignee: Luoyang Institute of Electro Optical Equipment AVIC
Current assignee: Luoyang Institute of Electro Optical Equipment AVIC
Priority date: 2020-11-06
Filing date: 2020-11-06
Publication date: 2021-03-16

Abstract

The invention relates to a motor current loop PI controller parameter self-tuning method, which is used for self-tuning of motor current loop PI controller parameters; the method comprises the following steps: firstly, under an open-loop mode, applying a voltage instruction to a motor, and sampling the current of the motor by taking the switching period of PWM as a sampling period to obtain a motor current sequence within a period of time; secondly, after the obtained current sequence is processed, the period and the amplitude of a main guide frequency component in the current sequence are obtained, and the gain of the current loop PI controller is obtained through calculation; and finally, calculating according to the Z-N self-setting rule to obtain a proportional coefficient and an integral coefficient of the PI controller. The method is simple and convenient, the defect of manual parameter adjustment is overcome, and the parameter setting of the motor current loop PI controller can be completed quickly and accurately.

Description

Motor current loop PI controller parameter self-tuning method

Technical Field

The invention belongs to the field of motor control, and relates to a parameter self-tuning method for a motor current loop PI controller.

Background

The current loop is the innermost loop in the motor drive and the performance of the current inner loop determines the performance of the entire motor system. The PI controller is the most commonly used controller for the current loop, and the parameters of the PI controller determine the performance of the current loop. The PI controller setting method commonly used in engineering comprises a manual regulation method and a self-setting method. The manual adjustment method is time-consuming and labor-consuming, and requires a strong engineering experience of workers. Self-tuning methods are classified into model-based parameter identification methods and non-model-based methods. The parameter identification method based on the model needs to identify the parameters accurately enough and is not suitable for the occasions with system parameter changes. The method is not based on a model, and the setting parameter has strong adaptability and high robustness.

Disclosure of Invention

Technical problem to be solved

In order to avoid the defects of the prior art, the invention provides a parameter self-tuning method of a motor current loop PI controller, which adopts a parameter self-tuning strategy not based on a model, reduces the time of manual adjustment, and has strong adaptability of the tuned parameters and high robustness compared with the self-tuning strategy based on model parameter identification.

Technical scheme

A motor current loop PI controller parameter self-tuning method is characterized by comprising the following steps:

step 1: in an open loop state, applying a voltage command u-h to a motor, collecting motor current I by taking a PWM period T as a sampling period, applying the voltage command u-h when I is greater than I and I is greater than 0, and collecting motor current for more than 10 seconds when I is less than-I to obtain an original motor current sequence I (k);

the voltage command h is more than or equal to 3 multiplied by R multiplied by I, R is the nominal resistance value of the motor, I is the current switching threshold value, and I is more than or equal to 5 multiplied by delta I; delta I is the resolution of the current sampling of the motor;

step 2: low-pass filtering the original motor current sequence i (k) to obtain a filtered motor current sequence i^/(k) (ii) a For motor current sequence i^/(k) Performing fast Fourier transform to obtain a motor current sequence i^/(k) The period Tu and amplitude d of the pilot frequency domain portion on the frequency domain component;

and step 3: performing data processing on the period Tu and the amplitude d by adopting a relay feedback method to obtain a gain Ku of a motor current loop PI controller; and calculating to obtain a proportional coefficient Kp integral coefficient Ki of the motor current loop PI controller by adopting a Z-N controller setting rule:

wherein: d is the filtered motor current sequence i^/(k) The amplitude of the dominant frequency component obtained by fast Fourier transform, Tu is the filtered motor current sequence i^/(k) The period of the dominant frequency component resulting from the fast fourier transform.

The low-pass filtering process of the step 2 is as follows: i.e. i^/(k)＝α×i(k)+(1-α)×i^/And (k-1), alpha is a low-pass filter coefficient.

Advantageous effects

The invention provides a parameter self-tuning method of a motor current loop PI controller, which is used for self-tuning of the motor current loop PI controller parameters; the method comprises the following steps: firstly, under an open-loop mode, applying a voltage instruction to a motor, and sampling the current of the motor by taking the switching period of PWM as a sampling period to obtain a motor current sequence within a period of time; secondly, after the obtained current sequence is processed, the period and the amplitude of a main guide frequency component in the current sequence are obtained, and the gain of the current loop PI controller is obtained through calculation; and finally, calculating according to the Z-N self-setting rule to obtain a proportional coefficient and an integral coefficient of the PI controller. The method is simple and convenient, the defect of manual parameter adjustment is overcome, and the parameter setting of the motor current loop PI controller can be completed quickly and accurately.

Drawings

Fig. 1 is a motor current loop control block diagram.

FIG. 2 is a parameter self-tuning flow of a motor current loop PI controller.

FIG. 3 is a schematic diagram of a voltage command applied by the motor.

Fig. 4 is a response curve of motor applied voltage and motor current.

Fig. 5 is a process flow diagram of a motor current sequence.

Detailed Description

The invention will now be further described with reference to the following examples and drawings:

in a specific implementation case, the nominal resistance R of the motor is 2.49 Ω, the rated voltage is 24V, the sampling resolution of the driver current is 5mA, and the desired closed-loop bandwidth f of the current loop is 1 kHZ.

As shown in fig. 1, it is a control block diagram of a motor current loop, and the motor current loop adopts a PI controller.

As shown in fig. 2, the method for self-tuning the parameters of the motor current loop PI controller of the present invention includes the following steps:

step 1, as shown in fig. 3, in an open loop state, starting to apply a voltage command u-h (h >0) to a motor, collecting a motor current I with a PWM period T as a sampling period, and then applying different voltage commands according to the situation of the current I, wherein when I > I (I >0), the voltage command u-h is applied, when I < -I, the voltage command u-h is applied, and the current within a certain period of time is collected and stored, so as to obtain an original motor current sequence I (k), and a current response curve is shown in fig. 4;

step 2, as shown in fig. 5, performing low-pass filtering on the motor current sequence i (k) acquired in step 1 to obtain a filtered motor current sequence i^/(k) For motor current sequence i^/(k) Performing fast Fourier transform to obtain a motor current sequence i^/(k) The period Tu and amplitude d of the pilot frequency domain portion on the frequency domain component;

and 3, obtaining the gain Ku of the motor current loop PI controller according to a data processing mode of a relay feedback method, and calculating to obtain a proportional coefficient Kp and an integral coefficient Ki of the motor current loop PI controller according to a setting rule of the Z-N controller.

In step 1, the voltage command h and the current switching threshold I are selected according to the following formula,

wherein, Δ I is the resolution of the motor current sampling, and R is the nominal resistance value of the motor. According to the implementation case, the current sampling resolution is 5mA, in the implementation case, I is 0.1A, and the command voltage h is 1V. The motor current curve obtained after the motor applies the voltage command is shown in fig. 4.

In step 2, the original motor current sequence i (k) is subjected to low-pass filtering according to the following formula to obtain a filtered motor current sequence i^/(k)，

i^/(k)＝α×i(k)+(1-α)×i^/(k-1)

Where α is a low-pass filter coefficient, which is selected in relation to the desired bandwidth of the current loop of the motor, and for the embodiment where the desired bandwidth f of the current loop is 1kHZ, α is selected

In step 3, the gain Ku of the motor current loop PI controller is obtained according to a data processing mode of a relay feedback method, the proportional coefficient Kp and the integral coefficient Ki of the motor current loop PI controller are calculated according to the setting rule of a Z-N controller, as shown in the following formula,

wherein h is the amplitude of the voltage command applied in the step 1, and d is the filtered motor current sequence i^/(k) The amplitude of the dominant frequency component obtained by fast Fourier transform, Tu is the filtered motor current sequence i^/(k) The period of the dominant frequency component resulting from the fast fourier transform.

Claims

1. A motor current loop PI controller parameter self-tuning method is characterized by comprising the following steps:

step 2: low-pass filtering the original motor current sequence i (k) to obtain a filtered motor current sequence i^/(k) (ii) a For motor current sequence i^/(k) Performing fast Fourier transform to obtainSequence of motor currents i^/(k) The period Tu and amplitude d of the pilot frequency domain portion on the frequency domain component;

2. The motor current loop PI controller parameter self-tuning method of claim 1, characterized in that: the low-pass filtering process of the step 2 is as follows: i.e. i^/(k)＝α×i(k)+(1-α)×i^/And (k-1), alpha is a low-pass filter coefficient.