CN105915144A - Permanent magnet synchronous motor rotating speed tracking control method - Google Patents

Abstract

The invention discloses a permanent magnet synchronous motor rotating speed tracking control method. The permanent magnet synchronous motor rotating speed tracking control method comprises the steps of acquiring a motor rotating speed estimated value by means of an extended Kalman filter, generating a control signal according to a current actual value and a reference value by means of a controller, and implementing control on motor rotating speed via an inverter. A control system for implementing the permanent magnet synchronous motor rotating speed tracking control method comprises an extended Kalman filtering module, a rotating speed control module, a current control module, the inverter and a controlled motor. The permanent magnet synchronous motor rotating speed tracking control method is simple and clear, and can perform tracking control on rotating speed of a permanent magnet synchronous motor accurately. Compared with the traditional vector control method, the permanent magnet synchronous motor rotating speed tracking control method is simple in system structure, and has a certain application prospect.

Description

Method for tracking and controlling rotating speed of permanent magnet synchronous motor

Technical Field

The invention relates to control and application of a permanent magnet synchronous motor, in particular to a method for controlling the rotating speed of the permanent magnet synchronous motor.

Background

The permanent magnet synchronous motor has the characteristics of stable operation, high efficiency and good speed regulation performance, and along with the rapid development of a novel motor control theory, the permanent magnet synchronous motor is rapidly popularized and applied in many fields.

In order to realize high-precision control of the motor, the rotation speed and position information of the rotor of the motor need to be known, and a position sensor is generally used for obtaining the information at present. The use of position sensors, however, can increase system costs and be detrimental to maintenance and repair. Under severe operating conditions, large errors may occur, reducing reliability. The sensorless control technology utilizes a mathematical model of the motor itself, and obtains estimated values of the speed and position information of the motor rotor by using an estimation algorithm through measured voltage and current of the motor, so that the sensorless control technology is widely researched.

The current permanent magnet synchronous motor control method mainly comprises a direct torque control method and a vector control method, wherein the methods generally comprise a superposed torque control loop and a superposed current control loop, a PI controller obtains a control signal, and finally an SVPWM control technology is utilized to control an inverter. These methods rely on accurate motor parameters and are relatively complex in structure and inconvenient to apply.

Disclosure of Invention

The purpose of the invention is as follows: the invention aims to provide an effective method for controlling the rotating speed of a permanent magnet synchronous motor, which simplifies the structure of a control system and ensures that the actual rotating speed of the motor can accurately track the given rotating speed.

The technical scheme is as follows: a rotating speed tracking control method of a permanent magnet synchronous motor comprises the following steps:

(1) estimating a motor rotating speed value by using an extended Kalman filter, and obtaining a torque reference value through a PI (proportional integral) controller;

(2) two effective voltage vectors are arbitrarily selected from 6 types of effective voltage vectors of the inverter, errors between actual currents and reference currents of the motor after the two voltage vector control signals are adopted are compared, and the voltage vector with the small error is selected as the control voltage at the sampling moment;

(3) controlling the switching state of the inverter according to the voltage vector with small error selected in the step (2), thereby controlling the motor;

(4) and (4) entering the next sampling time, and repeating the steps (1) to (4).

Further, in the two voltage vectors selected in the step (2), a current error corresponding to any one of the voltage vectors_nThe calculation method is

Wherein n is the serial number of the correspondingly selected voltage vector, and n is 1 or 2; i.e. i₀The current component calculated according to the motor equation; v. of_nThe voltage vectors are correspondingly selected; Δ t is the discrete sampling time, L_d、L_qEquivalent inductances of d and q axes of the motor, i^*Is a reference current; wherein i^*And i₀The following are calculated respectively:

wherein,is a torque reference value, p is the pole pair number of the motor, psi is a permanent magnet flux linkage, R is a stator resistance, i_d,k、i_q,kCurrent sampling time d, q axis current, omega_kIs the electrical angular velocity of the motor.

Further, the step (2) selects a voltage vector with a small error as the control voltage at the current sampling time, which specifically comprises:

order to

Wherein theta is the position of the motor rotor;

when T is less than or equal to 0, selecting v₁As a control voltage;

when T is more than 0, selecting v₂As a control voltage.

Further, the two voltage vectors selected in the step (2) are respectively

Wherein, V_DCIs the dc voltage and θ is the motor rotor position.

Has the advantages that: the inverter switching signal can be obtained by the proposed speed control method, and the inverter can be directly controlled. And an SVPWM module is omitted, only two voltage control vectors are selected, the system structure is simplified, and the engineering implementation is facilitated. In addition, the rotating speed and the position of the motor are obtained through extended Kalman filtering, and a position sensor is not needed, so that the system cost is reduced, the rotating speed control response speed of the system is increased, and the operation reliability is improved.

Drawings

FIG. 1 is a block diagram of the complete control system of the present invention;

FIG. 2 is a flow chart of a motor control method according to the present invention.

Detailed Description

The invention is based on a permanent magnet synchronous machine i_dAnd (5) calculating a target current value from the given rotating speed according to the control strategy of 0. Then, after comparing the current errors generated by the two voltage control vectors, selecting the current error with smaller error as a control voltage, and finally realizing the rotation speed of the motor through an inverterAnd (4) controlling. And the control of the permanent magnet synchronous motor without a position sensor can be realized by combining an extended Kalman filter, the system structure is simplified, and the cost is reduced.

The following describes the specific implementation method of the present invention with reference to the attached drawings.

As shown in attached figures 1 and 2, Clark and Park conversion is firstly applied to obtain equivalent currents of d and q axes of a motor, then an estimated rotating speed of the motor is obtained through an extended Kalman filter, and after the estimated rotating speed is compared with a given tracking rotating speed, a PI rotating speed controller can obtain a given electromagnetic torque value

According to the electromagnetic torque T of the permanent magnet synchronous motor_emComputational expression

When adopting i_dWhen the control strategy is 0, a reference current i is given^*The following were used:

where psi is permanent magnet flux linkage, p is motor pole pair number, i_d,k、i_q,kD and q axis currents, L at the current sampling time_d、L_qThe equivalent inductances of d and q axes of the motor are respectively.

Two effective voltage vectors are arbitrarily selected from 6 types of effective voltage vectors output by the inverter, the error between the actual current and the reference current of the motor after the two voltage vector control signals are respectively adopted is compared, and the voltage vector with small error is selected as the control voltage at the sampling moment. The following two voltage vectors are selected in this embodiment:

wherein, V_DCIs the dc voltage and θ is the motor rotor position. Matrix [ 001 ]]^T，[0 1 0]^TThe inverter switching state can be reflected.

Using voltage vectors v_nAfter the motor is controlled, the actual current vector i_nComprises the following steps:

in the formula, n is 1, 2, i₀Delta t is a discrete sampling time for a current component calculated according to a motor equation; wherein:

wherein R is stator resistance, i_d,k、i_q,kCurrent sampling time d, q axis current, omega_kIs the electrical angular velocity of the motor.

Then, after the two control voltage vectors are respectively adopted, the error between the actual current corresponding to each voltage vector and the reference current is calculated_nComprises the following steps:

calculating the module value of the error vector, selecting the vector with small error as the control voltage of the sampling moment, and specifically:

order to

When T is less than or equal to 0, selecting v₁As a control voltage;

when T is more than 0, selecting v₂As a control voltage.

And controlling the switching state of the inverter according to the selected voltage vector to control the motor.

And then entering the next sampling moment, and repeating the steps to realize the rotating speed tracking control of the permanent magnet synchronous motor.

However, the method is not limited to this, and any two of the 6 effective voltage vectors can be used as the control voltage selected by the present invention.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims (4)

1. A rotating speed tracking control method of a permanent magnet synchronous motor is characterized by comprising the following steps:

(1) estimating a motor rotating speed value by using an extended Kalman filter, and obtaining a torque reference value through a PI (proportional integral) controller;

(2) two effective voltage vectors are arbitrarily selected from 6 types of effective voltage vectors of the inverter, errors between actual currents and reference currents of the motor after the two voltage vector control signals are adopted are compared, and the voltage vector with the small error is selected as the control voltage at the sampling moment;

(3) controlling the switching state of the inverter according to the voltage vector with small error selected in the step (2), thereby controlling the motor;

(4) and (4) entering the next sampling time, and repeating the steps (1) to (4).

2. The method for tracking and controlling the rotating speed of the permanent magnet synchronous motor according to claim 1, characterized in that: the current error corresponding to any voltage vector in the two voltage vectors selected in the step (2)_nThe calculation method is

${\mathrm{\ϵ}}_n=i^{*}-i_0-v_n\·\mathrm{\Δ}t\left[\begin{array}{cc}1/L_d& \\ & 1/L_q\end{array}\right]$

Wherein n is the serial number of the correspondingly selected voltage vector, and n is 1 or 2; i.e. i₀The current component calculated according to the motor equation; v. of_nThe voltage vectors are correspondingly selected; Δ t is the discrete sampling time, L_d、L_qEquivalent inductances of d and q axes of the motor, i^*Is a reference current; wherein i^*And i₀The following are calculated respectively:

$i^{*}=\left[\begin{array}{c}0\\ \frac{2T_{em}^{*}}{3p\mathrm{\ψ}}\end{array}\right],i_0=\left[\begin{array}{c}{i}_{d.k}(1-\frac{R}{L_d}\mathrm{\Δ}t)+{\mathrm{\ω}}_k\frac{L_q}{L_d}\mathrm{\Δ}t\·i_{q,k}\\ i_{q,k}(1-\frac{R}{L_q}\mathrm{\Δ}t)-{\mathrm{\ω}}_k\frac{L_d}{L_q}\mathrm{\Δ}t\·i_{d,k}-{\mathrm{\ω}}_k\frac{\mathrm{\ψ}}{L_q}\mathrm{\Δ}t\end{array}\right]$

wherein,is a torque reference value, p is the pole pair number of the motor, psi is a permanent magnet flux linkage, R is a stator resistance, i_d,k、i_q,kCurrent sampling time d, q axis current, omega_kIs the electrical angular velocity of the motor.

3. The method for tracking and controlling the rotating speed of the permanent magnet synchronous motor according to claim 2, characterized in that: selecting a voltage vector with a small error as a control voltage of the current sampling moment in the step (2), and specifically:

order to

$\begin{array}{c}T={\mathrm{\ϵ}}_1-{\mathrm{\ϵ}}_2\\ =|i^{*}-i_0-v_1\·\mathrm{\Δ}t\left[\begin{array}{cc}1/L_d& \\ & 1/L_q\end{array}\right]|-|i^{*}-i_0-v_2\·\mathrm{\Δ}t\left[\begin{array}{cc}1/L_d& \\ & 1/L_q\end{array}\right]|\\ =\mathrm{\Δ}t\·\[(2+\sqrt{3})\cos \mathrm{\θ}-\sqrt{3}\sin \mathrm{\θ}\]-6i_{d,k}(L_d-R\mathrm{\Δ}t)-{\mathrm{\ω}}_k{L}_q\mathrm{\Δ}t\·i_{q,k}\end{array}$

Wherein theta is the position of the motor rotor;

when T is less than or equal to 0, selecting v₁As a control voltage;

when T is more than 0, selecting v₂As a control voltage.

4. The method for tracking and controlling the rotating speed of the permanent magnet synchronous motor according to claim 1, characterized in that: the two voltage vectors selected in the step (2) are respectively

$v_1=V_{DC}\left[\begin{array}{cc}cos\mathrm{\θ}& \sin \mathrm{\θ}\\ -sin\mathrm{\θ}& cos\mathrm{\θ}\end{array}\right]\left[\begin{array}{ccc}\frac{2}{3}& -\frac{1}{3}& -\frac{1}{3}\\ 0& \frac{1}{\sqrt{3}}& -\frac{1}{\sqrt{3}}\end{array}\right]\left[\begin{array}{c}0\\ 0\\ 1\end{array}\right],v_2=V_{DC}\left[\begin{array}{cc}cos\mathrm{\θ}& \sin \mathrm{\θ}\\ -sin\mathrm{\θ}& cos\mathrm{\θ}\end{array}\right]\left[\begin{array}{ccc}\frac{2}{3}& -\frac{1}{3}& -\frac{1}{3}\\ 0& \frac{1}{\sqrt{3}}& -\frac{1}{\sqrt{3}}\end{array}\right]\left[\begin{array}{c}0\\ 1\\ 0\end{array}\right]$

Wherein, V_DCIs the dc voltage and θ is the motor rotor position.