阅读说明：本技术 一种五相异步电机按定子磁场定向的控制策略 (Control strategy for five-phase asynchronous motor according to stator magnetic field orientation ) 是由 孟大伟 徐艺玲 于 2019-09-09 设计创作，主要内容包括：本发明涉及一种五相异步电机按定子磁场定向的控制策略。考虑五相异步电机的特点,该控制策略综合了矢量控制和直接转矩控制的优点。从转矩控制效果出发,在定子电阻压降补偿的基础上,通过定子直轴电势控制定子磁链,并通过控制电流转矩分量来达到控制转矩的目的,既实现了定子磁链和转矩的连续控制,又避开了系统控制器对转子参数的依赖性。采用了连续的控制方法克服了滞环控制带来的转矩脉动。本发明适用于电力电子与电力传动领域。(The invention relates to a control strategy for a five-phase asynchronous motor according to stator magnetic field orientation. The control strategy integrates the advantages of vector control and direct torque control by considering the characteristics of the five-phase asynchronous motor. From the torque control effect, on the basis of the compensation of the resistance voltage drop of the stator, the stator flux linkage is controlled through the direct axis potential of the stator, and the torque is controlled through controlling the current torque component, so that the continuous control of the stator flux linkage and the torque is realized, and the dependence of a system controller on rotor parameters is avoided. And a continuous control method is adopted to overcome torque pulsation caused by hysteresis control. The invention is suitable for the fields of power electronics and power transmission.)

1. A control strategy for a five-phase asynchronous motor according to stator magnetic field orientation is characterized in that:

firstly, the stator flux linkage adopts continuous closed-loop control, and the change rate of the stator flux linkage is directly controlled on the basis of compensating the resistance voltage drop of a stator;

the rotating speed control adopts a structure similar to vector control, and the inner ring is used for controlling the current and torque components of the stator, so that the torque current can be quickly followed;

and the third ring is electromagnetic torque closed-loop control and is used for inhibiting disturbance of stator flux linkage on torque, and the outermost ring is a rotating speed closed loop.

2. The stator flux linkage of claim 1 employing continuous closed loop control to directly control the rate of change of the stator flux linkage based on compensating for stator resistive voltage drops, wherein: the stator flux linkage and the stator current torque component act together to generate electromagnetic torque, the stator current torque component also affects the stator flux linkage at the same time, and the coupling is large, so that stator flux linkage closed-loop control is needed to inhibit the influence of the stator current torque component on the stator flux linkage, and the stator flux linkage set value psi is obtained according to the stator flux linkage set value _sdAnd actual valueψ _sdDeviation of [ delta ] phi _sdDesigning flux linkage actuators to produce direct axis electricity

Given potential value e _dAnd generating a stator voltage direct-axis component given value u by adding the stator resistance voltage drop _sdThe change rate of the amplitude of the stator flux linkage is as follows:

wherein: r _sdIs a stator straight axis resistance i _sdFor stator direct axis current u _sdIs the stator direct axis voltage, e _dIs a direct axis potential.

3. The inner loop of speed control as claimed in claim 1 is stator current torque component control, characterized by: splitting a stator current into two components i _sdAnd i _sq，i _sqIs the torque component of the stator current, i _sdThe excitation component of the stator current, when in steady state, is:

wherein: psi _sdFor stator flux linkage, /) _sIs a stator side inductance, T _rIs the rotor time constant, sigma is the magnetic leakage coefficient,

ω _mis the angular velocity of rotation, omega, of the stator field _rIs the motor speed.

4. The second ring of speed control of claim 1 is a closed loop electromagnetic torque control characterized by: the output of the speed regulator being given T of the torque regulator _eWith the output of the torque regulator being input i of the current regulator _sqWhen the stator flux linkage changes, the electromagnetic torque changes, and the torque regulator regulates the torque deviation to timely change _sqSo that the electromagnetic torque follows the given value, and the disturbance of the stator torque is restrained, wherein the electromagnetic torque of the motor is expressed as:

wherein: n is _pThe number of pole pairs of the motor.

Technical Field

The invention relates to the field of power electronics and electric traction, in particular to the field of a variable-frequency speed regulation control system of a multiphase asynchronous motor.

Background

For the variable frequency speed regulating system of the asynchronous motor, the torque characteristic of the motor is controlled, and the rotating speed of the motor is also controlled. Thus, the fundamental problem with ac governor systems is torque control.

The torque of an ac motor is generally related to the rotating magnetic fields of the stator and rotor and the angle between them, so that in a governor system, if the torque is to be controlled, the magnetic flux must be controlled first. In field oriented control (or vector control, FOC), each alternating current in a stationary coordinate system is converted into two mutually perpendicular components in a synchronous coordinate system, namely an excitation component and a torque component, by means of coordinate transformation, thereby realizing respective closed-loop control (or decoupling) of magnetic flux and torque. Direct Torque Control (DTC) abandons coordinate transformation, does not consider how to decouple the stator currents, but directly focuses on torque control, and the concept of "direct self-control" is not only used for torque control, but also for self-control of magnetic flux.

Analysis on the mathematical model of the five-phase asynchronous motor can prove that the mathematical model of the five-phase asynchronous motor under a static coordinate system is consistent with the mathematical model of the three-phase asynchronous motor. Therefore, the FOC, DTC and other speed regulation control technologies widely used for three-phase asynchronous motors can be used for variable frequency speed regulation of five-phase asynchronous motors. However, the characteristics of the five-phase asynchronous motor determine that the application occasion of the five-phase asynchronous motor is a system with high reliability requirement, small steady-state rotating speed pulsation and stable operation. The control quantity of the five-phase asynchronous motor is far more than that of a three-phase system, so that the speed regulation control strategy of the system is simplified as much as possible on the premise of meeting the performance requirement. From this perspective, the DTC is advantageous because links such as coordinate transformation and magnetic field orientation in the vector control algorithm are complex, which greatly increases the burden on the processor, and the influence of the rotor magnetic field orientation control by the variation of the rotor parameters is large. However, in the conventional DTC control, because the flux linkage and the torque are regulated by adopting a hysteresis loop or a two-position pop-pop control, the torque pulsation is large at a low speed, so that the low-speed performance of the DTC system is deteriorated, and the speed regulation range is not wide. Therefore, the advantages of vector control and direct torque control can be integrated, a control strategy is found, and the method is simple and can meet the requirement of high-performance transmission. This is one of the goals in high performance governor systems. This is especially necessary for a speed regulating system of a five-phase asynchronous motor.

Disclosure of Invention

The invention aims to provide a control strategy for a five-phase asynchronous motor according to stator magnetic field orientation, the control strategy can be used for the analysis and research of other multi-phase asynchronous motor variable frequency speed control systems, and in order to achieve the aim, the invention adopts the following technical scheme:

the invention provides a control strategy for a five-phase asynchronous motor according to stator magnetic field orientation, which is characterized in that:

firstly, the stator flux linkage adopts continuous closed-loop control, and the change rate of the stator flux linkage is directly controlled on the basis of compensating the resistance voltage drop of a stator;

the rotating speed control adopts a structure similar to vector control, and the inner ring is used for controlling the current and torque components of the stator, so that the torque current can be quickly followed;

and the third ring is electromagnetic torque closed-loop control and is used for inhibiting disturbance of stator flux linkage on torque, and the outermost ring is a rotating speed closed loop.

In one embodiment, the stator flux linkage adopts continuous closed-loop control, and directly controls the change rate of the stator flux linkage on the basis of compensating the resistance voltage drop of the stator, wherein the conversion rate of the stator flux linkage is expressed as:

wherein: r _sdIs a stator straight axis resistance i _sdFor stator direct axis current u _sdIs the stator direct axis voltage, e _dIs a direct axis potential.

In the second step, the stator flux linkage is controlled by the stator direct axis potential, and when the system is in a steady state, the expression of the stator flux linkage is as follows:

ψ _sd＝l _si _sd-T _rσl _s(ω _m-ω _r)i _sq

wherein: psi _sdFor stator flux linkage, /) _sIs a stator side inductance, T _rIs the rotor time constant, σ is the leakage coefficient, ω _mIs the angular velocity of rotation, omega, of the stator field _rIs the motor speed.

In the third step, in order to restrain the influence of the stator flux linkage on the torque, electromagnetic torque closed-loop control is used, and the expression of the electromagnetic torque is as follows:

T _e＝n _pi _sqψ _sd

wherein: n is _pThe number of pole pairs of the motor.

In conclusion, a schematic diagram of a system for directionally controlling the five-phase asynchronous motor according to the magnetic field of the stator can be obtained.

According to the control strategy, the variable frequency speed regulation of the five-phase asynchronous motor is directionally controlled according to the stator magnetic field, the speed regulation performance requirement of the five-phase asynchronous motor is better met than that of the five-phase asynchronous motor which is directly controlled by FOC or DTC, and further analysis and research can be carried out on speed regulation control systems of other multiphase asynchronous motors.

Drawings

In order to more clearly illustrate the practice of the invention, reference will now be made to the appended drawings, which are required in describing embodiments.

FIG. 1 is a schematic diagram of a system for directionally controlling a five-phase asynchronous motor according to a stator magnetic field, FIG. 2 is a stator flux linkage control diagram, FIG. 3 is an electromagnetic torque control diagram

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the present application, and it is obvious that the described embodiments are some, not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.