CN-117458923-B - Permanent magnet synchronous motor maximum torque current ratio control method considering core loss

CN117458923BCN 117458923 BCN117458923 BCN 117458923BCN-117458923-B

Abstract

The application provides a control method for the maximum torque current ratio of a permanent magnet synchronous motor considering the core loss, comprehensively considers the influence of the core loss, winding loss and magnetic saturation effect, enables an established model to be more attached to the actual working condition of the permanent magnet synchronous motor in the corresponding deduction process, can fully utilize the stator current of the permanent magnet synchronous motor in control, improves the control accuracy and the motor efficiency, and is beneficial to reducing the motor heating, thereby effectively overcoming the defect of insufficient consideration of the important loss and influencing factors in the prior art.

Inventors

ZHANG CHENGNING
Ba xin
GONG ZHENJIE

Assignees

北京理工大学

Dates

Publication Date: 20260505
Application Date: 20220718

Claims (3)

1. The control method for the maximum torque current ratio of the permanent magnet synchronous motor taking the core loss into consideration is characterized by comprising the following steps of: Step one, respectively establishing d-axis and q-axis equivalent circuit models of a permanent magnet synchronous motor under a rotating coordinate system by considering core loss, winding loss and magnetic saturation effect, wherein in the equivalent circuit models, the topological structure of the d-axis is formed by the internal resistance R s of a phase winding, The d-axis inductance L d and the rotary electromotive force omega e L q I q are connected in series firstly and then are connected in parallel with an equivalent load iron loss resistor R i to form a loop, the two ends of the loop are d-axis voltage V d , the q-axis topological structure is formed by phase winding internal resistance R s , The q-axis inductance L q and the rotating electromotive force omega e L d I d are firstly connected in series and then connected in parallel with an equivalent load iron loss resistor R i , an equivalent abnormal loss resistor R an connected in parallel with each other, An equivalent eddy current loss resistance R e , The equivalent hysteresis loss resistor R h and the counter electromotive force omega e λ f are sequentially connected to form a loop, the two ends of the loop are provided with q-axis voltage V q , wherein omega e is the rotor electric angular velocity, and I d 、I q is d-axis voltage, q-axis current, lambda f is the permanent magnet flux linkage; step two, aiming at the maximum torque current ratio control of the permanent magnet synchronous motor, the following stator current optimization targets are set: and constructs the following auxiliary function F: Wherein P is the number of poles of the permanent magnet synchronous motor, and χ is the Lagrangian multiplier; Step three, solving partial derivatives of the auxiliary function F on d-axis current, q-axis current and Lagrange operator: let each partial derivative equal to 0 and based on the L d <L q relation in the permanent magnet synchronous motor, successively solve the q-axis current and the d-axis current: And combining the stator current optimization targets to obtain optimal stator currents, and calculating to obtain the electromagnetic torque of the corresponding permanent magnet synchronous motor.
2. The method of claim 1, wherein the mathematical model of the permanent magnet synchronous motor is obtained based on the topological structures of the d axis and the q axis of the equivalent circuit model in the first step: Wherein, I cd 、I cq is d-axis and q-axis load iron-loss current respectively, I md 、I mq 、I oq is d-axis and q-axis magnetizing current respectively, I can 、I ce 、I ch is no-load iron-loss current corresponding to no-load abnormal loss, no-load eddy-current loss and no-load hysteresis loss respectively, p is differential operator d/dt, t is time variable; the current of each branch can be respectively solved to obtain: the electromagnetic torque of the permanent magnet synchronous motor considering the core loss, the winding loss and the magnetic saturation effect is calculated as follows:
3. The method of claim 1, wherein the d-axis current expression is substituted into the electromagnetic torque expression after the optimal stator current is solved in the third step, so that the electromagnetic torque with the following form can be obtained: In the formula,

Description

Permanent magnet synchronous motor maximum torque current ratio control method considering core loss Technical Field The invention belongs to the technical field of permanent magnet synchronous motor control, and particularly relates to a maximum torque current ratio control strategy which comprehensively considers core loss, winding loss and magnetic saturation effect aiming at permanent magnet synchronous motor design. Background In the prior art, a precondition of neglecting core loss, magnetic saturation effect of motor core materials and the like is generally adopted for a maximum torque current ratio control strategy of a permanent magnet synchronous motor, and the maximum output torque under the minimum current is calculated by taking the minimum winding loss (namely copper loss) as an optimization target. However, with the development of the permanent magnet synchronous motor, indexes such as rotation speed and torque range of the permanent magnet synchronous motor are continuously widened, and under the working conditions of high speed and load, the core loss gradually exceeds the winding loss to become the dominant loss of the permanent magnet synchronous motor, and larger calculation errors are probably caused by neglecting the core loss and the magnetic saturation effect of the core material. The main electromagnetic loss of the permanent magnet synchronous motor comprises winding loss and core loss, which not only directly determine the efficiency of the motor, but also are closely related to the heat generation of the motor, thereby influencing the power density and the torque density of the motor, and therefore, the power density and the torque density of the motor are not ignored in a control strategy. Therefore, how to fully consider the influences of core loss, winding loss and magnetic saturation effect in the maximum torque current ratio control strategy of the permanent magnet synchronous motor and build a more scientific and reasonable model is a technical problem to be solved in the field. Disclosure of Invention Aiming at the technical problems in the art, the application provides a control method for the maximum torque current ratio of a permanent magnet synchronous motor considering core loss, which specifically comprises the following steps: Step one, respectively establishing d-axis and q-axis equivalent circuit models of a permanent magnet synchronous motor under a rotating coordinate system by considering core loss, winding loss and magnetic saturation effect, wherein in the equivalent circuit models, the topological structure of the d-axis is formed by the internal resistance R s of a phase winding, The d-axis inductance L d and the rotary electromotive force omega eLqIq are connected in series firstly and then are connected in parallel with an equivalent load iron loss resistor R i to form a loop, the two ends of the loop are d-axis voltage V d, the q-axis topological structure is formed by phase winding internal resistance R s, The q-axis inductance L q and the rotating electromotive force omega eLdId are firstly connected in series and then connected in parallel with an equivalent load iron loss resistor R i, an equivalent abnormal loss resistor R an connected in parallel with each other, An equivalent eddy current loss resistance R e, The equivalent hysteresis loss resistor R h and the counter electromotive force omega eλf are sequentially connected to form a loop, the two ends of the loop are provided with q-axis voltage V q, wherein omega e is the rotor electric angular velocity, and I d、Iq is d-axis voltage, q-axis current, lambda f is the permanent magnet flux linkage; step two, aiming at the maximum torque current ratio control of the permanent magnet synchronous motor, the following stator current optimization targets are set: and constructs the following auxiliary function F: Wherein P is the number of poles of the permanent magnet synchronous motor, and χ is the Lagrangian multiplier; Step three, solving partial derivatives of the auxiliary function F on d-axis current, q-axis current and Lagrange operator: let each partial derivative equal to 0 and based on the L d<Lq relation in the permanent magnet synchronous motor, successively solve the q-axis current and the d-axis current: And combining the stator current optimization targets to obtain optimal stator currents, and calculating to obtain the electromagnetic torque of the corresponding permanent magnet synchronous motor. Further, in the first step, based on the topological structure of the d axis and the q axis of the equivalent circuit model, a mathematical model of the permanent magnet synchronous motor is obtained: Wherein, I cd、Icq is d-axis and q-axis load iron loss current respectively, I md、Imq、Ioq is d-axis and q-axis magnetizing current respectively, I can、Ice、Ich is no-load iron loss current corresponding to no-load abnormal loss, no-load eddy current loss and no-load hysteresis loss respec