Design And Simulation Of Brushless DC Motor Based On Modelica

Brushless DC motor with many advantages,such as good mechanical characteristics,simple structure,higher output torque in unit mass,is widely used in the field of aerospace.For example,attitude control system in spacecraft commonly uses brushless DC motor as its power source.Complex application environment puts forward high requirements on the performance of brushless DC motor.However,the traditional design methods is inefficient,lack verification means of verification,is difficult to accumulate the key technology,lack corresponding system-level simulation model.With the rapid development of computer simulation technology,through the computer simulation to assist the motor performance analysis and optimization design has become one of the important methods for motor system design and verification.The existing research on the modeling and simulation of brushless DC motor only aim at the problem of a certain aspect of motor,and it is difficult to analyze and study the whole system of brushless DC motor.In view of these problems,the design and calculation method of brushless DC motor for spacecraft and digital simulation is studied based on Modelica,in this paper.Then,the method is used to design,verify and optimize a motor.The main work is as follows:In this paper,the structural characteristics,operating principle and mathematical model of brushless DC motor is analyzed in detail.Based on the above theory,component model library and system model of brushless DC motor is established in the multi-domain unified modeling language Modelica on the MWorks platform by the method of top-down decomposition and bottom-up modeling.This model is modularized,extensible,reusable and parameterized,so can be applied as a component to a more complex drive system,to prepare for further simulation analysis.Then,the calculation method and formula of brushless DC motor structural parameters,winding parameters,circuit parameters,magnetic circuit parameters and motor characteristic parameters are analyzed in this paper.Based on these theories,a calculation model of brushless DC motor parameters is established to solve the large number of repeated numerical calculation in the calculation of motor parameters with computer.And a set of parameters of brushless DC motor is calculated to meet the requirements.Finally,the multi-domain model of brushless DC motor is used to simulate with the motor parameters calculated above.The operating characteristics of the motor,such as no-load characteristic,starting characteristic,performance characteristic,mechanical characteristic and speed regulation characteristic are analyzed to provide a reference for the design of motor.Based on the analysis of the torque ripple of brushless DC motor,the optimum overlap angle of overlapping commutation method is determined through simulation test to reduce brushless DC torque ripple,which is caused by commutation.