Research On Sensorless Control Based On Detecting Terminal Voltage Of Three-phase Doubly Salient Electro-Magnetic Motor

Doubly salient electro-magnetic machine(DSEM)has the advantages of simple and reliable structure,running at high speed conveniently and good speed regulation performance.These advantages contribute that DSEM is widely used in aerospace and other high-demand fields.However,the application of position sensor is limited by adverse factors such as bad working environment and complex installation process.Therefore,the sensorless electric control technology of three-phase 12/8-pole DSEM,which is regarded as the research object of this task,is studied and the influence of different working conditions is analyzed and verified in this paper.Firstly,the structure of DSEM is introduced.The mathematical model is developed and the inductance model is developed with the help of finite element simulation.The standard angle control of DSEM is discussed and provides a theoretical basis for future research on sensorless technology.This paper mainly studies the sensorless technology based on terminal voltage filtering for DSEM.Terminal voltage of DSEM is analyzed and the fundamental wave of terminal voltage is achieved by high-order low-pass digital filter and coordinate transformation.The selection of coordinate transformation angle under different speeds is analyzed in detail and accurate rotor commutation signal is obtained.Filters with different cut-off frequencies are set up and a speed-based hysteresis control is introduced to achieve smooth switching between these filters,then the smooth operation of the motor in a wide speed range is realized.The influence of different DC bus voltage values and different phase current chopper limits,based on sensorless control method proposed in this paper,is simulated and analyzed.These results lay the foundation for later experiment debugging.The influence of chopping mode selection of main power switch on sensorless control method is analyzed.It is pointed out that this method can avoid the influence of different chopping modes of switch when motor operates electronically.Finally,the feasibility of the sensorless control proposed in this paper is verified and analyzed on the experimental platform.As for the influence of different working conditions on the sensorless control method,the accuracy of theoretical analysis is verified on the experimental platform.