Research On The Control Technology For High-Speed Doubly Salient Electro-Magnetic Motor Driving System

Doubly salient electro-magnetic motor(DSEM)has many advantages such as simple structure,low cost,high reliability and high power density,etc,exhibiting good prospect in aeronautic starter/generator power,wind power generation,automobiles and smart home application.If running at higher speed,the motor can output high power density with small volume and light weight,which is beneficial for installation.Meanwhile,the direct connection to the high-speed load removes the high-weight mechanical drive structure,which improves the system efficiency and space utilization further.The paper studies the drive control system for high-speed DSEM and researches control strategies and methods so as to improve the output torque and suppress the torque ripples,at the same time,reduing the current spikes caused by the control delay.When the motor runs at high speed,due to the high EMFs,the phase current injection is difficult.So the effective current value and the output torque are low.Owing to quick changing of the motor position,it’s hard to complete position judgment and angle control in an interruption cycle only with DSP controller.At fisrt,the paper introduces the structure and characteristic curves of DSEM and establishes the mathematical model.Then,three basic motoring modes are discussed.The work characteristics and output torque of different control strategies are compared by analyzing the curves of phase current.After that,this paper provides no-dead-time nine-state advanced angle control strategy,which improves the output torque.And the impact of the dead zone can be eliminated,decrasing the torque ripples.Besides,this strategy can simplify the two angle control parameters to one,reduce the control difficulty and thus be more suitable for high-speed operation.The paper also points out that the numericial decrease of one angle can be compensated by enlarging another.However,the advanced angles are very difficult to select.So the relationship between input voltage,rotor speed,load condition,parameters of the motor and the best advanced angles is researched.In order to acquire rational advanced angles,simplified analysis of the advanced angles is carried out.In addition,the generation of current control delay and its effect on the current spikes are analyzed.Besides,the control method of segmental current chopping is given so it can reduce the current spikes during advanced angles’ time and improve the reliability of power transistor,making the upper transistor and the lower one operate at a similar temperature.Finally,with digital controller based on DSP and FPGA,the experimental platform is built and the hardware circuits and software are designed.What’s more,laminated busbar is used for connection in the inverter,which decreases the voltage spikes caused by the stray inductor when DSEM works in high speed.With parallel algorithm,the stability of high-speed motor is improved.The simulation and experimental waveforms furtherly verify the correctness of theoretical analysis.