SRM Control System Based On The Sliding Mode Observer

Switched reluctance motor(SRM) is simple structure, firmness, and high faulttolerance. As a synchronous motor, it requires rotor position to finish phasecommutation. However, position sensor is not suitable for the small motor, it can’tmaintain easily, increase motor cost and volume, weaken the advantage of simplestructure, reduce the firmness, and restrict application field. In order to solve thisproblem, a SRM control system based on the sliding mode observer is proposed.Firstly, the background and meaning of the research, development of SRM speedregulating system, and development situation of sensorless detection technique is introduced.Secondly, by analysing motor model, calculated flux and estimated current is used toestimate current, then the actual current and estimated current is used to constitute indirectsliding mode surface, to instead rotor position and rotor speed sliding mode surface. In order toimpove movement performance, using indirect sliding mode surface to instead speed error,using exponential reaching law to instead constant reaching law, which has the advantages inrapidity of sliding mode movements and less chattering.Thirdly, sliding mode observer can’t obtain speed and rotor position at the start ofmotor. Under the effect of same votage pulse, different current reflects rotor position,as current is the biggest, rotor is at the position that inductance is the smallest, speedcan obtain from the interval of adjacent the smallest inductance.Lastly, simulation is finished in Matlab, and software and hardwar is designedwith DSP TMS320F2812as core control chip. The simulation and experiment resultsverify that votage pulse method is simple and effective, it can start motor. Sliding modeobserver can obtain rotor position and speed, own high robustness. Exponential reaching lawcan keep better movement performance.