Using on-line parameter estimation to improve efficiency of IPM machine drives

This paper presents a means to improve the efficiency of interior permanent magnet (IPM) synchronous machine drives which can be best implemented via continuous online self tuning. With this technique an improved maximum torque-per-ampere trajectory for IPM machine can be implemented including the effect of magnetic saturation. This improved trajectory can be shown to improve efficiency. The model-based estimation algorithm is based on commanded voltage and measured current and rotor position/velocity. The model has two equations where cross-coupled parameters can be eliminated for the robustness of parameter estimation. Parameter estimation is improved by combining the model with a closed loop observer. This algorithm is suitable for online estimation. The performance of this algorithm is illustrated by experimentation. The vector controller using this algorithm controls motor torque accurately under any load and speed.