A simplified sensorless speed control of permanent magnet synchronous motor using model reference adaptive system

A simplified sensorless speed control of permanent magnet synchronous motor (PMSM) using model reference adaptive system (MRAS) is presented. The MRAS is designed and incorporated in a complete closed loop PMSM control system fed by a three-phase inverter that utilizes a simplified hysteresis current control (HCC) to generate gating signals. Accurate rotor position, being essential in PMSM control, is estimated using MRAS rather encoders and resolvers which are explicit position sensors thereby eliminating the drawbacks of the traditional speed sensors in drive systems. The performance of this model is compared with an existing model that utilizes encoders and resolvers. Superior performance was obtained from this new model with MRAS. After initial starting transients, it is observed that the rotor speed for the model with MRAS settled to steady state at 0.10 seconds as against the model with speed sensor which attained steady state at 0.31 seconds. Torque response follows the same pattern to return to the load torque of 11Nm at steady state after starting. After speed reversal, the model with MRAS restored to steady state to track the negative speed command at 0.44 seconds. This is a superior performance compared to the model with speed sensor which settled at 0.60 seconds after speed reversal. The results have clearly shown the superiority of sensorless MRAS over traditional drive models with speed sensors. The software used for this research is MATLAB/Simulink 2017 model.