Sensorless Control of Non-Sinusoidal Permanent Magnet Brushless Motor using Selective Torque Harmonic Elimination Method and Sliding Mode Observer

Abstract

Nowadays, due to excellent advantages of permanent magnet brushless motors (PMBL), they are used in many industrial and variable-speed electrical drive applications. If the fabricated PMBL motors have neither ideal-sinusoidal nor ideal-trapezoidal back-EMF voltages, they are named non-sinusoidal (or non-ideal) PMBL motor. Employing the conventional control strategies of PMSMs and BLDCMs decreases the efficiency and leads to unwanted torque ripple, vibration and acoustic noises. Moreover, in many applications, to reduce the cost and to enhance the reliability, sensorless control techniques are used. This paper proposes a novel sensorless control for a non-sinusoidal PMBL motor with minimum torque ripple. To develop smooth torque, the selected torque harmonic elimination strategy is employed. Furthermore, to estimate the rotor position and speed, a novel full-order sliding mode observer is designed. Proposed observer estimates the position and speed of motor from standstill to final speed. The proposed observer is robust to uncertainty of harmonic contents in phase back-EMF voltage and able to run the motor from standstill with close loop control scheme. The capabilities of torque ripple minimization and sensorless strategies are demonstrated via simulations.