Sensorless Selective Torque Harmonic Elimination Control for a Non-Sinusoidal Permanent Magnet Brushless Motor Using a Full-Order Sliding Mode Observer

Nowadays, due to excellent advantages of permanent magnet brushless motors (PMBL) such as high efficiency and high torque/power density, they are used in many industrial and variable-speed electrical drives applications. If the fabricated PMBL motor has neither sinusoidal nor trapezoidal back-EMF voltages, it is named non-sinusoidal (or non-ideal) PMBL motor. Employing of 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 enhance the reliability of drive, 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. The proposed observer is robust to uncertainty in back-EMF voltage contents and able to run the motor from standstill with close loop control scheme. The advantages of torque ripple minimization rather than conventional control methods and capabilities of sensorless strategy are demonstrated with some simulations.