Sensorless Load Angle Control for Energy Optimal Sinusoidal Driven BLDC Motor Applications

Choosing sine-wave instead of square-wave shaped currents to drive a brushless DC (BLDC) motor can increase the energy-efficiency up to 9.5%.But, unfortunately, for sine-wave setpoint current generation, the typical electronic or sensing low-resolution commutation feedback techniques become unavailable. For broad industrial employability, other sensing techniques such as computationally complex observers or signal injection methods requiring access to the switching states of the power electronics are not preferred. This raises the need to develop a computationally sufficient simple sensorless controller that optimizes the energy efficiency. Therefore, the authors propose a PID algorithm controlling the estimated load angle technique that enables sinusoidal current supply without the need for position feedback or user input. The aim is to implement a controller for dynamic speed-varying BLDC motor applications, which means that accurate speed trajectory tracking behavior and high robustness against load changes should be guaranteed. The application-dependent PID settings for setpoint and disturbance rejection control are estimated during an initialization speed trajectory based on only one stator winding current and voltage measurement. The proposed control algorithm is validated through experimental measurements on a BLDC motor with a nominal speed and power of 3000 r/min and 225 $\mathrm{W}$ , respectively.