| Trapezoidal Back-EMF (Brushless DC) motors are gaining increasing importance in automotive industries, HVAC applications, home appliances etc. Traditionally, Brushless DC motors are commutated electronically using position sensors. In these systems, mechanical or electromagnetic sensors are used. In sensorless control, rotor back EMF detection is the most popular technique for speed and position control. Detection of back EMF by novel speed independent commutation function is a very well researched topic that has overcome most of the problems of traditional back EMF detection scheme.;In this thesis, a thorough study and speed control scheme for Brushless DC motors using position sensor is presented along with simulation and experimental results. An improved sensorless scheme based on speed independent commutation and state observer based back EMF sensing is analyzed. Both methods use hysteresis control for the current loop and a PI controller for the speed loop to reduce steady state speed error. |
