Control of Electronically Commutated Motors

Principle of operation and modeling of the brushless permanent magnet motor. Principle of operation and modeling of the switched reluctance motor. Principle of operation of the unipolar, bipolar and bifilar wound stepper motor. Bridge, half-bridge and asymmetric switched-mode power converter topologies with different number of switches for power supply of brushless motor. 120° el. and 180° el. angle switch-on control mode of brushless motor. Optimization of brushless motor control algorithm by magnetic flux weakening method and the modification of the switch-on angle. Optimization of torque-speed characteristic. Methods for cogging torque reduction. Sensors for position and speed detection of the rotor. Sensorless control of brushless motors. Phase current control. Design and implementation of rotor speed and motor torque controllers.

The objective of the course is to equip students with knowledge of modern control principles of brushless permanent magnet and switched reluctance motors. Special attention will be given to current, speed and torque control algorithms of brushless motors in order to achieve optimal parameters of the electric motor drive. Students will be able to design a control algorithm and to select an appropriate type of switch-mode power converter for a brushless motor drive.

Lectures