ABSTRACT
Variable-speed drives (VSDs) now cover 30–40% of all drives used in association with power electronics to increase productivity and save energy in variable-output energy conversion processes. VSDs imply motion control—position, speed, torque control—in motoring and output voltage amplitude (frequency) and power control in generating. Generating will not be considered in this chapter. However, regenerative braking is inherent to VSDs and thus will be investigated here. Control of VSDs, RSMs and PM-RSMs included, may be implemented with position sensors, encoder-VSDs; or without position sensors (sensorless), encoderless VSDs. Position sensors are planted in safety-critical and servo-drives when precise control of absolute position, speed, and torque is required down to zero speed.
