The direct load angle control of a CSI drive

There are many applications where high dynamic response, although desirable, is not essential. Such applications include many of the weight balancing and weight lifting drives. These drives operate with a gravitational loading applied to the shaft. Where a low speed operation is required such drives would benefit from the application of the PAM technique. The authors report on the digital implementation of a constant load angle control strategy, incorporating the PAM technique, applied to a stringent loading case. Novel aspects of the implementation include the calculation of the stator current reference as opposed to its formation by a conventional controller, while the inverter switching decisions are made with consideration of the predicted angle quantities at other possible stator current angular positions and their effect on the machine flux