Control Strategies for Electrical Drives

Abstract

Drives are devices used for imposing controlled variations of speed to moving components of machine tools and plants. Each one consists of an hydraulic or pneumatic or electrical actuator supplied by a power amplifier connected to a control device. The trend is to use electric motor, static converters and control devices realized by microprocessors or VLSI circuits.End users and designers of industrial plants generally choose the drive between the already existing ones. Very rarely the control strategies which on the contrary determine he global performance are taken into consideration. The aim of this paper is to propose this classification of drives relating the desired static and dynamic behavior of the moving components to the possible control strategies. A suitable presentation of the drive system by means of block diagrams allows to fix a general criterion to select the control strategy Independently of electric motors and circuitry of converters and control deVices. In order put into relieve the advantage of the different control strategies the starting up responses of drives implementing different control strategies are compared. The external transients (speed) and the internal one (current, flux, active power) are shown for an inverter fed induction drive.The selection criterion is the original contribution of this paper which is devoted to non experts m electrical drives.