The Field Orientation Principle in Control of Induction MotorsThe Field Orientation Principle was fIrst formulated by Haase, in 1968, and Blaschke, in 1970. At that time, their ideas seemed impractical because of the insufficient means of implementation. However, in the early eighties, technological advances in static power converters and microprocessor based control systems made the high performance a. c. drive systems fully feasible. Since then, hundreds of papers dealing with various aspects of the Field