A software modification procedure for conversion of a scalar controller to a vector type for an induction motor

This paper establishes a relationship between two techniques for the control of current controlled induction motors, namely scalar control with flux loop and direct vector control. This is accomplished through theoretical comparison of the governing equations that relate the input and the output signals in the respective controllers. In traditional scalar control, the controller outputs are |I*_s| and ω*_e, while in vector type they are i^s*_ds and i^s*_qs In each method two signals are produced which define the reference current. It is desirable to improve these two controllers, so that similar information is derived for the reference current. With this achievement, it will be shown how an existing scalar controller may be converted to a vector control type (with improved responses) by software modifications. Computer simulation is demonstrated for a typical 3 HP motor.