FPGA implementation of a speed controller for three phase induction machines based on the inversion of the electromagnetic field

Abstract

In the paper a field-programmable gate array (FPGA) implementation of a speed controller for the induction machine is presented. This control system is based on the modulation of the rotating field from two others that rotate in opposing directions. To implement this strategy it is used a sliding mode controller. In this way, the controller invert the direction of the field, by inverting the sequence of the three phase stator voltages applied, and in such a way that there is no risk of exceeding the operating currents of the drive. The sliding mode controller is embedded in the core of the Hardware Description Language (HDL) code. As for the FPGA itself, there are several tasks that have to be handled in parallel: calculate the rotor shaft speed from the linear encoder, read the speed set point value from the man-machine interface, apply the commutation switching law from the sliding mode controller, and finally, generate the PWM commands to the inverter. Experimental results from a laboratory prototype system are also presented.