Finite-State Machine Motion Controller: Servo Drives

Digital controllers are used for modern power converter control and industrial automation. The functionality of the finite-state machine (FSM) provides an ideal platform for building a high-frequency field-programmable gate array (FPGA) controller for power electronics applications. This article develops the design of a current-control loop and the selection of switching logic for three-phase switching converters and ac electrical machines. The main design specifications are robustness to load and electrical parameters, fast dynamic response, reduced switching frequency, and simple hardware implementation. A discrete-event-type controller is proposed to meet previous specifications, designed as finite state automaton and implemented with an FPGA device. Furthermore, the actual controller architecture is based on the FPGA Spartan 3E. The experimental results are presented using a brushless ac (BLAC) motor as the converter load. However, this does not limit the wider applicability of the proposed controller, as it is suitable for different types of ac loads (rectifiers, inverters).