Steady-State and Dynamic Study of Active Power Filter With Efficient FPGA-Based Control Algorithm

A new approach using field-programmable gate array (FPGA) to implement a fully digital control algorithm of active power filter (APF) is proposed in this paper. This FPGA-based controller integrates the whole signal-processing function of an APF, including synchronous-reference-frame transform, low-pass filter, three-phase phase-locked loop, inverter-current controller, etc. By case studies on the principle, performance, and architecture, these control blocks are implemented in real-time and synthesized into a medium-scale FPGA chip by adopting some useful digital-signal-processing techniques, such as pipelining, folding and strength reduction, with respect to minimization of hardware resource and enhancement of operating frequency. As a result, the whole algorithm needs around 5000 logic elements and can run at synchronous system-clock rates of up to 65 MHz. Experimental results on a laboratory prototype are given to demonstrate performance of the proposed approach during steady-state and dynamic operations.