Digitally Controlled Active Power Filter for AESA Radar

Abstract

This master thesis demonstrate a digitally controlled Active Power Filter, which is used for eliminating low frequency distortion from a pulsating load. As a result, the current on the power supply will be uniform. The main tasks in this master thesis was to design a circuit, build a prototype, program a Digital Signal Processor, do a verification and make an evaluation. The Active Power Filter is average inductance current controlled, with a voltage controller as an outer loop. A state space representation was used for creating a model for the Active Power Filter and a controller. The Active Power Filter with the controller was simulated in SIMULINK in order to evaluating the controller performance. Thereafter, the controller parameter was implemented in a microprocessor and verified with the Active Power Filter, a pulsating load and DC/DC-converter. The Active Power Filter has not been integrated with the existing DC/DC-converter except for the switching frequency being the same. Therefore, there are some conflicts between the controllers in the two devices. The result of this master thesis show that by combining a passive-filter, active-filter and a DC/DC-converter, it is possible to get an undisturbed power supply on the input of the DC/DC-converter. It has also been shown that it is possible to decrease 300Hz distortion. Also by using a digital control it is possible to create an adaptive system. As a result, the pulsating load characteristics can vary and the Digital Signal Processor will adjust the reference value for that specific load.