Development of a Simple Fuzzy Logic Controller for DC-DC Converter

Control of DC-DC converters is a complex task due to the inherent nonlinearity. There is intensive research in developing newer control strategies which should ensures stability of output voltage under varying load, input voltage and parameters variations. The paper is aimed to present possibilities of use fuzzy logic controller to control output voltage of a phase-shifted PWM (PS-PWM) soft-switching DC-DC converter. The converter is a full bridge DC-DC converter with a controlled output rectifier and an active snubber on the secondary side. Despite proven advantages of use of a fuzzy logic control for DC-DC converters, one of the main drawback can be considered computational demand, which could negatively affects the response of a converter on sudden changes of load and raise up the price of the converter, due that there is needed a microcontroller with higher computational capacity. To suppress the high computational demand of a FLC controller there is presented a look-up table controller, which is derived from the original FLC controller. In the paper are described two different suitable interpolation methods for look up table controller composition, and assessment of advantages and disadvantages of both methods.