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This paper describes the design and hardware implementation of a Single Input Fuzzy Logic Controller (SIFLC) to regulate the output voltage of a boost power converter. The proposed controller is derived from the signed distance method, which reduces a multi-input conventional Fuzzy Logic Controller (CFLC) to a single input FLC. This allows the rule table to be approximated to a one-dimensional piecewise linear control surface. A MATLAB simulation demonstrated that the performance of a boost converter is identical when subjected to the SIFLC or a CFLC. However, the SIFLC requires nearly an order of magnitude less time to execute its algorithm. Therefore the former can replace the latter with no significant degradation in performance. To validate the feasibility of the SIFLC, a 50W boost converter prototype is built. The SIFLC algorithm is implemented using an Altera FPGA. It was found that the SIFLC with asymmetrical membership functions exhibits an excellent response to load and input reference changes.

A simple and robust digital peak current mode controller is proposed in this study. The controller replicates an analogue peak current mode control in the discrete domain. The inner current loop has negligible delay, which results in a high controller bandwidth. The controller structure allows the compensation slope to be updated in each switching cycle; therefore, the controller can maintain a high bandwidth over a wide range of operating points. The modelling principles of an analogue peak current mode controller are used to model the proposed controller. For experimental verification, the controller is implemented in a field programmable gate array to control a 100 W buck converter. The measured loop gain of the system correlates very well with the modelling results. The achieved controller crossover frequency is ∼1/10 of the switching frequency which is close to the crossover frequency of analogue peak current mode controllers.

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