Design of Fixed-Frequency Pulsewidth-Modulation-Based Sliding-Mode Controllers for the Quadratic Boost Converter

The steady-state regulation error in power converters that use the pulsewidth-modulation (PWM)-based sliding-mode (SM) controllers can be alleviated via the use of a double-integral term of the state variables in the sliding surface. However, this not only increases the order of the controller but may also require more variables like two currents in feedback. Ideally, the controller should be of a lower order to reduce the cost and for ease of implementation. The main objective of this brief is to design a fixed-frequency PWM-based SM controller for the quadratic boost converter using a reduced number of state variables. The SM controller used in this brief requires only one current for its implementation while enjoying the advantages offered by both fixed-frequency and double-integral approaches. Apart from this, two SM controllers using the input and output inductor currents of the converter are separately designed to find the most suitable inductor current for the controller design. Such study is especially required for the higher order converters wherein more than one inductor currents are available for feedback purposes. It is shown that the controller using the input inductor current is preferred over the controller using the output inductor current. Some simulation and experimental results are also provided to validate the theoretical conclusions.