Fixed-frequency Pseudo Sliding Mode Control for a Buck-Boost DC-DC Converter in Mobile Applications: A Comparison with a Linear PID Controller

Interest is apparently growing in the four-switch noninverting Buck-Boost converter, which can be effectively used as a power supply for mobile devices. A typical application is a dynamic power supply for third-generation (3G) Wideband Code Division Multiple Access (WCDMA) Power Amplifiers (PA). While several control strategies based on the linear control theory have been proposed recently, there is still room for investigation of nonlinear control techniques. In this paper, a fixed-frequency nonlinear controller based on the sliding mode theory is presented and compared to a classical linear Proportional-Integral-Derivative (PID) implementation. The main differences from the design perspective and in terms of performance are then pointed out and commented. The main advantages of the proposed technique generally include an improvement of the dynamic performance and increased energy efficiency of the conversion. Simulation results are provided in order to evaluate and compare the different control strategies.