Analysis and design of sliding mode control for AC signal power amplifier

In this paper, sliding mode control strategy for a novel DC/AC buck inverter is proposed, which is composed of two independent symmetrical bi-directional buck converters and is used in sinusoidal power amplifier design. For the framework of the inverter, the sliding mode control is applied to track and amplify DC-biased sinusoidal signal. Based on application of inverse function theorem, a time-independent sliding mode surface and corresponding sliding control law are obtained in selected phase plane. The existence and stability of the sliding mode control are analyzed by applying equivalent control, and the surface is modified for ensuring sliding domain. System parameters and converter losses are discussed. The sliding mode control scheme has dynamics and robustness with respect to both external disturbances and variations on the load and input voltage. Experimental results are included to validate the analysis.