Design of a complex-valued sliding surface controller with applications to constant-voltage constant-frequency inverters

This paper presents a complex-valued sliding surface controller for constant-voltage constant-frequency (CVCF) inverters applications. Conventional variable structure control (VSC) with linear sliding surface offers robustness to system uncertainties, but in sliding motion, the system dynamics becomes a reduced-order dimension, thus losing the partial system dynamics, and resulting in system performance deterioration. For recovering incomplete system response, a complex-valued sliding surface will be designed, and applied to CVCF inverters. With the proposed inverter, the output voltages will have the features of low total harmonic distortion, and fast transient response. Simulation and experimental results show that the proposed controller can achieve good performance under nonlinear loads.