DSP-based implementation of terminal sliding mode control with grey prediction for UPS inverters

In this paper, a terminal sliding mode control (TSMC) with grey prediction for UPS inverters is proposed to maintain very low total harmonic distortion (THD) output voltage under rectifier-type loading conditions and fast dynamic response under step change loading conditions. The proposed controller combines the merits of terminal sliding mode control and grey prediction. TSMC can drive the system tracking error to converge to zero in finite time unlike exponential convergence of conventional sliding mode control, but the chattering and steady-state error still occur. Grey prediction is thus devoted to alleviate the chattering while the system uncertainty bounds are overestimated or to reduce the steady-state error while the system uncertainty bounds are underestimated. Simulation and experimental results on a single-phase UPS inverter laboratory prototype controlled by a dSPACE-based DSP controller are given to conform that the proposed controller can lead to low THD and fast dynamic response under different kinds of loads.