Power-Regulable Generalized Discrete Reaching Law Applied to Three-Level DC-DC Converters

A power-regulable generalized discrete reaching law-based discrete-time sliding mode control (DSMC) with application to flying capacitor three-level buck converters (FCTLBC) is developed in this article. The discrete-time models of the output voltage subsystem and flying capacitor voltage subsystem are established by zero-order holder. To overcome the chattering phenomenon of explicit discrete reaching law (DRL) and the realization obstacle of implicit DRL, this article proposes a novel power-regulable generalized DRL for discrete-time FCTLBC, which possesses an explicit recursive structure, and eliminates the numerical chattering to improve the control accuracy of output voltage. The influence rules of power parameters on the convergence rate is revealed, and the upper bound of sliding variable is deduced. The designed DRL provides a great degree of freedom in tuning power parameters, ensuring both fast convergence and high-precision sliding mode. On this foundation, an incremental DSMC with a discrete extended state observer is constructed to deal with the load variations of FCTLBC. Experimental results are presented to validate the good steady-state and transient performances of the proposed approach.