Capacitor voltage balancing control of multilevel DC-DC converter

This paper presents an complete investigation of an active capacitor voltage balancing strategy for multilevel dc-dc converter. The proposed technique may be applied to various dc-dc converters, such as the well-known flying-capacitor converter. The voltage balancing analysis is carried out for a five level dc-dc converter, in which the small-signal modeling is realized. The obtained converter mathematical model presents cross-coupling among the variables, as well as the dependence of the load current. Thus, a control strategy is proposed in this paper, in which incorporates a decoupling action. Besides that, a feedforward technique is used to eliminate the dependence of load current of the converter model, improving the performance of the closed loop system in light load. In order to demonstrate the performance of proposed capacitor voltage balancing control loop, it was applied to a 5-level dc-dc converter and experimental results are reported herein. The results attest the advantages of the proposed capacitor voltage balancing control.