Single-Stage Dual-Side Interleaved High-Frequency Isolated DC-AC Converter and Its Closed-Loop Control Strategy

In order to solve the problems of the large number of the power switches, high voltage and current stress, and double-line-frequency ripple on the dc-side current in the existing single-stage high-frequency isolated dc-ac converters, the novel single-stage isolated dc-ac topology is proposed in this paper. The interleaved parallel structures are used on both the dc and grid sides. The harmonic components of the currents in both the dc and grid sides are suppressed and the number of the power switches is reduced. Furthermore, based on the dual PWM method with the phase-shift modulation strategy, the operation principles, and characteristics of the proposed converter are analyzed thoroughly. In order to further achieve the suppression of the harmonic currents on both the dc and grid sides, the composite controllers based on the P-type iterative learning are proposed. By the composite controller, each harmonic current is effectively suppressed regardless of the harmonic frequency. The stability, convergence, and operation characteristics of the controllers are analyzed meticulously. The correctness and effectiveness of the proposed converter and closed-loop control strategy are validated through the experimental results.