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Unipolar sinusoidal pulsewidth modulation (SPWM) full-bridge inverter brings high-frequency common-mode voltage, which restricts its application in transformerless photovoltaic grid-connected inverters. In order to solve this problem, an optimized full-bridge structure with two additional switches and a capacitor divider is proposed in this paper, which(More)
Grid connected inverter can attenuate high frequency harmonics effectively through an LCL filter which has potential benefits for the inverter to get higher harmonic performance with lower switching frequency and less inductance in contrast with L filter. However, LCL filter is a third order system without damping and easy to resonate. In order to eliminate(More)
The current-voltage-fed bidirectional DC-DC converter can realize ZVS for the switches with the use of the phase-shift (PS) technology, however the current-fed switches suffer from high voltage spike and high circulating conduction losses. In order to solve these problems, a novel phase-shift plus PWM (PSP) control ZVS bi-directional DC-DC converter is(More)
This paper proposes a grid-connected PV system based on the series Z-Source inverter, and also proposes an indirect DC-link voltage control method for the system. The operation principle of the system is presented. The current control strategy is also designed, which makes the output current synchronize with grid voltage, thus the system could transform(More)
The influence on input current harmonics by single-edge modulation of conventional one-cycle control (OCC) in single-phase PFC converters is analyzed. The relation between low-frequency odd harmonics of the inductor current and modulation scheme is revealed. Based on the analysis, bi-edge modulation with triangular-wave as carrier is proposed. The inductor(More)
This paper presents a novel circuit for equalizing a series ultracapacitor stack based on DC-DC converter. The proposed voltage equalization circuit derives energy from the series ultracapacitor stack and transfers them to the weakest ultracapacitor cell. The equalizer balances the whole stack by compensating the weak ultracapacitor cells sequentially.(More)
This paper proposes a novel Z-source converter structure. The operating principle of Z-source unit reveals that there are two discontinuous regions in Z-source network. This paper also explores the Z-source converter topology design method, and all potential Z-source converter topologies are derived from traditional and new structure, respectively. Compared(More)