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Miniaturization and low cost contribute to the development and popularization of wireless power transfer (WPT). Reducing the number of power conversion stages can reduce the volume and cost of the WPT converter, and even make it possible to improve the efficiency. A single-stage WPT converter with constant current (CC) and constant voltage (CV) output and its asymmetric modulation method are proposed in this paper. A direct AC-AC converter is applied to the primary side of the WPT converter to directly convert line-frequency AC to high-frequency AC. The applied direct AC-AC converter that can replace the commonly used multi-stage primary converter reduces the number of circuit devices, thereby reducing the volume and cost of primary converter. The proposed WPT converter can realize zero voltage switching (ZVS) and power factor correction (PFC). In order to achieve CC and CV output, a switchable hybrid compensation topology is applied to the proposed WPT converter. A 720-W experimental prototype was manufactured to verify the rationality of the proposed WPT converter and the correctness of the theoretical analysis. [ABSTRACT FROM AUTHOR]

A class of single-stage multi-input Buck type high-frequency link's inverters with series and simultaneous power supply are proposed in this article, and the key technologies such as circuit structures and topological family, energy management control strategy (EMCS), power supply modes, steady-state principle characteristics are studied in depth, from which some important conclusions are obtained. The circuit structure is composed of a multi-input-single-output high-frequency inverter, high-frequency transformer, cycloconverter, and output filter in sequence. The EMCS is to generate bipolar tri-state multilevel sinusoidal pulse width modulation (SPWM) waves by phase shifting between right and left arms of the high-frequency inverting bridge, and the cycloconverter demodulates it into a unipolar tristate multilevel SPWM wave and performs commutation when the unipolar tristate multilevel SPWM wave is zero. In addition, the EMCS realizes the, smooth switching of different power supply modes and the stability of output voltage. 1 kVA multi-input inverter prototype is designed and developed, which has the advantages of single-stage power conversion, high-frequency electrical isolation, small volume and weight, wide duty cycle regulation range, high conversion efficiency, high output voltage waveform quality and strong load adaptability. It provides a kind of effective method for a variety of new energy joint power supply. [ABSTRACT FROM AUTHOR]

Different from the conventional photovoltaic (PV) inverters, a three-phase PV solid-state transformer (SST) based on the cascaded H-bridge (CHB) topology can be regarded as consisting of three single-phase CHB inverters in essence. During the low-voltage ride through (LVRT), some phases of three-phase PV SST may inversely absorb active power from ac grid affected by negative-sequence voltages, resulting in that the dc bus voltages of all H-bridges in these phases continue to rise, and that the system will shut down due to overvoltage protection. To deal with this problem, in this article, we study the mechanism of active power backflow during LVRT, analyzes and compares the main methods for suppressing active power backflow, and then proposes an LVRT control strategy based on the zero-sequence voltage compensation, which not only ensures that all modules in three-phase PV SST transmit the almost same active power but also can avoid effectively active power backflow problem even if the total output active of PV array is relatively low. The validity of the proposed method is verified by the simulation and experimental results. [ABSTRACT FROM AUTHOR]

A circuit configuration, a circuit topological family, a buck-mode active clamped circuit, and an instantaneous output voltage feedback control strategy of combined bidirectional buck–boost dc–dc chopper-mode inverter with high-frequency (HF) link (HFL) were proposed and fully investigated in this paper. The steady principle characteristic and the design criteria for the key circuit parameters were given in this paper. The circuit configuration is composed of two identical isolated bidirectional buck–boost dc–dc choppers with the same input and output filters. These two choppers in parallel at input end and in series at output end generate unipolarity sinusoidal pulsewidth modulation current waveforms with positive and negative half low-frequency cycles separately. The circuit topological family includes four circuit topologies, such as one-transistor mode. Taking the one-transistor mode circuit topology as an example, the 750VA48VDC/220V50HzAC prototype is designed and implemented. The theoretical analysis and principle test show the inverters have excellent performance. [ABSTRACT FROM PUBLISHER]

A novel circuit-topology family of the current-mode ac/ac converter with high-frequency ac link, based on a Flyback converter, is proposed. These circuit topologies, which can transfer one unregulated sinusoidal voltage with high total harmonic distortion (THD) into another regulated constant-frequency sinusoidal voltage with low THD, are composed of input cycloconverter, high-frequency storage transformer, and output cycloconverter. The circuit-topology family includes single four-quadrant power switch mode, push-pull mode, half-bridge mode, and full-bridge mode circuits. The single four-quadrant power switch mode and push-pull mode converters are suitable for low input voltage fields, but the half-bridge mode and full-bridge mode converters are suitable for high input voltage fields. The operational mode, steady principle, and transient voltage feedback control strategy of the kind of converter are investigated. The output characteristic curve, its relation to internal resistance, and the design criteria for the key circuit parameters are given. The theoretical analysis and the test result of the 500 VA 220 V ± 15% 50 HzAC/220 V 50 HzAC prototype have shown that the converters have advantages such as high-frequency galvanic isolation, simple topology, two-stage power conversion [low frequency alternating current (LFAC)/high frequency alternating current (HFAC)/LFAC], bidirectional power flow, high efficiency, high power density, low THD of the output voltage, strong adaptability to various loads, higher line power factor, low audio noise, etc. [ABSTRACT FROM AUTHOR]