A novel circuit topologies family of the current mode AC/AC converter with high frequency ac link, based on Flyback converter, are proposed. These circuit topologies which can transfer one unregulated sinusoidal voltage with high THD into another regulated constant frequency sinusoidal voltage with low THD, are constituted of input cycloconverter, high frequency storage transformer and output cycloconverter. The circuit topologies family include single four-quadrant power switch mode, push-pull mode, half-bridge mode,and fullbridge mode circuit. The single four-quadrant power switch mode and push-pull mode converter are suit for low input voltage fields, but the half-bridge mode and fullbridge mode converter are suit 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 criterions for the key circuit parameters are given. The current mode AC/AC converters with high frequency ac link have the advantages such as simple topology, two-stage power conversions, bi-directional power flow, high frequency electrical isolation, good line current waveform, strong load adapting ability. The correction and advance of the converters are verified by the Pspice simulation and test results.

A combined three-phase inverter based on the duty cycle extended active clamp forward mode inverter with high frequency pulse dc link is proposed in this paper. The three phase inverter is constituted of three same single inverter modules. The voltage-mode feed forward control strategy is introduced in the active clamp forward mode high frequency pulse DC link circuit, the three-state discrete pulse modulation (DPM) hysteresis current control strategy is introduced in the inverter. The circuit topology, steady principle, control strategy, load characteristic, criteria for the key circuit parameters of the combined three-phase inverter are deeply investigated. A designed and developed 3kVA 27VDC/200V400HzAC prototype has excellent comprehensive performances such as small bulk, lower weight, high conversion efficiency, high steady precision, wide input voltage range, low THD of output voltage, strong over-load and short-circuit ability, and strong ability with different nature load and unbalanced three-phase load.

A circuit topology family of the voltage mode ACIAC converters with high frequency ac link are proposed. The kind of circuit topologies are constituted of input cycloconverter, high frequency transformer, and output cycloconverter. The bipolarity phase-shifted control strategy and steady principles are deeply investigated. The output characteristics of the converters are given. By using commutation overlap of the output cycloconverter and the polarity selection of the input voltage and the output filtering inductance current, the leakage inductance energy and the output filtering inductance current are naturally commutated, and the surge voltage and the surge current of the cycloconverters are overcome. The converters have the advantages such as simple topology, two-stage power conversions (LFAC/HFAC/LFAC), bi-directional power flow, high frequency electrical isolation, good line current waveform and output voltage waveform, and strong load adapting function. The converters lay key technical foundation on new-type regulated sinusoidal ac power supplies and electronic transformers. The correction and advancement of the converters are well verified by simulation and principle test