Time-sharing space-voltage vector controlled inverter with new high-frequency transformer-assisted quasi-resonant DC link

A newly-improved quasi-resonant DC link (QRDCL) circuit topology operating under a commutation principle of the HF transformer-assisted zero voltage soft switching is proposed. The basic operating principle of this improved power conversion circuit (auxiliary transformer-assisted QRDCL TQRDCL) which is more suitable with the power factor correction input DC side expected in constant voltage-constant frequency (CVCF) UPS, power active filters and switched-mode PWM converters, and new energy-interfaced power supplies for utility-interactive interconnection, is presented. Its operating characteristics are discussed and evaluated in terms of computer-aided simulation results. The experimental circuit is tested and examined for CVCF/UPS systems. This tested equipment is considered for linear and nonlinear electrical loads under the conditions of large load variations and voltage fluctuations from a practical point of view