Matrix Converter fed Power Electronic Transformer with enhanced features

Power transformers are an integral part of power systems. In applications, like wind energy conversion and electric ship, the large weight and volume of 60 Hz power transformers is a limitation. The size of transformers can be reduced by replacing power transformers with high frequency (HF) transformers. HF transformer with power converters are termed as power electronic transformers (PET).;Matrix converter (MC) based PET are the focus of this doctoral research. Direct AC to AC conversion using MC have the major advantage of absence of storage capacitors over AC-DC-AC based conversion systems. A MC based PET with open ended primary is described in this thesis. It has the salient features of controllable output voltage and frequency, controllable input power factor, bi-directional power flow, zero common mode voltage and voltage transfer ratio of 1.5.;Commutation of current in the leakage inductance is one of the major challenges in PET. The problem of leakage inductance is first studied using clamp circuits. A source based commutation method is proposed to eliminate the use of clamp circuits. The overall efficiency of the PET is significantly improved by use of proposed method.;The commutation time is dependent on the value of leakage inductance. So, higher the leakage inductance, larger the commutation time and therefore, lower is the switching frequency. Leakage inductance is the only factor that limits the switching frequency of PET as both SiC power devices and nano-crystalline materials capable of operating at very high frequencies are available.;To solve the above mentioned problem, a family of sinusoidal current HF transformers with three novel PET topologies is proposed. In all of these the switching frequency is independent of the value of leakage inductance. ZVS and zero common mode voltage are obtained by use of modified PDM scheme proposed in the thesis for sinusoidal three winding HF transformer.;All the proposed topologies are analyzed and simulated in MATLAB/ SIMULINK environment and the simulation results are presented. A laboratory prototype is built for sinusoidal current HF transformer and the experimental results are presented.