Split Switched-Capacitor Cell - Coupled-Inductor Based DC-DC Converter with Ultra-High DC Gain and Very Low Voltage Stress for Renewable Energy Applications

Abstract

A new high dc gain converter is obtained by using a classical boost stage with a coupled-inductor, and by splitting the switched-capacitor (SC) voltage multiplier traditionally inserted in the output part into two SC cells, one inserted in the primary side and the other one in the secondary of the coupled inductor. The capacitor in the first SC cell serves two purposes: a) the traditional one of voltage multiplier; b) clamping the voltage across the switch for avoiding spikes induced by the leakage inductance at the switch turn-off. A switch of low voltage rating can be used. The capacitor in the second SC cell, besides the role of a voltage multiplier, makes the output diode to be submitted to a voltage smaller than the output voltage. Thus, one of the disadvantages of the boost-derived converters is avoided. The leakage inductance energy is recuperated via the capacitors in the two SC cells and transferred to the load. As a result, without affecting the high de gain, the efficiency is considerable improved. A description of the operation and a steady-state analysis of the proposed converter is presented. The proposed converter of 11V input, 400V output, nominal power 200W was simulated and tested in the laboratory.