Power electronic building-block using an inverse coupled inductor based on tape-wound cores

For renewable energies power electronics is a key technology whereas much of the power conversion in the future grid or power plants is done using power electronic converters. By establishing cheaper and smaller solutions to solve the problems dealing with high power transmission the expansion of renewable energies can be advanced. As highly efficient actuators these converters have to be properly designed to meet the standards in every possible issue. One commonly used topology element is the so called “hard switched” half bridge converter (two quadrant chopper, inverter leg) consisting of two semiconductor switches and a single filter inductance to limit current and voltage ripple. In high current applications this inductor is the largest and an expensive part. Thus reducing the size of this inductance will be a very important goal in future power electronic designs. This paper presents a new power electronic building block to use in many hard switched power electronic devices especially for high current applications. To reduce size and therefore increase power density an inverse coupled inductor (CI) is implemented and experimentally verified. Size and cost reduction are achieved by canceling out part of the magnetic DC-flux in the coupled inductor core. To do so the coupled inductor needs to be driven by two 180 degrees phase shifted inverter legs, resulting also in a reduced output capacitance. The converter corresponds to the principals of a two quadrant chopper hence bidirectional use. Renewable energy technologies will strongly benefit since the common hard switched converter legs can be replaced in nearly every wind, solar, storage etc. application by a smaller, cheaper CI solution. The system is operated at full duty cycle range (0...1), elevated power levels and can be controlled by commonly used control theory.