Inductor Design Considerations for Overload Conditions of LC-Filters in High Frequency GaN-Inverters

High frequency GaN inverters feature high power density and efficiency. Typically, they are used in conjunction with an output filter in order to keep high frequency noise away from the load. During overload conditions, while accelerating or braking, significantly higher output currents occur compared to nominal operation. Without dramatic oversizing the component, this can result in saturation of the filter inductance’s core in case of ferrite. Therefore, this paper proposes an air inductor as filtering element in order to tackle this problem. Small signal impedance measurements as well as results within a real inverter application demonstrate the feasibility of the designed air inductor.