PCB Based Inductor Structure for MV Applications

Silicon carbide (SiC) power semiconductor devices have opened up new areas of applications such as solid-state transformers for medium voltage (MV) high power applications. One of the key enabling factor for MV systems is the design of the MV inductor. The use of inductors in MV systems calls for a reliable insulation design of the inductor along with achieving good performance and more importantly offering good manufacturability and repeatability for the design. This letter focuses on the design of high frequency inductors and demonstrates a novel potting-free, simple to manufacture structure of the MV inductor using PCB based windings. The structure takes advantage of the voltage distribution in the windings to grade the electric field inside the PCB structure, and thus achieve a partial-discharge (PD) free operation. A peak PD inception voltage of 15.5 kV is showcased experimentally for the structure. This PCB based structure is also compared with other designs to demonstrate the advantages and challenges brought upon by the proposed designs. PD and electric field simulation results validate the design and operation of the inductor structures. The MV inductor design is aimed at providing a reliable and repeatable method to design and manufacture MV inductors for commercial applications.