Challenges and Design Aspects of Power Electronically Fed PCB Motor Windings

Abstract:
Windings based on printed circuit boards (PCB) are nowadays investigated in many research projects and are already used in several products. PCB winding systems can be applied as planar transformers, inductors to store energy or as motor windings. The realization of the actual winding geometry is based on the arrangement of conductive tracks on multilayer printed circuit boards. In this paper basic design considerations of inverter-fed PCB-based motor windings and the impact on power electronics are discussed. The focus will be on the different boundary conditions, the advantages, and the challenges of this technology. In general, there are many advantages of PCB windings, such as extremely cost-effective production, good cooling properties, thin realization, short and simple connection to the electronics. In contrast, there are numerous challenging topics to be considered in a winding design, which also have a direct impact on the power electronic stage used to feed the winding. These include relatively low inductances and low numbers of turns, resulting in tendentially low voltages and rather high currents. But there are also design criteria such as small track widths to reduce parasitic eddy currents and thus torques, no crossings in one winding layer, limited current density, etc. To enable smoothed currents, significantly higher switching frequencies are required than in conventional systems. This makes fast-switching transistors based on wide-bandgap materials such as GaN useful for the supply.