Analysis of a new topology of flexible PCB winding for slotless BLDC machines

The slotless BLDC motor is one of the most efficient motor in the fractional horse power range. However, the demand for higher performance, incessantly growing, asks for breakthrough improvements. A solution to achieve better performances is to use windings printed on a flexible PCB, allowing more elaborated winding shapes and topologies. In this paper, a new winding topology is introduced and compared to three other PCB windings. An analytical magnetic model is presented, and validated by FEM. The comparison shows that the new topology achieves a motor power density 10% higher than the best existing PCB winding. Further, this gain reaches 40% when comparing with the winding shape and topology currently used in the classical windings made of copper wire, suggesting a consequent breakthrough in the performances achievable in the fractional horse power range.