ABSTRACT
The claw-pole rotor is at its best when a large number of rotor poles is considered (2p > 8), to benefit from the “blessing” of a single circular DC excitation coil, which explains the drastic DC excitation power reduction. It is also possible to add a solid core on the stator and place two circular DC coils on the stator to excite the claw-pole rotor and thus avoid the slip ring brush hardware; however, in this case, the machine volume and weight increase notably. On the other hand, a contactless power transformer to transfer power to the rotor circular DC coil, which requires volume, weight, and costs (high-frequency transformer plus inverter and a fast diode rectifier on rotor) has recently been proven feasible (at 3–5 kW) for a regular DC-excited multipole rotor synchronous motor proposed for HEVs and EVs at 100 kW power/unit.
