Characteristics of a doubly salient-pole homopolar machine in a constant-power speed range

A doubly salient-pole homopolar machine has been proposed for high speed variable speed applications with a wide constant-power speed range. This machine is basically a permanent magnet synchronous machine that has permanent magnets between two stator cores aligned in a thrust axis. The machine has salient-poles in a stator similar to those in switched reluctance motors. A rotor is also very similar to the one in switched reluctance motors except a skew in 45 degrees. Thus, the rotor is very simple and mechanically robust. A control method of doubly salient-pole homopolar machines is made clear. A measurement of equivalent circuit parameters is also made clear. The experimental and calculated results in constant-power speed region of an optimized machine are shown in detail. It is found that 7 times of a constant-power speed range is realized with a power factor exceeding 0.9 in high speed region. A contribution of motor parameter variations is also shown.