Maximum power limits of small single-phase permanent magnet drives

The authors deal with the theoretical limitations on the field-weakening pe rformance of small single-phase nonsalient permanent-magnet motors when dri ven from an inverter with limited volt-ampere rating. A specific normalisat ion is introduced to obtain advantageous normalised parameters. Tt is shown that a theoretical infinite constant power speed range can be achieved, ev en with the ohmic voltage drop, by properly choosing the armature flux link age. The effect of normalised parameters on the output characteristics is a nalysed and presented in the normalised parameter plane. The number of turn s of the winding is computed and applied to an existing single-phase hybrid motor. A wide range of normalised parameter values exists for this structu re.