Torque Boost Operation of New Consequent-Pole Permanent Magnet Motor Using Zero-Phase Circuit

A novel consequent-pole permanent magnet (PM) motor is proposed in the paper, which has image pole pairs for every pole pair of N and S. The three-phase synchronous impedances of the motor are balanced owing to the rotor configuration. In addition, it is possible to carry out field weakening with less d-axis current, which leads to a highly efficient operation in a high-speed range. However the motor still has a drawback of low torque generation at low speeds due to less PM volume. In order to solve the problem, the paper discusses a torque boost operation by introducing a zero-phase winding to the motor and a three-phase four-wire motor drive circuit with an inverter. This paper describes a basic principle of the newly proposed consequent-pole PM motor and its operation characteristics, and investigates the torque boost approach using the proposed system.