Design of permanent magnetic motor speed controller drive with power supply inverter based on a new switching method

Abstract

Dual excitation permanent magnetic motor is a brushless squirrel cage permanent magnetic motor that have two separate three-phase coil winders with unequal poles and are typically fed by two separate three-phase inverters. Direct control is a convenient control method for the control of a permanent drive motor with a dual excitation squirrel cage. It is difficult to estimate the rotor flux in this control method for low speeds. This paper proposes a direct control method based on rotor flux compensator that the result is to maintain the standard drive performance of the motor at low speeds, which results in a lower power loss of the inverter unit than conventional control methods. The rotor flux in the proposed control method is compensated by a proportional-integral controller. The nature of the proposed control method is based on the separate control of the rotor flux and the electromagnetic torque along the direct (d) and orthogonal (q) axes, respectively, and rotor flux compensation is done by modifying the rotor reference flux. Also in this paper, for the first time, the number of inverter unit switching elements in the proposed drive of this motor is reduced by using five-cylinder and nine-circuit power converters. The benefits of using these proposed structures in drive are to reduce the cost of the inverter unit and reduce the power losses of the inverter unit.