A single-phase brushless dc motor utilizing a bifilar stator winding and having asymmetrical stator pole faces is investigated. The form of the permanent-magnet component of the stator winding flux linkage is analyzed considering the asymmetry of the stator pole faces. Equations describing the electromechanical dynamics of the motor are then derived along with an expression for the electromagnetic torque. The requirements of the dc-to-ac inverter which drives the motor are determined. Using the expression for electromagnetic torque and inverter characteristics, the form of the so-called static electromagnetic torque is analyzed. The so-called cogging torque is established, and in conjunction with the static electromagnetic torque, used to explain the starting characteristics of the motor. The equations for the electromechanical dynamics are converted into state-model form and two mathematical models of the inverter are developed for use in a computer simulation. This computer simulation is then used to demonstrate steady-state and dynamic operation of the motor.
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