The more electric aircraft provides 115 V/360~800 Hz variable frequency power supply for the variable frequency asynchronous motor, and the motor operation characteristics change with the power frequency variation. It causes the starting pulse vibration torque with the low-frequency power supply (360 Hz) to increase greatly and the mechanical shock and fatigue damage. Therefore, this paper proposes step-down starting method with the low-frequency power supply. Based on the electromagnetic principles generated by the starting pulse vibration torque, this paper uses a novel method of simulation data fitting to establish an approximate model of the starting pulse vibration torque. The parameter design formulas of the low-frequency step-down starting methods, including the reducing voltage, the series resistance, and the series inductance are proposed. The effectiveness of the different methods are verified, and the performance is compared through the simulation. The experimental verification of a small power asynchronous motor is completed. The simulation and experiment results show that the low-frequency step-down starting methods effectively reduce the starting peak torque, and also suppress the shock impact of starting current on the power supply.
Block diagram of asynchronous motor with short-circuit rotor for a variable frequency drive with scalar and vector control
