A new control strategy of ironless stator axial-flux PM motor fed by inverter with output LC filter

Axial-flux ironless stator PM motors are becoming a promising choice for aero applications due to their advantages of light weight, strong overload capacity, high efficiency and high reliability. However, it comes with extremely small inductance resulting in a challenging difficulty to the inverter that drives the motors. Considering the limitation on increasing the switching frequency of high-power device with high DC-link voltage, high-power level and high fundamental frequency, a practical and cost-effective power circuit for the driving operation of a 50kW axial-flux ironless stator PM motors is developed. A new and simple control strategy of the inverter with output LC filter is studied to achieve a good steady and dynamic performance for driving the axial flux ironless stator PM motors. The dual closed-loop of the phase-current of the motor and the branch current of capacitors ensures the stability and torque control of the system. Due to the dual-loop current regulator, the maximum torque per ampere (MTPA) control is achieved. The development of the power circuit topology and effective control method provides an effective solution for ironless stator motors or high-speed motor with small inductance.