This paper presents an axial flux stator coreless permanent magnet flywheel motor/generator set for pulsed power application. This structure can adjust the back electromotive force (EMF) by rotating one of the double stators. Detailed topology of the structure is presented and a closed-form analytical design approach is described. A downsized prototype machine and the corresponding driver are designed and constructed based on the presented analytical approach. No-load parameters of the prototype are measured and compared with the predicted one, showing good agreements. Then losses of the prototype are analyzed. Finally, the prototype is driven in both brushless DC (BLDC) mode and space vector pulse width modulation (SVPWM) mode; actual charging and discharging waveforms are presented.@en

In order to reduce the error introduced by the conventional motor model in the induction motor soft starting simulation, an induction motor model with variable parameters is proposed by investigating the variation patterns of the equivalent circuit parameters during starting. Based on the operating principle of the induction motor, the proposed model estimates the motor equivalent circuit parameters in starting and steady state directly from the nameplate data. During starting, the rotor resistance and leakage reactance are varied according to the increasing rotor speed to ensure that the simulation model is close to the actual motor on critical operating points. The proposed model is applied to soft starting simulation of a 16MW induction motor in Matlab. Simulation results are verified by experiment and the variation of the starting time is within 3%. It can be seen that the proposed model is simple in construction and high in accuracy, and can simulate the starting procedure of the induction motor validly.@en