Linear Drive Systems and their Related Technologies. PWM Converter Using Instantaneous Current Detection for Linear Generator of Maglev Vehicle.

Abstract

For power supply on-borad of Maglev vehicle using EDS (electrodynamic suspension) Maglev system and super-conducting magnets (SCM), an inductive power collection method is proposed, which gets electric power from induced voltage of the on-board power collection coils using magnetic field harmonics of ground coils. As for EDS, adoption of null-flux levitation and guidance is proposed because of less ground coil current being obtained than in the case of normal-flux levitation. In this case, a smaller magnetic field harmonics of ground coils and eddy currents of the outer vessel of the SCM result in a smaller electromotive force per one turn so that we need current collection coils with more turns, which means high source impedance. A normal full-wave rectifier can not give the needed electric power. So a PWM converter with a unity power factor control, which can cancel the power supply side impedance, is proposed. We have developed a PWM converter, which functions just like the active capacitor, using IGBT and instantaneous current control. We achieved a power factor × efficiency value of 0.97 in a stationary experiment of the system. Here are described the working principle, the simulation and the result of the stationary experiment.