Gyuláné Vincze, Gergely György Balázs
Budapest University of Technology and Economics Department of Electric Power Engineering
For the levitated and generally high-speed vehicles the overhead line energy supply cannot be applied. Non-contacting electric energy supply solutions should be found instead of the sliding pantograph, rolling wheels, rail circuit.
At levitated vehicles, the problem of the traction energy supply is solved by linear motor drive, where the active coil of the motor is installed on the track, the energy - required for the traction – shall not be conducted into the vehicle. Electronic device - installed along the track - supplies the stator coils of the motors with controlled current. For economic reason, the linear motor coils are supplied segment-by-segment, always those segments, where the locomotive is running.
Contactless solution should be designed for the energy supply of the auxiliaries, for supplying the electro magnets (magnets that create the levitating and pole flux), the air conditioning, and other consumers.
One solution is the linear generator built in the vehicle that takes the feature of the linear motor driven vehicle, that apart from the main flux, magnetic harmonics are generated because of the stator iron core slots installed along the track. The harmonic change of the flux density caused by the vehicle movement induces voltage in the linear generator coil, and it provides the energy supply of the auxiliaries. The linear generator energy source is always completed with battery energy storage. The transmittable energy of the linear generator depends on the vehicle speed. At low speed it does not transmit enough power, at standing position it transmits nothing.
At the stations or close to the stations, at low speed, additional energy supply shall be ensured. For this purpose traditional current supply could be applied with mechanical contact, powered by a third rail. However the moving transformer (so-called IPS system) is a much more intelligent solution. The primary side of the moving transformer is a part of the track, and the secondary side moves together with the vehicle. To reach high efficiency and small space demand, the moving transformer is designed for high-frequency transmission without iron core. The stator of the IPS (Inductive Power Supply) is a long primary loop installed along the track (e.g. at Transrapid vehicle 20 kHz, 200A sinusoidal current generator supply, shown in Fig.3.6.) the moving part is an on-board receiving-loop.
The nominal air gap between the primary- and receiving loop is approximately 40mm. The moving energy transmission is independent of the vehicle speed. In the primary loop there are two tuning capacitors, therefore the installation is not recommended in tunnels.