 | ||||||||||
 |  | |||||||||
 |  |  |  |  |  |  |  | |||
| ||||||||||
| | |||||||||
| | | | | | | | |||
SECTION III-B
SELF-REGULATING PERMANENT MAGNET LINEAR
MOTOR WITH EXTENDING POLES AND
POWER SYSTEM
Self-regulating permanent magnet linear motor
The Permanent magnet linear motor realizes ideas described above. The motor (Fig.1, Fig.4) comprises an extended stator’s winding common for all vehicles and a permanent magnet rotor installed on each vehicle. The winding is divided into several parts each of them bring powered by sinusoidal current from a separate step-down transformer. Current frequency in the winding is constant, however the length and cross section of its turns vary along the track [4].
The rotor comprises mirror-symmetrical halves of a steel yoke inserted into a longitudinal slit on the vehicle bottom. These halves are capable of moving apart and back together along the slit and are operated by a synchronizing mechanism (Fig. 4). Each half contains cells with permanent magnets capable of moving upward and downward within the cell and operated by a synchronizing device.
When the vehicle is in motion the synchronizing mechanism moves the yoke halves apart or together thus continuously changing the rotor’s pole pitch length according to the winding turn length while synchronizing devices gradually increase or decrease its pole length. The purpose of their joint work is to cause the rotor’s magnet poles to coincide with central parts of halves of the traveling wave where linear current density (and, consequently, the propulsion force) is greatest. This allows the linear motor to function in stable fashion without falling out synchronism.
Power system
The Amlev power system is a three-phased system of constant frequency (f=25Hz). A high voltage line extending along the Amlev track supplies step-down transformers with power. A vehicle passing a certain part of the track switches the next winding part on or off. Electronic inverters and converters of small capacity (about 3% of the transformer power) are installed with step-down transformers. Their purpose is to launch a vehicle at its start and to work in case of emergency. Any malfunction in the power system will cut the power to the stator winding and lead to a smooth stop of the vehicle. Proposed power system is simple, reliable, and inexpensive.
