Brake control characteristics of a linear synchronous motor for ropeless elevator

This paper represents an experimental ropeless elevator with a linear synchronous motor (LSM) of rated thrust of 3 kN. The LSM consists of an array of permanent magnets (PMs) as the secondary member and a layout of the double sided armatures located along the guide way as the primary member. By adoption of PM type yokeless secondary and double sided armatures, a light moving part and small normal force have been realized. The operating test using a PWM inverter has shown the following results. (1) The elevator has been able to move up and down smoothly and stopped at any position. The calculated velocity in normal operation has differed from the measured velocity by less than 3%. (2) In case of interruption of power supply, falling velocity of the cage has been suppressed at a speed of 0.25 m/s by the dynamic brakes. The difference of falling velocity between the measured and calculated values was within 5%. (3) The efficiency and power factor of the LSM were 64% and 0.93 respectively.