엘리베이터용 동기전동기 구동을 위한 시스템 개발 연구

Abstract

The speed of elevators has increased along with continuous development of the related technologies. Now, elevators with the traction machine of 1,010 [m] per minute are being installed, which can be operated at super high speed. Recently, the development of super-high-speed elevators has started. Especially, elevators based on permanent magnet synchronous motor (PMSM) with high energy density have developed mainly to satisfy some conditions of high performance, high efficiency, miniaturization and lightweighting. However, unlike conventional direct current motors and induction motors, PMSM has some disadvantages, that is, it needs position sensors and operation drives. Therefore, in this paper, a motor system for optimized elevators is proposed by considering the requirements such as design of high density motors, stable position sensors, high efficiency of operation drives, and reduction of torque ripple. In order to realize proposed motor system, firstly, IPMSM(Interior Permanent Magnet Synchronous Motor) is designed optimally for high density motor. Secondly, high efficiency and torque ripple reduction of the motor are achieved by configuring operation drive using maximum modulation ratio control technique to drive IPMSM optimally designed. Thirdly, two kinds of new type encoders are proposed for stability and low cost of position sensors. This leads to reduction of iron loss in the motor and high efficiency of the inverter. After designing IPMSM with nominal power of 10 [kW] and maximum power of 17 [kW] and producing its drive system, experiments are carried out. The results show that reduction of cogging torque more than 40% and maximum efficiency of 92.0% in the motor section. In addition, maximum modulation ratio control driving method is designed, which is linked with speed patterns for comfortable operation of the elevator. Appling this designed drive method to experiments, the results show that harmonic current draw of the motor is reduced by modulation ratio 1 drive in all speed ranges and torque ripple is greatly enhanced, which leads to improvement of the efficiency. Moreover, the results show that the absolute information for the position of every 60° is acquired in the section of proposed position sensor, position following error is within maximum 1% when the motor speed is more than 100 [rpm], and maximum position error is within 3.3% when the speed variation is within 3500 [rpm/sec]. As described above, a motor drive system is developed to have the performances such as high density and high efficiency of the motor, high reliability of the position sensor, and torque ripple reduction by maximum modulation ratio drive. This is expected to contribute to comfortable vertical transportation and efficiency improvement of the elevator. Additionally, according to continuous increasing demand for the elevators in the future, it is expected that the utilization of the proposed system will be increased as an energy saving system and a synchronous motor drive system for elevator.