Optimum Control Scheme for the Maximum Efficiency Drive of Linear Synchronous Motor Used for Rope-less Elevator

Abstract

The research group in Musashi Institute of Technology is currently concentrating on the increase of the total efficiency for driving rope-less elevator using Linear Synchronous Motor (LSM). Since it is rope-less, counter weight cannot be installed in the system. Thus, the linear motor should output higher thrust force. The increase of the efficiency of LSM itself is one of the concerns, and the other is the high-efficiency drive control method. The former is considered in our laboratory. Therefore, We think that it is necessary for the design of efficient control system to grasp the change of the efficiency depending on the driving condition, such as load mass, velocity and required thrust force. The dynamic control method changing the operating point to pursue the maximum power is known as the Maximum Power Point Tracking (MPPT). This approach is useful and can be applied to the control of LSM for rope-less elevator. The cage of rope-less elevator repeats acceleration and deceleration periodically, in ascent and descent. The optimum-minimum-energy consumption is obtained if the system is always operated at the maximum efficiency, even if the drive condition changes. The basic characteristics of LSM for rope-less elevator are discussed first in this paper. The efficiency characteristics of the LSM are shown and the maximum efficiency loci are derived next as the only pair of a current and a power angle for one condition. Moreover, the MPPT controller of LSM is fully designed, and the results of simulation in driving the LSM using MPPT are shown.