Optimum control scheme for the maximum efficiency drive of linear synchronous motor used for ropeless elevator

• Published in: Electrical engineering in Japan Vol. 155; no. 3; pp. 70 - 78
• Main Authors: Torii, Susumu, Izuno, Naoya, Watada, Masaya, Ebihara, Daiki
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.05.2006
• Subjects: linear synchronous motor; maximum power point tracking control method; ropeless elevator
• ISSN: 0424-7760; 1520-6416
• DOI: 10.1002/eej.20061

Our research group at Musashi Institute of Technology is currently concentrating on the improvement of the overall efficiency for driving ropeless elevators using a linear synchronous motor (LSM). Since these elevators are ropeless, counterweights cannot be installed in the system. Therefore, the linear motors must develop a higher thrust force. In addition to the improvement of the efficiency of LSM it is also necessary to develop a high‐efficiency drive control method. Our laboratory is involved in studies on efficiency improvement. In order to design an efficient control system, we believe it is necessary to understand changes of efficiency caused by variations of driving conditions, such as load mass, velocity, and required thrust force. The dynamic control method changing the operating point to achieve the maximum power is known as maximum power point tracking (MPPT). This approach is useful and can be applied to the control of LSM for ropeless elevators. The car cage of a ropeless elevator periodically repeats acceleration and deceleration cycles in the process of ascent and descent motions. The optimum‐minimum‐energy consumption is obtained if the system is always operated at the maximum efficiency, even if the drive conditions change. In this paper, we first discuss the basic characteristics of LSM for ropeless elevators. Then, based on these characteristics, we derive the maximum efficiency loci as a unique combination of a current and a power angle for a specific condition. We also provide a design of the MPPT controller of LSM and analyze results of simulation of driving the LSM using MPPT. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 155(3): 70–78, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20061