Considerations on electrical and mechanical time constants of a moving-magnet-type linear DC motor

The electrical and mechanical time constants of a moving-magnet-type linear DC motor (LDM) are required to have small values so as to realize a high-s peed response LDM. Simplified expressions of the electrical and mechanical time constants of the LDM are derived using the permeance method. These con stants are also computed using the finite element method (FEM) combined wit h the electric circuit equation. The measured electrical and mechanical tim e constants are 10.5 ms and 1.6 ms, respectively. The calculated values of the electrical time constant obtained by the permeance method and the FEM a re 13.4 ms and 10.2 ms, respectively. The calculated values of the mechanic al time constant obtained by the permeance method and the FEM are 1.6 ms an d 1.5 ms, respectively. It is clarified that both methods are useful for ca lculating the electrical and mechanical time constants of the LDM. (C) 2000 Elsevier Science SIA. All rights reserved.