The global and local dynamics of direct-drive brushless DC motors

The dynamic characteristics of direct-drive brushless DC motors (BLDCMs) are investigated. A model for BLDCMs which is governed by a set of nonlinear differential equations is presented. Both global and local characteristics are presented. Since most users of BLDCM incorporate linear control laws to control their nonlinear dynamic characteristics, the local dynamics are specially useful. The results presented provide guidelines for designing controllers for BLDCM systems. As an alternative to the use of linear current control loops, a nonlinear control law is presented which, while being more complex in terms of implementation, will work in a global sense.<
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