Investigation on Leading Angle Flux Weakening Control of Brushless DC Motor

Brushless DC motor (BLDCM) is hard to achieve field weaking operation by its intrinsical structure. The paper aim is researching of BLDCM field weakening technology. The distribution of air-gap flux density is properly used in leading angle flux weakening control of BLDCM. The key step of Flux Weakening Control is to conquer the limit of rising back EMF towards the rise of current. This paper analyzes the major affect reasons of flux weakening characteristic and gives an improved method. Experiment results agree with calculation results, proving the realization of above basic velocity operation of BLDCM in constant power state.