Brushless direct current motor control system without position sensor based on digital signal processor

The brushless dc motor (BLDCM) is widely used due to its particular advantages such as the perfect speed-torque characteristic, convenient speed regulation and high reliability etc. A speed regulating system was introduced for the permanent magnet (PM) BLDCM without rotor position sensor. The digital signal processor (DSP) ADMCF328 is the core of the control system. Its special inside circuit for motor control reduced the applique circuit, and its high data processing capacity make the control convenient and exact. The back electromotive force detection technique is used to confirm the rotor position, which simplifies the structure of the motor, minishes its bulk, improves its reliability and fits batch production.