1. The core constitute a magnetic circuit the magnetic flux generated by the exciting coil. It uses a high permeability silicon steel plates are laminated, the eddy current can be suppressed to reduce the iron loss.
Magnetic flux density of the motor torque is proportional to the magnetic field. Further, the magnetic flux density and the ampere-turns of the driving coil, the driving current is proportional to the number of turns X.
In order to increase the ampere-turns in a limited core space, we need to find solutions. With thin looks good, but the resistance of the coil increases.
X = resistance loss current coil resistance.
2. The main evolution driving mode as follows:
Canceling Hall element becomes sensorless drive method
· From rectangular wave driving to sinusoidal wave drive mode
· Evolution sensorless sine-wave drive mode and
Introduction of vector control
Sensorless control, cancel the Hall element, under severe conditions conducive to the brushless DC motor drive.
After the introduction of the sensorless vector control technology and the sine wave drive, brushless DC motor quiet performance, robust, and to increase energy efficiency limit
"Brushless DC Motor Control Vector"