The Introduction of Brushless DC Motor

What is a Brushless DC Motor?

　　Brushless motor consists of a motor and driver which is a typical mechatronics product.

The Working Principle and Construction of Motor:

　　　It is composed of a permanent magnet rotor, multi-pole winding stator, and position sensor. According to the position of the sensor, along a certain sequence, the current in stator winding is commutated (namely, detecting the position of rotor magnetic pole relative to the stator winding, and the position sensing signal is generated at the determined position. After the signal conversion circuit is processed and control power switch circuit, the current of winding is switched by a certain logical relationship). The working voltage of the stator winding is provided by an electronic switching circuit which is controlled by the position sensor.　

The Structure of Brushless Motor:

　　In terms of structure, there exists a similarity between the brushless motor and brushed motor, which also has a rotor and stator. But contrary to the brushless motor, The rotor of the brush motor is the coil winding, which is connected with the output shaft, and the stator is the permanent magnet steel. While the rotor of the brushless motor is permanent magnet steel which is connected with the output shaft. The stator is coil winding and there is no commutator brush.

The Characteristic of DC Motor:

　　1, Having a good external feature, it can output large torque at low speed.

　　2, The speed range is wide, it can operate in full power at any speed.

　　3, High efficiency, good overload capacity, which has an excellent performance in the drive system.

　　4, A small volume and high power density

　　5, A fully enclosed structure, which can prevent dust from entering the inter

The Drive mode of Motor:

　　(1)Driving waveform: square wave drive, whose drive function can be easily carried out and easy to control.

　　(2)Sinusoidal drive: this mode can improve operate effect and make the output torque uniform, but the realization is complicated. Meanwhile, this method has SPWM and SVPWM (space vector PWM) two ways, the effect of SVPWM is better than SPWM

The Applications of Brushless Motor:

　　(1)Computer devices and Electronic digital goods.

　　This is the most used and widespread scope. In the printer, fax machine, hard disk drives, tape recorders, we can find gear motor which is used. In common, there exists in the product's spindle.

　　(2)Industrial control

　　With the development and maturity of technology, the usage of the drive system in industrial production is more spread. This motor’s features are that it can reduce production costs and improve operating efficiency. At present, there exists in textile, metallurgy, CNC machine, etc.

　　(3)Medical equipment:

　　It can be used to drive a small blood pump in the artificial heart. Meanwhile, brushless motor is used in supercentrifuge and Infrared laser modulator in the thermal imager and thermodetector.