The brushless DC motor consists of a motor body and a driver, and is a typical mechatronic product. Brushless motor means a motor without brushes and commutators (or collector rings), also named as commutatorless motor. As early as the birth of the motor in the last century, the practical motor is the brushless form, that is, the AC squirrel-cage asynchronous motor, which has been widely used. However, asynchronous motors have many insurmountable defects, so that the development of motor technology is slow. The transistor was born in the middle of this century, so the DC brushless motor that uses the transistor commutation circuit to replace the brush and the commutator came into being. This new brushless motor, called an electronically commutated DC motor, overcomes the shortcomings of the first generation of brushless motors.
* Features of brushless motors
1. It can replace the speed regulation of DC motor, frequency converter + frequency conversion motor speed regulation, asynchronous motor + reducer speed regulation;
2. It has the advantages of traditional DC motors, and at the same time cancels the structure of carbon brushes and slip rings;
3. With brake and double steering function;
4. Small size, light weight and large output;
5. Excellent torque characteristics, good torque performance at medium and low speeds, large starting torque and small starting current;
6. Stepless speed regulation, wide speed regulation range and strong overload capacity;
7. Soft start and soft stop, good braking characteristics, can save the original mechanical braking or electromagnetic braking device;
8. High efficiency, the motor itself has no excitation loss and carbon brush loss, eliminating the multi-stage deceleration loss, and the comprehensive power saving rate can reach 20%~60%.
9. High reliability, good stability, strong adaptability, simple repair and maintenance;
10. Resistant to bumps and vibrations, low noise, small vibration, smooth operation and long life;
11. No sparks, especially suitable for explosive places, with explosion-proof type;
12. Trapezoidal wave magnetic field motor and sine wave magnetic field motor can be selected as required.
* The advantages of brushless motors
Different from brushed DC motors, brushless DC motors do not use mechanical brush devices, but use square wave self-controlled permanent magnet synchronous motors, use Hall sensors to replace carbon brush commutators, and use NdFeB as the permanent magnet material of the rotor. , Compared with the general traditional DC motor, it has great advantages in performance and is the most ideal speed regulating motor today.
High efficiency, low energy consumption, low noise, long life, high reliability, servo control, stepless frequency conversion, relatively low cost and easy to use.
The stator windings of the brushless DC motor are mostly made into a three-phase symmetrical star connection, which is very similar to the three-phase asynchronous motor. A magnetized permanent magnet is attached to the rotor of the motor. In order to detect the polarity of the motor rotor, a position sensor is installed in the motor. The driver is composed of power electronic devices and integrated circuits. Its functions are: accept the start, stop and braking signals of the motor to control the start, stop and braking of the motor; accept the position sensor signal and the forward and reverse signals to control the reverse. Change the on-off of each power tube of the bridge to generate continuous torque; accept speed commands and speed feedback signals to control and adjust the speed; provide protection and display, etc.
Brushless DC motors are widely used in household appliances, auto parts, power tools, office automation, industrial and commercial equipment, medical equipment, personal care, robots and many other industries