Brushless DC Motors and Brushed DC Motors: What are the differences.
The difference between brush DC motor and brushless DC motor speed regulation method
In fact, the control of both motors are voltage regulation, only because the brushless DC uses electronic commutation, so to have digital control can be achieved, and brush DC is commutated by carbon brushes, the use of thyristor and other traditional analog circuit can be controlled, relatively simple.
1, brush motor speed control process is to adjust the motor power supply voltage high and low. Adjusted voltage and current through the rectifier and brush ground conversion, change the electrode generated magnetic field strength, to change the speed of the purpose. This process is called variable voltage speed regulation.
2, brushless motor speed process is the motor power supply voltage remains unchanged, change the ESC control signal, through the microprocessor and then change the switching rate of high-power MOS tube, to achieve the speed change. This process is called variable speed regulation.
1, brush motor structure is simple, long development time, mature technology
As early as the nineteenth century, when the motor was born, the practical motor was the brushless form, that is, AC squirrel cage asynchronous motor, which was widely used after the generation of AC power.
However, the asynchronous motor has many insurmountable defects, so that the development of motor technology has been slow. In particular, DC brushless motors have been unable to be put into commercial operation, along with the rapid changes in electronic technology, until recent years slowly put into commercial operation, in essence, still belong to the AC motor category.
Soon after the brushless motor was born, the brush DC motor was invented. Because the DC brush motor mechanism is simple, easy to produce and process, easy to maintain, easy to control; DC motor also has a fast response, large starting torque, from zero speed to rated speed with the performance of rated torque, so once introduced, it has been widely used.
2, DC brush motor response speed, high starting torque
DC brush motor has fast starting response, high starting torque, smooth speed change, almost no vibration from zero to maximum speed, and can drive a larger load when starting. Brushless motor starting resistance is large (inductive resistance), so the power factor is small, the starting torque is relatively small, there is a humming sound when starting, and accompanied by strong vibration, driving a smaller load when starting.
3, DC brush motor running smoothly, good starting and braking effect
Brush motor is through voltage regulation speed, so the starting and braking is smooth, and also smooth when running at constant speed. Brushless motor is usually digital frequency control, first AC into DC, DC into AC, through the frequency change to control the speed, so brushless DC motor in the starting and braking operation is not smooth, vibration, only when the speed is constant will be smooth.
4, DC brush motor control precision
DC brush motor is usually used together with gearbox and decoder, so that the output power of the motor is bigger and the control precision is higher, the control precision can reach 0.01mm, which can make the moving parts stop almost anywhere you want. All precision machine tools use DC motors to control accuracy. Brushless DC motors are not smooth in starting and braking, so the moving parts will stop at different positions each time, and must be stopped at the desired position only through positioning pins or limiters.
5、Brush DC motor is low cost and easy to maintain
Because of the simple structure of DC brush motor, low production cost, many manufacturers, technology is more mature, so the application is also more widespread, such as factories, processing machine tools, precision instruments, etc., if the motor failure, only need to replace the carbon brush can be, each carbon brush only a few dollars, very cheap. Brushless DC motor technology is not mature, the price is higher, the application is limited, mainly should be in constant speed equipment, such as inverter air conditioners, refrigerators, etc., brushless DC motor damage can only be replaced.
6, Brushless, low interference
Brushless DC motor in addition to the brush, the most direct change is that there is no brush motor operation generated by electric sparks, which greatly reduces the interference of electric sparks on remote radio equipment.
7、Low noise, smooth running
Brushless DC motor without brushes, friction is greatly reduced when running, smooth operation, noise will be much lower, this advantage is a huge support for the stability of the model operation.
8、Long life, low maintenance cost
With less brushes, the wear and tear of brushless DC motor is mainly on the bearings. From the mechanical point of view, brushless DC motor is almost a kind of maintenance-free motor, and when necessary, it only needs to do some dust removal maintenance.