48v Brushless Motor: Custom Designed to Meet Your Application Requirements
Posted by Jack Wang on June 11th, 2015
Brushless motors otherwise known as electronically commutated motors or ECMs are synchronous motors, powered by an electric source through an inverter/switching power supply. This produces an AC electric signal, which drives the motor.
A typical brushed DC motor contains permanent magnets outside and a spinning armature inside. The magnets are permanent and stationary (stator) while the armature rotates (rotor). The rotor or armature likewise contains an electromagnet, which when acted upon by electricity, creates a magnetic field that attracts and repels the stator's magnets. The magnets make the armature spin 180 degrees, but to make a full 360 degree spin, the polarity of the electromagnet has to be changed. This is where brushes come to play, flipping the magnetic polarity of the electromagnet as it makes contact with the spinning electrodes while spinning.
The brushed set-up works quite well and offers the advantage of cheap manufacturing, but it does pose many problems, such as the eventual wear that the brushes experience and the sparks and electrical noises you get as the brushes make and break connections. Moreover, brushes limit the maximum speed that the motor can produce and the central position of the electromagnet makes the mechanism harder and slower to cool. Brush use also limits the number of poles armatures can have.
It is because of these limitations and problems that brushless motors came to be developed. Cheap computers and power transistors made it possible to turn the design inside out, thus eliminating the need for brushes. In a brushless motor design, the permanent magnets are placed on the rotor while the electromagnets are moved to the stator. A computer is then used to charge the electromagnets as the shaft turns, thus eliminating the need for a change in electromagnet polarity using brushes. This kind of system is a lot more advantageous as it allows more precise and efficient operation, where a computer controls the motor as opposed to mechanical brushes. Computers can also factor motor speed and eliminates other problems like sparking and overheating. While brushless motors do attract higher initial costs, they do offer greater advantages in the long run, while also offering greater efficiency over the motor's life.
Having brushless motors custom designed is also more possible to fit your design and system needs, unlike brushed motors that limit the number of electromagnets that can be installed on the armature (you can use as many electromagnets as you need on the stator to achieve more precise control).
About the Author:
This article is written by Jack Wang who is associated with GEMS Motor. Jack got his Bachelor's degree in Mechanical Engineering and Master's degree in Electrical Engineering, specialized in electric motor design and motor driver development. Jack was born in greater Shanghai area, China, and had several years of study and work experience in the United States. With the deep knowledge of electric motors and great bilingual skills in Mandarin and English, Jack helps market our electric motor products worldwide. Jack currently holds the position of Director of Marketing at GEMS Motor.
