You must be needing a small but powerful motor that can be throttled. Brushless DC motors, or BLDC, showed up in search results, and you probably bought one. They are becoming popular today in electric vehicles, ventilation, and air conditioning, as well as industrial areas. However, before using it, you must understand everything about it first.

Photo by Pablo Gentile on Unsplash

PROS AND CONS

A traditional motor has mechanical commutators fixed to its case. Commutators are brushes that transfer power by constantly scratching the rotating part. Your brushless DC motor has the advantage of not having those parts. Losing those brushes has advantages aside from having fewer parts. No rubbing parts means no wasted power and quicker response. Also, BLDC motors use rare earth magnets, the stronger version of what the traditional ones have. That makes the BLDC and the device using it become smaller but stronger. This upgrade makes brushless DC motors more reliable. The downside of using BLDC is having an extra part: its brain. That electronic brain, called ‘brushless motor controller’, contains a complex program to offer the advantage of throttling speed and torque.

MOTOR CONSTRUCTION AND OPERATION

The rotating component of your BLDC motor, called rotor, contains the rare earth magnets. Those strong magnets will be moved by the stator, its enclosing component. The stator is a donut-shaped array of electromagnets, which are copper windings that enclose several steel sheets. Think of the rotor as a carousel without internal power, and the stator as parents standing around it. The magnets function like the children riding the carousel, reaching the hands of their parents, who are the electromagnets. To spin the carousel, they both pull after reaching their hands, then push afterwards. Same goes for your BLDC motor, the rotor electromagnets pull the stator rare earth magnets, then push them afterward. The orientation of the rare earth magnets and electromagnets contribute to the rotating direction. The electromagnets produce a magnetic push or pull called ’EMF’ (electromagnetic force). To spin the rotor, these magnets – repelling and attracting in the right direction – needs the right timing. Controlling the spin direction is made by reversing the voltage on the coils at the right time.

CONTROLLER ELECTRONICS

The brushless DC motor resembles the induction motor assembly, but there are tricks used on the electronics. The voltage reversals and timing are made possible by the controller. To change the voltage, it needs to cooperate with the stator, just like the parents teaming up with children on the carousel. Some BLDC motors use sensors to communicate with the controller. They are called ‘Hall sensors’, which uses its assembly inside the motor. However, some BLDC motors just sense where the stator magnets face. The electromagnets can also act as sensors temporarily by transforming the force of rare earth magnets to electric signals, called ‘back EMF’. The brushless motor controller has another trick on its sleeve to throttle the torque. Motor drivers are programmable parts of the controller that regulates the voltage going through the motor coils. The function of the driver is made possible by the smart circuits inside it.

THREE-PHASE BRUSHLESS DC MOTOR

You can usually see three-phase BLDC motors on the market, which have three motor coils arranged in the “Y” formation. The-three phase works by having two of the three coils functioning at a time. Because the stator has two magnets, there are four magnetic poles existing, two north poles, and two south poles. The two coils push one of the magnets and pull the other, making the rotor spin. When the rotor changed its angle, one of the two coils will rest and the remaining one wakes up.

CONCLUSION

Brushless DC motors use complex electronics to have advantages of more control, having a long life and more power density.

Hopefully, this article helped you understand how your brushless DC motor is controlled. You can learn more about your brushless DC motor by contacting its manufacturer and hearing from other users.

Tereso sobo