Also referred to as synchronous DC motors or electronically commutated motors, these motors are powered by direct current supply. Each phase of the motor is driven by a closed loop controller and this controller provides the pulses of the current to the windings, controlling the speed and the torque in turn.
In this article, you will learn more about the operation of a brushless DC motor and their extensive applications.
How do Brushless DC Motors Work?
The advent of solid-state electronics in the sixties facilitated the creation of brushless DC motor. In a brushless motor, an electronic servo motor acts as the replacement for the mechanical commutator. This electronic device is able to detect the angle of the rotor and also control the semiconductor switches. This control is done via the windings and as the direction is altered, torque is created in the electromagnet.
The Advantages of Brushless DC Motor
One primary advantage of BLDC is the efficiency they offer. The motors can be controlled continuously at maximum torque, unlike brushed motors whose torque is only maximum at certain points of rotation. The implication of this is that before a brushed motor can deliver torque similar to that of a brushless motor, a larger magnet will be required.
Another reason why BLDCs are preferred is that of the controllability. Feedback mechanisms can be relied upon to provide a certain degree of control and this facilitates the precise delivery of torque and rotation speed. When such a high level of control is achieved, the energy consumed will drastically reduce, the heat generated will be minimized, and the battery life of the motor is also conserved.
Finally, BLDCs also have a high level of durability, reliability, and noiseless service, thanks to the absence of brushes. Other motors with brushes and commutators suffer from the constant moving contact, causing an eventual wear down. The sparks produced as a result of friction after contact is also a disadvantage. These sparks are the main cause of the electrical noise produced in the motor.
To recap, here’s a summary of the advantages of brushless DC motors.
- The speed vs torque characteristic is better than that of brushed motors.
- The motor has a high dynamic response.
- The efficiency is also very high.
- There’s a higher life expectancy for the motor as a result of minimized friction losses and the absence of brushes.
- The operation is noiseless.
- The speed range is also higher.
Applications of Brushless DC Motors
Now that we’ve seen the numerous advantages of BLDCs spanning efficiency, controllability, and operating life, it is expedient to proceed to see where they find an application.
Basically, their desirable features allow them to be used in machines that run continuously. In the past, we have seen BLDCs being used in washing machines, HVAC equipment, and even electronics gadgets. With recent advancements, these devices have also shifted to vacuum machines, fans, and conveyors and this is as a result of the high level of efficiency required in the operation of these devices.
One application that is not so popular is in miniaturized computing devices. Did you know that brushless DC motors are used to power hard disk drives? Well, they are. The drives, as a result, are able to operate steadily over a long period of time and their efficiency is also a plus.
The industrial applications are also very promising and brushless DC motors are used extensively in a servo, actuation, positioning, and other applications requiring variability of the speed or an accurate control of the motion. These motors serve as linear motors, servomotors, actuators, extruder drive motors, and feed drives for machine tools.
Helicopters and drones have also enjoyed the use of brushless DC motors in recent years. The power-to-weight ratio, as well as the flexibility in terms of size, were major reasons underpinning the switch. These motors totally revolutionized the industry and they ushered in an array of simplistic, lightweight electric model aircraft unlike the previous bulky machines using the combustion engine.
In the future, it is expected that BLDCs will be used in a wider array of applications; one of the most prominent being the service robots. BLDCs will also be used in drones and they will be able to precisely control the devices, especially those with multiple rotors. In general, the outlook for brushless DC motors seems promising.