What is a Brushless DC Motor?
Tags: motor, bldc
Published: 2024-01-18 01:31:11

A brushless DC motor ([BLDC Motor](https://www.omc-stepperonline.com/brushless-dc-motors): Brushless Direct Current Motor) is a 3-phase motor whose rotation is driven by the forces of attraction and repulsion between permanent magnets and electromagnets. It is a synchronous motor that uses direct current (DC) power. This motor type is often called a "brushless DC motor" because in many applications it uses brushes instead of a DC motor (brushed DC motor or commutator motor). The brushless DC motor is essentially a permanent magnet synchronous motor that uses DC power input and uses an inverter to convert it into a three-phase AC power supply with position feedback.


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The brushless DC motor is a motor based on the Hall effect. It consists of a rotor, a stator, a permanent magnet and a drive motor controller. The rotor of a brushless DC motor consists of multiple steel cores and multiple windings that are attached to the rotor shaft. When the rotor turns, the controller detects the rotor position via the current sensor and then controls the direction and strength of the current in the stator winding, thereby achieving a good torque.

Together with an electronic drive controller that controls the brush function and converts the supplied DC power into AC power, the performance of a BLDC motor is comparable to that of a brushed DC motor without the need for brushes, which have a limited service life. BLDC motors are therefore also referred to as EC motors (electronically commutated) to distinguish them from mechanically commutated motors with brushes.



**● Common Motor Type**

Motors are divided into the following types based on their type of power supply (AC or DC) and the method they use to produce rotation. Below, we briefly describe the characteristics and uses of each type.

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A brushed DC motor is a rotating electrical machine that contains a brush device and converts DC electrical energy into mechanical energy (DC motor) or mechanical energy into DC electrical energy (DC generator). Different from brushless DC motors, brush devices are used to introduce or extract DC voltage and DC current. DC brush motor is the basis of all motors. It has the characteristics of fast starting, timely braking, smooth speed regulation in a wide range, and relatively simple control circuit. One disadvantage, however, is that the brushes and commutator wear relatively quickly due to constant contact, requiring frequent replacement and periodic maintenance.

A stepper motor is an electromechanical device that directly converts electrical pulses into mechanical motion. By controlling the sequence, frequency and quantity of electrical pulses applied to the motor coil, the steering, speed and rotation angle of the stepper motor can be controlled. Without the use of a closed-loop feedback control system with position sensing, precise position and speed control can be achieved by using an open-loop control system with simple control and low cost composed of a stepper motor and its matching driver.

An induction motor or asynchronous motor is an AC motor in which the torque-generating current in the rotor is obtained by electromagnetic induction of the magnetic field of the stator windings. Therefore, induction motors do not require an electrical connection to the rotor.

With a synchronous motor, the rotation is synchronized with the frequency of the supply current. These motors are often used to drive rotating trays in microwave ovens; reduction gears in the motor unit can be used to obtain the appropriate rotational speed to heat food. For induction motors, the rotational speed also changes with frequency. But the movements are out of sync. In the past, these motors were often used in electric fans and washing machines.