What Are The Types Of BLDC Motor

Brushless DC motors have many types and they can be categorized on the basis of rotor type, absence or presence of hall sensors, number of phases, and drive method. Different types of brushless motors have different benefits and therefore can be used in different scenarios. In this blog, we will have a deeper exploration of the types of brushless DC motors and analyze the advantages and disadvantages of each type based on parameters such as torque, speed, and efficiency.

 

Classification according to rotor type

According to the rotor type of brushless DC motor, it can be divided into inrunner brushless DC motor and outrunner brushless DC motor.

 

1. Inrunnner brushless DC motor

Inrunner brushless DC motors have rotating parts (rotors) within an electromagnetic coil (stator) assembly. This type of BLDC motor construction allows heat to be dissipated by conduction because the stator coil is mounted on the motor housing. And it can easily reach peak speeds, which are best suited for applications requiring higher speed characteristics.

 

2. Outrunner brushless DC motor

Outrunner brushless DC motor, as the name suggests, is designed to place the rotor on the outside and the stator inside the rotor. In the outrunner, brushless DC motor, the magnets, which were originally in the center, are made into a piece and affixed to the shell. Outer rotor BLDC motors typically use a greater number of permanent magnet poles on the rotor, which means more torque and smoother operation. However, its main drawback is its slow speed. Therefore, these types of motors are better suited for low-speed, high-torque applications.

 

Classification according to Hall sensors

According to the presence or absence of a hall sensor, it can be divided into sensored brushless DC motors and sensorless brushless DC motors

 

1. Sensored Brushless DC motors

BLDC motors with Hall sensors are motors that rely on sensors to provide rotor position data. These types of brushless motors provide reliable performance at lower speeds. At lower speeds, the sensors provide accurate data for smooth rotation. However, it will have problems with untimely feedback at higher speeds and can also be affected by harsh conditions such as magnetic interference or high temperature environments, which can affect sensor operation and therefore motor operation.

 

2. Sensorless Brushless DC Motor

Sensorless brushless DC motors do not use Hall sensors; instead, its controller relies on the counter electromotive force generated in the stator coils to calculate rotor position. This type of brushless DC motors offer optimal performance at high speeds. You can also use them in high-temperature environments because they do not use sensors. These types of motors are suitable for high-speed, low-cost applications because the motor cannot be accurately controlled when the counter electromotive force is too low or stationary to be read by the controller.

 

Classification according to the Phase 

According to the number of phases, brushless DC motors can be divided into single-phase brushless DC motors, two-phase brushless DC motors, and three-phase brushless DC motors.

 

1. Single phase BLDC motor

The rotor of a single-phase brushless motor consists of a pair of north and south poles. There are advantages and disadvantages to this DC brushless motor design. The advantage is that it can initially reach very high speeds. The disadvantage is that the performance of this single-phase BLDC motor decreases significantly at low speeds, which affects rotational stability and efficiency.

 

2. Two Phase BLDC Motor

Two phase motors run smoother and are more efficient than single phase motors. However, they have relatively simple control systems compared to three-phase motors. While single-phase motors are suitable for simple applications, three-phase motors are superior in high-power applications but require more control. Two phase BLDC motors, on the other hand, combine high efficiency with a relatively simple control system for medium power and complex applications.

 

3. Three Phase BLDC Motor

Three-phase brushless motors use multiple poles on the rotor, up to 12 or more. Opposite poles face each other. More poles provide smoother rotation but at the expense of speed. As a result, these types of brushless motors are unable to achieve high rotational speeds and are suitable for low-speed, high torque applications.

 

Classification according to the Drive method

 

1. Sine Wave Driven Brushless DC Motor:

Sine wave drive for brushless DC motors involves supplying power with a sinusoidal waveform. This method offers smoother and quieter operation compared to other drive types. It reduces torque ripple and minimizes electrical noise. The sinusoidal waveform closely mimics the ideal behavior, resulting in improved efficiency and reduced vibrations. This type of drive is commonly used in applications where precise control and minimal electromagnetic interference are essential, such as in high-performance robotics or electric vehicles.

 

2. Square Wave Driven Brushless DC Motor:

Square wave drive for brushless DC motors involves supplying power with a square waveform. While simpler in control, it tends to produce more torque ripple and higher electrical noise compared to sine wave drive. Square wave drive is suitable for applications where cost-effective and straightforward control is a priority, such as in simple automation systems or low-cost consumer electronics. However, the trade-off is a compromise in terms of smoothness and efficiency when compared to sine wave drive.

 

Different types of brushless DC motors offer different advantages in specific applications. SIT is one of the largest BLDC motor manufacturers in China. We offer good quality BLDC motors to our clients with excellent after-sales service. Just contact us with your needs, and our engineering team will find the best solution for you.