Brushless motors

Introduction

Unlike their brushed counterparts, which rely on mechanical brushes to transfer power to the motor's rotor, brushless motors use electronic controllers to achieve similar results. This innovation has led to their widespread adoption in various fields, from robotics to electric drives in machinery.

How do brushless motors work?

In a traditional brushed motor, an electromagnet (the rotor) rotates within a magnetic field created by a stationary magnet (the stator). Brushes and a commutator are used to periodically reverse the direction of the current in the rotor windings, ensuring continuous rotation.

A brushless motor, on the other hand, eliminates the need for brushes. It relies on an external electronic controller to properly direct the current through the stator windings, generating a rotating magnetic field that drives the rotor. The rotor is usually equipped with permanent magnets and rotates as the magnetic field of the stator moves them.

Types of brushless motors

There are two main types of brushless motors: synchronous and asynchronous (also known as induction motors).

1. Synchronous brushless motors: this is the most commonly used type. The rotor speed is synchronized with the frequency of the current applied to the stator. Their high efficiency and precise control make them ideal for dynamic applications. A peak torque that is three times higher than the nominal torque is not uncommon.
2. Asynchronous brushless motors: these motors are typically used in industrial applications where the rotor speed is not necessarily tied to the frequency of the stator current. They are simpler and more robust, but they are generally less efficient than synchronous motors

Benefits of brushless motors

The advantages of brushless motors over their brushed counterparts are numerous:

• Increased efficiency: without the friction of brushes, brushless motors exhibit significantly less energy loss. This translates to better performance, especially in high-speed and high-torque applications.
• Longer lifespan: brushes wear out over time, and the friction they cause leads to heat generation, which can damage the motor. Since brushless motors do not have brushes, they generally have a longer lifespan, reducing maintenance costs and downtime.
• Higher reliability: fewer moving parts mean less wear and tear, making brushless motors more reliable over time. This is especially important in industries where failure can lead to costly downtime.
• Precision control: brushless motors offer better precision in speed and torque control, thanks to the position sensor (encoder) and electronic controller. This makes them ideal for applications such as robotics, where precise movements are crucial.
• Compact and lightweight: brushless motors are typically more compact and lighter compared to brushed motors, making them an excellent choice for mobile devices or machines (AGVs) and power tools.

Applications

Brushless motors can be found in a wide range of applications due to their efficiency and versatility:

• Electric vehicles (AGVs): electric vehicles in the intralogistics market heavily rely on brushless motors. Their high efficiency and ability to deliver consistent torque make them a popular choice for drive systems and lift systems.
• Industrial automation: brushless motors are used in robotics, CNC machines, and conveyor systems. Their precision and durability make them ideal for the high demands of automated industrial environments.

Challenges

Although brushless motors offer numerous advantages, there are also some challenges that need to be addressed:

• Cost: brushless motors and their controllers are usually somewhat more expensive than brushed motors. The cost of the controller and additional electronics can be a barrier for some applications.
• Complexity in control: since brushless motors require electronic controllers for operation, they are more complex to set up and maintain than brushed motors. This adds to the overall complexity of a system, especially in smaller devices.
• Electromagnetic interference (EMI): the electronic controllers used in brushless motors can sometimes cause electromagnetic interference, which can affect other sensitive electronics in certain applications

Conclusion

Brushless motors have transformed industries by offering a more efficient, reliable, and durable alternative to traditional brushed motors. Their precision, durability, and minimal maintenance requirements make them the preferred choice for a wide range of applications, from electric vehicles to industrial automation. Although there are still challenges to be addressed, such as cost and complexity, the benefits of brushless motors are undeniable. As technology continues to evolve, we can expect these motors to play an even more prominent role in the future of electric propulsion, automation, and robotics.