BLDC motor controllers vary depending on the method they use to determine the rotor position. Measurements can be made using position sensors or sensorless methods.
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Among sensors, there are various options, including:
– Hall sensors
– Rotary encoders
– Variable resistance sensors
– Resolvers
– Optical sensors
Sensorless controlling bldc motors work without a sensor; they determine the rotor position by estimating the back electromotive force (back EMF). This voltage is generated in the stator windings by the rotating rotor. By measuring the back EMF, the rotor position can be determined: the closer the rotor magnet, the higher the back EMF.
Applications of BLDC Motors and Controllers
Unlike their brushed counterparts, BLDC motors use electronic commutation instead of mechanical. This is their key advantage as it improves current switching, increases torque, and leads to efficient speed control over a wide range and enhances performance.
Mechanical parts of brushed DC motors wear out, while their brushless counterparts do not have this issue. Thus, BLDC motors last longer and require less maintenance. Additionally, since there are no brushes, they have minimal power losses and cause fewer electromagnetic interferences (EMI).
These features make BLDC motors ideal for systems and devices with long service lives, such as:
– Industrial applications
– Electric vehicles
– Unmanned aerial systems
– Computer equipment
– Consumer electronics
– Robotics
Due to their compact size, BLDC motors can power small yet high-performance devices, further expanding their application area.
While inexpensive low-power systems may not require a feedback-controlled programmable BLDC motor controller, opting for a simple controller with a BDC motor could make more sense. However, if you prioritize efficiency and durability over simplicity and cost-effectiveness, a brushless DC motor may be suitable for your project.
Designing a BLDC Motor Controller
Creating a BLDC motor controller requires in-depth knowledge in both electronic design and embedded software development. With proper setup, the control unit can ensure smooth operation of your motor and extend its service life. In the next section of this article, we will provide more detailed information on how to design a brushless DC motor controller.
BLDC Motor Controller Scheme
A typical BLDC motor controller has a half-bridge or full-bridge scheme. Unlike an H-bridge, this scheme has only two switches—one upper arm transistor and one lower arm transistor.
Most brushless motors use two- or three-phase power systems. Thus, on the schematic of the BLDC motor controller, it will appear as two or three half-bridges (depending on the number of phases) with a pair of switches each.
Let’s take a closer look at a three-phase BLDC motor controller with Hall sensors to understand the basic principles of its circuitry.
