BLDC drivers or controllers are utilized for running or controlling a Brushless Direct Current Motor (BLDC). Many people know them as speed controllers and often call the BLDC motor driver an Electronic Speed Control (ESC). The major function of these controllers is to make the motor run, however, they are constructed differently to suit the needs of different applications.
Open Loop vs. Closed Loop Drivers
The primary function of a Controller/Driver is to regulate the speed of a motor based on a provided signal representing the desired speed. When the motor’s speed is actively monitored, it operates as a Feedback speed controller, also referred to as a closed-loop speed controller. Conversely, when the motor’s speed is not monitored, it functions as an open-loop speed controller.
When it comes to Brushless DC motors with drives, the function of a closed-loop DC motor is considered as more complex than that of a standard open-loop DC motor. However, closed-loop DC motors make up for their intricacies by providing better efficiency in the long run. Although they might be more costly than their simpler counterparts, they have the added advantage of saving energy and being more productive.
The Intricate Workings of a Brushless Driver and Controller
The supply voltage determines the speed at which a DC motor operates. The higher the supply voltage, the greater the speed, and vice versa. But on the surface, the conundrum seems to be how to reduce the voltage without being inefficient. Let’s say, there is a 16 V motor and you want to reduce the speed, but also want to save some power. If you manually reduce the voltage, you will be wasting power and making the process inefficient. The only way this can be done efficiently is by turning the motor off while it is operational. However, this turning off and turning on needs to be done very quickly to have the desired impact. When done right, the motor will operate at a higher power when it is on for a long duration of time, and it will operate at reduced power when it is off most of the time.
The on/off switching of the motor is accomplished by a power Metal-Oxide-Semiconductor Field Effect Transistor(MOSFET). These MOSFETs are extremely good at converting large currents on and off when controlled by a low signal voltage. When we talk about the time it takes for a motor to slow down and speed up, it is directly dependent on the existing torque and friction. A good BLDC motor driver manufacturer will always use the best DC or AC brushless servo motor drive to ensure correct control of current for maximum efficiency. So, it is always advised that you procure these motors from the best manufacturers to ensure the highest cost-savings and productivity.
Types of BLDC Controller Drivers
Below are the different types of BLDC controller drivers that are extensively used in various industries:
Sensorless BLDC Controllers: Unlike sensor-based controllers, sensorless BLDC controllers use algorithms to estimate the rotor position based on the back electromotive force (EMF) of the motor phases. This eliminates the need for additional sensors, reducing cost and complexity.
Sinusoidal BLDC Controllers: Sinusoidal controllers generate sinusoidal currents in the motor phases, resulting in smoother operation and reduced torque ripple. They are commonly used in applications requiring high efficiency and low noise, such as electric vehicles and appliances.
Trapezoidal BLDC Controllers: Trapezoidal controllers generate trapezoidal currents in the motor phases, providing a simpler and more cost-effective control solution compared to sinusoidal controllers. They are often used in applications where cost is a primary concern, such as ceiling fans and computer cooling fans.
Field-Oriented Control (FOC) BLDC Controllers: FOC controllers, also known as vector control, offer precise control of BLDC motors by independently controlling the motor’s magnetic field and torque components. This allows for efficient operation across a wide range of speeds and loads, making them suitable for high-performance applications like industrial automation and robotics.
Integrated BLDC Motor Drivers: Some BLDC controllers come integrated with power stages and other necessary components, simplifying the design and assembly process for applications where space and cost are critical factors.
Sensor-Based BLDC Controllers: These controllers rely on sensors, such as Hall effect sensors, to detect the rotor position and control the motor’s operation accordingly. They are cost-effective but may have limited performance in certain applications.
Different types of sensor drivers are used for different applications. For instance, when it comes to a ceiling fan, trapezoidal BLDC controllers are the ones that work the best.
Final Thoughts
A BLDC motor is a great innovation that has brought new efficiency to the world of motor operations. However, it can be tough for a novice to understand the intricacies of DC or AC brushless servo motor drive functionality. In this article, we have discussed the main reason why motor drivers are needed – to change the speed of a motor as per the requirement of a particular application without wasting power. We have also discussed in brief the various driver types and how/when/where they are used.