Sensorless Brushless DC (BLDC) Motor Control
Outer Reef Technologies
Brushless DC motors or BLDC motors have the popular choice of motors these days and for a strong reason. They weigh less, are more compact, durable, and reliable than brushed DC motors. Moreover, BLDC motors are efficient and high-performing motors that deliver more torque and a wide speed range.
Hence, they are becoming so popular, especially in applications where compact and efficient motors are desired. Of course, BLDC motors need motor control solutions, and this is where sensorless BLDC motor control comes in.
There are also 'sensored 'BLDC motors that use Hall-effect sensors to determine the motor rotor's speed and detect its position with respect to the stator. However, for the purpose of this article, we will be focusing on 'sensorless' BLDC motor control.
Sensorless BLDC motor control is also known as sensorless trapezoidal control due to the trapezoidal voltage waveform of the motors’ phases. It utilizes back EMF to determine the speed and detect the position of the rotor with respect to the stator.
To activate the motor, current/voltage is passed through the windings.
However, brushless DC motors are quite similar to generators or dynamos; thus, they also produce their own voltage when activated. This excess voltage is known as back EMF, and it is proportional to the speed of the BLDC motor.
Sensorless brushless DC motor controllers can use this proportional back EMF to accurately determine the speed and position of the rotor without the need for any sensors.
However, controlling BLDC motors this way is a complex task and typically requires a digital signal processor, a microcontroller, or a dedicated driver IC.
Sensorless, brushless DC motor controllers use a closed-loop system to adjust the speed of the motor. They can also be left as they are in an open loop system.
The closed-loop motor controller in a BLDC motor can perform impressively accurate speed maintenance. However, they also dose performance in small diaphragm pumps or gear pumps since the precise measurement of back EMF can be used to accurately monitor speeds and count revolutions.
A back-EMF motor controller, like in closed-loop control, offers greater control and can also be used in applications where maintaining a fixed speed under a variable load is required. Moreover, sensorless BLDC motors and brushless DC motor controllers are less expensive than sensored BLDC motors.
Brushless DC motor controllers and motors are chosen with application in mind. Sometimes, sensored hall-effect brushless DC motor controllers are the preferred choice, and sometimes, sensorless BLDC motor control is preferred.
Whichever BLDC motors and motor control solutions you choose depend on your own requirements, and whether a particular system is right for you or not depends on your applications.
If you want to learn more about sensorless BLDC motor control, other brushless DC motor controllers, or you want BLDC motors and motor control solutions, please visit our website today.
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A motor controller is a device that acts as an intermediary between motors, batteries, and the robot's microcontroller. A motor controller is essential because a typical microcontroller cannot provide much more than 0.1 Amps of current. The controllers receive voltage from the supply and transfer signals to the motor drives that are connected to the motors. They are effective in starting, stopping, and running motors in a systematic manner. They are used to control the motor's speed, reverse its rotational direction, or increase torque.
There are four different types of Motor Controllers,namely, DC, AC, Stepper, and Servo. The input power of each of these types can be easily modified to get the required output function.
AC: The AC motor controller regulates the input power to motors by adjusting the frequency of the motor's power.
DC: They are electrical devices that can regulate the speed, position or torque of a DC motor.
Servo Motor: Servo Motors are electronic devices that control the position of the servo motor.
Stepper Motor: They control how the stepper motor works by providing current through various phases in the form of pulses to the stepper Motor.
Compact and configurable motor controllers are designed based on the requirements defined by consumers. They are used to serve high-reliability and efficiency applications. The motor solutions are reconfigurable to meet future and current system requirements without costly updates. This allows the reusability of the system and offers flexibility in design.
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