Classification of brushless DC motors
Brushless DC motors not only have a series of advantages such as simple structure, reliable operation, and convenient maintenance of AC motors, but also have the characteristics of high operating efficiency, no excitation loss, and good speed regulation performance of DC motors. Therefore, they are increasingly popular in various fields of the national economy today, such as medical devices, instrumentation, chemical engineering, light textile, and household appliances.
The applications of brushless DC motors are mainly divided into the following categories:
1. Constant speed drive machinery
In general industrial applications, where speed regulation is not required, three-phase or single-phase AC asynchronous and synchronous motors are often used. With the progress of power electronics technology, in order to reduce volume, save materials, improve efficiency, and reduce losses, more and more motors are being replaced by brushless DC motors, such as automatic doors, elevators, water pumps, and fans, when the power is not greater than 10kW and running continuously. In high-power applications, due to the high primary cost and investment, in addition to permanent magnet motors, it is also necessary to add drivers and other equipment, so currently brushless motors are rarely used.
2. Adjustable speed drive machinery
Speed control systems that require arbitrary setting and adjustment of speed, but do not require high control accuracy. This type of system is divided into two types: one is an open loop speed regulation system, and the other is a closed loop speed regulation system (at this time, the speed feedback device mostly uses low resolution pulse encoders or AC/DC speed measurement, etc.). There are three main types of motors commonly used: DC brushless motors, asynchronous motors, and DC brushless motors. This is widely used in packaging machinery, food machinery, printing machinery, material conveying machinery, textile machinery, and transportation vehicles.
At the beginning, DC motors were widely used in the application field of adjustable speed systems. With the development of AC speed regulation technology, especially power electronics technology and controllers, AC frequency conversion technology has been widely used, and frequency converters and AC motors have penetrated into the vast majority of the original DC speed regulation system applications. In recent years, due to the increasingly prominent advantages of brushless DC motors such as small size, light weight, and high efficiency and energy conservation, small and medium-sized power AC frequency conversion systems are gradually being replaced by brushless DC speed control systems, especially in areas where the original frequency conversion systems were widely used, such as textile machinery and printing machinery. In some applications directly powered by batteries, DC brushless motors are now more commonly used.
3. Precision control
Servo motors have always played a very important role in high-precision control in the field of industrial automation. The control performance requirements for servo motors vary depending on the application situation. In practical applications, servo motors have various control forms: torque control/current control, speed control, and position control. Due to its excellent control performance, brushless DC motors have gradually replaced DC motors and stepper motors in high-speed and high-precision positioning systems, becoming one of the motors of choice for modern servo systems. Currently, brushless DC motor servo systems are widely used for precision control in scanners, cameras, CD drives, medical diagnostic CT, computer hard disk drives, and CNC lathe drives.
4. Other applications
Household appliances such as automatic washing machines, CD players, etc; Military applications such as submarines and warships; There are also start-up of large synchronous motors.