The brushless DC motor was originally born in this context.
In order to overcome the drawbacks of mechanical commutation, brushless DC motors that replace mechanical commutation with electronic commutation have emerged.
DC motors have been widely used in the field of motion control due to their excellent torque characteristics. However, ordinary DC motors require mechanical commutation and brushes, resulting in poor reliability and frequent maintenance; Electromagnetic interference and high noise are generated during commutation, which affects the further application of DC motors in control systems. In 1955, D. Harrison and others in the United States first applied for a patent to replace mechanical brushes with transistor commutation circuits, marking the birth of modern brushless DC motors. The brushless DC motor with electronic commutation truly entered the practical stage with the introduction of the classic MAC brushless DC motor and its driver in 1978. Afterwards, in-depth research was conducted on brushless DC motors internationally, resulting in the development of square wave brushless motors and sine wave DC brushless motors.
After more than 20 years of development, with the advancement of permanent magnet new materials, microelectronics technology, automatic control technology, and power electronics technology, especially high-power switching devices, brushless DC motors have made significant progress. Nowadays, brushless DC motors no longer specifically refer to DC motors with electronic commutation, but generally refer to electronic commutation motors with external characteristics of brushed DC motors. Brushless DC motors not only maintain the good dynamic and static speed regulation characteristics of traditional DC motors, but also have a simple structure, reliable operation, and easy control. Its application has rapidly expanded from the initial military industry to aerospace, medical, information, home appliances, and industrial automation fields.
Structurally, unlike brushed DC motors, brushless DC motors use the stator winding as the armature and the excitation winding is replaced by permanent magnet materials. According to the different waveforms of the current flowing into the armature winding, brushless DC motors can be divided into square wave DC motors (BLDCMs) and sine wave DC motors (PMSMs). BLDCMs replace the mechanical commutation of the original DC motor with electronic commutation and use permanent magnet materials as rotors, eliminating the need for electric brushes; PMSM replaces the excitation winding in the synchronous motor rotor with permanent magnet materials, eliminating the need for excitation winding, slip ring, and electric brush. Under the same conditions, it is relatively easy for the driving circuit to obtain square waves and the control is simple, so the application of BLDCM is much more extensive than PMSM.
A brushless DC motor is generally composed of three parts: an electronic commutation circuit, a rotor position detection circuit, and the motor body. The electronic commutation circuit is generally composed of a control part and a drive part, while the detection of the rotor position is generally completed by a position sensor. During operation, the controller triggers various power transistors in the drive circuit in an orderly manner based on the position of the motor rotor measured by the position sensor, and performs orderly commutation to drive the DC motor.
