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• Introduction of brushless DC motors
• Introduction of permanent magnet synchronous motor
• Comparison between permanent magnet synchronous motor and brushless DC motors
Introduction of brushless DC motors
Brushless DC motors usually use tile-type magnets for the rotor poles. After the magnetic circuit design, the air gap flux density of the trapezoidal wave can be obtained. Most of the stator windings use concentrated full-pitch windings, so the induced back electromotive force is also trapezoidal wave. The control of the brushless DC motor requires position information feedback, and it must have a position sensor or adopt a position sensorless estimation technology to form a self-controlled speed regulation system. When controlling, the current of each phase is also controlled as a square wave as much as possible, and the output voltage of the inverter can be controlled in accordance with the PWM method of the brushed DC motor. In essence, the brushless DC motor is also a permanent magnet synchronous motor, and the speed regulation actually belongs to the category of variable voltage and frequency conversion speed regulation.
Introduction of permanent magnet synchronous motor
Generally speaking, the AC permanent magnet synchronous servo motor has a stator three-phase distributed winding and a permanent magnet rotor. In the magnetic circuit structure and winding distribution, it is ensured that the induced electromotive force waveform is sine, and the external stator voltage and current should also be sine waves, generally relying on AC The transformer frequency converter is provided. Permanent magnet synchronous motor control systems often use automatic control, and position feedback information is also required. Advanced control methods such as vector control (field-oriented control) or direct torque control can be used.
Enneng permanent magnet motor uses a motor with a temperature rise lower than 60K, ensuring the compressor has a longer life. The motor is made from rare earth permanent magnet material, which requires a low current due to its high magnetic strength and load torque during motor start-up and operation. The combined use of this motor and permanent magnet rotor achieves soft-start and electricity saving of up to 50%, with the motor’s efficiency up to 10%-15% when compared with an asynchronous motor with the same specifications, thus avoiding a powerful mechanical impact on the compressor under the motor’s full pressure start and ensuring a longer service life.
Comparison between permanent magnet synchronous motor and brushless DC motors
The difference between the two can be considered to be the different design concepts caused by the square wave and sine wave control. Finally, a concept is clarified. The so-called “DC frequency conversion” of brushless DC motors is essentially AC frequency conversion through inverters. In theory, brushless DC motors are similar to AC permanent magnet synchronous servo motors and should be classified as AC permanent magnet synchronous servo motor; but it is customarily classified as a DC motor, because from the point of view of its control and drive power supply and control object, it is also suitable to call it a “brushless DC motor”.
The inverter output voltage can be controlled in accordance with the method of a brushed DC motor. In essence, the brushless DC motor is also a permanent magnet synchronous motor, and the speed regulation actually belongs to the category of variable voltage and frequency conversion speed regulation.
ENNENG, as a China leading permanent magnet motor provider, is devoted to the research and development of various special high & low voltage Low-speed High-torque permanent magnet motors, constant-speed permanent magnet motors, and special direct-drive permanent magnet motors. We adhere to the quality concept of “Precision Performance “, introduce advanced product design and manufacturing processes at home and abroad, and offer products that meet national and international quality standards. ENNENG permanent magnet motors are widely used in China famous companies of different fields including gold mines, coal mines, tire factories, oil wells, and water treatment plants have benefited customers for energy saving as well as for environmental protection.
