Compared with induction motors, permanent magnet synchronous motors do not require reactive excitation current, can significantly improve the power factor of the motor, reduce stator current and stator resistance losses, and have no rotor resistance losses during stable operation, which in turn can reduce total losses due to And reduce the fan and the corresponding wind friction loss, so that its efficiency can be increased by 2 to 8 percentage points compared with the induction motor of the same specification. Moreover, the permanent magnet synchronous motor can maintain high efficiency and power factor in the range of 25% to 120% of the rated load, so that the energy-saving effect is more significant during a light load operation.
With the rapid development of power electronics technology and the continuous reduction in the price of related components, more and more variable frequency power supplies and AC motors are used to form AC speed control systems to replace DC motor speed control systems.
In the AC motor, the speed of the permanent magnet synchronous motor maintains a constant relationship with the power supply frequency during stable operation. This inherent characteristic makes it directly used in the open-loop frequency conversion speed control system, especially for multiple motors powered by the same variable frequency power supply. In the transmission system where the motor requires accurate synchronization, this can simplify the control system, and can also achieve brushless operation, and the higher efficiency and power factor can reduce the capacity of the expensive matching variable frequency power supply, so it is used in various speed regulation systems. The application is more and more extensive.
Permanent Magnet DC Motor Overview
A permanent magnet DC motor is a DC motor in which an excitation field is established by permanent magnets. In addition to the drooping mechanical characteristics, linear regulation characteristics, wide speed regulation range, and easy control of ordinary electric excitation DC motors, it also has a small size, high efficiency, less copper consumption, simple structure, and reliable operation. Etc. After being equipped with a speed stabilizer, it can also be applied to occasions that require stable speed under the condition of power supply voltage and load fluctuation. Therefore, it has been widely used in household appliances, office machinery, electric tools, medical equipment, precision machine tools, bicycles, motorcycles, automobiles, and computer peripherals. With the development of high-performance permanent magnet materials such as sensitive iron and boron, permanent magnet DC motors are expanding from micro and low-power motors to small and medium-sized motors.
There are many types of permanent magnet DC motors, and there are various classification methods. Generally, it can be divided into control and transmission according to the purpose. According to the movement mode and structural characteristics, it can be divided into the linear type and rotary type, and the rotary type includes slotted structure and non-slotted structure. Slotted structures include ordinary permanent magnet DC motors and permanent magnet DC torque motors; slotless structures include slotless armature permanent magnet DC motors with iron cores and coreless armature DC motors, printed winding water magnetic DC motors, and Wire-wound disc armature hydromagnetic DC motors.