The Advantages And Applications of Permanent Magnet Synchronous Motors

A Permanent Magnet Synchronous Motor is composed of a stator and a rotor. The stator is the same as an asynchronous motor, consisting of a three-phase winding and a stator core. A pre-magnetized permanent magnet is installed on the rotor, and a magnetic field can be established in the surrounding space without additional energy, which simplifies the motor structure and saves energy.

Outstanding advantages of permanent magnet synchronous motors

(1) Since the rotor is made of permanent magnets, the magnetic flux density is high, no excitation current is needed, and excitation loss is eliminated. Compared with the asynchronous motor, it reduces the excitation current of the stator side winding and the copper and iron loss of the rotor side, and greatly reduces the reactive current. Because the stator and rotor magnetic potentials are synchronized, the rotor core has no fundamental wave iron loss, so the efficiency and The power factor is higher than that of Synchronous Motor. Permanent magnet synchronous motors are generally designed with high power factor and efficiency even when running at light loads.

(2) Permanent magnet synchronous motors have harder mechanical characteristics, and can withstand motor torque disturbances caused by load changes. The rotor core of the permanent magnet synchronous motor can be made into a hollow structure to reduce the rotor inertia, and the starting and braking time are much faster than the asynchronous motor. The high torque/inertia ratio makes the permanent magnet synchronous motor more suitable for the fast response condition than the asynchronous motor Run down.

(3) Compared with asynchronous motors, the size of permanent magnet synchronous motors is greatly reduced, and the weight is relatively lighter. The power density of a permanent magnet synchronous motor with the same heat dissipation conditions and insulating materials is more than twice that of a three-phase asynchronous motor.

(4) The structure of the rotor is greatly simplified, which is convenient for maintenance and improves the stability of operation.

Permanent Magnet Synchronous Motor

Typical applications of permanent magnet synchronous motors

1 Electro-hydraulic servo injection molding machine application program

The traditional injection molding machine uses a three-phase Asynchronous Motor with a quantitative pump. During the operation of the injection molding machine, the motor needs to run for a long time. Through the energy-saving transformation of the servo oil pump drive system, the rapid response and large starting torque of the permanent magnet synchronous motor, the permanent magnet synchronous motor can be started to drive the oil pump to generate pressure when the injection molding machine needs to complete the injection molding process. During the process of blanking and clamping , The main motor of the oil pump is in a shutdown state, achieving intermittent zero power consumption, and the energy saving rate can reach up to 85% through comparison.

Under the control of excellent servo motor algorithm, the noise is much lower than ordinary injection molding machine. In an ideal state with a low-noise screw pump, the overall noise of the injection molding machine is less than 70 decibels, achieving quiet operation and improving the working environment.

2 Energy-saving application on iron ore dry separator

The site of use is a mining farm in the northwest with a dusty environment. The equipment uses a total of 125 motors. When the hoisting equipment starts, a larger starting torque is required. During normal operation, the motor runs at a light load state of 30% to 50% of the rated power for a long time. The efficiency of the original three-phase asynchronous motor is It is only about 65%, and the power factor is about 0.4 to 0.6, causing serious energy waste. The use of permanent magnet synchronous motors has obvious energy-saving effects.