Comparison of earth permanent magnet motors and asynchronous motors

Previously, we have learned about the structural characteristics and functions of earth permanent magnet motors. It can be seen that this motor has the characteristics of simple structure, high efficiency and energy saving, high performance, large gap, and easy to form a new magnetic circuit. So what are the advantages of earth permanent magnet motors compared with asynchronous motors? And what's the difference between the two? Please read the following introduction below!

1. High efficiency

The high efficiency mentioned here does not only mean that the efficiency at the rated power point is higher than that of ordinary three-phase asynchronous motors, but also refers to its average efficiency in the entire speed range. The excitation magnetic field of the earth permanent magnet motor is provided by the permanent magnet. The rotor does not require excitation current, and the motor efficiency is improved. Compared with the asynchronous motor, electric energy can be saved at any speed point, especially when the speed is low. This advantage more obvious.

2. Starting torque

Rare earth permanent magnet motors generally use asynchronous starting. Since the rotor winding of this motor does not work when it is working normally, when designing the permanent magnet motor, the rotor winding can fully meet the requirements of high starting torque, such as starting Times 1.8 times rose to 2.5 times, or even greater.

3. Impact on power grid operation

Due to the low power factor of the asynchronous motor, the motor absorbs a large amount of reactive current from the power grid, resulting in a large amount of reactive current in the power grid's substation equipment and power generation equipment, which in turn reduces the quality factor of the power grid, thereby aggravating the power grid and The load on the power grid, substation equipment and power generation equipment, and the reactive current in the power grid, substation equipment and power generation equipment all consume part of the electric energy, causing the efficiency of the power grid to become low and affecting the effective use of electric energy. Also due to the low efficiency of asynchronous motors, in order to meet the power requirements, it is necessary to absorb more electric energy from the power grid, which further increases the loss of electrical energy and increases the load on the power grid. There is no induced current excitation in the permanent magnet motor rotor, and the power factor of the motor is high, which improves the quality factor of the power grid and eliminates the need to install a compensator in the power grid. At the same time, due to the high efficiency of the permanent magnet motor, electric energy is also saved.

4. Small size and light weight

Due to the use of high-performance permanent magnet materials to provide the magnetic field, the air gap magnetic field of the permanent magnet motor is larger than that of the induction motor. The size and weight of the permanent magnet motor can be greatly reduced compared with the induction motor. For example, an 11kW asynchronous motor weighs 220kg, while a permanent magnet motor weighs only 92kg, which is equivalent to 45.8% of the weight of an asynchronous motor.

By comparing earth permanent magnet motors and asynchronous motors, it can be seen that based on the above comparative advantages, earth permanent magnet motors are currently more efficient and energy-saving than ordinary three-phase asynchronous motors! I also hope that the content explained in this article will be helpful to everyone, and thus better help you choose products that are more suitable for you.