Structure:

Permanent magnetic synchronous motor is mainly composed of stator, rotor, chassis, front rear cover, bearings, etc. The structure of the stator is basically the same as that of ordinary asynchronous motors, and the main difference between the permanent magnetic synchronous motor and other kinds of motor is on its rotor.

The permanent magnet material with pre-magnetized (magnetic charged) magnetic on the surface or inside the permanent magnet of motor, which provides the necessary air gap magnetic field for the motor. This rotor structure can effectively reduce the motor volume, reduce loss and improve efficiency.

Working principle:

The principle of a permanent magnetic synchronous motor is as follows: In the motor’s stator winding into the three-phase current,after the pass-in current,it will form a rotating magnetic field for the motor’s stator winding. Because the rotor is installed with the permanent magnet, the permanent magnet’s magnetic pole is fixed, according to the principle of magnetic poles of the same phase attracting different repulsion, the rotating magnetic field generated in the stator will drive the rotor to rotate, The rotation speed of the rotor is equal to the speed of the rotating pole produced in the stator.

Due to the use of permanent magnets to provide magnetic fields, the rotor process is mature, reliable, flexible in size, the design capacity can be as small as tens of watts, up to megawatts. At the same time, by increasing or decreasing the number of pairs of rotor permanent magnets, it is easier to change the number of poles of the motor, which makes the speed range of permanent magnet synchronous motors wider. With multi-pole permanent magnet rotors, the rated speed can be as low as single digit, which is difficult to achieve by ordinary asynchronous motors.

Especially in the low-speed high-power application environment, the permanent magnetic synchronous motor can be directly driven by multi-pole design low speed, compared with ordinary motor plus reducer, the advantages of permanent magnetic synchronous motor can be highlighted.

The operation of the permanent magnetic synchronous motor needs to be combined with the special drive system, the motor has good controllability, high control accuracy, continuous adjustable speed, large torque, small start-up current, high overload multiple, high efficiency, high power factor and good energy saving effect. Applications cover almost all areas of aerospace, defense, industry, agriculture and daily life.

Characteristics:

Compared with traditional electric excitation motors, permanent magnet motors, especially rare earth permanent magnet motors, have the advantages of simple structure, reliable operation, small size, lightweight, small loss and high efficiency, and flexible and diverse shape and size of the motor. The application is extremely wide, covering almost all areas of aerospace, national defense, industrial and agricultural production, and daily life.

The permanent magnetic synchronous motor has the following characteristics:

1. Rated efficiency is 2% to 5% higher than normal asynchronous motors;
2. The efficiency rises rapidly with the increase of the load. When the load changes within the range of 25% to 120%, it maintains high efficiency. The high-efficiency operating range is much higher than that of ordinary asynchronous motors. Light-load, variable-load, and full-load all have significant energy-saving effects;
3. Power factors up to 0.95 and above, no reactive compensation required;
4. The power factor is greatly improved. Compared with asynchronous motors, the running current is reduced by more than 10%. Due to the decrease in operating current and system losses, energy-saving effects of about 1% can be achieved.
5. Low-temperature rise, high power density: 20K lower than three-phase asynchronous motor temperature rise, the design temperature rise is the same and can be made into a smaller volume, saving more effective materials;
6. High starting torque and high overload capacity: according to requirements, it can be designed with high starting torque (3-5 times) and high overload capacity;
7. The variable frequency speed control system is used, which is better in dynamic response and better than that of asynchronous motors.
8. The installation dimensions are the same as the asynchronous motors currently widely used, and the design and selection are very convenient.
9. Due to the increase in power factor, the visual power of the power supply system transformer is greatly reduced, which improves the power supply capacity of the transformer, and can also greatly reduce the cost of the system cable (new project);
10. When the new project is built, all the drive systems use permanent magnetic synchronous motors, the project investment is basically the same as the use of asynchronous motors, and the project can continue to obtain energy-saving benefits after the project is put into operation;

In the general industrial sector, the replacement of low-voltage(380/660/1140V) high-efficiency asynchronous motors, system saves 5%to30%energy, and the high-voltage (6kV/10kV) high-efficiency asynchronous motors, the system saves 2% to10%.

The difference between permanent magnet motor and asynchronous motor:

1. Rotor Structure

Asynchronous motor: The rotor consists of an iron core and a winding, mainly squirrel-cage and wire-wound rotors. A squirrel-cage rotor is cast with aluminum bars. The magnetic field of the aluminum bar cutting the stator drives the rotor.

PMSM Motor: The permanent magnets are embedded in the rotor magnetic poles, and are driven to rotate by the rotating magnetic field generated in the stator according to the principle of magnetic poles of the same phase attracting different repulsion.

2. Efficiency

Asynchronous motors: Need to absorb current from the grid excitation, resulting in a certain amount of energy loss, motor reactive current, and low power factor.

PMSM Motor: The magnetic field is provided by permanent magnets, the rotor does not need exciting current, and the motor efficiency is improved. 

3. Volume And Weight

The use of high-performance permanent magnet materials makes the air gap magnetic field of permanent magnet synchronous motors larger than that of asynchronous motors. The size and weight are reduced compared to asynchronous motors. It will be one or two frame sizes lower than asynchronous motors.

4. Motor Starting Current

Asynchronous motor: It is directly started by power frequency electricity, and the starting current is large, which can reach 5 to 7 times the rated current, which has a great impact on the power grid in an instant. The large starting current causes the leakage resistance voltage drop of the stator winding to increase, and the starting torque is small so heavy-duty starting cannot be achieved. Even if the inverter is used, it can only start within the rated output current range.

PMSM Motor: It is driven by a dedicated controller, which lacks the rated output requirements of the reducer. The actual starting current is small, the current is gradually increased according to the load, and the starting torque is large. 

5. Power Factor

Asynchronous motors have a low power factor, they must absorb a large amount of reactive current from the power grid, the large starting current of asynchronous motors will cause a short-term impact on the power grid, and long-term use will cause certain damage to the power grid equipment and transformers. It is necessary to add power compensation units and perform reactive power compensation to ensure the quality of the power grid and increase the cost of equipment use.

There is no induced current in the rotor of the permanent magnet synchronous motor, 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.

6. Maintenance

Asynchronous motor + reducer structure will generate vibration, heat, high failure rate, large lubricant consumption, and high manual maintenance cost; it will cause certain downtime losses.

The three-phase Permanent magnet synchronous motor drives the equipment directly. Because the reducer is eliminated, the motor output speed is low, mechanical noise is low, mechanical vibration is small, and the failure rate is low. The entire drive system is almost maintenance-free.

Application:

Permanent magnet synchronous motors can be combined with frequency converters to form the best open-loop steppless speed control system, which has been widely used for speed control transmission equipment in petrochemical, chemical fiber, textile, machinery, electronics, glass, rubber, packaging, printing, paper making, printing and dyeing, metallurgy and other industries.

Company profile:

ENNENG permanent magnet motors are mainly used in China’s large tire factories, oil fields, large water companies, coal mines, and gold mines this kind of large industrial and factories.

ENNENG provides complete customized drive solutions. Not only familiar with the mechanical equipment and application, but also the motor and its driving system. 

Contact us：

WhatsApp： +86 18562780228

Email:  sales@enpmsm.com

Address: No.18 Xinye Road, High-Tech Zone, Qingdao, Shandong, China.