QINGDAO ENNENG MOTOR CO.,LTD.
QINGDAO ENNENG MOTOR CO.,LTD.
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Maintenance Free Direct Drive Interior Permanent Magnet Motor
Analysis of the principle of the technical advantages of permanent magnet motor
The principle of a permanent magnet 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.
Differences Between The Permanent Magnet Motor And Asynchronous Motor:
01. 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.
02. 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.
03. 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.
04. 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.
05. 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.
06. 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.
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.
The motor is excited by rare earth neodymium iron boron permanent magnet materials, and is supplied with a permanent magnet special frequency converter. It has the characteristics of large starting torque, wide speed range, compact structure, small size, lightweight, low noise, high power factor, and high efficiency. It is an ideal power choice for high-efficiency and energy-saving air compressors.
1. The motor can operate normally under the following conditions:
1.1 The ambient temperature does not exceed 40℃;
1.2 Relative humidity ≤90%;
1.3 The altitude does not exceed 1000m.
2. The rated voltage of the motor is 380V, also according to user requirements.
3. The reference work system of the motor: S1.
4. Insulation grade: F grade.
5. Protection level: IP55.
6. Motor structure and installation type: B3, B35.
7. The motor outlet is located on the top of the base, or it can be located on the right or left of the base according to user requirements.
8. Motor service factor: 1.15, 1.2 (or as per technical agreement).
Safety Precautions
1. The lifting ring must be used for lifting during transportation, and the rated load of the spreader must be greater than the weight of the motor, otherwise, it may cause injury to the person and the motor.
2. The motor is forbidden to be used in places with flammable, explosive gas, steam, and corrosive gas.
3. Please install, wire, and debug in strict accordance with the requirements of this manual.
4. Confirm the direction of motor rotation before running.
5. The power supply must be cut off during installation and wiring.
A few small problems that are easily overlooked about the motor
1. Why can't general motors be used in plateau areas?
Altitude has adverse effects on motor temperature rise, motor corona (high voltage motor) and commutation of DC motor. The following three aspects should be noted:
(1) The higher the altitude, the higher the temperature rise of the motor, the lower the output power. However, when the temperature decreases with the increase of altitude enough to compensate for the influence of altitude on the temperature rise, the rated output power of the motor can remain unchanged;
(2) Anti-corona measures should be taken when the high-voltage motor is used in the plateau;
(3) The altitude is not good for the commutation of the DC motor, so pay attention to the selection of carbon brush materials.
2. Why is the motor not suitable for light load operation?
When the motor runs at light load, it will cause:
(1) The power factor of the motor is low;
(2) The motor efficiency is low.
(3) It will cause equipment waste and uneconomical operation.
3. Why can't the motor start in a cold environment?
Excessive use of the motor in a low-temperature environment will cause:
(1) Motor insulation cracks;
(2) Bearing grease freezes;
(3) The solder powder of the wire joint is powdered.
Therefore, the motor should be heated and stored in a cold environment, and the windings and bearings should be checked before running.
4. Why can't a 60Hz motor use a 50Hz power supply?
When the motor is designed, the silicon steel sheet generally works in the saturation region of the magnetization curve. When the power supply voltage is constant, reducing the frequency will increase the magnetic flux and the excitation current, resulting in an increase in the motor current and copper consumption, which will eventually lead to an increase in the temperature rise of the motor. In severe cases, the motor may be burned due to overheating of the coil.
5. Motor soft start
The soft start has a limited energy-saving effect, but it can reduce the impact of start-up on the power grid, and can also achieve smooth start to protect the motor unit. According to the theory of energy conservation, due to the addition of a relatively complex control circuit, soft start not only does not save energy, and also increases energy consumption. But it can reduce the starting current of the circuit and play a protective role.