Compared with ordinary three-phase asynchronous motors, permanent magnet synchronous motors have the advantages of high starting torque, shorter starting time and high overload capacity, which can reduce the installed capacity of the driving motor of the equipment according to the actual shaft power, saving energy and reducing the investment in fixed assets at the same time.
Comparatively speaking, permanent magnet synchronous motor control is convenient, the speed is only determined by the frequency, the operation is smooth and reliable, and does not change with the load and voltage fluctuations. In view of the characteristics of the permanent magnet synchronous motor speed strictly synchronous, determines the motor dynamic response performance is good, more suitable for frequency control.
The advantage of permanent magnet synchronous motor lies more in its two low and two high, that is, low loss and temperature rise, high power factor and efficiency, which is exactly what people are seeking for the performance of the motor, which also determines the market application status of permanent magnet motor.
Permanent magnet motors have low losses and low temperature rise
As the magnetic field of the permanent magnet synchronous motor is generated by the permanent magnets, thus avoiding the excitation current to generate the magnetic field through the excitation loss, that is, we say the copper loss; motor operation rotor operation without current, significantly reducing the temperature rise of the motor, according to incomplete statistics, in the same load conditions, the temperature rise will be lower by about 20K.
High power factor and high efficiency of permanent magnet synchronous motors
Compared with asynchronous motors, permanent magnet synchronous motors have much higher efficiency values at light loads, with a wide range of high efficiency operation, and an efficiency of more than 90% within the range of 25% to 120% of the load rate. The rated efficiency of permanent magnet synchronous motors can reach the requirements of the current national standard for class 1 energy efficiency, which is one of the biggest advantages in energy saving compared with asynchronous motors.
In actual operation, motors rarely run at full power when driving loads. The reason is: on the one hand, the designers in the motor selection, generally based on the load limit working conditions to determine the motor power, and the opportunity of the limit working conditions is very rare, at the same time, in order to prevent the motor burned in the abnormal working conditions, the design will also be further to the motor power to leave a margin; on the other hand, the motor manufacturer in order to ensure the reliability of the motor, usually in the user’s requirements of the power basis, and further leave a certain power margin. On the other hand, in order to ensure the reliability of the motor, the motor manufacturer will usually leave a certain power margin on the basis of the power required by the user. This leads to the actual operation of the motor, most of the work in the rated power below 70%, especially driving fans or pumps loads, the motor is usually working in the light load area. For asynchronous motor, its light load efficiency is very low, while the permanent magnet synchronous motor in the light load area, can still maintain a high efficiency.
Permanent magnet synchronous motor power factor is high, and has nothing to do with the number of motor stages, the motor full load power factor is close to 1, so compared with asynchronous motor, its motor current is smaller, and accordingly the stator copper consumption of the motor is smaller, and the efficiency is also higher. The power factor of asynchronous motor is getting lower and lower as the number of motor stages increases. Moreover, because of the high power factor of the permanent magnet synchronous motor, the power supply (transformer) capacity of the motor can theoretically be reduced, and at the same time the specifications of the supporting switchgear and cables can be reduced.
Post time: May-24-2024
