The starting torque and overload capacity of the rare earth permanent magnet synchronous motor are one power level higher than that of the three-phase asynchronous motor, and the ratio of the maximum starting torque to the rated torque can reach 3.6 times, while the general asynchronous motor is only 1.6 times.
The characteristics of
1. Rare earth permanent magnet synchronous motor has no slip, and no fundamental wave iron and copper consumption on the rotor.
2. Rare earth permanent magnet synchronous motor is bilateral excitation, and mainly rotor permanent magnet excitation, its power factor can reach or close to 1.0.
3. The improvement of power factor, on the one hand, saves reactive power, on the other hand, also makes the stator current drop, the stator copper consumption is reduced, the efficiency is improved. The polar arc coefficient of rare earth permanent magnet synchronous motor is generally larger than that of asynchronous motor. When the power supply voltage and stator structure are constant, the average magnetic induction intensity of rare earth permanent magnet synchronous motor is smaller than that of asynchronous motor, and the iron loss is smaller.
4. As for the stray loss of rare earth permanent magnet synchronous motor, it is generally believed that the stray loss is increased due to the non-sinusoidal magnetic field of its permanent magnet, but on the other hand, the large air gap of rare earth permanent magnet motor reduces the stray loss.
5. The constant loss of rare earth permanent magnet synchronous motor (iron loss +) mechanical consumption is small, variable loss (stator copper loss) change than asynchronous motor variable loss (stator copper loss + rotor copper loss) changes slowly, make the efficiency characteristic has the characteristic of Gao Erping, rare earth permanent magnet motor during light load fairly wide area as the highest efficiency. This area coincides with the area where the average load of the oil field shearer is located, if used on the oil field shearer. For this reason, the rated efficiency of rare earth permanent magnet synchronous motors is 4%-7% higher than that of asynchronous motors, but the average efficiency of rare earth permanent magnet synchronous motors is 12% higher than that of three-phase asynchronous motors over the entire load range.
6. Using rare earth permanent magnet synchronous motor, the reactive power saving rate can reach 85%. The power saving rate of active power can reach 23%-25%, and the power saving effect is very obvious.
Advantages
1. Rare earth permanent magnet synchronous motor needs no current excitation, no brush and shoulder ring, so it has simple structure, convenient operation and high reliability.
2. Due to the characteristics of the above structure, there is no excitation loss on the rotor of the rare earth permanent magnet synchronous motor, no friction loss and contact electrical loss between the brush and the slip ring. Therefore, the efficiency of a rare earth permanent magnet synchronous motor is higher than that of an electromagnetic synchronous motor, and its power factor can be designed around 1.0.
3. The rotor structure of rare earth permanent magnet synchronous motor is diverse and flexible, and different rotor structures often bring their own performance characteristics, so the rare earth permanent magnet synchronous motor can choose different rotor structure forms according to the use needs.
4. Rare earth permanent magnet synchronous motor can have smaller volume and weight than electromagnetic synchronous motor within a certain power range.
Application
AC permanent magnet synchronous motor (PMSM) has attracted more and more attention because of its small size, light weight, high efficiency and energy saving, etc. Its control technology is becoming more and more mature, and the controller has been productized. The variable frequency speed regulation of medium and small power asynchronous motor is gradually replaced by the speed regulation system of permanent magnet synchronous motor. Elevator drives are a classic example. The elevator drive system has certain requirements on the acceleration, speed stabilization, braking and positioning of the motor. Early people used DC motor speed control system, its shortcomings are self-evident.
In the 1970s, the frequency conversion technology developed and the frequency conversion speed regulation drive of asynchronous motor quickly replaced the DC speed regulation system in the elevator industry. In recent years, the latest drive technology in the elevator industry is the speed control system of permanent magnet synchronous motor, which is small in size, energy saving, good control performance, and easy to be made into a low speed direct drive, eliminating gear reduction device; Its low noise, flat precision and comfort are better than the previous drive system, and it is suitable for use in the machine room less elevator. The drive system of permanent magnet synchronous motor is soon favored by the elevator companies, and the series products of special frequency converter supporting it have been listed in many brands. It can be predicted that in the case of speed-regulating drive, permanent magnet synchronous motor will be the world.
