Permanent magnet synchronous motor working mode

Permanent magnet synchronous motor working mode

1. Excitation mode of DC generator power supply

The generator with this excitation mode has a special DC generator, which is called DC exciter. The exciter is generally coaxial with the generator. The excitation winding of the generator obtains DC current the exciter through the slip ring fixed brush installed on the large shaft. This excitation mode has the advantages of independent excitation current, reliable operation reduction of self consumption. It is the main excitation mode of generator in the past few decades has relatively mature operation experience. The disadvantage is that excitation regulation speed is slow maintenance workload is large, so it is rarely used in units above 10MW.

2. Excitation mode of AC exciter power supply

Some modern large capacity generators use AC exciter to provide excitation current. The AC exciter is also installed on the main shaft of the generator, its output AC current is adjusted

At this time, the excitation mode of the generator belongs to other excitation mode, the static rectifier device is adopted, so it is also called other excitation static excitation, the AC auxiliary exciter provides excitation current. The auxiliary exciter can be a permanent magnet measuring device an alternator with self excitation constant voltage device. In order to improve the speed of excitation regulation, the medium frequency generator of 100-200hz is usually used for AC exciter, while the medium frequency generator of 400-500hz is used for AC auxiliary exciter. The DC excitation winding three-phase AC winding of the generator are wound in the stator slot. The rotor has only teeth slots but no winding, like a gear. Therefore, it has no brush, slip ring other rotating contact parts. It has the advantages of reliable operation, simple structure convenient manufacturing process. The disadvantage is that the noise is large the harmonic component of AC potential is also large.

3. Excitation mode without exciter

In the excitation mode, no special exciter is set, but the excitation power is obtained the generator itself, then supplied to the generator itself after rectification, which is called self excitation static excitation. Self excited static excitation can be divided into self shunt excitation self compound excitation. The self shunt excitation mode obtains the excitation current through the rectifier transformer connected at the generator outlet supplies the generator excitation after rectification. This excitation mode has the advantages of simple structure, less equipment, less investment less maintenance work. In addition to rectifying transforming voltage, the self compound excitation mode is also provided with a high-power current transformer connected in series in the stator circuit of the generator. The function of this kind of transformer is to provide large excitation current to the generator in case of short circuit, so as to make up for the shortage of rectifier transformer output. There are two kinds of excitation sources in this excitation mode, the voltage source obtained by rectifying transformer the current source obtained by series transformer