Working mode of permanent magnet synchronous motor

1. Excitation mode of DC generator power supply

This type of excitation generator has a special DC generator, the special DC generator is called DC exciter, the exciter is generally coaxial with the generator, the generator's excitation winding through the slip ring installed on the large shaft fixed brush the exciter to obtain DC current. This excitation mode has the advantages of independent excitation current, reliable operation reducing self-use electricity consumption, etc., is the main excitation mode of generators in the past decades, has more mature operation experience. The disadvantage is that the excitation regulation speed is slow the maintenance workload is large, so it is rarely used in units above 10MW.

2. Excitation mode of AC exciter power supply

Some modern high-capacity generators use AC exciter to provide excitation current. Ac exciter is also installed on the main shaft of the generator, its output alternating current flows through the whole

At this time, the excitation mode of the generator belongs to the other excitation mode, because of the static rectifier device, it is also called the other excitation static excitation, the AC secondary exciter provides excitation current. The AC secondary exciter can be a permanent magnet measuring device an alternator with a self-excited constant voltage device. In order to improve the excitation regulation speed, the AC exciter usually uses a 100-200Hz intermediate frequency generator, the AC secondary exciter uses a 400-500Hz intermediate frequency generator. The DC excitation winding three-phase AC winding of this generator are wound in the stator slot, the rotor only teeth slots without winding, like a gear, therefore, it has no brush, slip ring other rotating contact parts, with reliable work, simple structure, convenient manufacturing process other advantages. The disadvantage is that the noise is larger, the harmonic component of the AC potential is also larger.

3, no exciter excitation mode

No special exciter is set up in the excitation mode, the excitation power is obtained the generator itself, then the generator itself is excited after rectification, which is called self-excited static excitation. Self-excited static excitation can be divided into two ways: self-shunt excitation self-compound excitation. Self-shunt excitation mode it obtains excitation current through the rectifier transformer connected to the generator outlet, supplies the generator excitation after rectification. This excitation mode has the advantages of simple junction, less equipment, less investment less maintenance work. In addition to the rectifier transformer, the self-compound excitation mode is equipped with a high-power current transformer in series in the generator stator loop. The function of the transformer is to provide a larger excitation current to the generator when a short circuit occurs, so as to make up for the deficiency of the output of the rectifier transformer. This exciting mode has two exciting power sources, the voltage power source obtained by the rectifier transformer the current source obtained by the series transformer