Descriptor brushless motor synchronous generator excitation system 1 Introduction The excitation system of synchronous generator is of great significance to the reliability of generator and power system, it directly affects the performance reliability and technical requirements of the generator, so the research of excitation system It has become an important lesson in the development of electric motors. Originally, DC generators were used to excite, but as motor capacity continues to increase, DC motor commutation has become a major problem, and carbon brushes and slip rings are required. Carbon brush wear and carbon brush powder contamination coil insulation and others With the development of rotary rectifiers, the brushless excitation method has become more and more perfect, which has promoted the development of brushless motors. At present, industrial developed countries have formed a trend of brushlessness of motors. 2 Development of Synchronous Generator Excitation Mode Since the advent of synchronous generators, DC exciters have been used directly, which are divided into coaxial DC exciters and different shaft DC exciters. The DC exciter is essentially a DC generator. With the development of semiconductor technology, large-capacity motors have evolved into semiconductor excitation. There are two types of excitation systems: self-excitation system and self-excitation system. Commonly used excitation methods are self-excited, some products of the company; phase compound excitation or with voltage regulator. The phase compound excitation has reactive reactance phase shift electromagnetic phase compound excitation and reactance phase shift current phase compound excitation, and the excitation power source is taken from the generator output or the additional winding on the stator winding of the generator. The generator of this principle is called a self-excited constant voltage generator. In general, in order to improve the reliability of the excitation, in order to improve the reliability of the excitation, not only the excitation circuit is taken in the excitation circuit, but also a small permanent magnet is placed at the stator pole shoe of the AC exciter to be excited. According to the installation method of the rectifier, it can be divided into a static device and placed in a special cabinet. The slip ring is required to introduce the direct current into the rotor winding of the generator. In essence, the AC exciter is used instead of the DC exciter, and the rectifier is used to replace the converter. The semiconductor rectifying device is mounted on the shaft of the main generator, fixed by a steel ring and a screw, and rotated coaxially with the main generator, and the alternating current output of the exciting electromechanical armature is rectified into a direct current by a rotary rectifying device, and then sent to the main generator. Excitation of the rotor windings. Therefore, the carbon brush slip ring is eliminated, so it is called brushless excitation. 3 Brushless excitation system design 3.1 AC exciter and rotary rectifier AC exciter and rotary rectifier are the key components to make synchronous motors evolve from brush to brushless. The excitation system of a brushless synchronous generator produced by a factory is described below. The AC exciter is essentially an alternator. Unlike the main generator, the AC exciter is pivot-type. The field winding is fixed on the stator frame, excited by DC, and the rotor is the armature. In order to increase the reaction speed of the excitation system, the frequency of the AC exciter is higher than that of the main generator, and can be as high as several hundred. Therefore, the number of poles of the AC exciter is more than the number of poles of the main generator, but it is better not to be a simple integer multiple. The purpose is to prevent the generator from being symmetrical. The induced current in the rotor field coil flows through the pole tube that is conducting, causing damage to the pole tube. The rotary rectifier is composed of a semiconductor rotating rectifier tube fast-fuse over-voltage protector and the like. The fast-blow fuse is connected in series as an overcurrent or short-circuit protection to each pole branch, and the surge suppressor or varistor is connected in parallel to the rotary rectifier. Both ends of the DC side can absorb transient overvoltage for overvoltage protection. The rotary rectifier and the main generator rotor are also coaxially mounted. The single phase of the rectifier circuit is the same as that of the AC exciter. It can be the input side of the full-bridge rectification or half-bridge rectification type 1 rotary rectifier connected to the AC exciter. At the output end, the DC side of the output end is connected to the rotor field winding of the main generator through the shaft hole at the center of the shaft, and the motor technology 2001 supplies the main generator for excitation. Principle 2. 1 stator outlet end 2 main body stator 3 main engine rotor 4 varistor 5 rotary rectifier 6, magnetic machine rotor 7 exciter stator 8 voltage regulator connection terminal 1 series resistor 1 voltage drop compensation current transformer 1 rectifier transformer, static rectifier rotation Rectifier 3.2 Brushless Synchronous Generator Working Principle When the prime mover drags the main generator to rotate, the AC exciter becomes DC after the rotary rectifier and enters the main generator rotor winding to excite. At this time, it is only necessary to adjust the excitation current of the AC exciter. It is possible to change the excitation current of the main generator to control the output voltage of the main generator, and stabilize the end of the main generator by means of an automatic voltage regulator connected between the output of the main generator and the stator field winding of the AC exciter. Voltage. Brushless synchronous generator wiring principle. Motor Technology 200123.3 Excitation System Fault Analysis and Preventive Measures Rotary rectifier not only works at high speed and high temperature and has high vibration failure rate, because the stator rotates between the rotating magnetic field and the rotor winding caused by the load current. There is no relative motion, but with the sudden change of the amplitude of the stator magnetic field, the transformer potential is induced in the rotor winding; when the motor load is asymmetric, the negative sequence current will flow in the stator winding, and this negative sequence current is generated. The negative sequence magnetic field has twice the synchronous speed relative to the rotor, which will induce the rotating potential in the rotor field winding; the out-of-phase closing often occurs after the synchronous equipment is repaired, due to the wrong connection of the voltage transformer phase, when the generator When the phase angle between the voltage and the system voltage is 60 degrees, it will cause a very high rotor voltage. During the asymmetric short circuit or the erroneous operation of the grid connection, the above-mentioned rotating potential and transformer potential will be generated at the same time. The two instantaneous potentials plus the potential of the AC excitation armature to the rotary rectifier, and then the main generator The original currents in the sub-field windings are superimposed. Note that the rotor field windings are inductive components that act together on the rotating rectifier tube to allow a large forward current to flow through the pole tube, or to withstand the cut-off pole tube. A very high reverse voltage will likely damage the pole tube, which is more pronounced in salient-pole synchronous generators where the air gap is less damped or undamped. If the pole pair number of the AC exciter is an integral multiple of the pole pair of the main generator, when the generator is symmetrical, the induced current in the rotor coil will flow through the pole tube that is conducting, causing damage to the pole tube. Based on the above analysis, appropriate measures must be taken to prevent possible failures from installing a damper winding on the rotor pole face. To improve the dynamic performance; the pole count of the AC exciter and the overcurrent protection of the main generator; there is a large margin when selecting the rated capacity of the rotating pole tube. Therefore, the rotary rectification device is tested in the insulation mode and the strict vibration overspeed and high temperature test, so that it has high reliability. The output side of the rectifier bridge is equipped with a varistor to prevent the rectifier from being damaged when the generator field winding is overvoltage. The pole tube, and the fuse is connected to each pole tube branch as an overcurrent or short circuit protection. If the 10,000 rectifier tube fails, the fast fuse connected in series can ensure that it is automatically disconnected, thereby preventing the excitation head from bending. The design of the plug-in rotor coil Dalian Burton Motor Co., Ltd. 1 16023 Wang Xiaoyu Wu Zuocheng Li Longshi coil end bending is usually done by hand. If the flat copper wire has a large cross section, the end shaping is difficult or even impossible. This paper introduces the structure and calculation process of the head-bending insert rotor winding based on practical experience. This method can reduce the difficulty of manual operation of the rotor coil and solve the key problem of the rotor winding of the medium-wound rotor motor. Descriptor Asynchronous Motor Rotor Coil Winding Rotor Full Coil 1 Introduction For a long time, the rotors of a large number of large-scale hoisting metallurgical wound rotor motors have generally adopted a single-turn flat copper wire-wave winding structure, which is characterized by a coil with a full distance. The flat copper wire is made up of upper and lower half coils, and the two coil sides are respectively composed of upper and lower half coils. The rotor coil is often bent at the end of the tire, and the other end is made straight. After being inserted into the rotor core, it is manually bent and shaped. This kind of process is acceptable for motors with a height of 400 or less in the center. If it is used in a larger model, the copper wire is rough and hard to operate, and the end insulation is easily damaged. For this reason, we do not need to bend the straight end of the traditional line. This method was adopted in the design of a medium-sized wound rotor motor 2560 River 10, and received very good results. 2 coil structure and calculation for the whole distance coil known data rotor external warp, 2 pole number 2 core length 1 rotor slot number coil pitch gauge 3 parent insulation specification and connection method. The mechanical angle of the groove where the two coils are located is adjacent to the distance between the two beveled wires of the two coils. The gap between the two adjacent coils of the two sides of the coil is 3.0, and the length of the edge of the upper layer of the coil is so long that the luck is fortunate. Fortunately, life is desperately contending for a serious overload and overheating; the design capacity of the rectifier bridge and the exciter should consider providing excitation current to the generator even when the rectifier is disconnected. Then the generator can still be operated with light load and no fault expansion. If an appropriate fault monitoring device is fitted in the control system, it is possible to stop and troubleshoot at the most appropriate time. 4 Conclusion Effectively prevent the impact of overvoltage and overcurrent on the pole tube, and install the rotary rectifier and the AC exciter on the outside of the non-drive end. The hole is punched from the center of the rotating shaft, and the direct current rectified by the rotating rectifier is sent through the shaft hole to the main generator rotor field winding by the wire, which adds trouble to the bearing replacement, but can bring convenience to the maintenance and repair of the rotary rectifying device. It makes it easier to change the pole fuse and improves the reliability of operation. Deng Qiu Ling female 1966 student lecturer motor technology 20012 High Gloss Spray Powder Coating Professional High Gloss Spray Powder Coating manufacturer is located in China, including Advanced Powder Coating,Alloy Wheel Powder Coating, etc.
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