When the motor is rotating, the coil of the relevant winding will pass through the magnetic field in the same direction twice per revolution, which will change the direction of the induced current in the winding. The function of the commutator is to keep the direction of the output current unchanged.
According to this principle, Japan developed the first 20Mvar forcedSelf commutationBridge type ofASVGAfter more than 10 years of development, the capacity of ASVG continues to increase. In 1991 and 1994, Japan and the United States successively developed 80Mvar and 100Mvar ASVGs. In 1995, Tsinghua University and Henan Electric Power Bureau jointly developed the first ASVG in China, with a capacity of 300kvar, opening the way for China to develop ASVG compensation equipment.
brief introduction
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ASVG adopts the multiple technology of bridge circuit to realize multi-leveltechnologyOr PWM technologyhandleTo eliminate lower harmonics and limit higher harmonics to a certain range;Because ASVG does not need energy storage components to exchange reactive power with the system, it actually uses DC capacitors to maintain a stable DC power supply voltage. Compared with the AC capacitors used by SVC, the DC capacitance is relatively small and the cost is low;In addition, when the system voltage is very low, the rated reactive current can still be output, and the SVC compensated reactive current decreases with the decrease of the system voltage.
Figure 1 Commutator
Because of these advantages, ASVG has incomparable advantages in improving system voltage quality and stability, which also shows that ASVG is the development direction of SVC technology in the future.In addition, with the development of power electronics technology, electronic active filters are increasingly improvedActive power filterThere is no resonance with the power system when filtering harmonics, so many power system workers are committed to the research of combining active power filter with ASVG to eliminate the resonance problem caused by parallel passive filters in traditional ASVG equipment.
Classification and application
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There are many kinds of commutators, and the following categories are commonly used.
Small commutator with 3~5 slots
It is mainly used to manufacture general DC motors with low voltage and low current, such as toy motors, small hairdryer motors, camera winding motors, radio recorder motors, etc[1]。
General purpose commutator for 8~16 slots
Generally, the AC and DC motors are below 30000 r/min and have no special working environment requirements, such as juice machine motor, meat grinder motor, egg beater motor, sewing machine motor, car heater motor and wiper motor.
7~30 slot reinforced commutator
It is mainly used for motors with high current and power when working at speeds above 30000 r/min, such asVacuum cleaner motorAir conditioner motor, automobile starter motor, motorcycle starter motor, etc.
Heavy task enhanced commutator
It is mainly used for motors with harsh working environment, high current and high speed, such as electric tools, electric saws, electric drills, etc[2]。
purpose
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According to this principle, Japan developed the first 20Mvar forcedSelf commutationAfter more than 10 years of development, the capacity of ASVG continues to increase. In 1991 and 1994, Japan and the United States successively developed 80Mvar and 100Mvar ASVGs. In 1995, Tsinghua University and Henan Electric Power Bureau jointly developed China's first ASVG, with a capacity of 300kvar, opening the way for China to develop ASVG compensation equipment[3]。
