The Research And Development Of Special Power Supply For Three-phase Four-wire Intelligent Meters

Due to the rapid improvement of microelectronics science, manufacturing technology, magnetic material and other relative technological sciences, as the driving force of electronic products’ control system, the importance of switch power is continuously increasing. The property of switch power, which plays the role the direct power supply unit of the users’ host and control system, is closely related the stability of the equipment. Switch power with excellent performance can give a full play to the functions of electronic products.Switch power supply has been widely used in Digital intelligent meters. With the rapid growth of the total electricity consumption and users’ increasing requirements on electric power quality, the demand for three-phase intelligent meters is soaring.Three-phase intelligent meters based on electronic metrology principles enjoy the advantages of high-precision, multi-parameter measurement, and power energy metering. However, the current power supply technology for electric meters’ special power module still remains using of facies controlled power supply based on power frequency technology. This kind of power supply technology has the weak points of low efficiency, large volume and heavy weight which cause a large occupation of space and waste of device materials. The special power supply for three-phase four-wire intelligent meters are not only suitable for three-phase three-wire and three-phase four-wire system digital intelligent meters, but also can be used as the monitoring device for electric power quality.This thesis firstly reviews the development and prospect for special power supply of intelligent meters, then compares it with the currently used facies-controlled technology, and highlights its advantages of small size, light weight, high efficiency, Large power factor, diversified output forms, and wide voltage range. Secondly, the classification and basic principles for its technology is introduced. Among them, three kinds of important topology structures and four types of working mode of the flyback switch power are specifically introduced. The design of this research adopts the plan of non-continuous-non-ideal power mode. Thirdly, the design plan and procedures of the AC-DC switch power are introduced, the working principle of the switch power supply chip LNK306developed by PI company is highlighted, and the specific switch power supply module for AC-DC flyback three-phase intelligent meter is researched. Through the analysis of the electrical parameters of three-phase intelligent meter’s functional modules and the simulating experiment requirements, the technical indexes of the AC-DC switch power are determined and the protection circuit, filter circuit, high frequency transformer, and control feedback system are designed. Finally, the research endeavors to realize the optimal performance of the three-phase intelligent meter through reasonable wiring, appropriate electronic components and repeated testing of the switch power module. The special power supply module for the intelligent meter not only meets the standards of performance test for intelligent meters including electrostatic discharge test, group pulse test, lightning surge tests, high and low temperature test, humidity test alternating, but also passed the experiment of electromagnetic radiation disturbance. The experiment shows that, the design plan of special power supply for three-phase intelligent meters can be used successfully in three-phase intelligent meters to replace the previous phase control power supply which mainly consists of transformers.The specific switch power supply for three-meter intelligent meters can not only provide enough power for the load to keep it operate smoothly, but also widen its input voltage range. Meanwhile, it can match the space structure of the intelligent meter successfully to improve the working efficiency of the power supply, reduce weight and volume of the meters and cut down the cost, which is of great practicability.