Design of the hottest electronic neon lamp transfo

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The design of electronic neon lamp transformer

1 introduction

with the development of socialist market economy and the needs of spiritual and material civilization construction, the requirements for urban brightness and beautification are higher and higher. As a traditional means of commodity publicity, neon lights have become one of the main scenic spots of urban and rural lighting projects, and the requirements for their quantity and quality have also been correspondingly improved. The transformer supporting neon lights will also become an indispensable element in urban lighting projects and commodity publicity

the first commercial neon lamp in the world appeared in 1910, and the first neon lamp made in China was in 1927. The production technology of inductive neon lamp transformer supporting neon lamps is still in use today. It has many problems, such as high power consumption (power factor is 0.5 ~ 0.6), heavy weight (8 ~ 1kg), large volume, short service life (because of temperature rise), etc. In particular, the problem of high power consumption is particularly serious. It is understood that the annual demand for inductive neon light transformers in Beijing is 1million. Assuming that each transformer is used for an average of 4 hours per day, the annual power consumption is 1.9 million kwh. Compared with the electronic neon transformer with a power factor of 0.9, the power of a medium-sized power station is wasted, and the wasted power is more serious in the country

considering energy conservation, the upgrading of neon lamp transformer has become an urgent problem to be solved at present. Electronic neon lamp transformer is an ideal product for upgrading. Compared with inductive products, it has the advantages of energy saving (power factor is 0.9 ~ close to 1), weight is about 4 times lighter, volume is reduced by 1/3, long service life, full-automatic protection function of open circuit and short circuit of lamp tube, and brightness does not change with the change of input mains voltage

however, many kinds of electronic neon lamp transformers on the market are not ideal. For example, it can only be used indoors (because it is an open structure), the brightness is not high enough, the reliability and cost of the automatic protection system are poor, and the technical economy has become one of the main obstacles to its popularization and application

due to the lack of published technical monographs, comrade caizuquan's "neon lamp principle and manufacturing technology" is the first technical work in China that comprehensively discusses the principle and manufacturing of neon lamp and its transformer. It has played a great role in improving the driving effect of technology trade in China's neon lamp industry. But how to design the electronic neon lamp transformer is less discussed. The papers and special issues published in other newspapers and periodicals only have specific circuits and do not involve the problem of how to design. This paper discusses how to design

2 load characteristics of electronic neon lamp transformer

cold cathode neon lamp produces glow discharge and emits light after the low gas pressure inert gas in the lamp tube is broken down by high voltage. When the neon lamp enters the normal glow discharge state, the voltage drop of the lamp tube maintaining the constant discharge current is not very high, which is usually a constant value. For a 10m long neon lamp, the general starting voltage is about 15kV, the working voltage of the lamp tube is about 8 ~ 10kV, and the working current is about 20 ~ 60mA. The power supply that adapts to the working characteristics of neon lights is the inductive neon light transformer commonly known as magnetic leakage transformer. It is essentially a high leakage reactance transformer. Use a vernier caliper to measure the diameter of the fracture, and its volt ampere characteristics are shown in Figure 1

curve a in the figure is the load characteristic curve of the transformer, and the intersection of the curve and the horizontal axis is the short-circuit current of the transformer, which is greater than the working current of the lamp. The intersection of the curve and the vertical axis is the no-load voltage at the output end of the transformer, which is higher than the starting voltage of the lamp. Curve B is the volt ampere characteristic curve of neon lamp with cold cathode glow discharge. The intersection P of curves a and B is the stable working point of neon lights

figure 1

electronic neon lamp transformer, like inductive products, is also a high leakage reactance transformer, and its load characteristics are also nonlinear. However, its starting voltage, working voltage and working current are lower than those of inductive type, which is determined by its high working frequency

3 design of electronic neon lamp transformer

electronic neon lamp transformer is essentially a switching power supply, that is, 220V mains power is converted into a high-frequency voltage higher than 20kHz through ac/dc/ac/and input to the high-frequency step-up transformer to start the neon lamp. If you do not consider the economy of the product, it is easier to design and the performance can be done very well. However, the products designed in this way will cost a lot and cannot enter the market. This is also the fundamental reason for the slow improvement of electronic neon lights in technology. Therefore, it is very difficult to design under the conditions of low cost and good performance

3.1 transformer centered design

when designing switching power supply, it is generally designed centered on the circuit, and then the switching transformer is required to meet the performance of the circuit. If this design method is adopted, it is difficult to meet the requirements of electronic neon lamp transformer. Therefore, the design must be centered on the transformer, because only the transformer with high leakage reactance can meet the working characteristics of neon lights, and the circuit is in an auxiliary position to meet the requirements of transformer leakage reactance

3.2 optimal leakage inductance design

when designing the switching power supply, it is hoped that the leakage inductance of the switching transformer will not be too large, so as to prevent the switch tube from being damaged by the peak voltage generated by the leakage inductance. However, it can be seen from the load characteristics of electronic neon lamp transformer that an optimal leakage inductance is required under the optimal lamp working current. This leakage inductance is much larger than that of general switching power transformer, because its general lead screw has thousands of turns, and the leakage inductance is proportional to the square of the number of turns

effectively promote the development of the material industry with broad market prospects, low resource consumption, large driving coefficient, many employment opportunities and good comprehensive benefits

when designing electronic neon lamp transformers, the magnetic leakage structure of the windings should be determined first, and then the appropriate magnetic core should be selected according to the power, but it should be appropriately increased (the calculation method is the same as that of switching transformers). Then determine the leakage reactance according to the no-load voltage output by the transformer, the working voltage of the lamp and the switching frequency, and finally calculate the leakage inductance (the calculated leakage inductance value is inaccurate and needs to be corrected through experiments). At the same time, determine the circuit as needed

3.3 circuit selection principle

various single ended and double ended switching power supply types without power frequency transformer can be used as the switching power supply of electronic neon lamp transformer. But it must meet the requirements of low cost and good performance. Therefore, in the design, on the premise of meeting the performance requirements, the circuit must be simple and there must be fewer components

considering the working characteristics of electronic neon lamp transformer (such as high peak voltage), it is generally suitable to use half bridge type

3.4 the safe working area of the switch tube and the insulation of the transformer's high-voltage winding

because of the large leakage inductance and its peak voltage of 1000V, the selection of the blocking voltage of the switch tube and the calculation of the buffer circuit must be considered to make the switch tube work in the safe area

the no-load voltage at the output end of electronic neon lamp transformer is as high as more than ten kV. Therefore, we must pay attention to the insulation design between high and low voltage windings and between windings and ground. The ideal insulation structure is to use epoxy resin to pour the winding, and the pouring thickness should not be less than 3mm

the above two design links are the guarantee to improve the reliability of products, and they are also the focus of the product quality assurance system

3.5 ways to improve brightness

low brightness is the problem of most electronic neon lamp transformers, and it is also one of the obstacles to promote their use. Two aspects can be considered for design

(1) increase the output power. The output power of the inductive neon lamp transformer is about 250W, and the electronic neon lamp transformer can be increased to 130 ~ 180W due to its high frequency (the power with low frequency can be larger, and the power with high frequency can be smaller)

(2) increase the switching frequency. The switching frequency can be designed as 20 ~ 80kHz

after improving from the above two aspects, it is estimated that the brightness can be increased from 800 ~ 1100 lumens to 1500 lumens, or even higher

4 Conclusion

this paper proposes to design the electronic neon lamp transformer from five aspects, including experience, lessons and design strategies, which are not necessarily correct. Please criticize and correct. In the future, there are still many works to be studied in depth, such as the principle that increasing frequency can improve brightness, using computer simulation to improve the design level in theory, how to increase the length of electronic neon lamp transformer ignition tube (currently 12m in China), how to further promote the use, etc

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