Application of Power Electronic Technology in Green Lighting Circuits of Shangqiu Teachers College JIANG Fengchun ZHOU Xin LIU Xiaojuan WANG Zhaoan =1 Department of Physics, Shangqiu Teachers College, Shangqiu 476000, China; 2. School of Electrical Engineering, Xi'an Jiaotong University, Xi'an 710049, Shaanxi, China.
Green lighting is a visual representation of the lighting system that uses energy-saving to protect the environment in the early 1990s. It is an item of lighting and energy saving. Environmental protection, improving lighting quality and developing cross-century projects in the electrical industry. 12. Implementing green lighting not only saves electricity but also reduces environmental pollution and energy consumption. Improve energy efficiency. The way to achieve green lighting is to transform the light source. Is to improve the circuit, this article will focus on the power electronics technology in the green lighting circuit should be.
1 Introduction to traditional lighting circuits Electric light sources can be divided into two categories: thermal radiation sources such as incandescent lamps, etc., and gas discharge sources such as fluorescent neon lights.
Incandescent lamp resistive loads use utility power directly as a power source. Although it will not produce harmonic pollution to the power grid. But it is a heat radiation source, and less than 5 of the electrical energy used to illuminate 95 is converted into heat and wasted. Therefore, the light efficiency is very low. Life is very short. The national 15 incandescent lamps were replaced by high-efficiency energy-saving lamps. The electricity consumption was equivalent to the annual power generation of Gezhouba Hydropower Plant, so it was gradually replaced and eliminated by high-efficiency energy-saving light sources. The new light source is mainly based on gas discharge lamps, and ultra-thin diameter fluorescent lamps are used as high-efficiency energy-saving light sources.
Fluorescent lamps rely on gas molecules in the tube to be continuously broken down. It generates an arc discharge and emits light. A higher voltage is required to start the luminaire to ensure breakdown and to maintain a lower voltage during operation. Therefore, it is not possible to connect the fluorescent lamp directly to the grid. A ballast with a constant flow arc must be added. Traditional ballasts are inductive. The working frequency is 50 days, the bulk is heavy, the power factor is low, and the energy consumption is large; there is severe stroboscopic. Harmful visual noise is large; when the grid voltage is lower than the rated voltage 10. It is often not possible to start normally. And the starter is very easy to damage.
Neon lights are glow discharges. The working principle is slightly different from other lights. Its starting voltage needs about 15 or so. The operating voltage is a few thousand volts, so a transformer is needed to raise the mains voltage. Usually this transformer and ballast are doing it. Known as the neon transformer. The traditional transformer uses an inductive power frequency leakage transformer. It is difficult to control and the noise is heavy.
2 Green lighting circuit With the proposal of environmental protection and energy saving, the traditional lighting circuit has not been able to meet the requirements of the green lighting system. They will gradually be replaced by newer circuits. Electronic ballasts for floodlights and electronic transformers for neon lights are typical of new lighting circuits. The development of these two instruments is maturing. It has been used in actual systems and is described below.
2.1 Electronic ballast structure and working principle High-frequency converter circuit rtll electronic ballast basic structure ffl2 electric ballast principle circuit electronic ballast basic structure 1. It consists of two basic functional units. The high frequency converter circuit operates in a high frequency state. The load resonant circuit implements basic functions such as startup and current limiting. The rectifier circuit changes the power frequency alternating current into a pulsating direct current, and the direct current amount is inverted into a high frequency alternating current through the high frequency inverter circuit. The high frequency AC then supplies power to the fluorescent lamp through a load resonant circuit.
The filter is filtered to remove the high frequency of 1 rush. Reduce input current distortion. Change the power factor. After full bridge rectification. Turn the incoming AC into a DC voltage.
And through two large capacitors to store energy. The switch tube 31.32 and the like constitute a half bridge inverter circuit control circuit, and the control duty ratio reaches the role of adjusting the high frequency inverter. The switching frequency is 50 kHz, the pulsating DC is changed to the high-frequency AC square wave voltage, and filtered by the output filter to obtain a high-frequency voltage of approximately sine wave with a frequency of 50 kHz on the tube. The inverter generates an electric 1 at a resonant frequency at startup to generate a very high voltage across the resonant capacitor. Lights up the light.
2.2 The principle of electronic transformers for neon lights Electronic transformers can be seen as a combination of electronic ballasts and high-frequency transformers. 3 is an input and rectification filtering link of an electronic transformer structure frame using active power factor correction. The 220 AC is mainly converted into a pulsating DC by rectification, and the resulting waveform is subjected to a filtering process by a passive filter.
The circuit is looped to adjust the switching frequency of the inverter circuit, protect the circuit, and the neon fault line fault occurs when the circuit is abnormal. Force the inverter to stop working. It protects the transformer and the load. High-frequency transformers boost the low-voltage high-frequency AC to several thousand volts. Even tens of thousands of volts, power the load. The circuit principle 4 rectification part control and protection circuit is not shown. A detailed analysis of the literature 4 uses a new type of power electronic device as a high-speed switch, compared with a conventional bipolar transistor.
Easy to control. A series of advantages such as low switching loss and good thermal stability.
2.3 Characteristics of Electronic Ballasts and Electronic Transformers Electronic ballasts and electronic transformers are the result of a combination of power electronics and microelectronics. They are the best products that have been found to replace magnetic ballasts and transformers. They are designed with high frequency. The working frequency is 3050 1 out, which eliminates the bulky and large power frequency inductance and greatly reduces the size. It eliminates the power frequency and realizes the warm-up start, which effectively extends the life of the lamp. The power factor is high, which improves the utilization level of the power grid and achieves real energy saving.
Harmonic analysis and solution of 24 electronic ballasts Electronic ballasts contain large harmonic components. This is a big drawback of electronic ballasts. The cause of the harmonic current is mainly caused by the power rectifier filter circuit.
General electronic ballasts use bridge rectification and capacitive filtering. such. Only near the peak of the power supply voltage, the rectifier tube can be turned on to charge the filter capacitor. This causes the input current to be a narrow pulse with a narrow width. It is rich in harmonic components but has a very low fundamental rms value.
The electronic ballast input power factor depends on the product of the displacement factor and the fundamental factor of 1. It is known that if 168 is taken, even if it is. 95 power factor is only about 064. It can be seen that the harmonic current is the main cause of the power factor drop. In addition, harmonics can also cause pollution to the grid and damage the phase balance of the grid. Batch electronic ballasts work simultaneously. It may cause the phenomenon of tripping and sparking mutual interference. Therefore, the harmonic content must be strictly controlled. There are two basic methods for solving the problem, which are designed to correct the compensation device. Decreasing the harmonic component increases the power factor; the other is an active filter that uses the elbow technique, which approximates the displacement factor and the fundamental factor to an output power factor that is very close to 1. The former adds little cost. It is more practical; the latter has an ideal filtering effect. In recent years, western developed countries have begun to use electronic ballasts, but the structure is complex and the cost is high. It is still difficult to adopt China's current technical level and economic level. The application of 25 soft switching technology electronic ballasts and electronic transformers use high frequency design, the switching frequency in the inverter circuit reaches 50 or so. This takes into account the losses in the switching process and electromagnetic interference, which is where soft switching technology comes into play. Soft-switching technology is a newly developed technology in power electronics technology. It improves the switching trajectory of power switching devices and reduces electromagnetic interference elbow. 1. Improve power conversion efficiency. Increase product reliability and reduce volume and weight. Play an important role. Soft switching technology adds small inductance and capacitance to the circuit, introducing resonance before and after the switching process. Thereby zero voltage turn-on or zero current turn-off is achieved. The switching conditions are improved. Reduce switching losses and switching noise 3. Soft switching technology has now been applied to the development of electronic ballasts.
26 Developments and trends at home and abroad The electronic ballasts in the United States and Japan started earlier. The scope and scale of application are also the largest. Since 1991, the United States has gradually stopped using energy-consuming magnetic ballasts since 1991, replacing high-performance electronic ballasts with high performance. In Japan, the proportion of electronic ballasts used in lighting fixtures has been considerable. After more than ten years of development. Power factor harmonic content in foreign electronic ballasts The main problems of preheating abnormal protection of the lamp against the peak voltage and working life of the power grid have been solved. And the development of small integrated multi-functional and diverse program control system.
The development of electronic ballasts in China began in 1986. It was not until 1990 that the product took shape. There are very few manufacturers that currently form mass production. Only electronic ballasts produced by manufacturers with less than a tenth of the total are reliable, reaching the ministerial industry standard or the 10 standard. Some have also entered the international market. However, in general, the quality of China's electronic ballasts is still far from the international advanced level. The main performance indicators are poor and the reliability is poor.
The future development direction of electronic ballasts is generalization, intelligent realization of remote control light control and voice control, integration and modularization.
3 Conclusion From the above analysis can be seen, the development of lighting circuits. Thanks to the application of power electronics technology. With the rapid development of power electronics technology. The cost of various electronic components is reduced, and the function of the lighting circuit will be more perfect. Green lighting will soon become a reality.
1 Lantian. Green lighting is an important measure to improve the ecological environment. China Energy, 200032 2 Liu Yuexing. Green lighting overview. China Lighting Appliances, 199712223.
3 Wang Zhaoan, Huang Jun. Power Electronics Technology 4th Edition Elbow. Beijing Machinery Industry Press. 2000.
4 Wenfeng, Zhao Jianping. A new type of neon electronic transformer design. Journal of Qufu Normal University, 200025863.
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