Application of Electronic Technology in Green Lighting Circuit

The concept of green lighting came from the early 1990s. It was an action plan to increase lighting electricity efficiency, save electricity, and reduce air pollution. It gradually became an international energy saving, environmental protection, and improved lighting quality. A cross-century project to develop the electronics industry. Subsequently, China launched the "China Green Lighting Project," which promotes efficient lighting fixtures and gradually replaces traditional low-efficiency lighting sources. The implementation of green lighting can not only save electricity, but also reduce the degree of environmental pollution and improve the efficiency of energy use. There are two options for achieving green lighting: transforming the light source and improving the circuit, among which the research on improving the light source is relatively common.

First, the high-frequency AC electronic ballast technology and application of high-frequency AC electronic ballast circuit consists of two basic functional units: high-frequency converter circuit to ensure high-frequency work, and the load resonant circuit can start and limit Basic functions such as streaming. The rectifier circuit converts the industrial frequency AC into pulsed DC, and inverts the DC amount into high-frequency AC through a high-frequency inverter circuit, and then the high-frequency AC supplies power to the fluorescent lamp through the load resonance circuit. In addition to the high-frequency AC power output from the inverter circuit, the lamp circuit network needs to deliver the high-frequency AC power output from the inverter circuit to the lamp tube to complete the electrical-to-light efficient conversion, including such things as filament preheating, lamp current detection feedback, and assistance of the entire electronic ballast system. For power and other functions. The power transformer T is initially connected to the inverter circuit, and the lamp current required for the normal light emission of the lamp is directly transmitted to the lamp through the capacitor, and the secondary winding provides the lamp tube with preheating and maintaining the working filament current. The current transformer TA performs the detection and sensing of the lamp current, and the signal concerning the working condition of the lamp is sent to the control circuit at any time through the change of the lamp current.

The control circuit can determine the light intensity of the lamp according to the size of the lamp current (even including the lamp disconnection and disconnection), and then send a corresponding control signal to the inverter circuit. The main function of the inverter circuit is to convert the high-voltage direct current output by the power factor correction circuit into a high-frequency alternating current for use in a fluorescent lamp, realize a zero-voltage switch (ZVS), and perform chopping on the high-voltage direct current. The commercial power supply is converted to a DC power supply through an RFI filter, a full-wave rectification, and a passive (or active) power factor corrector (PPFC or APFC). Through a DC/AC converter, a high-frequency AC power source of 20K-100KHZ is output, which is applied to the LC series resonant circuit heating filament connected to the lamp. At the same time, a resonant high voltage is generated on the capacitor, which is added to both ends of the lamp to make the lamp “discharge” into a “conducting” state and then enter the luminous state. At this time, the high-frequency inductor plays a role of limiting the increase of the current, ensuring the lamp To obtain the lamp voltage and lamp current required for normal operation, various protection circuits, such as abnormal protection and temperature protection, are often added in order to improve reliability.

Second, the electronic ballast harmonics and control One of the insurmountable drawbacks of electronic ballasts is that they contain a large harmonic content, and the formation of harmonics will cause pollution to the power grid, thereby breaking the three-phase balance of the power grid . Once a large number of electronic ballasts work together, they easily cause electronic phenomena such as tripping, ignition or mutual interference. Therefore, controlling the harmonic content is a top priority. There are three basic ways to control the operation in practice: First, design an effective correction compensation device, increase the power factor of the circuit, and reduce the harmonic components. Using this method to increase the cost is not high, is a more practical choice; the second is to add a quantitative ballast hybrid ballast, the introduction of high power factor low harmonic components of the hybrid ballast, for the implementation of green lighting is very favorable The third is the development of active filters, which effectively reduce harmonic components due to the application of PWM techniques. The filtering effect of this method is quite obvious. Recently, it has been applied in highly developed countries. However, its disadvantage is that the structure is complex and the cost is high, which is not applicable to China's current technology and economic development level.

Third, the application of soft-switching technology Soft-switching technology is mainly through the addition of small inductors or capacitors and other resonant electronic components on the basis of the original switch circuit to build an auxiliary converter network, making the switching process before and after the formation of resonance phenomenon. Before the switch is turned on, the voltage first drops to zero, or before closing, the current drops to zero first, which eliminates the overlap of voltage and current in the switching process and reduces the rate of change. Soft-switching technology can control the switching trajectory, reduce electromagnetic interference, increase the efficiency of circuit power conversion, strengthen product safety performance, and reduce the size and weight of electronic ballasts, thereby greatly reducing or even eliminating losses and switching noise. . Increasingly mature soft switching technology has been applied in the development of electronic ballasts.

Fourth, the development prospect of green lighting circuit The development of green lighting circuit, depend on the progress of power electronic technology to a great extent. Due to the rapid advancement and wide application of electronic technologies, energy consumption and equipment costs continue to decrease, and the function of green lighting circuits has become more perfect. Specifically: First, use the computer's remote control console and indoor computer to control the lighting system. According to the degree of natural lighting, realize the lighting brightness control, and the entire lighting system parameter settings, changes and monitoring can be achieved through the computer screen. The second is that the integration technology is gradually merging with the development of modern lamps. After various lamps adopt integrated circuits, the energy-saving effect is significant. The third is to use bus technology to realize the lighting system's point control, group control and group control. It has a series of advantages such as obvious energy-saving effect, convenient use and flexible control. Fourth, the future design of electronic ballasts tends to be generalized in terms of standards, intelligent in control (remote control, light control and sound control), circuit integration and functional modularization.

With the development and application of integration of lamps and luminaires, electronic lighting technology represented by electronic ballasts has developed rapidly, and various integrated lighting devices and computer control systems have made remarkable progress in the application of lighting systems. The lamp dimming, remote control, lighting fixtures and lighting systems that control light color will be greatly improved.