Design and implementation of a high-frequency electrodeless lamp driving device

High-frequency electrodeless lamp is a high-tech product that integrates electronic technology, vacuum science, power electricity, plasma science, magnetic material science and other disciplines. Electrodeless lamp uses magnetic field to stimulate gas discharge and emit light, so there is no electrode inside the bulb, breaking through the light-emitting mechanism of traditional incandescent lamp and gas discharge lamp, and is gradually becoming a new generation of practical long-life, high-light-efficiency light source recognized by people, with advantages such as ultra-long life, good energy-saving effect, high luminous efficiency, no flicker, low maintenance cost, and no pollution. The
promotion of high-frequency electrodeless lamp has positive significance for energy conservation and emission reduction. Taking street lighting as an example, in 2009 alone, China installed a total of 20 million street lamps, and the annual electricity bill reached more than hundreds of billions of yuan. In addition, maintenance and replacement of bulbs consume a lot of manpower and material resources, which has always been a drawback that traditional street lamps are difficult to overcome. In recent years, with the intensification of energy tension, the application of clean light sources such as LED lamps and electrodeless lamps has been increasingly valued. Compared with other clean light sources such as LED lamps, electrodeless lamps have advantages in heat dissipation and power, so the development of electrodeless lamps has been valued in various countries. This paper studies the driving device of high-frequency electrodeless lamps and proposes a design and implementation scheme of high-frequency electrodeless lamp driving device based on digital IC. The actual test results show that this scheme can stably and efficiently drive high-frequency electrodeless lamps at 2.65MHz and can be applied to production.

1 Principle of light emission of electrodeless lamps
The electrodeless lamp uses the principle of electromagnetic induction. The alternating current first generates a magnetic field, and then the magnetic field generates an induced current. The high-frequency voltage generated is injected into the vacuum glass shell or glass tube using the principle of coupled oscillation, and it reacts with the three-primary color phosphor and inert gas to emit light. After the high-frequency stepless lamp inputs a certain range of power supply voltage, the high-frequency generator generates a high-frequency constant voltage and sends it to the power coupler. The power coupler establishes a strong electrostatic magnetic field in the discharge space of the glass shell, ionizes the atmosphere in the discharge space, and forms a large amount of plasma. When the excited atoms of the plasma return to the ground state, they radiate 253.7nm ultraviolet light; the three-primary color phosphor on the inner wall of the glass bulb is stimulated by the strong ultraviolet light to emit visible light. In terms of power supply design, the electrodeless lamp adopts APFC power supply control technology and IC technology, which makes the power factor of the power supply as high as 0.95 or above, and makes the high-frequency generator always light the lamp with high-frequency constant voltage. Therefore, when the input power supply voltage fluctuates within a certain range, its luminous brightness remains unchanged.

2 Research on high-frequency electrodeless lamp driving device
The driving device is an important component of high-frequency electrodeless lamp. The high-frequency driving device of electrodeless lamp currently in use is realized by a combination of capacitor, resistor and transistor oscillator, and the output pulse is used to drive the MOS tube. However, the electrodeless lamp driving device made of discrete components has the following disadvantages:
(1) The amplitude of the driving signal is unstable, so that the MOS tube cannot be in the best working state, affecting the power consumption of the electrodeless lamp. Today, when the country vigorously advocates low-carbon and environmental protection, this problem must be solved.
(2) The control frequency drifts seriously and there is harmonic interference. Since the operating frequency of high-frequency electrodeless lamp is high (higher than 2MHz), if the frequency harmonic problem cannot be effectively solved, it will seriously interfere with the communication of other bands, such as wireless broadcasting, airport radio communication, etc., which will seriously affect the promotion and application of electrodeless lamps.
(3) The driving circuit composed of discrete components is troublesome to debug in actual application, and it is difficult to make. The controller has a high failure rate and low technical indicators.
In order to overcome the existing controller frequency drift and the unstable state of the driving signal, this paper proposes a solution that has a constant high-frequency driving output and greatly reduces the failure rate of the electrodeless lamp controller. It is the first time in China to drive a high-frequency power supply at 2.65MHz using an IC driver, which can effectively overcome the shortcomings of making an electrodeless lamp driving device with discrete components.
The design scheme given is as follows: In the combined module, the PCB board, the crystal oscillator, and the driver chip are connected to the PCB board, and two voltage inputs are set so that one end of the device is connected to the mainboard power supply and the other end is connected to the internal crystal oscillator. When the nominal voltage reaches the crystal oscillator, a 2.65MHz standard pulse square wave is output, which is directly output to the DF803SI driver chip. The power supply of DF8031SI is connected to another power supply of the mainboard through a plug-in. When the oscillation signal reaches DF803SI, DF803SI outputs two sets of driving signals, which directly drive the MOS tube to work through the components of the mainboard, thereby reducing the number of components, and the driving signal attenuation is extremely small, the driving signal stability is good, and the dissipated power is greatly reduced.

As shown in Figure 2, 1 is the interface channel between the mainboard and the driver, and provides power to the crystal oscillator through 2. Component 3 is a high-frequency module that outputs a 2.65MHz high-frequency signal. Component 4 is connected in series with the IXDF404SI driver chip, 5 is connected to the DF803SI driver chip at one end of the power supply, and DF803SI outputs dual drive signals through 6.

As shown in Figure 3, 1 is a PCB board, 2 is a 2.65MHz crystal oscillator, 3 is a DF803SI driver chip soldered to the PCB board 1, and 5 connects the pin end of the DF803SI driver chip and the connector 4 to the PCB main board. One end of the connector 4 is connected to the driver device, and the other end is soldered to the PCB interface 7 on the main board 6.

As shown in Figure 4, the 2.65MHz crystal pin end is connected to the PCB board, and the DF803SI driver chip 3 of the 6 longitudinal section is welded to the PCB board at 4 phases.

3 Test results and conclusions
This project cooperated with Zhejiang Keshi Electronic Technology Co., Ltd., and the electrodeless lamps produced have been used in several demonstration projects, such as Ningbo Zhenhai Industrial Park, Hangzhou Qige Sewage Plant Area Street Light Renovation, Wenzhou Tengqiao Industrial Park and other projects.

The area originally used 400W sodium lamps with a pole height of 12 meters. After adopting 200W electrodeless lamps, both the illumination and various parameter indicators meet the requirements of the park road reconstruction and the national road lighting requirements. However, the power is reduced by 50%, and the color rendering is high.
After physical testing, this solution can stably and efficiently drive high-frequency electrodeless lamps at 2.65MHz, and there is no harmonic output. It can be widely used for lighting in public transportation fields such as highways, bridges and airports. It has significant social and economic benefits.