1. Electrodeless ballast electronic ballast
The principle of operation of the induction lamp and the energy saving lamp is completely different. Although the induction lamp and the energy-saving lamp must have a box similar to the energy-saving lamp ballast to work properly, this box is still called high-frequency power supply (more precisely, it should be: high-frequency electromagnetic wave generator) as well. It should not be called an electronic ballast for induction lamps. Because the high-frequency electromagnetic wave generator has no ballasting during operation, some people think that there is a negative resistance effect in the electrodeless lamp. The higher the temperature, the lower the resistance value. Until the electrodeless lamp does not work. So where does this negative resistance effect occur? How does negative resistance cause bad consequences? Those who can't say clearly can't make it clear. In fact, this phenomenon is caused by the Curie temperature effect of the ferrite core in the coupler, as shown in Figure 1.
Ferrite power cores have an important physical feature, that is, they have a Curie temperature point of approximately 180-280
Between °C, this is a critical point for the presence or absence of magnetic properties of the magnetic medium. As the temperature increases, the inductance of the ferrite core increases as shown in Fig. 1. When the inductance is large, the coupling will increase the transmission power, and the ferrite core will be stronger. The temperature will be higher. This is a vicious cycle. Once the temperature accumulation cannot be quickly dissipated and exceeds the Curie temperature point of the ferrite core, the ferrite core will immediately lose its magnetic properties. The coupler detuned electrodeless lamp will of course not work. We know that electronic ballasts have evolved from inductive ballasts. Inductive ballasts are purely used to control the lamp current. Starting the fluorescent lamp depends on the starter. In essence, electronic ballasts and ballasts have little to do with, but there are also chokes in electronic ballasts. This kind of name has little effect on the analysis of the working principle of electronic ballasts. It will cause people to misunderstand electronic ballasts. The high-frequency power supply of the electrodeless lamp is different because it generates high-frequency electromagnetic waves. The electromagnetic wave passes through the coupler (transmitting antenna) to excite the mercury atoms in the electrodeless bulb to step and generate 253.7nm ultraviolet light to deactivate the phosphor. Produces visible light. When the induction lamp is started, there is a voltage drop inside the bulb, but this voltage drop cannot affect the working state of the high-frequency power source, and the high-frequency power source does not protect itself by ballasting. The so-called ballast may affect people's misunderstanding of high-frequency electromagnetic wave generators, and its modeling and circuit analysis will bring erroneous results, which will interfere with our correct understanding of the working principle and working state of the electrodeless lamp. , making us go the wrong way in technology.
2. Magnetic elements are added to the electrodeless lamp
Someone replied when questioning the induction lamp question: Why do the magnetic induction lamps they produce have better illumination than other light sources? The reason is that magnetic elements are added to their magnetic induction lamps. The so-called magnetic element here undoubtedly means that a ferrite power core is added to the coupler. So why do you want to add a ferrite core in the electrodeless lamp coupler? Is it really because the addition of ferrite can improve the performance of the lamp? The biggest difference between the working principle of the electrodeless lamp and the energy-saving lamp is that the energy-saving lamp is made of filament The electron beam is heated to work; and the electrodeless lamp is operated by a high-frequency electromagnetic wave generator, and is converted into electromagnetic wave energy by a coupler, that is, the electromagnetic wave energy of the electrodeless lamp is emitted by the antenna. According to the antenna emission theory, the electromagnetic wave is radiated by the full energy of the antenna. The condition that the wave source is no longer returned is that the length of the transmitting antenna is equal to λ/2, and λ is the wavelength of the electromagnetic wave. We can call the antenna and the electromagnetic wave that needs to be transmitted to match. In the good matching state, it can be tested that the standing wave ratio of the antenna is 1. The operating frequency of the high-frequency electrodeless lamp is 2.65MHz, its wavelength is 113 meters, the length of the λ/2 coil is 56.5 meters; the low-frequency electrodeless lamp is even more, its wavelength is 1.3Km, and the length of λ/2 is 650 meters. It is almost impossible for such a long coil to be inserted into the electrodeless lamp. Fortunately, we have found a ferrite magnet. An important electrical property of a ferrite magnetic material is that it can add a strong inductance to the coil wound around it. The equivalent of a 1 meter coil immediately has the performance of a tens of meters long coil, so there is a ferrite. The winding of the magnetic material like the high-frequency electrodeless lamp coupling coil only needs 24~28åŒ, which is only about 1.3 meters. But ferrite magnets have their own inherent electrical characteristics, namely:
1 large size and bulky;
2 The electromagnetic power loss is large and the heat is severe;
3 There is a Curie temperature point, and it is easy to detune to bring reliability problems;
4 The coupling of the coupler is rough and the reflection is severe, which causes the power device in the high-frequency power source to be easily damaged.
5 In order to guide the heat, expensive copper is used to increase the cost.
It can be seen that if the ferrite magnetic material is not used, it is better not to use it. Now, the technical solution is to find a way to abandon it. The newly developed electrodeless RF fluorescent lamp adopts a relatively high RF frequency, completely abandoning the ferrite magnetic material. The newly selected transmitting coil has a standing wave ratio test of less than 1.1, which has excellent electrical performance, and the light effect is not only greatly improved. Increase, the cost is greatly reduced, there is no ferrite core in the bubble body, there is no problem of Curie temperature point, the heat is very small, the whole lamp no longer needs expensive copper. In the newly developed electrodeless RF fluorescent lamp, the ferrite magnetic material--magnetic element is removed, and the lighting performance of the lamp is not reduced but it is improved. It can be seen that those who advocate the addition of magnetic elements are flickering.
3, the working life of the electrodeless lamp
Many manufacturers promote the working life of the electrodeless lamp for 100,000 hours. Some people can understand this question. The working life of high-frequency power supplies is difficult to exceed 15,000 hours due to component constraints. The life of a calcium halophosphate phosphor is typically 3,000 hours at its rated operating temperature of 45 °C. There is some controversy about the working life of the three primary color phosphors at a rated working temperature of 90 ° C. It is generally believed to be between 8,000 and 15,000 hours. Of course, experts in the phosphor industry are expected to give definitive conclusions. Statistics show that the life of the three primary color phosphors is expected to exceed 80,000 hours under low light conditions, but this data may be problematic if used as a reference for high temperature highlights in induction lamps. At present, it is still not appropriate to exaggerate the life expectancy of the electrodeless lamp, so as not to get the counterproductive effect.
4, the working frequency of the electrodeless lamp
When some manufacturers of induction lamps celebrated the development of 100KHz low-frequency induction lamps, they have actually entered a muddy swamp area without any hope and future. The only benefit that a low-frequency electrodeless lamp can get is that its EMC index is better. In order to bring more difficult technical problems to this technical indicator that is not too difficult to solve, is it that sesame has lost watermelon? I have raised a very serious question: What is the direction of the development of the electrodeless lamp? Is it really necessary to develop to a lower working frequency? I remember that a 100KHz switching power supply was developed ten years ago, and I am very pleased that it is better than The 40KHz switching power supply circulating in the market has to be advanced a lot. What is the truth? In fact, there are also a lot of questions about the switching power supply with higher operating frequency. The same is true: higher operating frequency will bring more radiation. The ripple is poor, which may cause more damage to the power device. In fact, today's 600KHz switching power supply on the market is no longer rare, and the excellent technical parameters are really amazing. Foreign countries even introduced a 2000KHz aerospace-class switching power supply. Higher operating frequencies have higher power density, higher conversion efficiency, smaller size and lighter shape. Isn't such a technical indicator a target for lighting sources? Low-frequency electrodeless lamps are used. The external coupling method is not suitable for the higher operating frequency due to its external mode of the coupler. This external method, which does not obstruct the radiation of any space, is not easily resonated at a lower operating frequency because the wavelength of the electromagnetic wave is too large, so its radiation value is not too large and can be tolerated. However, the radiated electromagnetic waves generated by this external method at high frequencies cannot be ignored. If the electrodeless lamp wants higher power density, higher conversion efficiency, smaller size and lighter shape of the light source product, it must use a higher operating frequency. If you want to use a higher operating frequency, you can't Outcoupling is used. Some people say that the EMC index of high-frequency electrodeless lamps cannot pass the detection. I want to say that the most important thing about the high-frequency electrodeless lamp is not the EMC index, but the fact that its temperature rise brings the power to be too low, and this is the root cause of the current dilemma of the electrodeless lamp. The problem of light efficiency and temperature rise is solved, and the problem of EMC indicators can be solved naturally. This is a good understanding: the efficiency of electromagnetic wave emission is improved, the light efficiency is improved, and the waste is less on the useless emission. The EMC index will definitely be better.
5, the effective light effect of the electrodeless lamp
In the detection data of the electrodeless luminous flux, the electrodeless lamp can not be compared with the sodium lamp and the metal halide lamp, and even the light efficiency of the straight tube fluorescent lamp at 105 Lm/W is much higher than that of the electrodeless lamp. Some people came out to argue that the luminous flux seen by the human eye is related to the light energy P(λ) of the light source itself, and also to the spectral light efficiency under different visual conditions. As the brightness of the surrounding environment changes from bright to dark vision, The entire spectral light efficiency curve shifts to the short-wave direction, the wavelength range visible at the long-wave end is reduced, and the visibility of the short-wave end is expanded, that is, the sensitivity of the human eye of blue light is increased. The electrodeless lamp emits three-color phosphors for ultraviolet light. The red, green and blue components of the lamp are matched with each other, and there is continuous strong blue-green light, which meets the requirements of the intermediate visual spectrum. The actual effective light of the electrodeless lamp follows the surrounding environment. The brightness decreases and rises. In night lighting, the adaptation range of the human eye is in the middle vision category, that is, the effective brightness of the electrodeless lamp in night illumination is high. They proposed to increase the correction coefficient on the infinite lighting effect data based on the so-called dark vision and clear vision concept, and reduce the correction coefficient of the light effect data of the sodium lamp and the metal halide lamp, and then obtain the effective light of the electrodeless lamp. The effect is higher than the conclusion of sodium lamp and metal halide lighting effect. Does this make sense? In the detection system and testing process, in order to ensure the fairness of testing, it is necessary to eliminate the intervention of human factors, which is purely based on the instrumentation test data, which is the basic requirement specified in any testing standard. Therefore, it is not allowed to give this coefficient to the reduction factor on the test result. We can laugh at it. In fact, the perception of the human eye under lighting is related to many factors, such as the intensity of the light, the color rendering of the light, the environmental background, etc., and even has a considerable relationship with the mood of the person. The poor light efficiency of the electrodeless lamp is a major flaw that is well known. We can make up for this shortcoming through technical improvement. It is not necessary to cover up the saga of the Western painting. In essence, the electrodeless lamp, despite such defects, will not shake its position as a future light source. After facing its shortcomings and overcoming its perfection, the electrodeless lamp will surely mature and glory in the constant technological improvement and controversy.
6, the electrodeless lamp model
The emergence of gas discharge lamps is a milestone breakthrough in the electric light source industry. In particular, the light source products we call energy-saving lamps have become a daily necessity for people. Gas discharge lamps emit light by discharge between electrodes, so the life of the electrodes determines the life of the light source, which undoubtedly limits the upper limit of the life of the light source. At the same time, the high-heat electrode will inevitably have the sputtering and consumption of the electrode body during the discharge process, which will cause the arc tube to blacken, reduce the luminous flux of the light source, and also cause the filament electrode to slowly ablate and break. These unfavorable factors prompted people to develop gas discharge sources that do not have electrodes. The first ç›-free fluorescent lamp was introduced in 1991, and it has also opened a new era of electrodeless gas discharge lamps. The purpose of building a circuit model for an electrodeless lamp is to help us analyze the circuit and find the best matching value of each component of the circuit to obtain higher electrical performance of the circuit. If the simulation can be finally done, the design process can be simplified to improve work efficiency. Established earlier on the induction lamp is the transformer model, which is based on several MHz. One of the most important parameters given is K, the coupling coefficient. Since the model is rough, the K-factor is preset or how to solve it without giving an answer. It is only if the power loss on the coil and the core is tested, the model can be used to solve the coupling coefficient. Therefore, this model has little significance for the design and actual production of the electrodeless lamp. Later, some people transplanted it into the field of low-frequency electrodeless lamp analysis, and established an externally coupled double-coil model. By measuring the voltage and current parameters of the primary side, the transformer model can be used to gradually find the relevant parameters of the secondary side, and then derive the system's parameters. Equivalent impedance and equivalent inductance. For RF induction lamps, it cannot be described by a transformer model. It should be described using the theory of high frequency radiation. According to the theory of high frequency radiation, there are four technical requirements for the performance of the coil antenna:
1 Match the coil and high-frequency electromagnetic wave generator according to the 75Ω system, and the standing wave ratio is below 1.1;
2 The electromagnetic waves emitted by the antenna coil are mainly concentrated on the surrounding wall;
3 The working frequency band of the antenna coil is 2MHz, that is, f0±1MHz.
4 The antenna coil emits a circularly polarized electromagnetic wave;
The RF electrodeless lamp is developed and developed according to the guidance of this mature theory. It is currently being declared in the national invention patent procedure, and the key technical points will be released publicly soon.
Edit: Sophy
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