Overview of dimming energy-saving lamp electronic ballast ASICs Yang Long (Shanghai Fudan Microelectronics Co., Ltd., Shanghai analysis of an electronic ballast from the first generation to the third generation of development and its characteristics in the world today Some popular practices and some related circuits for dimming energy-saving lamp electronic ballasts, and examples of dedicated control ICs for dimming energy-saving lamps electronic ballasts.
Key words electronic ballast power factor control circuit picture classification number document identification code article number one preface electronic ballast as a new type of electric light source energy-saving electronic products developed rapidly, has evolved from the first generation to the third generation.
A common feature of the first generation of electronic ballasts is the use of a conventional rectifying and filtering circuit to obtain a DC voltage.
The disadvantage is that the current waveform of the unrectified line is distorted, the harmonic content is too high, and the power factor of the electronic ballast.
It must only reach a certain point, especially when many lights are concentrated at a certain point of the power supply line. The impact and harm are very prominent.
At the same time, the output voltage of such a circuit is unstable and will vary with fluctuations in the AC voltage, causing the lamp voltage and current to deviate from the rated value, affecting lamp life.
The second generation of electronic ballasts employs an active power factor preamplifier.
As the core of the electronic ballast pre-converter, the active power factor control circuit effectively suppresses the harmonic content and makes the power factor of the electronic ballast reach greater than the ideal result.
At the same time, the lamp voltage and the lamp current do not fluctuate with the change of the AC input power voltage of the electronic ballast, thereby ensuring that the lamp always works at the rated state, which is a very significant measure for extending the service life of the lamp.
In addition to the functions of the third-generation electronic ballast's dedicated control IC, it also has the function of driving the preheating start abnormal protection overheat protection and has the dimming function.
The application of this electronic ballast is simplified, the performance is complete, and the work is reliable.
Our domestic electronic ballast products are still in the first generation. This article is based on the understanding of the basic principles of electronic ballasts, the analysis of ASICs for foreign companies' electronic ballasts, in order to get the ingredients for reference. Make some contributions to the development of domestic electronic ballasts.
The first generation of electronic ballasts of the first generation of electronic ballasts work as follows: the power frequency voltage becomes pulsating DC through the bridge rectifier circuit, and then the filter is broken. Overview of the electric vibration filter capacity wave filter dance electric power wave circuit amplification tube diagram General electronic ballast principle block diagram for the RF interference filter oscillation circuit and power amplifier circuit, into high frequency AC to drive the fluorescent tube to emit light.
The figure is a block diagram of a general electronic ballast.
Defined by the power factor corpse F, the corpse of the corpse, the two people, the Deng 12, and the effective value of the fundamental voltage and the fundamental current are the total harmonic current content, which can be seen from the The existence of the wave current is the root cause of the power factor drop, so the elimination of the harmonic current is uniform with the improvement of the power factor.
The peak ratio is defined as the ratio of the peak value of the lamp current to its effective value, so the difference in lamp current waveform will result in different peak ratios.
In the electronic ballast, different filter circuits are used, and the waveform of the filter voltage is different.
The oscillating circuit is powered by the filtered voltage, so the current waveform output to the lamp is a high frequency current with a packet wave similar to the filtered voltage waveform.
Similar envelope waves are limited.
Most of the oscillating circuits of various domestic electronic ballasts are series-synchronous self-oscillating circuits, so the high-frequency working current of the lamps basically works on sine waves.
Second-generation electronic ballasts In recent years, electronic ballast technology has developed rapidly, and many well-known semiconductor companies are working on the development of electronic ballast-specific control ICs.
So far, there have been three types of dedicated control. The first type is the active power factor control circuit. The product has this type of control, which greatly improves the input characteristics of the electronic ballast. The input current waveform tracks the input voltage waveform and becomes sinusoidal. Wave, the power factor is close to the ideal effect that the total harmonic of the input current is less than 10.
The second type is the drive of the power tube, etc.
This type of control Cl greatly simplifies the inverter circuit and works well.
The second type is to integrate the first two categories and concentrate the advantages of the first two categories.
The second generation of electronic ballasts is marked by an active power factor preamplifier.
The core of the active power factor preamplifier is the active power factor control circuit.
The figure is a block diagram of the electronic ballast using control technology.
In the figure, the main circuit form of the switching regulator is not specified, so the basic circuits of step-up buck, buck-boost and flyback can be used.
The figure uses the double loop control network side current feedback is the control inner loop, its role is when the rectified voltage (essentially the input voltage.: when changing, that is, the current feedback network detects, the signal is sent to the multiplier, Finally, by controlling the switching regulator to adjust the duty cycle of the power switch, to achieve stability, the hands of the hands of the friends, Wan Chun, the second, the eight-knife, the switch, the regulator, the lamp, the filter, the tube, the wave comparator, the The schematic diagram of the electronic ballast using technology is pulse width modulation...
the goal of.
The output DC voltage feedback is the control outer loop, which acts to filter the voltage.
When the change occurs for some reason, the voltage feedback network detects it and sends it to the multiplier after error amplification. Finally, it also controls the duty cycle of the switching regulator power switch to...
stable.
Thanks to the dual-loop control, the system has fast transient response and high static voltage stability.
Therefore, the input voltage range is expanded, and the peak ratio of the lamp operating current is greatly improved.
The switching regulator adjusts the duty cycle of the power switch, and also causes the input current to follow the input voltage change, that is, close to the sine wave, so that the power factor approaches the total harmonic content and is greatly reduced.
礴The third-generation electronic ballast dimmable compact fluorescent electronic ballast has the following characteristics: The bulb brightness is continuously adjustable. It can detect that the bulb is not on the lamp holder. The bulb is broken or will be damaged. There is overheating and overvoltage protection. Soft flashing lights extend lamp life and more.
SCR is usually used for dimming.
The dimming principle of a fluorescent lamp using a two-way thyristor is to change the power supplied to the fluorescent lamp by controlling the conduction rate of the current in each alternating current, which is basically no different from the principle of the incandescent lamp.
Incandescent lamps are basically pure resistors when they are hot. Unlike fluorescent lamps, the load is a negative resistance discharge tube and a ballast containing an inductance component. Therefore, for a fluorescent lamp dimming circuit, the load current becomes a hysteresis power factor.
This is a different point and must be designed differently from incandescent lamps as described below.
Because the load contains inductance, the gate pulse must be widened. The current conduction rate changes within one, and it is possible to control the brightness one. (3) When the conduction angle is reduced, a slight asymmetry occurs in the positive and negative half cycles. Therefore, there is a phenomenon of flickering. (4) In the case of a fluorescent lamp, since the filament must always have a current flowing therethrough, there are usually five external terminals of the dimmer, and the wiring is complicated during installation.
If the dimming characteristics of the fluorescent lamp and the incandescent lamp are compared, the conduction angle of the fluorescent lamp is zero, the brightness is zero, and the change in the conduction angle is sharp.
When the conduction angle of the incandescent lamp is zero, the brightness is zero, and the purpose is.
In the range of large variation of the conduction angle, the brightness does not change much.
The above is only for the dimming, and the fluorescent lamp warm-up start abnormal state protection and other issues must be designed with a special circuit.
Narrative.
In recent years, many large companies in the world have been working to develop new solutions to the above problems.
Such as the introduction of the South Korean company launched by the US company.
In addition to its function, this CI also includes the above-mentioned driver warm-up start abnormal protection overheat protection and dimming function.
The electronic ballast using this CI design is called the third-generation electronic ballast by the error amplifier reverse input and the comparator input error amplifier output and compensation.
The figure is the internal basic block diagram of the chip of the US company, using the BI process, and now the design ideas of the third-generation electronic ballast ASIC are also roughly the same.
Its pin is defined as follows: setting the preheating and interrupting timing lamp output power detection cycle current limiting period of the inductor current and peak current sampling sampling current amplifier output error amplifier output voltage analog ground lamp error amplifier reverse input power supply ground n lamp current error transconductance amplifier output a n ballast M tube drive output a flower set oscillator maximum frequency and charge current external resistance set oscillator start frequency ballast tube drive output power factor tube drive output call oscillation The device timing positive power supply 0 is used for the buffered output of the input reference when the lamp is not in and restarted.
Power factor controller and 犷 gated anti-flicker compensation logic.
And the power of the prison power adjustment interface 滋 double é¨ Luo Yin circle æ›° mouth mouth variable frequency oscillator output giant 竺 plastic å’§, corpse drive three frequency control sequence......
The second test lamp life undervoltage and the inspection lamp in the country power off thermal shutdown and automatic restart diagram internal block diagram half-handed friend Jun Wan Li Jun persuaded the two strokes eight knife review in the electronic ballast work, you can Three different frequencies are generated when the warm-up starts to work stably, and its dimming function is realized by adjusting the frequency.
When an abnormal situation occurs, it can be automatically turned off, and when the abnormal situation is released, it can be automatically restarted.
Concluding remarks on the development of electronic ballast-specific control ICs, the addition and some protection functions are the current trends in the development of this type of dedicated CI.
The leading production technology of power integrated circuits in the world today is as well as technology. However, there are still few BI production lines with mass production capability in China, especially in the development of power integrated circuits, and there is a shortage of talents and technologies. How to be short-term The development of integrated power ICs is a work that industry insiders should pay attention to.
Received date Yang Longnan.
He graduated from the University of Science and Technology of China with a double bachelor degree.
First degree, Bachelor of Science, Department of Applied Physics, Microelectronics.
Second degree, Bachelor, Department of Computer Science and Technology, Department of Electronic Science and Technology.
Technical expertise is in microelectronics and computers.
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