TWI442813B - Led illuminating system - Google Patents

Description

LED lighting system

The present invention relates to a light emitting diode lighting system, and more particularly to a light emitting diode lighting system that does not require an electrolytic capacitor.

In recent years, the technology of light-emitting diodes (hereinafter referred to as LEDs) has advanced by leaps and bounds, so it has gradually replaced traditional lighting (such as fluorescent tubes, light bulbs) and become the star of tomorrow in the lighting industry. LED manufacturers often claim that LED lighting systems have the advantages of energy saving, carbon saving, and long service life. However, in most LED lighting systems, the electrolytic capacitors are often provided, which shortens the service life of LED lighting systems.

In order to avoid the phenomenon of LED flashing, the voltage supplied to the LED must be stable, so an electrolytic capacitor with a high capacitance value needs to be set in the LED lighting system. Electrolytic capacitors are a passive component, and the more common ones are aluminum electrolytic capacitors. The aluminum electrolytic capacitor is made of aluminum as an anode, and a paste composed of ethylene glycol, glycerin, boric acid, ammonia, or the like as an electrolyte. Compared to ceramic capacitors, electrolytic capacitors can withstand high voltages and have high capacitance values. However, electrolytic capacitors are also susceptible to temperature and their lifetime is reduced. According to the experiment, when the operating temperature is at 105 ° C, the life of the electrolytic capacitor is about 15,000 hours, and when the temperature is higher than the operating temperature of 10 ° C, the life of the electrolytic capacitor is halved.

Therefore, even if the LED in the LED lighting system has a service life of nearly 40,000 hours, since the service life of the electrolytic capacitor is much smaller than that of the LED and the replacement of the electrolytic capacitor is not easy, the service life of the LED lighting system is greatly drawn. low. In addition, electrolytic capacitors have the disadvantage of being bulky and exposing to high temperatures. Therefore, designing an LED lighting system without an electrolytic capacitor is worthy of consideration by those of ordinary skill in the art.

It is an object of the present invention to provide an LED lighting system that does not require an electrolytic capacitor and therefore has a long service life.

In accordance with the above and other objects, the present invention provides an LED illumination system including: a rectifier, a buck converter, a buck-boost converter, an LED array, and a capacitor. The input end of the buck converter is electrically connected to the output end of the rectifier, and the input end of the buck-boost converter is electrically connected to the output end of the buck converter. The LED array is electrically connected to the output of the buck-boost converter, and the capacitor is electrically connected between the buck-boost converter and the LED array.

In the above LED lighting system, the buck-boost converter is a single-ended primary-inductor converter (hereinafter referred to as SEPIC converter) or a flyback converter.

In the above LED lighting system, the rectifier is a bridge rectifier.

In the above LED lighting system, a ceramic capacitor or a multilayer ceramic (hereinafter referred to as SMD) capacitor is electrically connected between the LED array and the step-up/down converter.

In the above LED lighting system, a power factor corrector and a control integrated circuit (hereinafter referred to as IC) are further included. Wherein, the power factor corrector is connected between the rectifier and the buck converter, and the output of the control IC is electrically connected to the power factor corrector. The input end of the control IC is electrically connected to the output end of the buck-boost converter, and the control IC controls the power factor corrector according to the voltage output by the buck-boost converter. Further, the power factor corrector and the buck converter are, for example, integrated with each other.

In the above LED lighting system, a voltage stabilizing compensation circuit is further included, and the voltage stabilizing compensation circuit is electrically connected between the buck-boost converter and the control IC.

Since the current will decrease after passing through the buck converter, the current will be lower. Ceramic capacitors at voltages provide higher capacitance values. Moreover, since the output voltage of the buck-boost converter has been relatively stable, a relatively smooth output voltage can be provided by the ceramic capacitor for use in the LED array. Among them, when the capacitance value of the ceramic capacitor is higher, the voltage supplied to the LED array will be more stable.

The above described objects, features, and advantages of the present invention will become more apparent from the following description.

Please refer to FIG. 1. FIG. 1 is a block diagram of an LED illumination system according to a first embodiment of the present invention. The LED lighting system 100 includes a rectifier 110, a buck converter 120, a buck-boost converter 130, and an LED array 160. The LED array 160 is a combination of a plurality of LEDs.

The rectifier 110 is, for example, a bridge rectifier that is connected to an external power source 20. Please refer to FIG. 2A at the same time. FIG. 2A illustrates the waveform of the output voltage V1 of the external power source 20. As shown in FIG. 2A, the external power source 20 is an AC voltage source. In the present embodiment, the voltage peak of the external power source 20 is approximately 264 volts. The AC voltage V1 supplied from the external power source 20 becomes a pulsating DC voltage V2 after passing through the rectifier 110, and the waveform of the voltage V2 at the output of the rectifier 110 is as shown in Fig. 2B. After passing through the rectifier 110, the voltage peak is about 264. volt. In addition, since the rectifier 110 is a bridge rectifier, it has the function of filtering high-frequency noise. [The bridge rectifier should have no function of filtering high-frequency noise. Usually an EMI filter is added between the external power supply and the bridge rectifier. To filter out high frequency noise].

In addition, the input end of the buck converter 120 is connected to the output end of the rectifier 110, and the pulsating DC voltage V2 output by the rectifier 110 is output to the buck converter 120. The buck converter 120 is used to The voltage value of the pulsating DC voltage V2 is lowered, and the waveform of the voltage V3 at the output thereof is as shown in Fig. 2C. In this embodiment, After the buck converter 120, the voltage peak is reduced to approximately 50 volts.

In addition, the input end of the buck-boost converter 130 is connected to the output of the buck converter 120, and the voltage V3 outputted by the buck converter 120 is passed through the buck-boost converter 130, and the voltage value thereof is Adjustment. In this embodiment, the buck-boost converter is a flyback converter or a SEPIC converter. Comparing FIG. 2C with FIG. 2D, originally at the input end of the step-up and step-down converter 130, the portion with a higher voltage value will fall after passing through the step-up and step-down converter 130, and the portion with a lower voltage value is subjected to buck-boosting. The converter 130 will then go up. Therefore, the voltage V4 outputted by the step-up and step-down converter 130 is relatively stable, that is, the amplitude of the ripple is small and approaches the ideal DC voltage.

In addition, the output of the buck-boost converter 130 is also provided with a ceramic capacitor 170 electrically connected between the buck-boost converter 130 and the LED array 160 and in parallel with the LED array 160. With the ceramic capacitor 170, the ripple of the voltage V4 can be greatly reduced, and the output voltage of the ceramic capacitor 170 approaches the ideal DC voltage. Compared with the electrolytic capacitor, the ceramic capacitor 170 has a high service life, its service life is not lower than the LED, and the cost of the ceramic capacitor 170 is also low. In addition, compared to electrolytic capacitors, ceramic capacitors 170 do not use high voltages and do not provide high capacitance values, so conventional LED lighting systems do not use ceramic capacitors. However, in the present embodiment, since the voltage value of the voltage V2 is lowered after passing through the buck converter 120, the ceramic capacitor 170 which is less resistant to high voltage can be mounted in the LED illumination system 100. Moreover, since the output voltage of the buck-boost converter 130 has been relatively stable, a relatively stable output voltage can be provided by the ceramic capacitor 170 having a lower capacitance value for use by the LED array 160. Wherein, the higher the capacitance value of the ceramic capacitor 170, the smoother the voltage supplied to the LED array 160.

In the LED illumination system 100 of the present embodiment, since the electrolytic capacitor is not required to be disposed, the service life of the LED illumination system 100 is not limited by the electrolytic capacitor. System, so it can have a higher service life. In addition, the LED lighting system 100 can also have a lower cost because it is not necessary to provide an electrolytic capacitor.

In the above embodiments, a ceramic capacitor is used as the capacitor. However, those skilled in the art can also replace the ceramic capacitor with an SMD capacitor or other type of capacitor, as long as the capacitor has a smaller electrolytic capacitor than the electrolytic capacitor. High service life can be.

In addition, please continue to refer to Figure 1. The LED lighting system 100 further includes a voltage stabilizing compensation circuit 140, a control IC 150, and a power factor corrector 180, wherein the power factor corrector 180 is connected between the rectifier 110 and the buck converter 120, which is used In order to increase the power factor, the power utilization efficiency is increased. The control IC 150 is based on the voltage output from the buck-boost converter 130 to control the power factor corrector 180. In addition, the voltage stabilizing compensation circuit 140 is designed in response to the control IC 150 to ensure that the voltage and current through the control IC 150 can be stabilized.

Please refer to FIG. 3. FIG. 3 is a block diagram of an LED illumination system according to a second embodiment of the present invention. In contrast to the first embodiment, in the LED illumination system 100' of the present embodiment, the power factor corrector is integrated with the buck converter, referred to herein as a buck power factor correction converter 120'. .

The present invention has been described above by way of examples, and is not intended to limit the scope of the claims. The scope of patent protection is subject to the scope of the patent application and its equivalent fields. Modifications or modifications made by those skilled in the art, without departing from the spirit or scope of the invention, are equivalent to the equivalents or modifications made in the spirit of the invention and should be included in the following claims. Inside.

20‧‧‧External power supply

100, 100’‧‧‧LED lighting system

110‧‧‧Rectifier

120‧‧‧Buck converter

120'‧‧‧Buck Power Factor Correction Converter

130‧‧‧Buck-boost converter

140‧‧‧Regulator compensation circuit

150‧‧‧Control IC

160‧‧‧LED array

170‧‧‧Ceramic capacitor

180‧‧‧Power Factor Corrector

1 is a block diagram of an LED illumination system in accordance with a first embodiment of the present invention.

FIG. 2A illustrates the waveform of the output voltage of the external power source.

Figure 2B shows the waveform of the output voltage of the rectifier.

Figure 2C shows the waveform of the output voltage of the buck converter.

FIG. 2D illustrates the waveform of the output voltage of the buck-boost converter.

3 is a block diagram of an LED lighting system in accordance with a second embodiment of the present invention.

20‧‧‧External power supply

100‧‧‧LED lighting system

110‧‧‧Rectifier

120‧‧‧Buck converter

130‧‧‧Buck-boost converter

140‧‧‧Regulator compensation circuit

150‧‧‧Control IC

160‧‧‧LED array

170‧‧‧Ceramic capacitor

180‧‧‧Power Factor Corrector

Claims (8)

A light-emitting diode lighting system includes: a rectifier; a buck converter, an input end of the buck converter is electrically connected to an output end of the rectifier; a buck-boost converter, the buck-boost type The input end of the converter is electrically connected to the output end of the buck converter; a light emitting diode array electrically connected to the output end of the buck-boost converter; and a capacitor, The capacitor is electrically connected between the buck-boost converter and the array of light-emitting diodes; wherein the capacitor is a non-electrolytic capacitor. The illuminating diode lighting system of claim 1, wherein the buck-boost converter is a single-ended primary inductor converter. The illuminating diode lighting system of claim 1, wherein the buck-boost converter is a flyback converter. The illuminating diode lighting system of claim 1, wherein the rectifier is a bridge rectifier. The LED lighting system of claim 1, wherein the capacitor is a ceramic capacitor or a multilayer ceramic capacitor. The illuminating diode lighting system of claim 1, further comprising: a power factor corrector, wherein the power factor corrector is connected between the rectifier and the buck converter; and a control An integrated circuit, the output end of the control integrated circuit is electrically connected to the power factor corrector, and the input end of the control integrated circuit is electrically connected to the buck-boost type An output of the converter, and the control integrated circuit controls the power factor corrector according to a voltage output by the buck-boost converter. The illuminating diode lighting system of claim 6, wherein the power factor corrector and the buck converter are integrated into a buck power factor correction converter. The illuminating diode lighting system of claim 6 or 7, further comprising a voltage stabilizing circuit electrically connected to the buck-boost converter and the control integrated circuit between.