[Source: "High-tech LED - Technology and Applications" July issue / Li Yunhao]
Since the LED enters the lighting era, the driving method has been continuously innovated according to the characteristics of the LED, from the original switching power supply, to constant voltage constant current, and then to the LED constant current driving scheme controlled by a dedicated chip. The cost and price of the power supply are gradually reduced, but the price difference is quite different from the price of the LED. Take the 10 watt lamp as an example. In 2009, the price of the light source was 60-80 yuan, and the driving price was 18 yuan. However, the price of the light source dropped in 2012. To 10-20 yuan, and the driving power supply price is still greater than 13 yuan, the power supply price has been equivalent to the light source, it is certain that after 2013, the cost of the light source in the lamp will be lower than the driving price, and the driving cost is high. A major cause of scale promotion. Therefore, the development of new low-cost, high-efficiency, long-life drive solutions has become the focus of future development of LED lamps. According to the characteristics of the most widely used and widely used bulbs and fluorescent lamps in the luminaire, the future LED driver should have the following characteristics:
1. Long life, the life of LED is recognized as 50,000-100,000 hours. As an accessory, its life should be greater than the life of LED, and it should exceed 70,000 hours.
2. Small size, whether it is a bulb or a fluorescent lamp, the volume of the internal mounting drive is limited, so the power supply is required to be very small.
3. High temperature resistance, because the LED light source is in the process of illuminating, 70%---80% of the energy is converted into heat energy. The temperature of the lamp manufactured by the LED light source exceeds 50 degrees, and the internal temperature is more than 50 degrees.
4. High power factor and high efficiency. As an energy-saving product, the excessive consumption of energy will directly affect the conversion efficiency of the entire luminaire. Products with too low power factor may be prohibited from entering the market.
5. The lamp is easy to manufacture, the light source power supply is integrated, and the light source power supply integration can reduce the labor cost of the lamp assembly.
In order to manufacture LED drivers that meet the above requirements, many scientists have proposed many different solutions. The most classic solution is the segmentation drive scheme proposed by Yamamoto and Sri Lanka from Singapore in 2006. The scheme is characterized by AC. After rectification, the LEDs of different numbers are illuminated according to the instantaneous voltage. The program applied for invention patents in 2007. After five years of review, it obtained patent rights in March 2012. Its claims are as follows:
An LED lighting device characterized by comprising:
1. A rectifier circuit for rectifying an alternating current source;
2. An LED array consisting of a plurality of LEDs connected in series;
3. A floating current source connected in series between the rectifier circuit and the LED array;
4. The control unit determines a magnitude of an output voltage of the rectifier circuit, and controls conduction and deactivation of driving currents flowing into the LEDs in the LED array according to the determination result.
The theory creates and applies. Once the method is announced, it immediately triggers the LED-driven revolution. Many companies in various countries immediately invested a lot of manpower and resources to develop. In 2009, Shaanxi Xidian Keda Huacheng Electronics Co., Ltd. was in the State Science and Technology Commission and Shaanxi Science and Technology Commission. With the support, this method was used to develop different power drive power sources, and in March 2011 passed the identification of the National Science and Technology Commission. Its 40 watt power supply structure is shown in Figure 1. The power supply produced by this method is transformerless, non-inductive, non-capacitor, small in size, high in efficiency, and can be implemented by an integrated circuit method. And apply for invention patents, the main claims are as follows:
LED AC direct power supply circuit, including rectifier bridge, current limiting circuit, electronic switch circuit and LED light string, characterized in that: the rectifier bridge rectifies the input 50HZ sine wave alternating current into 100Hz full wave, loads the LED light string and the current limiting circuit in series The two ends of the circuit; the maximum operating current of the current limiting circuit is less than or equal to the maximum operating current of the LED; the electronic switch Ki uses a bipolar transistor or a field effect transistor, i=1,...n, n≥1; Divided into n+1 segments; the voltage peak Umax of the full wave is divided into n+1 copies by a voltage dividing circuit, and the base or gate of the electronic switch Ki is connected to the output terminal i/n+1Umax of the voltage dividing circuit, and the electronic switch The collector or leakage of Ki is connected to the intersection of the Ki-segment LED string and the Ki+1-segment LED string, and the emitter or source of the electronic switch Ki is connected to the intersection of the LED string and the current limiting circuit.
Since the LED enters the lighting era, the driving method has been continuously innovated according to the characteristics of the LED, from the original switching power supply, to constant voltage constant current, and then to the LED constant current driving scheme controlled by a dedicated chip. The cost and price of the power supply are gradually reduced, but the price difference is quite different from the price of the LED. Take the 10 watt lamp as an example. In 2009, the price of the light source was 60-80 yuan, and the driving price was 18 yuan. However, the price of the light source dropped in 2012. To 10-20 yuan, and the driving power supply price is still greater than 13 yuan, the power supply price has been equivalent to the light source, it is certain that after 2013, the cost of the light source in the lamp will be lower than the driving price, and the driving cost is high. A major cause of scale promotion. Therefore, the development of new low-cost, high-efficiency, long-life drive solutions has become the focus of future development of LED lamps. According to the characteristics of the most widely used and widely used bulbs and fluorescent lamps in the luminaire, the future LED driver should have the following characteristics:
1. Long life, the life of LED is recognized as 50,000-100,000 hours. As an accessory, its life should be greater than the life of LED, and it should exceed 70,000 hours.
2. Small size, whether it is a bulb or a fluorescent lamp, the volume of the internal mounting drive is limited, so the power supply is required to be very small.
3. High temperature resistance, because the LED light source is in the process of illuminating, 70%---80% of the energy is converted into heat energy. The temperature of the lamp manufactured by the LED light source exceeds 50 degrees, and the internal temperature is more than 50 degrees.
4. High power factor and high efficiency. As an energy-saving product, the excessive consumption of energy will directly affect the conversion efficiency of the entire luminaire. Products with too low power factor may be prohibited from entering the market.
5. The lamp is easy to manufacture, the light source power supply is integrated, and the light source power supply integration can reduce the labor cost of the lamp assembly.
In order to manufacture LED drivers that meet the above requirements, many scientists have proposed many different solutions. The most classic solution is the segmentation drive scheme proposed by Yamamoto and Sri Lanka from Singapore in 2006. The scheme is characterized by AC. After rectification, the LEDs of different numbers are illuminated according to the instantaneous voltage. The program applied for invention patents in 2007. After five years of review, it obtained patent rights in March 2012. Its claims are as follows:
An LED lighting device characterized by comprising:
1. A rectifier circuit for rectifying an alternating current source;
2. An LED array consisting of a plurality of LEDs connected in series;
3. A floating current source connected in series between the rectifier circuit and the LED array;
4. The control unit determines a magnitude of an output voltage of the rectifier circuit, and controls conduction and deactivation of driving currents flowing into the LEDs in the LED array according to the determination result.
The theory creates and applies. Once the method is announced, it immediately triggers the LED-driven revolution. Many companies in various countries immediately invested a lot of manpower and resources to develop. In 2009, Shaanxi Xidian Keda Huacheng Electronics Co., Ltd. was in the State Science and Technology Commission and Shaanxi Science and Technology Commission. With the support, this method was used to develop different power drive power sources, and in March 2011 passed the identification of the National Science and Technology Commission. Its 40 watt power supply structure is shown in Figure 1. The power supply produced by this method is transformerless, non-inductive, non-capacitor, small in size, high in efficiency, and can be implemented by an integrated circuit method. And apply for invention patents, the main claims are as follows:
LED AC direct power supply circuit, including rectifier bridge, current limiting circuit, electronic switch circuit and LED light string, characterized in that: the rectifier bridge rectifies the input 50HZ sine wave alternating current into 100Hz full wave, loads the LED light string and the current limiting circuit in series The two ends of the circuit; the maximum operating current of the current limiting circuit is less than or equal to the maximum operating current of the LED; the electronic switch Ki uses a bipolar transistor or a field effect transistor, i=1,...n, n≥1; Divided into n+1 segments; the voltage peak Umax of the full wave is divided into n+1 copies by a voltage dividing circuit, and the base or gate of the electronic switch Ki is connected to the output terminal i/n+1Umax of the voltage dividing circuit, and the electronic switch The collector or leakage of Ki is connected to the intersection of the Ki-segment LED string and the Ki+1-segment LED string, and the emitter or source of the electronic switch Ki is connected to the intersection of the LED string and the current limiting circuit.
For more information, please refer to the July issue of "High-tech LED - Technology and Applications" magazine.
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