[Source "High-tech LED - Technology and Applications" March issue Ge Liangan / Zhang Huajian]
1 Introduction
1.1 Problems with LED Drivers
Low reliability, difficult standardization and high cost are the main problems of current LED drivers. Solving these problems is the long-term development goal and direction of drive design.
1.1.1 Reliability issues
According to statistics, more than 90% of LED lamp failures are caused by drive failure. The high failure rate of LED drivers once affected people's doubts about the application prospects of LED lighting. The reliability of LED drivers is:
1) The working environment is bad
Because the LED driving power source is close to the LED light source, it is affected by the heating of the LED light source itself. The ambient temperature around the driving power supply can reach up to 60~70 °C, and it has high waterproof, moistureproof and lightning protection requirements for outdoor applications.
2) Heavy load
In the non-dimming state, the LED driving power supply is running at full load for a long time, and the other common application fields of the switching power supply, such as the communication power supply, the computing power supply, the consumer electronic product, and the long-term average power of the switching power supply are generally much lower than the rated power.
1.1.2 Standardization difficulties
The difficulty of standardizing LED drivers is caused by the characteristics of the LED light source itself. The LED light source is usually composed of a large number of single small light sources. The power levels of the single light sources are different or the series-parallel combination is different, and the driving requirements are different. Switching power supplies are difficult to achieve highly integrated electronic products. The number of components in a single product is often as high as hundreds. The demand for a large number of customized non-standard driving power supplies is a big challenge for design and production. New products are introduced to mature. Need a process.
1.1.3 High cost
The light efficiency of LED light sources is rapidly increasing and the price is rapidly decreasing. The proportion of LED drivers in the overall cost of lamps is gradually increasing.
The poor working environment and high reliability requirements of LED drivers are a factor in the high cost of the driver; the difficulty in standardizing the driver products not only makes the product share more research and development costs, but also makes it difficult to produce and purchase small-volume and multi-standard driver products. Large-scale, the cost has increased greatly.
1.2 Status of LED Driver Technology
From the connection mode of the LED light source, the drive can be simply divided into two modes: single drive and multiple drive.
1.2.1 Single constant current drive:
The simplest LED driver is driven by a single output power supply that drives the LED source as a single load. Figure 1 shows the connection of all LED lights in series. Since all the lamps are connected in series, there is no current sharing problem, but when the number of LEDs is large, the lamp voltage will be too high. If the lamp voltage is too high, the lamp will meet the safety standards and need to pay higher insulation cost; LED lamp and radiator The higher the insulation requirement, the greater the thermal resistance and the poor heat dissipation.
1 Introduction
1.1 Problems with LED Drivers
Low reliability, difficult standardization and high cost are the main problems of current LED drivers. Solving these problems is the long-term development goal and direction of drive design.
1.1.1 Reliability issues
According to statistics, more than 90% of LED lamp failures are caused by drive failure. The high failure rate of LED drivers once affected people's doubts about the application prospects of LED lighting. The reliability of LED drivers is:
1) The working environment is bad
Because the LED driving power source is close to the LED light source, it is affected by the heating of the LED light source itself. The ambient temperature around the driving power supply can reach up to 60~70 °C, and it has high waterproof, moistureproof and lightning protection requirements for outdoor applications.
2) Heavy load
In the non-dimming state, the LED driving power supply is running at full load for a long time, and the other common application fields of the switching power supply, such as the communication power supply, the computing power supply, the consumer electronic product, and the long-term average power of the switching power supply are generally much lower than the rated power.
1.1.2 Standardization difficulties
The difficulty of standardizing LED drivers is caused by the characteristics of the LED light source itself. The LED light source is usually composed of a large number of single small light sources. The power levels of the single light sources are different or the series-parallel combination is different, and the driving requirements are different. Switching power supplies are difficult to achieve highly integrated electronic products. The number of components in a single product is often as high as hundreds. The demand for a large number of customized non-standard driving power supplies is a big challenge for design and production. New products are introduced to mature. Need a process.
1.1.3 High cost
The light efficiency of LED light sources is rapidly increasing and the price is rapidly decreasing. The proportion of LED drivers in the overall cost of lamps is gradually increasing.
The poor working environment and high reliability requirements of LED drivers are a factor in the high cost of the driver; the difficulty in standardizing the driver products not only makes the product share more research and development costs, but also makes it difficult to produce and purchase small-volume and multi-standard driver products. Large-scale, the cost has increased greatly.
1.2 Status of LED Driver Technology
From the connection mode of the LED light source, the drive can be simply divided into two modes: single drive and multiple drive.
1.2.1 Single constant current drive:
The simplest LED driver is driven by a single output power supply that drives the LED source as a single load. Figure 1 shows the connection of all LED lights in series. Since all the lamps are connected in series, there is no current sharing problem, but when the number of LEDs is large, the lamp voltage will be too high. If the lamp voltage is too high, the lamp will meet the safety standards and need to pay higher insulation cost; LED lamp and radiator The higher the insulation requirement, the greater the thermal resistance and the poor heat dissipation.
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