Because LED has environmental protection, long life, high photoelectric efficiency (current light efficiency has reached 100LM/W), seismic and many other advantages, in recent years, the application in various industries has been rapidly developed. In theory, the service life of LED is about 100,000 hours. However, in the actual application process, some LED lamp designers have insufficient understanding of the LED driver power supply or improper selection or blind pursuit of low cost. As a result, the life of LED lamp products is greatly shortened, and the advantages of LED lamps are not well played.
The LED driving power supply is a voltage converter that converts the power supply into a specific voltage and current to drive the LED to emit light. Usually, the input of the LED driving power source includes high-voltage power frequency AC, low-voltage direct current, high-voltage direct current, low-voltage high-frequency alternating current (such as electronic Transformer output) and so on. The output of the LED driver is mostly a constant current source that changes the voltage as the LED's forward voltage drop changes. The core components of the LED power supply include a switch controller, an inductor, a switching component (MOSfet), a feedback resistor, an input filter component, an output filter component, and the like. According to the requirements of different occasions, there are also input overvoltage protection circuit, input undervoltage protection circuit, LED open circuit protection, overcurrent protection and other circuits.
To do a good LED lighting product, the key lies in heat dissipation, driving power supply and light source, and heat dissipation is particularly important. The heat dissipation effect directly affects the quality of life of the lighting product, while the life of the driving power supply itself and the stability of the output current and voltage are on the product. The overall quality of life also has a large impact, and the light source is the core of the entire product. The following provides some knowledge about LED driver power.
Constant current drive:
Due to the particularity of LED processing and manufacturing, the current and voltage characteristics of LEDs produced by different manufacturers and even the same manufacturer in the same batch of products have large individual differences. Taking the typical specification of high-power 1W white LED as an example, according to the current and voltage variation rules of LED, a brief description is given. Generally, the forward voltage of 1W white light application is about 3.0-3.6V, that is, when it is labeled as 1W LED. When the current flows through 350 mA, the voltage across it may be 3.1V, or 3.2V or 3.5V may be other values. To ensure the life of 1WLED, the general LED manufacturer recommends that the lamp factory use 350mA current. Drive, when the forward current through the LED reaches 350 mA, the small increase in the forward voltage across the LED will cause the LED forward current to rise sharply, causing the LED temperature to rise linearly, thereby accelerating LED light decay. To shorten the life of the LED and even burn out the LED when it is serious. Due to the particularity of the voltage and current changes of the LED, strict requirements are imposed on the power supply for driving the LED.
Constant current source driving is the best LED driving method. It is driven by constant current source. It does not need to connect current limiting resistors in the output circuit. The current flowing through the LED is not affected by external power supply voltage changes, ambient temperature changes, and discrete LED parameters. The effect is to keep the current constant and give full play to the various excellent characteristics of the LED.
A Battery Management System (BMS) is any electronic system that manages a rechargeable battery (cell or battery pack), such as by protecting the battery from operating outside its Safe Operating Area, monitoring its state, calculating secondary data, reporting that data, controlling its environment, authenticating it and / or balancing it.
A battery pack built together with a battery management system with an external communication data bus is a smart battery pack. A smart battery pack must be charged by a Smart Battery Charger.
Battery Management System
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