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At present, the most commonly used LED dimming power supplies are: LED thyristor dimming power supply, 0-10V dimming power supply, PWM dimming power supply. The principles of these three dimming power supplies are as follows:

1, thyristor dimming power supply

The thyristor dimming has been applied to the dimming mode of incandescent lamps and energy-saving lamps earlier, and is also the most widely used dimming method for LED dimming.

It works by cutting the waveform of the input voltage through the conduction angle to produce a tangential output voltage waveform. Applying the principle of tangential direction, the effective value of the output voltage can be reduced to reduce the power of the normal load (resistive load). The advantages of thyristor dimming are high work efficiency and stable performance.

2, 0-10V dimming power supply

The power supply design has a control chip. When the 0-10V dimmer is connected, the 0-10V voltage change is used to change the power supply output current and reduce the light. For example, when the 0-10V dimmer is modulated to 0V, the current drops to 0. The brightness of the light is also off (there is a switch function). When the 0-10V dimmer is turned up to a maximum of 10V, the output current will also reach 100% of the power output, and the brightness will also be 100%. (The output voltage is not changing).

1-10V dimming principle: As explained above, only the dimmer is 1-10V: when the resistance dimmer is adjusted to a minimum of 1V, the output current is also 10%, such as to 10V (to the maximum), the output The current will also reach 100% of the power output, and the brightness will also be 100%. (The output voltage is constant.) Remarks: 1-10V has no switching function, and the lamp cannot be turned to the minimum closing function!

3, PWM dimming power supply

Digital dimming, also known as PWM dimming, turns the LED on and off to change the on-time of the forward current to achieve the effect of brightness adjustment. The method is based on the fact that the human eye is not sensitive enough to the brightness flicker, so that when the LED is loaded, it is bright and dark. If the frequency of light and dark exceeds 100 Hz, the average brightness is seen by the human eye, not the LED is blinking. PWM adjusts the brightness by adjusting the ratio of light to dark time. In a PWM period, because the human eye flickers more than 100Hz, the perceived brightness is a cumulative process, that is, the proportion of bright time in the whole cycle. The bigger the person, the brighter the human eye feels. However, for some high-frequency sampling devices, such as high-frequency sampling cameras, it is possible to take images when the LEDs are dark when sampling. Therefore, this paper combines analog and digital to design the driving circuit of LED dimming power supply.