LED constant current PWM drive circuit and three-primary-color LED light mixing driving circuit

Abstract

The invention provides an LED constant current PWM drive circuit and a three-primary-color LED light mixing driving circuit. The LED constant current PWM drive circuit comprises a three-end bilateral switch circuit, a PWM waveform signal generating circuit and an LED constant current drive circuit, wherein the three-end bilateral switch circuit is connected with an alternating current power source and used for converting a sine alternating current signal provided by the alternating current power source into a sine chopped wave waveform signal; the PWM waveform signal generating circuit is connected with the three-end bilateral switch circuit and used for generating a PWM waveform signal by utilizing the sine chopped wave-shaped signal; the LED constant current drive circuit is connected with the PWM waveform signal generating circuit and used for controlling the on-off state of an LED light source by utilizing the PWM waveform signal, and the constant current PWM driving of an LED is achieved. According to the LED constant current PWM drive circuit, the direct driving load of the three-end bilateral switch circuit is a resistive load rather than a capacitive load, and therefore the technical scheme can guarantee high-power factors, and the quality of the whole power grid cannot be affected.

Description

Technical field [0001] The present invention relates to the technical field of LEDs, in particular to an LED constant current PWM drive circuit and a three-primary color LED mixed light drive circuit. Background technique [0002] Light Emitting Diode (LED for short) has become one of the most potential alternatives to traditional light sources due to its small size, energy saving, environmental protection, and long service life. [0003] There are many methods for producing white LED light sources. One is to use blue LEDs to excite yellow phosphors to produce white light. However, the white light LEDs manufactured by this method have greater randomness, and due to the aging of the phosphors, the efficiency of the LEDs will be reduced. Will decrease. The three primary color mixing is a better method of white light generation. The three-primary color mixing is the use of red LED, blue LED and green LED to mix light. According to the CIE (International Commission on Illumination) c...

AI Technical Summary

Problems solved by technology

[0005] For LED lighting fixtures with capacitive loads, TRIAC dimmers will bring five major adverse effects, so strictly speaking this is not a high-quality dimming technology

The first major adverse effect is that TRIAC dimming will inevitably destroy the power factor, because it uses a chopping method for dimming, especially when deep dimming, the power factor will become very low, and then affect the quality of the entire power grid; The second major adverse effect is that TRIAC dimming will produce serious EMI interference, because when the load is capacitive, the thyristor will be turned on and off to generate a strong surge on the output current waveform, and this surge current will cause serious EMI interference; the third major adverse effect is that TRIAC dimming will cause the power conversion efficiency of the entire lamp to be low, and when deep dimming is performed, the efficiency will be lower than 20%; the fourth major adverse effect is the TRIAC dimmer and LED lighting fixtures It is not matched, and this will easily cause the problem of output light flicker, affect the consumer experience, and even cause health problems; the fifth major adverse effect is that TRIAC dimmers will cause serious THD (Total Harmonic Distortion) problems , while international energy standards such as current harmonic standards compatibility testing EN61000-3-2 began to require strict THD specifications

Images