High-linearity TRIAC dimming compatible LED drive circuit

Abstract

The invention discloses a high-linearity TRIAC dimming compatible LED drive circuit, which adopts a GaN-based high electron mobility transistor (GaN HEMT) and a drive circuit thereof to replace a traditional silicon-based MOSFET so as to realize a MHz high-frequency working environment. Due to the fact that the frequency is greatly improved, values of filtering capacitance and inductance can be reduced, impact current and current oscillation in a circuit can be greatly reduced, and the TRIAC dimming compatibility is improved. A chip FB pin voltage linear regulation technology and a voltage compensation technology are adopted, and high linearity in the LED dimming process is achieved. Besides, an MCU intelligent control module is used for detecting a conduction angle, providing a compensation signal for a chip FB pin and controlling disconnection of the dummy load at the same time, and loss caused by access of the dummy load is effectively reduced under the condition that it is guaranteed that the conduction current is greater than TRIAC starting ignition current.

Description

technical field [0001] The invention relates to the field of LED driving, in particular to a high linearity TRIAC dimming compatible LED driving circuit. Background technique [0002] TRIAC thyristor dimmer can adjust the effective value of the input AC voltage and then adjust the brightness of the LED output. It was originally used for dimming incandescent lamps. Incandescent lamps present purely resistive characteristics, which can be applied to TRIAC thyristor dimming. Because the new generation of solid-state LED lighting is actually a low-voltage diode, in order to obtain high driving efficiency, it usually needs to be powered by a nonlinear high-frequency constant-current switching power supply. However, the nonlinearity of high-frequency constant current switching power supply makes it difficult to be compatible with TRIAC thyristor dimmers. [0003] Due to the inertia of the market, there are still a large number of TRIAC thyristor dimming methods. Therefore, it is...

AI Technical Summary

Problems solved by technology

[0004] At present, all TRIAC dimming solutions only monitor the phase angle, not the output current. In the case of unsatisfactory compatibility between TRIAC dimmers and LEDs, it is impossible to guarantee that the current passing through the LED load and the voltage after phase-cutting of the thyristor are effective. Value-to-one linearity, there will be non-monotonic power changes and dimming delays, and even LED flickering, jumping and shaking

[0005] At present, the frequency of the switching signal in the PWM mode in the TRIAC dimming scheme is generally around 100kHz, which is due to the frequency limitation caused by the large parasitic capacitance of the silicon-based MOSFET device.

The low driving frequency makes the non-linear problem of the input current of the drive converter more prominent, thus affecting the working state of the TRIAC dimmer

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