AC LED lighting systems and control methods without flickering

摘要

A LED lighting system performs no flicking. A rectifier receives an AC input voltage to generate a rectified input voltage at an input power line and a ground voltage at a ground line. A LED string comprises LEDs connected in series to have a main anode and a main cathode. The main anode is coupled to the input power line. A power bank is connected to the input power line and the main cathode. The circuit conducts a first driving current from the main cathode to the ground line, and a second driving current from the power bank to the ground line. The second driving current increases electric energy stored in the power bank. Both the first and second driving currents flow through the LED string. The power bank releases the electric energy to make at least one of the LEDs illuminate when the AC input voltage is about 0V.

主权项

1. A LED lighting system, comprising:
a rectifier for receiving an AC input voltage to generate a rectified input voltage at an input power line and a ground voltage at a ground line; a LED string, comprising LEDs connected in series to have a main anode and a main cathode, wherein the main anode is coupled to the input power line; a power bank connected to the input power line and the main cathode, for storing electric energy; and a LED controller coupled to the LED string and the power bank, for conducting a first driving current from the main cathode to the ground line and for conducting a second driving current from the power bank to the ground line, wherein the second driving current increases the electric energy, and a combination of the first and second driving currents flows through the LED string; wherein the power bank releases the electric energy via the input power line to make at least one of the LEDs illuminate when the AC input voltage is about 0V.