Systems and methods for controlling power factors of LED lighting systems

A system for controlling a bleeder current to increase a power factor of an LED lighting system without any TRIAC dimmer, the system comprising:

• a first current controller configured to receive a rectified voltage generated by a rectifier that directly receives an AC input voltage without through any TRIAC dimmer;
• and
• a second current controller configured to:
• control a light emitting diode current flowing through one or more light emitting diodes that receive the rectified voltage not clipped by any TRIAC dimmer;
• and
• generate a sensing voltage based at least in part upon the light emitting diode current, the sensing voltage representing the light emitting diode current in magnitude;
• wherein the first current controller is further configured to:
• receive the sensing voltage from the second current controller;
• and
• generate a bleeder current based at least in part on the sensing voltage;
• wherein the first current controller is further configured to:
• if the light emitting diode current is larger than zero in magnitude, generate the bleeder current equal to zero in magnitude;
• and
• if the light emitting diode current is equal to zero in magnitude, generate the bleeder current larger than zero in magnitude;
• wherein the first current controller is further configured to, if the light emitting diode current is equal to zero in magnitude:
• increase the bleeder current with the increasing rectified voltage in magnitude;
• and
• decrease the bleeder current with the decreasing rectified voltage in magnitude;
• wherein a rectifier current generated by the rectifier is approximately equal to a sum of the bleeder current and the light emitting diode current in magnitude;
• wherein, with the light emitting diode current being equal to zero in magnitude, the rectified voltage and the rectifier current contribute to an active power to increase the power factor of the LED lighting system without any TRIAC dimmer.

A method for controlling a bleeder current to increase a power factor of an LED lighting system without any TRIAC dimmer, the method comprising:

• receiving a rectified voltage generated by a rectifier that directly receives an AC input voltage without through any TRIAC dimmer;
• controlling a light emitting diode current flowing through one or more light emitting diodes that receive the rectified voltage not clipped by any TRIAC dimmer;
• generating a sensing voltage based at least in part upon the light emitting diode current, the sensing voltage representing the light emitting diode current in magnitude;
• receiving the sensing voltage;
• and
• generating a bleeder current based at least in part on the sensing voltage;
• wherein the generating a bleeder current based at least in part on the sensing voltage includes:
• if the light emitting diode current is larger than zero in magnitude, generating the bleeder current equal to zero in magnitude;
• and
• if the light emitting diode current is equal to zero in magnitude, generating the bleeder current larger than zero in magnitude;
• wherein the generating the bleeder current larger than zero in magnitude if the light emitting diode current is equal to zero in magnitude includes:
• increasing the bleeder current with the increasing rectified voltage in magnitude;
• and
• decreasing the bleeder current with the decreasing rectified voltage in magnitude;
• wherein a rectifier current generated by the rectifier is equal to a sum of the bleeder current and the light emitting diode current in magnitude;
• wherein, with the light emitting diode current being equal to zero in magnitude, the rectified voltage and the rectifier current contribute to an active power to increase the power factor of the LED lighting system without any TRIAC dimmer.

A method for controlling a bleeder current to increase a power factor of an LED lighting system without any TRIAC dimmer, the method comprising:

• receiving a rectified voltage generated by a rectifier that directly receives an AC input voltage without through any TRIAC dimmer;
• controlling a light emitting diode current flowing through one or more light emitting diodes that receive the rectified voltage not clipped by any TRIAC dimmer;
• generating a sensing voltage based at least in part upon the light emitting diode current, the sensing voltage representing the light emitting diode current in magnitude;
• receiving the sensing voltage;
• and
• generating a bleeder current based at least in part on the sensing voltage;
• wherein the generating a bleeder current based at least in part on the sensing voltage includes:
• if the light emitting diode current is larger than zero in magnitude, generating the bleeder current equal to zero in magnitude;
• and
• if the light emitting diode current is equal to zero in magnitude, generating the bleeder current larger than zero in magnitude;
• wherein the generating the bleeder current larger than zero in magnitude if the light emitting diode current is equal to zero in magnitude includes:
• increasing the bleeder current with the increasing rectified voltage in magnitude;
• and
• decreasing the bleeder current with the decreasing rectified voltage in magnitude;
• wherein a rectifier current generated by the rectifier is approximately equal to a sum of the bleeder current and the light emitting diode current in magnitude;
• wherein, with the light emitting diode current being equal to zero in magnitude, the rectified voltage and the rectifier current contribute to an active power to increase the power factor of the LED lighting system without any TRIAC dimmer.