Systems and methods for two-level protection of power conversion systems

A system controller for regulating a power conversion system, the system controller comprising:

• a modulation component configured to receive a feedback signal associated with an output signal of a power conversion system and generate a modulation signal based on at least information associated with the feedback signal, the modulation signal being associated with a modulation frequency;
• a driving component configured to generate a drive signal based on at least information associated with the modulation signal and output the drive signal to a switch associated with a primary current flowing through a primary winding of the power conversion system, the drive signal being associated with the modulation frequency;
• and
• a two-level protection component configured to detect an output power of the power conversion system, generate a protection signal based on at least information associated with the output power of the power conversion system, and output the protection signal to the driving component;
• wherein the modulation component is further configured to:
• increase the modulation frequency from a first frequency magnitude to a second frequency magnitude in response to the feedback signal increasing from a first feedback magnitude to a second feedback magnitude;
• keep the modulation frequency at the second frequency magnitude if the feedback signal is larger than the second feedback magnitude and smaller than a third feedback magnitude;
• and
• increase the modulation frequency from the second frequency magnitude to a third frequency magnitude in response to the feedback signal increasing from the third feedback magnitude to a fourth feedback magnitude;
• wherein the driving component is further configured to:
• generate the drive signal corresponding to a first switching frequency to generate the output power equal to a first power threshold;
• and
• generate the drive signal corresponding to a second switching frequency to generate the output power equal to a second power threshold, the second power threshold being larger than the first power threshold, the second switching frequency being larger than the first switching frequency;
• wherein the two-level protection component is further configured to:
• in response to the output power being equal to or larger than the first power threshold for a first predetermined period of time, generate the protection signal to cause the switch to open and remain open to protect the power conversion system;
• and
• in response to the output power being equal to or larger than the second power threshold for a second predetermined period of time, generate the protection signal to cause the switch to open and remain open to protect the power conversion system, the second predetermined period of time being shorter than the first predetermined period of time.

A method for protecting a power conversion system, the method comprising:

• detecting an output power of a power conversion system;
• generating a protection signal based on at least information associated with the output power of the power conversion system;
• receiving the protection signal;
• processing information associated with the protection signal;
• generating a drive signal based on at least information associated with the protection signal;
• and
• outputting the drive signal to a switch associated with a primary current flowing through a primary winding of the power conversion system;
• wherein the generating a drive signal based on at least information associated with the protection signal includes:
• generating the drive signal corresponding to a first switching frequency to generate the output power equal to a first power threshold;
• and
• generating the drive signal corresponding to a second switching frequency to generate the output power equal to a second power threshold, the second power threshold being larger than the first power threshold, the second switching frequency being larger than the first switching frequency;
• wherein the generating a protection signal based on at least information associated with the output power of the power conversion system includes:
• in response to the output power being equal to or larger than the first power threshold for a first predetermined period of time, generating the protection signal to cause the switch to open and remain open to protect the power conversion system;
• and
• in response to the output power being equal to or larger than the second power threshold for a second predetermined period of time, generating the protection signal to cause the switch to open and remain open to protect the power conversion system, the second predetermined period of time being shorter than the first predetermined period of time.

A method for regulating a power conversion system, the method comprising:

• receiving a feedback signal associated with an output signal of a power conversion system;
• processing information associated with the feedback signal;
• generating a modulation signal based on at least information associated with the feedback signal, the modulation signal being associated with a modulation frequency;
• receiving the modulation signal;
• processing information associated with the modulation signal;
• generating a drive signal based on at least information associated with the modulation signal;
• outputting the drive signal to a switch associated with a primary current flowing through a primary winding of the power conversion system, the drive signal being related to the modulation frequency;
• detecting an output power of the power conversion system;
• generating a protection signal based on at least information associated with the output power of the power conversion system;
• and
• outputting the protection signal;
• wherein the generating the modulation signal based on at least information associated with the feedback signal includes:
• increasing the modulation frequency from a first frequency magnitude to a second frequency magnitude in response to the feedback signal increasing from a first feedback magnitude to a second feedback magnitude;
• keeping the modulation frequency at the second frequency magnitude if the feedback signal is larger than the second feedback magnitude and smaller than a third feedback magnitude;
• and
• increasing the modulation frequency from the second frequency magnitude to a third frequency magnitude in response to the feedback signal increasing from the third feedback magnitude to a fourth feedback magnitude;
• wherein the generating the drive signal based on at least information associated with the modulation signal includes:
• generating the drive signal corresponding to a first switching frequency to generate the output power equal to a first power threshold;
• and
• generating the drive signal corresponding to a second switching frequency to generate the output power equal to a second power threshold, the second power threshold being larger than the first power threshold, the second switching frequency being larger than the first switching frequency;
• wherein the generating the protection signal based on at least information associated with the output power of the power conversion system includes:
• in response to the output power being equal to or larger than the first power threshold for a first predetermined period of time, generate the protection signal to cause the switch to open and remain open to protect the power conversion system;
• and
• in response to the output power being equal to or larger than the second power threshold for a second predetermined period of time, generate the protection signal to cause the switch to open and remain open to protect the power conversion system, the second predetermined period of time being shorter than the first predetermined period of time.