Systems and methods for over-temperature protection and over-voltage protection for power conversion systems

摘要

Systems and methods are provided for protecting a power conversion system. A system controller includes a first controller terminal and a second controller terminal. The first controller terminal is configured to provide a drive signal to close and open a switch to affect a first current flowing through a primary winding of a power conversion system. The second controller terminal is configured to receive first input signals during one or more first switching periods and receive second input signals during one or more second switching periods. The system controller is configured to determine whether a temperature associated with the power conversion system is larger than a predetermined temperature threshold, and in response to the temperature associated with the power conversion system being larger than the predetermined temperature threshold, generate the drive signal to cause the switch open and remain open to protect the power conversion system.

主权项

1. A system controller for protecting a power conversion system, the system controller comprising:
a first controller terminal configured to provide a drive signal to close and open a switch to affect a first current flowing through a primary winding of a power conversion system, the drive signal being associated with one or more switching periods including one or more first switching periods and one or more second switching periods; a second controller terminal configured to receive one or more first input signals during the one or more first switching periods and receive one or more second input signals during the one or more second switching periods; and an over-temperature-protection component configured to receive a first voltage signal associated with a first input current flowing through a first resistor during a third switching period of the one or more first switching periods and receive a second voltage signal associated with a second input current flowing through the first resistor during a fourth switching period of the one or more first switching periods, the first input current and the second input current being different in magnitude; wherein the system controller is configured to:
process information associated with the one or more first input signals;determine whether a temperature associated with the power conversion system is larger than a predetermined temperature threshold based on at least information associated with the one or more first input signals; andin response to the temperature associated with the power conversion system being larger than the predetermined temperature threshold, generate the drive signal to cause the switch to open and remain open to protect the power conversion system; wherein the system controller is further configured to:
process information associated with the one or more second input signals;determine whether an output voltage associated with a secondary winding of the power conversion system is larger than a predetermined voltage threshold based on at least information associated with the one or more second input signals; andin response to the output voltage associated with the secondary winding of the power conversion system being larger than the predetermined voltage threshold, generate the drive signal to cause the switch to open and remain open to protect the power conversion system; wherein the over-temperature-protection component is further configured to, in response to a difference between the first voltage signal and the second voltage signal being larger than a first predetermined threshold in magnitude, output a protection signal to generate the drive signal to cause the switch to open and remain open to protect the power conversion system.