Systems and Methods for Over-Temperature Protection and Over-Voltage Protection for Power Conversion Systems

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

• a system controller including 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, and a second controller terminal configured to receive one or more input signals, the power conversion system further including a secondary winding and an auxiliary winding, the primary winding coupled to the secondary winding;
• a first resistor including a first resistor terminal and a second resistor terminal, the first resistor terminal being coupled to the second controller terminal;
• one or more first diodes including a first diode terminal and a second diode terminal, a first diode terminal being coupled to the second controller terminal;
• and
• a second resistor including a third resistor terminal and a fourth resistor terminal, the third resistor terminal being coupled to the second diode terminal;
• wherein the second resistor terminal is configured to receive an output signal associated with the auxiliary winding coupled to the secondary winding.

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 a first switching period and a second switching period;
• and
• a protection component configured to receive a first voltage signal associated with a first input current flowing through a resistor during the first switching period and receive a second voltage signal associated with a second input current flowing through the resistor during the second switching period, the first input current and the second input current being different in magnitude;
• wherein the 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 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.

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

• a first controller terminal configured to receive an input current;
• a first resistor configured to receive a first current and the input current and generate a first voltage based on at least information associated with the first current and the input current;
• a second resistor configured to receive a second current and generate a second voltage based on at least information associated with the second current;
• and
• a processing component configured to, in response to the first voltage becoming larger than a first voltage threshold in magnitude, increase the second voltage in magnitude, discharge a capacitor coupled to the processing component, and decrease a third voltage in magnitude associated with the capacitor.

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

• providing 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;
• receiving one or more first input signals during the one or more first switching periods;
• processing information associated with the one or more first input signals;
• determining 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;
• in response to the temperature associated with the power conversion system being larger than the predetermined temperature threshold, generating the drive signal to cause the switch open and remain open to protect the power conversion system;
• receiving one or more second input signals during the one or more second switching periods;
• processing information associated with the one or more second input signals;
• determining 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;
• and
• in response to the output voltage associated with the secondary winding of the power conversion system being larger than the predetermined voltage threshold, generating the drive signal to cause the switch to open and remain open to protect the power conversion system.

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

• providing 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 a first switching period and a second switching period;
• receiving a first voltage signal associated with a first input current flowing through a resistor during the first switching period;
• receiving a second voltage signal associated with a second input current flowing through the resistor during the second switching period, the first input current and the second input current being different in magnitude;
• and
• in response to a difference between the first voltage signal and the second voltage signal being larger than a predetermined threshold in magnitude, outputting a protection signal to generate the drive signal to cause the switch to open and remain open to protect the power conversion system.

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

• receiving an input current and a first current;
• processing information associated with the input current and the first current;
• generating a first voltage based on at least information associated with the first current and the input current;
• receiving a second current;
• processing information associated with the second current;
• generating a second voltage based on at least information associated with the second current;
• and
• in response to the first voltage becoming larger than a first voltage threshold in magnitude,
• increasing the second voltage in magnitude;
• discharging a capacitor, and
• decreasing a third voltage in magnitude associated with the capacitor.