Output overvoltage protection for a totem pole power factor correction circuit

A power factor correction (PFC) system comprising:

• an alternating current (AC) source configured to output a line voltage that changes a polarity at half cycles;
• a PFC circuit configured to receive the line voltage at an input and having a fast-leg portion;
• and
• a controller configured to:
• detect that the line voltage received at the PFC circuit is in a negative half cycle;
• transmit a PWM signal to a first transistor of the fast-leg portion of the PFC circuit for a conversion process corresponding to the negative half cycle, the conversion process generating a bulk voltage at an output of the PFC circuit;
• detect that the line voltage is at a first polarity change;
• pause the PWM signal;
• and
• transmit a pulse sequence to a second transistor of the fast-leg portion of the PFC circuit to change a voltage on an EMI capacitor from a first voltage corresponding to the negative half cycle to a second voltage corresponding to a positive half cycle.

A controller for a power factor correction (PFC) circuit, the controller configured to:

• detect that a line voltage received at the PFC circuit is in a negative half cycle;
• transmit a PWM signal to a first transistor of a fast-leg portion of the PFC circuit for a conversion process corresponding to the negative half cycle, the conversion process generating a bulk voltage at an output of the PFC circuit;
• detect that the line voltage is at a first polarity change;
• pause the PWM signal;
• and
• transmit a pulse sequence to a second transistor of the fast-leg portion of the PFC circuit to change a voltage on an EMI capacitor from a first voltage corresponding to the negative half cycle to a second voltage corresponding to a positive half cycle.