Power conversion system

A power conversion system, comprising:

• a power switch;
• a driving circuit comprising a driving input terminal and a driving output terminal, wherein the driving output terminal is electrically connected to a gate of the power switch and configured to output a control signal to control the operation of the power switch;
• a voltage detection circuit electrically connected to a drain of the power switch and a voltage source and comprising a current source, a detecting switch and a detecting terminal, wherein the current source is electrically connected between the voltage source and the detecting terminal and configured to output a detecting current along a direction toward the detecting terminal, and the detecting switch is electrically connected between the detecting terminal and a drain of the power switch;
• and
• a logic circuit electrically connected to the current source, the detecting terminal, the driving circuit and a source of the power switch and comprising a first logic input terminal, a second logic input terminal and a logic output terminal, wherein the first logic input terminal is electrically connected to the current source, the second logic input terminal is configured to receive a PWM signal, and the logic output terminal is electrically connected to the driving input terminal, wherein the logic circuit is configured to determine whether a drain-source voltage of the power switch is less than zero through the detecting terminal, and the logic circuit outputs a first high-level voltage through the logic output terminal when the drain-source voltage of the power switch is less than zero, wherein the driving circuit outputs a second high-level voltage to the power switch through the driving output terminal according to the first high-level voltage, so that a gate-source voltage of the power switch is pulled high.