Conversion system and conversion method

A conversion method, applicable to a conversion system, wherein the conversion system comprises:

• a conversion unit, comprising:
• a first bridge arm, comprising a first switch and a second switch that are connected in series in a same direction;
• a second bridge arm, comprising a first conduction element and a second conduction element that are connected in series in a same direction, wherein the second bridge arm is connected in parallel to the first bridge arm;
• an input inductance element, coupled to a first center point of the first bridge arm, wherein the input inductance element and a second center point of the second bridge arm are configured to be coupled to a power supply;
• a main capacitor element and an magnetizing inductance element, wherein the main capacitor element and the magnetizing inductance element are connected in series and connected in parallel to the second bridge arm;
• and a voltage transformation element, wherein a primary side of the voltage transformation element is connected in parallel to the magnetizing inductance element;
• and a control unit, wherein the conversion method comprises the following steps performed by the control unit:
• (a) generating a first duty cycle based on an output voltage of the conversion unit;
• (b) controlling, based on the first duty cycle, the first switch and the second switch to be simultaneously turned on in an interval within a switching interval;
• and
• (c) prolonging turn-on of one of the first switch and the second switch according to a polarity of an input voltage generated by the power supply until a stop condition is met.