Power conversion system

A power conversion system, comprising:

• X power conversion circuits, where X is an integer larger than or equal to one, the power conversion circuit comprising:
• an input port configured to receive an input voltage;
• an output port configured to output an output voltage;
• N cascaded switching power conversion units, wherein each of the N switching power conversion units comprises a first switch and a second switch connected in series, the second switch is grounded, the first switch of the first switching power conversion unit is coupled to the input port, the first switch of any other of the N switching power conversion units is serially coupled to the first switch of the preceding switching power conversion unit, and N is an integer larger than or equal to 2;
• and
• N nodes, wherein the (n)th node is located between the first switch of the (n)th switching power conversion unit and the first switch of the (n+1)th switching power conversion unit, and the (N)th node is located between the first and second switches of the (N)th switching power conversion unit, and n is an integer larger than or equal to 1 and smaller than N;
• X bootstrap circuits electrically connected to the X power conversion circuits respectively, wherein in each of the X bootstrap circuits and the corresponding power conversion circuit, the bootstrap circuit comprises N bootstrap capacitors and N bootstrap switches, the N bootstrap switches are serially connected in sequence, the bootstrap switch has a first terminal and a second terminal, a negative electrode of the (n)th bootstrap capacitor is electrically connected to the (n)th node, a positive electrode of the (n)th bootstrap capacitor is electrically connected to the second terminal of the (n)th bootstrap switch, a negative electrode of the (N)th bootstrap capacitor is electrically connected to the (N)th node, a positive electrode of the (N)th bootstrap capacitor is electrically connected to the second terminal of the (N)th bootstrap capacitor, the first terminal of the (N)th bootstrap switch receives a supply voltage;
• and
• at least N driving circuits, wherein each of the X bootstrap circuits is electrically connected to the corresponding N driving circuits, in each of the X bootstrap circuits and the corresponding N driving circuits, the driving circuit is connected to the corresponding bootstrap capacitor, the driving circuit supplies power for driving the corresponding first and second switches according to a positive electrode voltage of the corresponding bootstrap capacitor and the supply voltage, and the driving circuit outputs a first driving signal and a second driving signal for controlling the corresponding first and second switches respectively.