Charging System and Dual Mode Power Conversion Circuit Thereof

A charging system, comprising:

• a power supplying unit configured to generate a direct current (DC) power source according to an input power source, wherein, in a switched-capacitor conversion mode, a direct current included in the direct current power source is constant;
• and
• a charging circuit, connected to the power supplying unit with a detachable manner, configured to convert the DC power source into a charging power source to charge a battery, wherein the DC power source and the charging power source respectively correspond to one and the other of a first power source and a second power source, wherein the charging circuit includes:
• an N-level Pulse Width Modulation (PWM) power converter, configured to switch electrical connections of an inductor and at least one capacitor in an N-level PWM mode to perform conversion between the first power source and the second power source;
• and
• a switched-capacitor power converter, configured to switch electrical connections of the at least one capacitor in a switched-capacitor conversion mode to perform conversion between the first power source and the second power source;
• wherein the N-level PWM power converter includes:
• a plurality of high-side switches serially coupled between the first power source and a switching node, wherein the plurality of high-side switches are sequentially coupled to at least one corresponding high-side intermediate node;
• and
• a plurality of low-side switches serially coupled between the switching node and a ground potential, wherein the plurality of low-side switches are sequentially coupled to at least one corresponding low-side intermediate node;
• wherein the plurality of high-side switches and the plurality of low-side switches are configured to periodically switch the electrical connections of the at least one capacitor in the N-level PWM mode, such that N-level voltages are generated at the switching node, enabling the inductor to perform conversion between the first power source and the second power source in an N-level pulse width modulation manner, where N is an integer equal to or greater than 3;
• wherein the switched-capacitor power converter includes:
• a plurality of shared switches, including a first portion of the plurality of high-side switches and a first portion of the plurality of low-side switches, wherein the shared switches are shared with the N-level PWM power converter;
• and
• a plurality of auxiliary switches, wherein the shared switches and the auxiliary switches are configured to periodically switch the electrical connections of the at least one capacitor in the switched-capacitor conversion mode to perform switched-capacitor power conversion between the first power source and the second power source;
• wherein in the switched-capacitor conversion mode, a second portion of the plurality of high-side switches and a second portion of the plurality of low-side switches are configured to remain non-conductive, such that a first terminal of the inductor is in a floating state;
• wherein in the N-level PWM mode, the plurality of auxiliary switches are configured to remain non-conductive, such that the at least one capacitor is not directly connected to the second power source;
• wherein during a mode transition between the N-level PWM mode and the switched-capacitor conversion mode, the power conversion circuit is configured to perform a soft-transition operation, in which, during a soft-transition period, when a first switch is in a conduction state while being periodically switched, a voltage at a control terminal of the first switch is controlled to a bias voltage to limit a first switch current flowing through the first switch;
• wherein the first switch corresponds to one of the plurality of high-side switches, the plurality of low-side switches or the plurality of auxiliary switches.