Inductive current simulation circuit of switching circuit, inductive current simulation method of switching circuit, and switched-mode power supply

An inductive current simulation method of a switching circuit, wherein the switching circuit comprises a main power transistor and a synchronous rectifier, and the inductive current simulation method comprises the following steps:

• based on an error amplification circuit, performing an error amplification on a first sampling signal representing a current of the synchronous rectifier and a second sampling signal representing an inductive current simulation signal when the synchronous rectifier is turned on to obtain an error amplification signal;
• and
• reconstructing an inductive current according to the error amplification signal when the synchronous rectifier is turned on and a first current when the main power transistor is turned on to obtain the inductive current simulation signal, wherein the first current is generated according to the inductive current simulation signal, a topological structure of the switching circuit, an input voltage and an output voltage, and wherein a charging current of a first capacitor is set according to the inductive current simulation signal, and a discharging current of the first capacitor is set according to the charging current, the topological structure of the switching circuit, the input voltage and the output voltage;
• the first capacitor is charged with the discharging current throughout a work cycle, and the first capacitor is discharged with the discharging current during a conduction period of the main power transistor;
• and a voltage of the first capacitor drives a first switching transistor, and a current of the first switching transistor is the first current.

A switched-mode power supply, comprising an inductive current simulation circuit to simulate an inductive current of a switching circuit, wherein the switching circuit comprises a main power transistor and a synchronous rectifier, and the inductive current simulation circuit comprises:

• an error amplification circuit, configured to receive a first sampling signal representing a current of the synchronous rectifier and a second sampling signal representing an inductive current simulation signal in a conduction stage of the synchronous rectifier, and output an error amplification signal;
• and
• an output current generating circuit, configured to generate the inductive current simulation signal, wherein in the conduction stage of the synchronous rectifier, the error amplification signal drives the output current generating circuit, and in a conduction stage of the main power transistor, the output current generating circuit is driven by a first current, wherein the inductive current simulation circuit further comprises a first current generating circuit, configured to generate the first current according to the inductive current simulation signal, a topological structure of the switching, circuit, an input voltage and an output voltage, and wherein the first current generating circuit comprises a first capacitor and a first switching transistor, a charging current of the first capacitor is set according to the inductive current simulation signal, and a discharging current of the first capacitor is set according to the charging current, the topological structure of the switching circuit, the input voltage and the output voltage;
• the first capacitor is charged with the charging current throughout a work cycle, and the first capacitor is discharged with the discharging current during a conduction period of the main power transistor;
• and a voltage of the first capacitor drives the first switching transistor, and a current of the first switching transistor is the first current.