Switching cycle adaptive control method for switching power supply

A switching cycle adaptive control system for a switching power supply, the system comprising:

• a bus voltage detection module, a loop control module, and a valley number mapping module;
• wherein the bus voltage detection module is configured to set a voltage threshold for a bus voltage and form voltage partitions by the voltage threshold;
• and the bus voltage detection module acquires the bus voltage and determines the voltage partition where the acquired bus voltage belongs;
• the loop control module is configured to set a power threshold for an output power of the switching power supply and form power partitions by the power threshold;
• the loop control module performs closed-loop control on a reference voltage and an output voltage of the switching power supply to acquire the output power of the switching power supply and determining the power partition where the acquired output power belongs;
• the valley number mapping module sets different reference valley numbers P for the voltage partitions respectively and sets different power valley numbers Q for the power partitions respectively;
• and the valley number mapping module determines a real-time reference valley number P and a real-time power valley number Q according to the voltage partition of the bus voltage and the power partition of the output power;
• the valley number mapping module adds the reference valley number P and the power valley number Q to obtain the number of valleys required for a switch element in the switching power supply to pass from turning off to next turning on, and controls the switch element to be turned on at (P+Q+1)th valley bottom;
• and
• when the output power is greater than 60% of a maximum output power of the switching power supply, the corresponding power valley number Q is 1;
• when the output power is greater than 50% of the maximum output power of the switching power supply and less than or equal to 60% of the maximum output power of the switching power supply, the corresponding power valley number Q is 2;
• when the output power is greater than 40% of the maximum output power of the switching power supply and less than or equal to 50% of the maximum output power of the switching power supply, the corresponding power valley number Q is 3;
• and when the output power is less than or equal to 40% of the maximum output power of the switching power supply, the corresponding power valley number Q is 4.