| CPC H02M 3/156 (2013.01) | 10 Claims |

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1. A switching cycle adaptive control method for a switching power supply, comprising:
setting a voltage threshold for a bus voltage and forming voltage partitions based on the voltage threshold; acquiring the bus voltage and determining which voltage partition of the formed voltage partitions the acquired bus voltage belongs to;
setting a power threshold for an output power of the switching power supply and forming power partitions based on the power threshold; performing 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 which power partition of the formed power partitions the acquired output power belongs to;
setting different reference valley numbers P for the voltage partitions respectively; setting different power valley numbers Q for the power partitions respectively; determining 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;
adding the real-time reference valley number P and the real-time power valley number Q to obtain a number of valleys required for a switch element in the switching power supply to pass from turning off to next turning on, and controlling the switch element to be turned on at (P+Q+1)th valley bottom; and
adjusting a frequency of a pulse-width modulation (PWM) signal of the switching power supply according to the number of valleys required to pass,
wherein when the output power is greater than 60% of a maximum output power of the switching power supply, a 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, a 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, a 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, a corresponding power valley number Q is 4.
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