Control method and device for switching power supply and switching power supply

The invention provides a control method and device for a switching power supply and a switching power supply The method comprises the following steps of: acquiring an input electrical parameter, an output electrical parameter, an output load value and an energy storage inductance value of the switching power supply; calculating the duty ratio of the switching power supply according to the input electrical parameter and the output electrical parameter; and calculating the critical frequency of the switching power supply according to the duty ratio, the output load value and the energy storage inductance value, and controlling the switching power supply to work at the critical frequency, so as to make the switching power supply work in a CRM mode. The working reliability of the switching power supply can be improved. 本发明提供一种开关电源控制方法、装置及开关电源。该方法包括：获取开关电源的输入电参数、输出电参数、输出负载值和储能电感值；根据输入电参数和输出电参数计算开关电源的占空比；根据占空比、输出负载值和储能电感值计算开关电源的临界频率，并控制开关电源以临界频率工作，以使开关电源工作在CRM模式。本发明能够提高开关电源工作的可靠性。