The invention discloses a method of optimizing
stress equilibrium in a
switching power supply, which comprises steps: a first
diode is used for building an
energy matching relationship among a first
capacitor, an
inductor and a
transformer, that is, when a switching tube is conducted, an exciting circuit of the
inductor and an exciting circuit of the
transformer are separated via the first
diode, when the switching tube is cutoff, the
inductor and the
transformer are connected via the first
diode, within a half
power frequency cycle, the first
capacitor is divided into a charging period and a non-charging period, and when the first
capacitor is in the non-charging period, the first diode is in a non-conduction period; the average power when the first capacitor is in the charging period and the average power when the first capacitor is in the discharging period are regarded as the same; and according to the
energy matching relationship among the inductor, the first capacitor and the transformer, the principle of
conservation of energy is used, and the inductor parameter selection range is calculated by the
capacitance value of the first capacitor, the transformer turn ratio and the source-side winding
inductance. Compared with the prior art,
voltage stress of each element can be balanced, and
electromagnetic interference caused by a large
voltage change rate can be reduced.