1. Switching: Power electronic devices operate in a switching state rather than a linear state
2. High Frequency: Power electronic devices operate at high frequencies rather than the low frequencies close to the working frequency.
3. Direct Current: The output of a switching power supply is direct current (DC), not alternating current (AC). The voltage feedback circuit of a linear power supply operates in a linear (amplification) state, while the switching power supply refers to tubes used for voltage adjustment that work in the saturation and cutoff regions, i.e., in the switching state. 400Hz Power Supply
