Why is the switching power supply using a high-frequency transformer small in size?

The reasons for the small volume of switching power supplies using high-frequency transformers mainly include the following aspects:
1. The high-frequency transformer in the switching power supply works at a frequency much higher than the power frequency (such as 50/60Hz), usually at a few kHz to tens of kHz or even MHz level. According to the inductance formula, under the requirement of a certain inductance value, the higher the frequency, the fewer coil turns are required, because the inductive reactance is proportional to the frequency.

2. Reduce the size of the core At high frequencies, the loss of the transformer core (or magnetic core) mainly comes from eddy current loss and hysteresis loss, both of which will increase with the frequency. In order to reduce these losses, high-frequency transformers use high permeability and low loss materials such as thin silicon steel sheets or amorphous alloys, and their cross-sectional area will be much smaller than the power frequency transformer, which greatly reduces the core volume of the transformer.

3. Optimized structure High-frequency transformers can use more compact winding and efficient heat dissipation design, such as flat transformers or ring transformers, to further reduce space occupation.

4. Efficiency improvement High frequency switching power supply adjusts the output voltage through PWM (pulse width modulation) technology to control the duty cycle of the switching components, rather than relying solely on the electromagnetic induction proportional relationship, which allows the use of simpler filtering circuits and fewer energy storage components, improving the integration of the overall power supply.

5. The output ripple suppression high-frequency switching action can provide fast response and accurate control, which is conducive to reducing the output voltage ripple, and then simplify the subsequent filtering circuit, making the entire power system more miniaturized. Because of its high-frequency operating characteristics, material selection and the advantages of the power conversion mechanism, the high-frequency transformer can greatly reduce the size in the case of realizing the same function, so that the switching power supply using the high-frequency transformer can achieve miniaturization and lightweight design.