Problems of feedback circuit of dual-output switching power supply

If your appliance uses the same amount of electricity for two power supplies, as long as the output impedances of the two power supplies are relatively balanced, you can use two series connections between the positive pole of the positive power supply and the negative pole of the negative power supply for sampling.

If it is unbalanced, choose the one with large output current as the main circuit, and use inductive coupling (tight coupling) to stabilize the voltage with small current. Generally, this effect is also very good. This is how most power supplies are used. It is also a better method.