A device that can make a constant current form in the circuit, such as a dry battery, a storage battery, a DC generator, etc., is called a DC power supply. DC power supply has two electrodes, positive and negative, the potential of the positive electrode is high, and the potential of the negative electrode is low; When the two electrodes are connected to the circuit, the DC power supply can maintain a constant potential difference between the two electrodes, thus forming a constant current from the positive electrode to the negative electrode in the external circuit.

In order to keep the potential difference between the two poles of the DC power supply constant, the positive charge flowing from the positive electrode to the negative electrode in the external circuit must return from the negative electrode to the positive electrode in the direction of the electric field force in the power supply. This process cannot be achieved by electrostatic force, but only by some kind of "non-electrostatic force" that is opposite to the direction of the electrostatic force. The role of the AC-DC power module.

Isolation:

1. Safety isolation: strong and weak current isolation, IGBT isolation drive, surge isolation protection, lightning isolation protection (such as isolation protection of medical electronic equipment in contact with the human body).

2. Noise isolation: (isolation of analog circuit and digital circuit, isolation of strong and weak signals). Grounding loop elimination: remote signal transmission distributed power supply system. Protection Short-circuit protection, over-voltage protection, under-voltage protection, over-current protection, and other protections.

3. Voltage conversion Boost Conversion Buck Conversion AC/DC Conversion (AC/DC, DC/AC) Polarity Conversion (Positive and Negative Polarity Conversion, Single Supply and Positive and Negative Supply Conversion, Single Supply and Multiple Supply Conversion) Fourth, voltage stabilization AC mains power supply, remote DC power supply, distributed power supply system, battery power supply.