Voltage protection circuit of switching power supply, method and switching power supply

Abstract

The invention discloses a voltage protection circuit of a switching power supply, a method and the switching power supply and relates to the technical field of power. The protection circuit comprisesa relay, wherein a normally-closed contact of the relay is arranged in a secondary-side circuit of the switching power supply, and an exciting coil of the relay is electrically connected with the secondary-side circuit; when a primary-side winding group and a secondary-side winding group of a transformer are isolated to fail and the secondary-side voltage on the secondary-side circuit is the inputvoltage of the primary-side winding group of the transformer, the secondary-side voltage is used for supplying exciting voltage to the exciting coil; the normally-closed contact is cut off so as to cut off the secondary-side circuit. The voltage protection circuit, the method and the switching power supply disclosed by the invention have the advantages that when the primary-side winding group andthe secondary-side winding group of the transformer are short-circuited or isolated to fail, the secondary-side circuit and the loads at the rear end can be disconnected by the relay of the protection circuit, so that the purpose of protecting the safety of experimenters and the loads at the rear end can be achieved; the product intellectualization is improved and the use experience of a user isimproved.

Description

technical field [0001] The invention relates to the field of electric power technology, in particular to a voltage protection circuit and method of a switching power supply and a switching power supply. Background technique [0002] Switching power supply is a kind of power supply that uses modern power electronic technology to control the time ratio of switching on and off to maintain a stable output voltage. There are many types of switching power supplies, such as forward and flyback single-ended switching power supplies. The primary side winding of the transformer in the switching power supply is connected to the bus potential of the strong current range, and the DC voltage output by the secondary side winding generally belongs to the weak current range. The primary side winding and the secondary side winding are isolated by magnetic coupling. When there is an abnormal situation such as a short circuit between the transformer primary side winding and the transformer sec...

AI Technical Summary

Problems solved by technology

For example, if the load is a signal isolation chip, when the primary side winding of the transformer is short-circuited with the transformer secondary side winding, the high DC voltage of the bus will be connected to the signal isolation chip along with the secondary side circuit. If the power ground is the bus reference point, the signal isolation chip may be broken down

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