Isolation type positive-negative output constant current protective device

Abstract

The invention relates to an isolation type positive-negative output constant current protective device electrically connected with current output side phase, comprising a sampling circuit, an operation amplifying circuit electrically connected with the sampling circuit, an optical coupler isolation circuit and a primary side control circuit which is electrically connected with the operation amplifying circuit by virtue of the optical coupler isolation circuit; wherein the sampling circuit comprises a positive terminal sampling device electrically connected with positive terminal output phase and a negative terminal sampling device electrically connected with negative terminal output phase; the sampling circuit samples positive and negative output currents simultaneously, the sample signals are input into the operation amplifying circuit, the operation amplifying circuit judges whether output current reaches protection threshold, if yes, the operation amplifying circuit transmits the signal to the primary side control circuit by virtue of the optical coupler isolation circuit, and the primary side control circuit controls the output current to be in constant state. The invention can realize sampling on positive and negative output currents at secondary side, long-term constant current protection can be realized without damaging circuit while realizing positive and negative outputs, and structure is simple, thus being convenient for integration.

Description

technical field [0001] The invention relates to a power output short-circuit and overcurrent protection technology, specifically, an isolated positive and negative output constant current protection device applicable to isolated switching power supplies, motor drives and power amplifiers. Background technique [0002] Overcurrent protection devices are required in switching power supplies, motor drives, and power amplifiers to prevent circuit damage caused by overcurrent and short circuits. For isolated power supplies, motor drives, and power amplifiers, the peak input current of the primary side is generally detected. When the output is short-circuited or over-current, the input peak current will surge to trigger the protection circuit. When using this protection device, since the sampling of the primary current cannot accurately and timely reflect the change and state of the secondary output current, the device needs to withstand a large peak current when a short circuit o...

AI Technical Summary

Problems solved by technology

When using this protection device, since the sampling of the primary current cannot accurately and timely reflect the change and state of the secondary output current, the device needs to withstand a large peak current when a short circuit or overcurrent occurs, which affects the reliability of the circuit. There is damage, and the output cannot be protected effectively and for a long time

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