A high power factor constant current control circuit with open circuit protection

Abstract

The invention belongs to the technical field of constant-current driving and provides a high-power-factor constant-current control circuit with open circuit protection. According to the high-power-factor constant-current control circuit with the open circuit protection, an open circuit protection control circuit is added to a constant-current driving chip, the open circuit protection control circuit outputs an open circuit detection signal to a pulse signal generating circuit when an open circuit happens to load, the pulse signal generating circuit drives a switch circuit to be switched on and switched off according to the open circuit detection signal, and therefore the purpose of open circuit protection is achieved. Compared with an open circuit protection achieving method of an existing active power factor corrector, the high-power-factor constant-current control circuit with open circuit protection is small in size, small in area of occupied board surface, low in cost and high in reliability due to the fact that use of an auxiliary winding and a divider resistor or a clamper tube of a transformer is avoided.

Description

technical field [0001] The invention belongs to the technical field of constant current driving, and in particular relates to a high power factor constant current control circuit with an open circuit protection function. Background technique [0002] Obtaining alternating current from the power grid and supplying power to load equipment after rectification is a common conversion scheme. However, if the power factor of the load equipment connected to the AC grid is low, it will cause a certain degree of harmonic pollution to the public grid. [0003] In the field of constant current drive technology, in order to meet the high power factor requirements of the load equipment while satisfying the constant current drive, the following two implementation methods of the constant current drive control circuit are currently proposed: [0004] 1. On the basis of the traditional power conversion circuit, a corresponding passive power factor correction circuit is added to meet the requ...

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Problems solved by technology

[0010] The purpose of the embodiment of the present invention is to provide a high power factor constant current control circuit with open-circuit protection, aiming at solving the problem of high cost due to the implementation of open-circuit protection of the existing active power factor corrector or the feedback method of the auxiliary winding of the transformer , Occupy a large area and have poor reliability, or connect the clamp tube at the output end of the switching power supply in parallel, resulting in high cost and poor reliability

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