Passive isolation sampling circuit for output direct current of three-phase rectifier bridge

Abstract

The invention relates to a passive isolation sampling circuit for the output direct current of a three-phase rectifier bridge. The output direct current of the conventional three-phase rectifier bridge is sampled by a current divider, so that interference over the transmission of a signal line is easily produced. A three-phase rectifier bridge output circuit rectifies three-phase alternating current into direct current, and the direct current is transmitted to a load through a direct current filter reactor. The heavy three-phase alternating current is converted into alternating current signal voltage with low amplitude through an incoming current transformer and a current conversion resistor, and the three-phase alternating current signal voltage is converted into direct current signal voltage through a signal rectifier bridge by adopting a Y connection method. The amplitude of the direct current signal voltage completely corresponds to the direct current according to a certain sampling proportional relationship, the amplitude of the direct current is correspondingly displayed by a parallel direct current voltmeter, and the output of the signal rectifier bridge is connected in parallel with a capacitor for filtration. The Y connection method is adopted for independent sampling, so that an isolation property is high; and the sampling circuit is not required to be connected with a major loop, so that high voltage influence is avoided, loss and heat are reduced, and sampling safety and convenience are ensured.

Description

technical field [0001] The invention relates to a three-phase rectifier bridge output sampling circuit, in particular to a three-phase rectifier bridge output DC current passive isolation sampling circuit. Background technique [0002] The output sampling circuit of the three-phase rectifier bridge is used for sampling the output DC current. The existing DC output of the three-phase rectifier bridge is sampled by a shunt. The current sampling signal of the shunt is directly connected to the high-voltage main circuit. The transmission of the signal line is prone to interference, and the high-current shunt has a large heating power, which is prone to loss and heat generation. In addition, there is also an active circuit sampling using a Hall DC current sensor, which needs to provide a regulated DC power supply for the Hall sensor to work. The circuit is complicated and the cost is increased. SUMMARY OF THE INVENTION [0003] The purpose of the present invention is to design...

AI Technical Summary

Problems solved by technology

The existing three-phase rectifier bridge output DC sampling adopts shunt sampling, the current sampling signal of the shunt is directly connected to the high-voltage main circuit, the transmission of the signal line is prone to interference, and the heating power of the high-current shunt is relatively large, which is prone to loss and heat generation

In addition, there are active circuit samples using Hall DC current sensors, which need to provide a regulated DC power supply for the Hall sensor to work. The circuit is complex and increases the cost.

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