Control method for achieving independent zero crossing turn-off of three-phase current

Abstract

The invention relates to a control method for achieving independent zero crossing turn-off of three-phase current. The method comprises the steps of treating three N channel insulated gate field effect tubes as a solid-state power controller in a three-phase current load circuit so as to enable complete independence of three-phase triggering loops; operating zero crossing turn-off logic of the current by the combination of an analog circuit and a digital circuit; outputting to driving circuits of the three independent N channel insulated gate field effect tubes; outputting transient DC high voltage through the driving circuits; the three-phase current is in a form of three independent analog channels; the digital signals are synchronously converted through three A / D converters; the three-phase N channel insulated gate field effect tubes are completely independent from each other. With the adoption of the method, the drop voltage and the power consumption can be obviously reduced, thus the AC current zero crossing turn-off can be achieved; the shortages of the original synchronous three-phase triggering are overcome, the power consumption of each phase vacuum tube can be obviously reduced, and the electromagnetic interface can be removed.

Description

[technical field] [0001] The invention relates to the technical field of switch control in an alternating current load circuit, in particular to a control method for realizing independent zero-crossing shutdown of three-phase current. [Background technique] [0002] In the traditional AC power distribution system, contact switches are used, and mechanical circuit breakers are connected in series in the power supply circuit to realize power distribution. The mechanical contact parts often move to cause mechanical wear, and the contacts often break a large current to form an arc, which affects the life of the switch. Moreover, at the moment of turning on and off the load circuit, the arc generated by sudden changes in voltage and current is likely to ablate the contacts, causing electromagnetic interference, increasing the on-state resistance, increasing the heat generated by the switch itself, and affecting the reliability of electrical equipment. . An effective way is to r...

AI Technical Summary

Problems solved by technology

At present, many thyristors are used as AC solid-state power switches. Although the thyristors are turned on quickly and can be triggered by zero crossing, the operating frequency is low and the turn-off time is long, especially in the case of a large loop current, such as a short circuit state. Need to wait until the zero-crossing trigger, the current flowing through the thyristor lasts too long, which is easy to cause thermal damage. On the other hand, the conduction voltage drop of the thyristor is relatively large, which is not suitable for high-voltage systems and requires high heat dissipation.

Images