Research Of Electrical Fast Transient (EFT) Generator

Electrical Fast Transient (EFT) generator is one of the testing equipments for electromagnetic compatibility, that simulates interference produced by switching of little inductive load, contact bounce of relay or switching of high-tension switchgear. It is very important equipment for electrical fast transient (EFT) testing and has become the important tool in the electromagnetic compatibility design of the products with national compulsory certification put in practice. Pulse train generators on the domestic market is mostly imported from abroad at present, which adopt the advanced semiconductor device, and cost very high, it is difficult to bear to the general manufactures. Works in this paper adopts hydrogen thyratron as the switch of mainly discharging circuit. Comparing with semiconductor switch, it can be with higher tolerance voltage and bear large rate of change of electric current of voltage and work reliable. Hydrogen thyratron can be use to improve stability, reduce cost. To make full use of thyratron performance, we design a better triggering circuit and optimize the main return circuit to reduce loop inductance, that ensure the pulse produced meet the demand of qualifications. In the instrument a system of MCU is applied to charge voltage collect, convert and operate, and then makes the communication interface circuit with LED display, and realizes the computer intellectual control.In addition, in order to reduce the volume and weight of the generator, improve the efficiency of the power, we replace the past linear power with switch power supply. In order to restrain strong electromagnetic radiation and electromagnetic interference produced by switch power supply, we use the balance transformer to restrain high-frequency transformer's radiation, and then analyze equivalent circuit to reduce electromagnetic radiation greatly. An improved filter is used to restrain common mode interference and difference mode interference. In order to improve the whole anti-interference of circuit, we also design a new-type mere optoelectronic isolating circuit. All these measures improved the EMC of switch power supply greatly, can make it run steadily in the complicated electromagnetic environment.It has been proved by experiments that the pulse train generator has a favorable interface, can be handled simply and cost low.