Research On Radar Pulse Modulator With Series Connection Of IGBT

The hydrogen thyratron as discharge switch of modulator in the troop's air-defense warning radar are used in large quantities. But when it is used in high altitude and cold area, it has got lots of problems, such as long preheating time, unsteady operation, high fault ratio. These issues have seriously impaired the accomplishment of the forces combat mission . Beause of the immovable pulse width of hydrogen thyratron modulator, it is not suitable for the special situation that require changing pulse width of hydrogen thyratron modulator in the modern air defence. And then the emergence and popularity of the full controlled high power solid state switching IGBT cause the probablity that it may be a kind of new discharge switch of modulator. But at present, beause of the limitation of the IGBT's withstanding voltage, it cann't meet the high voltage level of high power modulator, so series connection is applied. The technical study has important theoretical and practical value.In the paper, a new structure of rigid pulse modulator was presented. The main circuit of 3kV rated voltage rigid modulator on series IGBT was designed. The equivalent models of pulse modulation front, top and back along the process of forming were also established respectively. And detailed analysis of the pulse modulation mechanism was done. Thus it was proved that the solid rigid system modulator practical program was effective. Secondly, we designed a series IGBT driver for the smart drive circuit and protection circuit, completed the 3kV grading Series IGBT modulator driver circuit protection program design, and gave the driver protection circuit parameters calculated. Then static and dynamic switching model of IGBT was established and the reasons of voltage imbalance in series IGBT were further analyzed. A balanced voltage approach was presented, and so a side gate passive pressure control circuit was designed. Third, modulation voltage circuit parameters of a 3kV class IGBT series were calculated. Experimental circuit of pressure balancing was established and a series of simulations and experimental verification were done. Experimental results are very good.Application series IGBT switching modulation as a group, the radar pulse modulation form can be changed, thus a new rigid structure of pulse modulator was achieved. Based on such a rigid modulator, comprehensive and in-depth analysis of its operation mechanism and load suitability were finished. A method was presented for static and dynamic voltage imbalance problem of series IGBT. Theoretical analysis and experimental results show that the method is feasible.