The Reserch And Design Of High-Power Digital Trigger

Three-phase fully- bridge controlled rectifier is widely used in industry, can be adjusted by firing triggering angle to control the DC output voltage. In the rectifier system, the circuit of triggering pulse is critical, The forefront ,power and phase shift range of the pulse have a direct impact on the quality of the circuit. With the development of digital control technology, analog trigger who is made up by discrete components or integrated circuits is gradually replaced by digital trigger which can simplify the hardware, and improve the control precision. This paper introduces an digital trigger whose control core is microcontroller AT89S52.The high-power thyristors have high requirements of the triggering pulse , so the design is more difficult. In large-scale industrial systems, multiple inverters need high-power DC power supply and the high-power digital trigger who is used in 2000A rectifier unit is designed and developed .First this article fully introduces the theory and application of three-phase fully- bridge controlled rectifier , theoretically analyzes the requirements of high-power thyristor's triggering pulse, and designs the main circuit with a combination of theoretical and engineering experience, including the choices of thyristors, and other protective and detective devices.The paper introduces the hardware design of the high-power digital trigger , including the detective circuit, protective circuits, display circuits, sync signal input circuit, a pulse driver output circuit and so on. Environment for the industrial scene is more complex, so the trigger has the protection of overcurrent, overvoltage, overheating, and lack of phase. When an external fault happens, the trigger will in time to protect and make the system run more secure. The subject adopts a parametric approach , this can constantly monitor the working status of the trigger. This can not only expand the scope of application of the trigger, and make operation more convenient and flexible. Then the paper introduces the software of the digital trigger, gives the flow chart of main program and other branch program, describes the control method of the firing angle.It takes into account the interference of the system in the design of hardware and software. The trigger can still work properly in the industrial environment where the interference is srtong .The experiment of triggers found that the digital trigger is stable and its performance meets the design requirements. Finally, the paper concludes with the improvement of the trigger, and lay a good foundation for optimizing the technology in the future.