Design Of Pulse Excitation Source Used For Electromagnetic Loading

Stress wave signals will be produced at the crack of metal structures under the condition of electromagnetic loading, this phenomenon can be used to non-destructive test of metal defects. Pulse excitation source, as a core component of electromagnetic loading device, can output the current pulse of different parameters, such as, amplitude, frequency and so on, which have an obvious effect on the electromagnetic loading. According to requirements of electromagnetic loading, the design requirements of the pulse excitation source are as follows: the frequency of output pulse is continuously adjustable within the scope of low frequency, peak current is adjustable within 1200 A, pulse width is between 10 ~ 50?s.First of all, based on the half-bridge switching circuit theory, an adjustable power supply, which takes the mode of constant frequency pulse width modulation, was designed with MOSFET as the core. Secondly, the module of charging and discharging circuit is composed of a polypropylene capacitor used for storing energy and MTC500-16 as main switching device, using control system with STC89C52 as the core to achieve frequency adjustment, display and drive signal output of the main loop. Finally, by debugging and testing the pulse excitation source, its output parameters meet the design requirements.This power supply can work under the mode of DC adjustable power supply or pulse excitation source. As adjustable power supply, its voltage can be continuously adjusted between 0~300V. As pulse excitation source, its maximum output peak current is up to 1500 A,single loading or continuous and repeated loading can be easily achieved, it is conducive for electromagnetic loading smoothly applied to fatigue experiments.