A Modular Multilevel Structure Impulse Voltage Generation Device

Some of the current mechanisms for dielectric breakdown are not fully understood.In order to study the physical phenomena of various media and devices under the impact voltage,in most scenarios,it is still necessary to rely on experiments for analysis.At this time,the impulse voltage generator plays a key role.In the current test,the Max circuit is usually used.The following problems exist.First,the discharge through the ball gap capacitor has the characteristics of distribution,and the discharge uncertainty may cause the synchronization problem of the experiment.Second,the highest value of the output surge voltage cannot be reached.DC voltage,there are efficiency problems;Third,due to different sample parameters,when the test load changes,the calculation of the wave head tail resistance needs to be matched to generate the lightning waveform.At present,scholars have used power electronic devices in the impulse voltage generator instead of the ball gap,which makes the trigger more controllable,but still belongs to the Max circuit.In the process of generating the surge voltage,it still needs to be different according to the The load reconfigures the wavefront resistor and the discharge resistor.In view of the above three problems,this paper proposes a surge voltage generator based on modular structure,and builds a simulation platform based on Matlab/Simulink simulation software,and finally builds a physical experiment platform to verify the structure of this structure relative to the traditional Max loop structure.Superiority and practicality.Firstly,based on theoretical derivation and analysis,the shortcomings of the traditional Max loop are studied.The function of the generator and the parameters of the standard lightning and operating surge voltage waveforms are introduced.The calculation of the equivalent circuit is deduced for the structural composition of the traditional Max circuit impulse voltage generator.Based on the software platform in Matlab,the impact voltage waveform is generated by using the Max equivalent circuit and the equivalent formula,and the output of the Max loop and the equivalent output of the formula are compared.A new modular structure of the impulse voltage generator structure was subsequently proposed.The structure of the switch tube is used instead of the ball gap trigger discharge,which solves the synchronization problem and reduces the interference,and the process of resistance matching can be omitted.The circuit components of the voltage doubling circuit and the modular multi-level structure and their respective working principles are specifically explained.The output equation of the modular structure is derived.Considering the circulation problem,a full-level modulation strategy is adopted to perform the loop suppression.The structure and dead zone concept of the voltage doubler loop are introduced.The basic theory of the modulation strategy and the process of capacitor charging and waveform generation are described.Then,in the Matlab/Simulink simulation software,the simulation platform of the Maxim circuit equivalent circuit and the 100-level output modular structure surge voltage device is built.Experiments under lightning and operational surge voltage were carried out and the simulation results were compared.The simulation experiment under the load change was carried out,and the output was compared.Considering that the surge voltage waveform only has a positive voltage value,it is possible to reduce the number of 3/4 sub-modules by simplifying the loop,reducing the cost and simplifying the control.Finally,a solid experimental platform is built on the basis of better simulation results.In the early stage,the screening and determination of experimental devices and related circuits were carried out.The FPGA control board is used to generate signals,and the circuit is isolated by the optical fiber line.Under the cooperation of the isolated power supply and the driving chip,a driving signal that meets the requirements is generated,and the switching of the silicon carbide MOS tube is controlled,thereby controlling the output of the sub-module.Since the delay spur parameter of the circuit will shorten the set dead time,a comparison of dead time is made.In the low-voltage experiment of single-stage sub-module and multi-level sub-module structure,the requirements of this structure in time and waveform compliance are verified.