Investigation Of A Tesla Transformer For Water PFL Charging

In pulse power field, the high power pulse transformer type charging system with storage capacitors is widely used to substitute the traditional Marx generator for Pulse Forming Line (PFL) charging, because of its compact structure, small volume. The air-core pulse transformer has no magnetic saturation, but it has small coupling coefficient, low energy conversion efficiency and unsuitable for repetition applications. The traditional Tesla pulse transformer with magnetic core, which can operate repetitively to charge the oil-PFL due to its high coupling coefficient and high-energy conversion efficiency, however, it cannot be employed to charge water-PFL due to its long charging time, which may result in energy loss in the charging process, or water breakdown. Therefore, a high voltage pulse Tesla transformer for water-PFL charging is studied in the thesis.The main parameters of the high power Tesla pulse transformer such as magnetizing inductance, leakage inductance, coupling coefficient, resistance and core loss etc, are calculated. The circuit of Tesla transformer type-high power pulse modulator is analyzed, and the input and output voltage and current approximate expressions of the transformer are deduced. The calculation and derivation results are helpful in the Tesla transformer design.For the Tesla transformer type-high power pulse modulator based on water-PFL, the Pspice circuit analysis is used to model the modulator. To study the output voltage waveform effect by the parameter changes, the parameter sweep analysis is simulated for each part of the modulator. The electromagnetic field analysis on the transformer is carried out by employing an ANSYS software for calculating the electromagnetic field, which is based on the finite element method (FEM).On the base of the investigating of the magnetic material and insulation material, a Tesla transformer is designed and experimentally investigated. The parameter is measured with primary inductance 2.26μH, secondary inductance 1465.48μH and coupling coefficient 0.75. When the primary input voltage is 50kV, the transformer can charge the PFL to 720kV with an energy conversion efficiency of 36%.In the end, based on the theoretical calculation, simulation and experimental result, a structure of magnetic core and windings of high power Tesla pulse transformer is designed. The transient coupled-field analysis between circuit and magnetic field and the static electromagnetic field analysis are carried out by employing ANSYS software. The voltage and current waveforms of primary and secondary windings are obtained. The transient intensity distribution of magnetic field is also obtained. From the simulation, the primary inductance, secondary inductance and coupling coefficient of the high voltage pulse transformer are 5.24μH, 2506.56μH and 0.966, respectively.