An air insulated linear pulse transformer for electrodischarge technology

A linear pulse transformer with air insulation at atmospheric pressure was created and tested under both constant resistance and non linear loads. The maximum power of the transformer output pulse reached ∼500 MW at a matched load with a charge voltage 50 kV. The transformer transferred ∼60% of the stored energy to the load over a characteristic time of about 1 μs. The scalability the generator was studied by connecting two identical transformers in series which gave a power output of ∼850 MW with doubled output voltage and reduced current. The frequency mode of operation was studied using one and two transformers with a charge voltage of 50 kV and a load that was, close to matched. In both cases, the power maximum and jitter showed no significant changes at any of the frequencies tested (up to 5 Hz). These results mean that the use of this generator can be recommended for a wide field of applications due to its scalability and low internal impedance.

Compact High-Voltage AC Generator with Pulse Transformer for High-Frequency Irreversible Electroporation (H-FIRE)

This paper is focused on a design of a high-voltage (HV) generator, which is proposed for a high-frequency irreversible electroporation (H-FIRE). The generator produces bursts of bipolar symmetrical pulses. Most HV sources used for cell electroporation are based on a controlled discharge of a capacitor into a resistive load. This solution is very simple, but it is associated with a certain risk of an uncontrolled discharge of the capacitor. We present a different type of the generator, where a DC-AC inverter with pulse transformer is used and where the mentioned risk is eliminated. Our generator is able to deliver bursts with variable length from 50 to 150 μs and a gap between bursts can be set from 0.5 to 1.5 s. Pulse frequency can be varied from 65 to 470 kHz and the output voltage is controlled in two ranges from 0 to 1.3 kV or from 0 to 2.5 kV. Results are presented with resistive load and with tissue impedance load.

Design and Comparison of the Performance of 12-Pulse Rectifiers for Aerospace Applications

In this paper, a conventional 12-pulse transformer unit (CTU) and an autotransformer 12-pulse transformer unit (ATU) are compared in the view of the RTCA DO-160 standard for aircraft applications. The design of the magnetic components is proposed via a coupled FEM-circuital analysis in the time domain for an 800 Hz/2 kW system. Input AC distortion, power factor, and output DC ripple are evaluated through simulations. An accurate power loss analysis is carried out, taking into account copper losses, magnetic losses, and power losses due to power switches. The reduction in the size and weight of the ATU with respect to the CTU solution is discussed, including the need for filtering systems and the standard requirements.

Investigating the Shielding Effect of Pulse Transformer Operation in Isolated Gate Drivers for SiC MOSFETs

Wide-bandgap technology evolution compels the advancement of efficient pulse-width gate-driver devices. Integrated enhanced gate-driver planar transformers are a source of electromagnetic disturbances due to inter-winding capacitances, which serve as a route to common-mode(CM) currents. This paper will simulate, via ANSYS Q3D Extractor, the unforeseen parasitic effects of a pulse planar transformer integrated in a SiC MOSFET gate-driver card. Moreover, the pulse transformer will be ameliorated by adding distinctive shielding layers aiming to suppress CM noise effects and endure high dv/dt occurrences intending to validate experimental tests. The correlation between stray capacitance and dv/dt immunity results after shielding insertion will be reported.