Long-duration bipolar linear transformer driver based on a multi-turn half-bridge structure

Abstract

All-solid linear transformer driver(LTD) generators are widely used to output unipolar high-voltage rectangular pulses in nanoseconds. However in some applications, the bipolar output is necessary and the size of the generator is limited, which is challenging for LTD topology because the size of the magnetic core is related directly to the amplitude and pulse duration of the output waveforms. In this paper, a bipolar long-duration pulse generator based on the topology of a linear transformer driver combined with a half-bridge and multi-turn structure is put forward. The half-bridge topology can output bipolar waveforms easily and can save the number of switches used in the generator. To eliminate the crosstalk voltage that appears during operation, a differential mode inductance is used to protect the circuit. A snubber circuit is applied to suppress the reverse overshoot. The multi-turn design is chosen to make the size more compact. However, the multi-turn usually leads to a lower rise speed. To improve the performance, an optimization method that improves the rising speed by changing the turns of each stage is discussed. The strategy is useful and can be applied on some other occasions. The generator can output bipolar waveforms whose amplitudes are 4 kV and the duration can be adjusted from 200 ns to 800 ns. The rise time can be limited to 70 ns. The size of the generator is 10 cm * 10 cm * 15 cm, which is compact compared to the generators put forward before.