High bandwidth non-resonant high voltage generator for X-ray systems

High-voltage supplies for medical X-ray systems require up to 150 kV DC at up to 100 kW to supply the tube. The challenge for the power supply however is not only to deal with the high voltage and high power demand, but also to provide short voltage rise- and fall times in the range of 100μs. A coupled interleaved circuit variant of a single active bridge concept, the coupled interleaved single active bridge converter, is demonstrated in this work providing very fast output voltage control due to its non-resonant structure. The conduction modes of the circuit are analysed in detail and compared to the uncoupled interleaved single active bridge approach, demonstrating the advantages of low inverter RMS current, zero voltage switching (or at least zero current switching) over the full operating range with constant switching frequency. Analytic expressions for the output current-duty cycle relationship are provided. Experiments on a 60 kW (low voltage equivalent) prototype show that rise times as low as five switching cycles are possible, allowing to reach the target of 100μs rise time using a switching frequency of only 50 kHz.