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We report on the first demonstration of a novel self starting DC-DC converter to supply power to a wireless sensor node for deployment in high temperature environments. Utilising SiC devices we have realised a novel boost converter topology which is suitable for boosting a low voltage to a level sufficient to power a sensor node at temperatures up to 300 °C. This topology is able to self start and so requires no external control circuitry, making it ideal for energy harvesting applications, where the energy supply may be intermittent. Here we demonstrate the potential of this topology to power a direct frequency modulated Colpitts oscillator for RF transmission, when used in conjunction with a thermoelectric generator.

A comparison of radiated noise for Silicon and Silicon Carbide converters is presented. SiC JBS diodes were used in this evaluation to enable fast switching times, whilst minimizing the transistor junction temperature. Radiated electromagnetic-interference measurements showed the highest noise signature for the SiC JFET and lowest for the SiC MOSFET. The negative gate voltage requirement of the SiC MOSFET introduces up to 6 dBµV increase in radiated noise, due to the induced current in the high frequency resonant stray loop in the negative power plane of the gate drive. The SiC JFET and MOSFET have shown overall converter efficiencies of 96% and 95.5% respectively. This efficiency shows only a weak frequency dependence, in contrast to the CoolMOS/SiC JBS diode combination which demonstrated an efficiency drop from 95% to 92.5% when increasing the frequency from 100kHz to 250kHz.

To fulfill the space and weight requirements of the photovoltaic systems, an all-SiC transformer less dc-dc multilevel converter based on the Cockcroft-Walton voltage multiplier capable of providing high voltage conversion ratios without an extremely high duty cycle has been realised. The evaluation of converter performance utilising SiC devices have been detailed and presented. The converter offers self-balancing which maintains the same output at all output levels, reducing the complexity of the control strategy. SiC Schottky diodes were used to achive lowest reverse recovery and fast switching while evaluating the high voltage and high frequency performance of the SiC MOSFET in the multilevel boost converter.

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