High-Bandwidth Sensing for Wide-bandgap Power Conversion

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This project develops new sensing technology for use in power electronic systems, helping the UK to better compete with global leaders in power electronics. Power electronics is a key electrification technology: it is needed in electric vehicles, renewable energy generation, our electricity grid, and anywhere where the flow of power needs to be accurately dosed. This dosing is carried out by rapidly switching currents on and off to create the desired average. This technology reduces our carbon footprint and contributes nearly £50bn per year to the UK economy and supports 82,000 skilled jobs in over 400 UK-based companies (2016 data).The power electronics industry is undergoing significant change, as ultra-fast transistors made from silicon carbide (SiC) or gallium nitride (GaN) have recently emerged, to replace silicon transistors.These new transistors switch 10x faster, which results in 75% less energy being lost in power converters, and enables converters to be shrunk to less than half their previous size. This makes it much easier to build them into other systems, e.g. electric vehicles, resulting in lighter cars with more space for batteries.This project is about helping to maximise the potential of the new transistors. Many companies are struggling to adopt them, because whilst the very fast switching provides the benefits of improved efficiency and radically smaller system size, it also creates problems with electromagnetic interference, and device and system reliability. The transistors switch current on or off so fast (in less than ten nanoseconds, the time it takes light to travel 3 meters), that engineers cannot accurately measure how the voltages and currents change during this time, even with their best equipment, which means it is difficult to fix problems such as interference. Because of this, even the leading companies are slowing down these new transistors, and losing some of their efficiency potential.Our project develops small, low-cost sensors, that make these nanosecond-scale changes visible. They will allow engineers to see exactly how the transistors are switching, helping them develop better, smaller, lighter, and more reliable power electronics. They will allow computer-controlled SiC and GaN power converters to sense when they are creating too much electromagnetic noise, and reduce this by switching more intelligently. It will allow power circuits to detect external short circuits and isolate these before they damage the power converter. We are also developing sensors that provide engineers, or control systems, directly with information that they need (e.g. device temperature), rather than having to infer this indirectly from volts and amps, making the measurements faster and more efficient.The sensors work by detecting electric or magnetic fields via coils, conductive plates, or antennas. The received signal is fed into a chip inside the sensor that computes the required parameter. These new SiC and GaN transistors have made small field sensors on circuit boards viable for the first time, because as signal speeds increase, the wavelengths of these signals become shorter (cm-scale), meaning that their fields can be picked up with millimetre-size coils or antennas. In order to ensure that we develop what industry needs, we are working with 12 partners across automotive, renewable energy, semiconductors, commercial R&D organisations with deep sector experience, and we are accepting new collaborators on request. Our project provides partners and other UK companies and universities with sample sensors. Their feedback, and discussions with partners helps us prioritise our research, and ensures that we are using our research funds to solve the most important problems. We are providing workshops to help keep engineers up-to-date with advanced measurement techniques, and keeping our results online (publications and a dedicated website) for companies to use as desired.