2021 Scott Medal: Cost-effective superconductors
Dr Zhenan Jiang, a Principal Scientist at the Robinson Research Institute, has been presented the Scott Medal by Royal Society Te Apārangi for global leadership in measuring and modelling the response of superconductors, leading to cost-effective superconducting machines.
The medal is presented for an outstanding contribution towards advancing a branch of engineering sciences, technologies, and their applications.
High Temperature Superconductors (HTS) offer the promise of very low energy losses and increased power in electrical machines. However, the time-varying currents and magnetic fields typically found in these machines create electrical losses and generate excess heat. These efficiency losses and additional need for costly cryocooling negatively impact on HTS's commercial advantages.
Zhenan has developed the demanding measurement techniques required to understand the relationships between energy losses and magnetic fields, computational modelling to allow its prediction, and engineering methodologies to support its application. This work has been widely cited and is being applied in the development of HTS electrical machines. He has made significant contributions to the research field regarding the design and analysis of a wide range of applications, including electrical machines, flux pumps, magnets, transformers and cables.
His work is supporting development of next-generation superconducting electrical machines, which will be a key technology for the electrification of aircraft, low-noise and low-emission transportation, lighter and faster high-speed trains, and compact fusion systems.
Zhenan has significantly advanced understanding of the response of type-II superconductors – in wire, cable and coil forms, to time-varying applied currents and magnetic fields.
To achieve this, Zhenan developed and implemented the very demanding measurement techniques to quantify the energy losses. The difficulty is because the measured voltages have two components: a loss and dispersion component that are close to 90 degrees out-of-phase, and in superconductors the loss component can be very small.
He has combined these world-leading and extensive experimental measurement techniques to quantify superconducting losses with his strong theoretical understanding via advanced analytical and numerical methods.
Implementing both methodologies to calculate alternating current loss in actual machines ensures and simplifies machine optimisation. This has enabled much more rapid and lower cost development of cost-effective superconducting electrical machinery – wires, cables, magnets, transformers, and rotating machines. Previously developers relied upon ad hoc experimentation on a case-by-case basis.
More recently he has tackled the complicated and challenging problem of dynamic resistance, where a time-varying magnetic field interacts directly with a DC current. This phenomenon is of particular importance for ensuring highly efficient and cost-effective operation of electrical machines and flux pumps. HTS flux pumps allow the transfer of current into a cryostat, replacing thermally leaky current leads. These pumps address a significant source of loss in HTS machines. He developed an electrical circuit model for them identifying the dynamic resistance limits pumped current; calculated the working limit of the flux gap; developed a model for the dynamic resistance in a coated conductor excited by a DC current and a perpendicular AC magnetic field.
His work has been applied to New Zealand power transformers, a wind power generator in South Korea, high speed trains in China—where it was demonstrated that HTS can reduce the transformer weight by half and increase efficiency from 95% to 99.5%—and for aircraft motors and generators.
Dr Zhenan Jiang received his Bachelor of Engineering from Chongqing University in China and his PhD in Engineering from Yokohama National University in Japan before coming to New Zealand in 2008 to join Industrial Research Limited (now the Robinson Research Institute). In 2019 he was elected as a senior member of the Institute of Electrical and Electronics Engineers. In 2021 he became an editorial board member of Elsevier Journal, Superconductivity.
Upon receiving this medal, Zhenan said: “I would like to thank many of my colleagues at the Robinson Research Institute, particularly, Bob Buckley, Nick Long, Rod Badcock, Mike Staines, and Chris Bumby for their strong support of my research activities. Special thanks go to my wife, Rachel Jin. Her support has been critical to my success.”
The Scott Medal is awarded to the researcher who, working within New Zealand, has undertaken work of great merit and has made an outstanding contribution towards the advancement of the particular branch of engineering sciences, technologies, and their applications.
To Zhenan Jiang for global leadership in measuring and modelling the response of superconductors to applied currents and magnetic fields, thereby enabling cost-effective superconducting machines.