Design and Construction of a Testbed for Superconducting Transformer Rectifier Flux Pumps
High field superconducting magnets are crucial in medical and research imaging applications such as MRI and NMR as well as having the potential to be a catalyst for the electrification of transport. Typically, these magnets are powered via current leads which are inefficient when working at hundreds of amperes of current needed to produce high fields. In addition, superconducting magnets need to be operated at cryogenic temperature meaning current leads also present a second problem of thermal loading of a cryogenic environment. A solution to both these problems is a category of wireless power transfer devices called flux pumps.
In this, thesis a modular testbed was developed to test a novel superconducting switch rectifier flux pump that was cryogenically cooled. Switching operation was based upon the Jc(B) characteristics of superconducting materials. The testbed was designed to accommodate a variety of rectifier configurations and other transformer rectifier-based flux pumps in future. This modularity allows on-the-fly changes to the layout and configuration. Control software was developed and tested such that the parameter space of the rectifier could be explored in detail.
The first experimental verification of this rectifier was achieved, and performance iteratively improved as data was gathered using the testbed. The system could charge a superconducting load coil to its critical current of 54.3 A in 20 seconds. The parameter space was systematically explored to learn how best to optimize the rectifier. A range of individual control strategies have been proposed based upon the data collected, some of which have been tested successfully. Future work includes collating the results from the smaller control strategies into a single coherent program.
In summary, the first steps to a new superconducting rectifier topology have been taken. The rectification mechanism has been proven in a laboratory setting with a wealth of data generated with guide future research. The results from this research demonstrated the viability of this technology in small form factor cryogenic high current supplies.
