Modelling of inhomogeneous magnetic fields in electromagnetic devices

Modelling complex electromagnetic devices incorporating inhomogeneous magnetic fields typically requires computationally intensive solutions based on numerical methods. Simple magnetic path problems are often solved using less computationally intensive analytical techniques such as equivalent circuit approximations. Deciding upon which model to use depends on device complexity and involves a tradeoff between accuracy and computational efficiency. By expanding upon existing magnetic circuit theory, considering stored magnetic energy and vector analysis, it is possible to use magnetic circuit analysis to accurately model complex electromagnetic devices. The focus on energy facilitates the ability to incorporate inhomogeneous magnetic fields into magnetic circuit analysis that would traditionally require the use of numerical methods. This thesis derives closed form equations to describe electromagnetic device characteristics for a toroid, solenoid and a case study induction machine. By considering stored magnetic field energy, this approach allows the relationship between electrical, magnetic and kinetic energy to be quantified and analyzed in ways that allows improved accuracy compared with conventional magnetic circuit modeling methods. This thesis also provides insights into how geometric parameters impact energy transfer and operational characteristics of electromagnetic devices.