The reference frame theory that was detailed in critically acclaimed first edition of <i>Analysis of Electric Machinery and Drive Systems</i> has become the universally accepted approach for the analysis of both electric machines and electric drive systems. This thoroughly updated third edition features numerous changes in the early chapters that make the derivation of many of the equations more direct and understandable. The authors have developed several new models and model structures for electric machines that improve the accuracy and computational efficiency of coupled machine/power electronic circuit models.