An unexpected failure might lead to the loss of valuable human life or a costly standstill in industry, which needs to be prevented by precisely detecting or continuously monitoring the working condition of a motor. This book was written to provide a full review of diagnosis technologies and as an application guide for graduate and senior undergraduate students in the power electronics discipline who want to research, develop, and implement a fault diagnosis and condition monitoring scheme for better safety and improved reliability in electric motor operation.

Furthermore, electrical and mechanical engineers in the industry are also encouraged to use portions of this book as a reference to understand the fundamentals of fault cause and effect and to fulfill successful implementation. This book approaches the fault diagnosis of electrical motors through the process of theoretical analysis and then practical application. First, the analysis of the fundamentals of machine failure is presented through the winding functions method, the magnetic equivalent circuit method, and finite element analysis.

Second, the implementation of fault diagnosis is reviewed with techniques such as the motor current signature analysis (MCSA) method, frequency domain method, model-based techniques, and pattern recognition scheme. In particular, the MCSA implementation method is presented in detail in the last chapters of the book, which discuss robust signal processing techniques and reference-frame-theory-based fault diagnosis implementation for hybrid vehicles as an example.

These theoretical analysis and practical implementation strategies are based on many years of research and development at the Electrical Machines & Power Electronics (EMPE) Laboratory at Texas A&M University. The population of electric motors has greatly increased in recent years, not only in the United States but also in the world market as shown in Table 1.1 and Table  1.2

The world market is expected to be arund $16.1 billion in 2011, which is assumed more than 50% growth just within 5 years [1]. Electric motors have been applied to almost every place in our daily life, such as manufacturing systems, air transportations, ground transportations, building air-conditioner systems, home energy conversion systems, various cooling systems in electrical devices, and even cell phone vibration systems.