control of electric machine drive systems pdf
The book is constructed in following order. Chapter 1 explains the features of the
electric drive system and trends of development in related technologies. Moreover,
Chapter 1 also explains basic knowledge of mechanics, which is used throughout this
book, and also a description for typical characteristics of the load driven by electric
machines is provided. The many end-of-chapter problems provide many examples of
the drive systems I designed and tested. By solving the problems, some knowledge of
the actual industry can be shared.
Chapter 2 discusses the basic structure and operation principle of the electric machine, which converts mechanical energy to electrical energy like a generator or converts electrical energy to mechanical energy, like a motor. Steady-state equivalent circuits of several machines are introduced to understand the steady-state characteristics and control of machines. Also, several examples of machine control from the motor viewpoint with control features are discussed. In addition, power converters, which convert electrical energy to another form of electrical energy based on power
semiconductors, are modeled as equivalent circuits.
In Chapter 3, the transformation of physical variables of AC machine using reference frame theory is introduced. The transformation makes the understanding and analysis of AC machine easy by
transforming time-variant differential equations to time-invariant differential equations. Electrical variables such as voltage, current, and flux in a, b, and c phases of a three-phase system can be transformed to the variables in d–q–n (direct, quadrature, neutral) orthogonal axis, where the magnetic couplings between axes are zero. And, the three-phase system can be easily represented only by d–q components assuming a balanced three-phase operation.
The d–q component, which is orthogonal to each other, can be expressed simply by a single complex number, where real part stands for d-axis components and imaginary for q-axis components. Transformation from the a, b, c phase to the orthogonal axis can be done easily by
complex vector algebra. This complex vector concept is used in this book.
Chapter 4 is the essence of this book because here several control algorithms of electric machines and power converters are discussed. At the first, the concept of active damping, which is a kind of state feedback control, is introduced. Next, how to regulate the current, speed, position in feedback manner are described. In order to regulate physical variables, sensors for the measurement of variables such as current sensors and position/speed sensors are introduced.
If variables are not measurable, the principles of the state observer are introduced and used for the regulation electric machine speed. Furthermore, some tricks to enhance control performance of electric machines are introduced. Finally the algorithm to detect the phase angle of an AC source and to control the DC link voltages of power converters is discussed. Most of the end-ofchapter Problems in this chapter come from industry collaboration and solving the problems enhance the understanding of this chapter conspicuously.