Synchronous Machine Modeling Concepts
In this chapter, attention is given to modeling three-phase AC synchronous machines with quasi-sinusoidally distributed stator windings. The excitation may be provided by a rotor winding which is connected via a brush/slip-ring set to an electrical excita
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Synchronous Machine Modeling Concepts
In this chapter, attention is given to modeling three-phase AC synchronous machines with quasi-sinusoidally distributed stator windings. The excitation may be provided by a rotor winding which is connected via a brush/slip-ring set to an electrical excitation source [1–3]. Alternatively, permanent magnets which produce a quasisinusoidal magnetic flux density distribution in the air-gap can be used. Both non-salient and salient IRTF based machine models are considered in this chapter from a dynamic and quasi-steady-state perspective. The field-oriented modeling approach, briefly introduced in Chap. 4, is extended to encompass a rotor flux oriented model of the non-salient and salient machine. Such an approach is deemed to be important in the context of the model inversion control principle embraced in this book. In contrast to the previous chapter, the modeling and control sections have been separated to facilitate readability. Subsequent to this chapter, a comprehensive set of tutorials is introduced to provide the reader with the opportunity to interactively examine the key concepts discussed in this chapter.
6.1 Non-salient Machine In this section, a brief review of the symbolic and generic models and the relevant equations of a non-salient synchronous machine is given. Furthermore, attention is given to the steady-state characteristics of a voltage source connected machine. For a detailed discussion the reader may refer to our book Fundamentals of Electrical Drives [4]. In a synchronous machine, the excitation may be provided by permanent magnets or by a rotor based excitation winding which carries a field current if . In both cases, the flux density distribution due to the excitation is assumed to be sinusoidal. Furthermore, it is assumed that the magnetizing inductance is equal along both axes © Springer Nature Switzerland AG 2020 R. W. De Doncker et al., Advanced Electrical Drives, Power Systems, https://doi.org/10.1007/978-3-030-48977-9_6
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6 Synchronous Machine Modeling Concepts
Fig. 6.1 Non-salient four-pole PM synchronous machine, showing a two-layer, three-phase stator winding and surface magnets on the rotor
of the xy plane that is linked to the rotor. A cross-sectional view of a four-pole PM non-salient machine is given in Fig. 6.1. It shows the stator and the rotor with a set of surface mount magnets. Note the presence of a dual set of xy axes, because a four-pole machine is shown in Fig. 6.1. The machine does not carry any damper windings given that these are normally not found in inverter fed servo drive applications (to avoid losses) which are predominantly considered in this book.
6.1.1 Symbolic Model of a Non-salient Machine The machine can be described by an IRTF based model as shown in Fig. 6.2. The model was derived from the elementary model introduced in Sect. 4.2.1 by accommodating the stator resistance Rs and the stator leakage inductance Lσs . The magnetizing inductance Lm is shown on the rotor side of the machine. In general, inductance
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