A new equivalent circuit of a salient-pole synchronous machine and its phasor interpretation

Abstract

Abstract-This paper examines a shortcoming of the classical phasor diagram of a salient-pole synchronous machine based on the well-established two-reaction theory. Unlike in the phasor diagram of a smooth-air-gap machine, it is not possible to readily identify the internally-developed electromagnetic power of a salient-pole synchronous machine from this phasor diagram. By de ning new machine reactances, a single equivalent circuit of a salient-pole synchronous machine is proposed together with a phasor diagram where the internally-developed electromagnetic power is made apparent. The revised two-reaction theory is illustrated using the mathematical model of a two-phase salientpole synchronous machine whose equations are manipulated using complex space vectors instead of traditional matrix transformations.

Simplified Current-Equivalent Circuit Models of Synchronous Reluctance Machines and Salient Pole Synchronous Machines Considering the Reluctance Torque

“…One model that includes the reluctance torque as a separate circuit element has been studied by Ahmed-Zaid and Oteafy [5]. This is illustrated in Figure 15, where the machine reactance is written as two series-connected parts [6] by using the average reactance X 0 = ωL 0 and the saliency reactance X 2 = ωL 2 .…”

“…Here, the pole saliency can be handled as a special separate current source, as in Figure 41a. Then, similar to the method in Section 3.1 by Ahmed-Zaid and Oteafy [5]. But a version with an equivalent current source can instead be rewritten even further.…”

“…However, this still considers that the pole saliency is dependent on the load angle. Another possible approach to model the reluctance torque is to handle it as a special separate voltage source in series with the classical EMF [5,6] based on the structure of a Thevenin equivalent model. The circuit element in this paper is instead written as a shunt susceptance and based on a current-equivalent source.…”

A New Interpretation of the Steady-State Two-Reaction Theory of a Salient-Pole Synchronous Machine

“…A numerical example is given to showcase both the importance of accounting for saliency and the ease of using the new model. An early version of this work was presented in [14] for a two-phase machine with a summarized development of the theory in the motor notation. More results are included in this work with detailed derivation that is generalized for the three phase salient pole machine.…”