CFE-SS approach for salient-pole synchronous generators under unbalances

Abstract

A time-stepping coupled finite element-state space approach was developed for synchronous machine unbalanced impedance load and balanced/unbalanced rectifier load operation, in the natural time-domain ABC frame of reference. Synergism between the space and time harmonics was inherently included in the simulated results by use of this approach. It offers an effective and powerful tool for synchronous machine design before prototype construction. A time-stepping coupled finite element-state space (CFE-SS) algorithm is applied to the modeling and analysis of the time-domain steady-state performance of high speed salient-pole synchronous generators when feeding unbalanced loads under sustained durations. This includes the effects of such unbalances on individual damper bar time-domain current profiles and losses, iron core losses, machine parameters (inductances) and other performance characteristics. For practical types of ac aircraft generator unbalances detailed in this work, it was found that such losses can increase by as much as 33.80% of their values under balanced steady-state rated load condition for an example 2-pole, 120 kVA, 24000 r/min salient-pole synchronous generator.

Saliency ratio and power factor of IPM motors optimally designed for high efficiency and low cost objectives

“…Here, the saliency ratio is defined as / . The dand q-axes inductances and were calculated at rated operation from Park's transformation of three-phase self-and mutual inductances [33]. The base value for the cost is defined with reference to the unity value design, which is a part of the Pareto front identified in Fig.…”

Computationally efficient finite‐element‐based methods for the calculation of symmetrical steady‐state load conditions for synchronous generators

“…The electrical network can be coupled with the synchronous machine transient FE model in order to perform detailed simulations. This type of coupling is also known as the coupled FE state-space (CFE-SS) [16][17][18][19]. This approach provides much better insight into machine non-linearities such as magnetic saturation, losses and performance compared to the standard dynamic model.…”

Time stepping finite element analysis of a variable speed synchronous generator with rectifier

“…In the direct coupling model, described by, amongst others, Deng and Demerdash [7], the circuit equations are incorporated in the system for the FE model. This may lead to extensive computer calculations.…”