Hysteresis loss in brushless doubly fed induction machines

Abstract

Brushless doubly fed machine (BDFM) is a potential for future wind energy generation, due to its lower maintenance costs and higher reliability than conventional doubly fed systems. While efficiency and design optimization of the machine has become critical issues recently, no analytical core loss model is investigated in the literature. Furthermore, core loss modeling is different from conventional induction machines, because of double frequency excitation of the machine. In this paper, a dynamical system is used for modeling of hysteretic behavior of iron core, and hysteresis losses of BDFM are analyzed and modeled mathematically. The flux waveforms of BDFM are assumed pure double sine, as in wound rotor BDFM lower harmonic values than nested loop design exist.

Steady‐state analysis and performance of a brushless doubly fed machine accounting for core loss

“…Rotor hysteresis loss depends on the rotor frequency and an exponent of the amplitude of rotor flux density, known as Steinmetz coefficient, which for simplicity has been taken to be 2. It has been proven in [28] that core loss is independent of the constant phase shift ( ψ s ) between the two fields. It is chosen zero for the sake of simplicity.…”

“…Unfortunately, more complexity arises when stator hysteresis loss is considered because of the existence of two MMFs of different frequencies in the BDFM stator. This subject has been studied in [28] using the concepts of dissipation and restoring functions. The stator hysteresis loss because of the two stator MMFs cannot be decoupled.…”

“…To calculate core losses, hysteresis and eddy currents were considered, but hysteresis loss was calculated using conventional singly fed machine classical models, incompatible with a BDFM model. In [19] an analytical hysteresis loss calculation model for the BDFM stator was proposed using dissipation and restoring functions. Although it is possible to obtain BDFM core loss values using this analytical model, no core loss equivalent circuit was presented, for either steady state or transient behaviour, as would needed for performance study or control of the BDFM.…”

Modified steady‐state modelling of brushless doubly‐fed induction generator taking core loss components into account

“…The literature review reveals that few published research works have considered the core loss in the steady-state model of BDFIG [7][8][9][10]. In [7], using two-dimensional finite element analysis (FEA), simulation of core loss including of non-linear effects and saturation of iron has been performed.…”

“…Also, analytic relationships have not been presented for calculating the core loss. In [8], an analytical model was presented for the calculation of hysteresis loss in the stator of BDFIM. However, the authors do not pay attention to eddy current loss and do not develop a model regarding the core loss.…”