A Global Convergence Estimator of Grid Voltage Parameters for More Electric Aircraft

Disturbance Rejection Ability Enhancement Using Repetitive Observer in Phase-locked Loop for More Electric Aircraft

“…Define the phase θ, grid frequency ω and grid frequency acceleration a as the three state variables in vector x, x=[θ ω a] T , the Kalman filter observes the three variables as x=[θ̃ ω̃ ã] T . Matrix A is derived based on the third-order model as in (1). Vector g=[g1 g2 g3] T is the observer gain vector which can be tuned according to the procedure in [12] by specifying the desired poles.…”

“…If the operation frequency is too far from the design point, the performance of those constantfrequency PLLs will degrade. For MEA, according to the recent research in [1], the key shortcomings for the few available variable frequency PLLs techniques can be summarized as the follows:…”

“…Therefore, authors in [1] has proposed an estimator to solve the d.c offsets issue. However, the harmonics in grid has not been considered in [1].…”

An enhanced fast fundamental frequency estimator for three-phase electric aircraft grid

“…Several control techniques were investigated for their application to EA, such as a discrete Fourier transform (DFT) based PLL [18], a steady-state linear Kalman filter (SSLKF)-PLL [19]- [22], a complex least mean square (CLMS) [23], a sliding mode observer (SMO) [24], an adaptive observer (AO) [25], [26], and a repetitive dual observer (RDO) based PLL [27]- [29]. The DFT-PLL and SSLKF-PLL schemes were found to be computationally more complex, and the frequency tracking abilities of the SSLKF based PLL were better than the those of the DFT based PLL [22].…”

“…Unfortunately, neither technique is capable of handling the DC-offset component present in the grid voltage signal. An improved AO based solution is proposed in [26], but it has a slower dynamic response in the presence of harmonics, leading to steady-state errors in the estimated parameters.…”