정성윤 교수

For the torque control of an interior permanent magnet synchronous motor (IPMSM), it is necessary to determine a current command set that minimizes the magnitude of the current vector. This is known as the maximum torque per ampere. In the field-weakening region, current minimizing solutions are found at the intersection with the voltage limits. However, the optimal problem yields fourth-order polynomials (quartic equations), and no attempt has been made to solve these quartic equations online f

Electrical conductivity at the microscopic grain level has been measured in densely sintered polycrystalline samples of and using a four-point microcontact technique. The absolute value of conductivity as well as its spatial variability have been measured, and are consistent with previously reported bulk measurements. The results support the interpretation of the conductivity increase upon doping of as a lattice effect. © 2003 The Electrochemical Society. All rights reserved.

We visualize the antisite exchange defects in LiFePO4 crystals with an ordered olivine structure by using annular dark-field scanning transmission electron microscopy (STEM). A recognizable bright contrast is observed in some of the Li columns of STEM images in a sample annealed at a lower temperature, which directly demonstrates the disordered occupations by Fe atoms. Furthermore, such exchange defects appear to be locally aggregated rather than homogeneously dispersed in the lattice, although

We provide general descriptions regarding the structure–stability correlations of iridium-based complex-oxide catalysts for oxygen evolution reaction in acid media.

Abstract A substantial amount of interest has been focused on AB O 3 -type perovskite oxides over the past decade as oxygen electrocatalysts. Despite many studies on various compositions, the correlation between the structure of the oxygen octahedra and electrocatalytic property has been overlooked, and there accordingly have been a very limited number of attempts regarding control of atomistic structure. Utilizing epitaxial Ln NiO 3 ( Ln = La, Pr, Nd) thin films, here we demonstrate that simple

To detect the rotor angle of the permanent-magnet (PM) synchronous motor (PMSM), two linear Hall sensors are utilized to measure the fringe field of the PM from one end of the rotor. The measured signals look like sin θ and cos θ but contain large third-order harmonics. To remove the third-order harmonics, an adaptive notch filter (ANF) is utilized. Furthermore, the ANF is closely connected with an orthogonal phase-locked loop (PLL): The ANF eliminates the harmonics from the PLL input, and the P

Abstract Although numerous studies on oxide catalysts for an efficient oxygen evolution reaction have been carried out to compare their catalytic performance and suggest new compositions, two significant constraints have been overlooked. One is the difference in electronic conduction behavior between catalysts (metallic versus insulating) and the other is the strong crystallographic surface orientation dependence of the catalysis in a crystal. Consequently, unless a comprehensive comparison of t

Atomic-scale direct probing of active sites and subsequent elucidation of the structure–activity relationship are important issues involving oxide-based electrocatalysts to achieve better electrochemical conversion efficiency. By generating Ruddlesden–Popper (RP) two-dimensional homologous faults via simple control of the cation nonstoichiometry in LaNiO 3 thin films, we demonstrate that strong tetragonal distortion of [NiO 6 ] octahedra is induced by more than 20% elongation of Ni–O bonds in th

Aggregated antisite cations of iron (see picture, red) in the lithium sites of doped lithium iron phosphate (LiFePO4) are arranged preferentially along the b axis. To probe the peculiar array of the defects, Z-contrast STEM with a spherical-aberration correction is utilized. The images obtained using Z-contrast STEM suggest that the distribution of antisite defects in LiFePO4 can be adjusted for improved lithium ion transport.

By comparison between amorphous and crystalline phases, we elucidate that the local structural factor of Fe–O has an impactful contribution to the electronic states of Fe boosting of OER catalytic activity in perovskite-type nickel oxides.