Estimation Method of State-of-Charge For Lithium-ion Battery Used in Hybrid Electric Vehicles Based on Variable Structure Extended Kalman Filter

Since the main power source of hybrid electric vehicle（HEV） is supplied by the power battery,the predicted performance of power battery,especially the state-of-charge（SOC） estimation has attracted great attention in the area of HEV.However,the value of SOC estimation could not be greatly precise so that the running performance of HEV is greatly affected.A variable structure extended kalman filter（VSEKF）-based estimation method,which could be used to analyze the SOC of lithium-ion battery in the fixed driving condition,is presented.First,the general lower-order battery equivalent circuit model（GLM）,which includes column accumulation model,open circuit voltage model and the SOC output model,is established,and the off-line and online model parameters are calculated with hybrid pulse power characteristics（HPPC） test data.Next,a VSEKF estimation method of SOC,which integrates the ampere-hour（Ah） integration method and the extended Kalman filter（EKF） method,is executed with different adaptive weighting coefficients,which are determined according to the different values of open-circuit voltage obtained in the corresponding charging or discharging processes.According to the experimental analysis,the faster convergence speed and more accurate simulating results could be obtained using the VSEKF method in the running performance of HEV.The error rate of SOC estimation with the VSEKF method is focused in the range of 5% to 10% comparing with the range of 20% to 30% using the EKF method and the Ah integration method.In Summary,the accuracy of the SOC estimation in the lithium-ion battery cell and the pack of lithium-ion battery system,which is obtained utilizing the VSEKF method has been significantly improved comparing with the Ah integration method and the EKF method.The VSEKF method utilizing in the SOC estimation in the lithium-ion pack of HEV can be widely used in practical driving conditions.

Efficient and Fast X-Ray Luminescence in Organic Phosphors Through High-Level Triplet-Singlet Reverse Intersystem Crossing

Organic scintillators that efficiently generate bright triplet excitons are of critical importance for highperformance X-ray-excited luminescence in radiation detection.However,the nature of triplet-singlet spinforbidden transitions in these materials often result in long-lived phosphorescence,which is undesirable for ultrafast X-ray detection and imaging.Here we demonstrate that the effect of hybridized local and charge-transfer(HLCT)excited states enables organic scintillators to exhibit highly efficient and fast radioluminescence(RL)in response to X-ray irradiation.Our experimental and theoretical investigation shows that the oxidized 1,8-naphthalimide-phenothiazine dyad(OMNI-PTZ 2)with HLCT-excited states has an enhanced overlap integral of the highest occupied molecular orbital(HOMO)and lowest unoccupied molecular orbital(LUMO)on MNIπ-orbitals,and moderate donor–acceptor electron interactions.As a result,the RL of these crystals exhibits a 61-fold increase and its monoexponential decay lifetime is three orders of magnitude faster compared to its corresponding thermally activated delayed fluorescence(TADF)molecule MNI-PTZ 1.We further demonstrate the practical utility of the OMNI-PTZ 2(G)in high-performance X-ray detection and imaging,achieving an X-ray dose sensitivity of 97 nGy s−1 and an exceptional spatial resolution of 20 lp/mm.Our study provides a promising molecular design principle for utilizing triplet excitons to develop high-efficiency and fast X-ray scintillators for the development of next-generation flexible and stretchable X-ray imaging detectors.

Energy Management Strategy for Hybrid Electric Vehicle Based on System Efficiency and Battery Life Optimization

A novel method to calculate fuel-electric conversion factor for full hybrid electric vehicle（HEV）equipped with continuously variable transmission（CVT）is proposed.Based on consideration of the efficiency of pivotal components,electric motor,system efficiency optimization models are developed.According to the target of instantaneous optimization of system efficiency,operating ranges of each mode of power-train are determined,and the corresponding energy management strategies are established.The simulation results demonstrate that the energy management strategy proposed can substantially improve the vehicle fuel economy,and keep battery state of charge（SOC）change in a reasonable variation range.