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Phase Shift Control Based Active Balancing Battery Management System
No full textThe use of electric power systems in the industrial field is continuously expanding due to the development and progress of new energy technology. As one of the core technologies of power systems, people are increasingly demanding higher performance from batteries. The battery management system plays an essential role in improving efficiency, safety and life-span of the battery pack and one of its main functions is the battery balancing function. This paper aims to discuss a novel battery balancing method using dual active bridge phase shift control technique. This technique has a much simpler circuit structure, reduced manufacturing cost, requires less space and offers more flexible control of balancing current than the current mainstream battery balancing methods
Difference in Bioimpedance Across the Knee in Un-Injured Young Adults
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Knee injuries induce swelling and resolution of swelling may be a useful factor in identifying states of healing and time to return to sports activities. Recent work has suggested that bioimpedance can provide an objective measure of swelling following total knee arthroplasty (TKA) and therefore may also provide guidance for clinical decision-making following knee injury. This study measures knee bioimpedance in young, active people to help define baseline variability and factors that influence limb to limb differences. Methods
Bioimpedance was measured via sensors placed at the foot/ankle and thigh, in positions similar to those suggested for monitoring post-TKA swelling. Initial tests were performed to verify method repeatability, then bioimpedance was measured in a convenience sample of 78 subjects (median age 21yrs). The influence of age, BMI, thigh circumference, and knee function (KOOS-JR) on the impedance measures and difference in impedance between the subject’s knees were examined using a generalized multivariable linear regression. Results
The repeatability study measurements were highly consistent with a COV of 1.5% for resistance and an ICC of 97.9%. Women exhibited significantly larger dominant limb impedance and larger limb to limb difference in impedance than men. Regression analysis indicated that subject sex and BMI significantly influenced bioimpedance but joint score and age did not. The limb to limb differences in impedance were small on average (\u3c5%), with larger magnitudes of difference associated with female sex, lower knee function scores, and larger limb to limb differences in thigh circumference. Conclusion
Bioimpedance measurements across right and left knees of healthy young people were similar, supporting use of bioimpedance measures from a patient’s uninjured knee as a benchmark to monitor healing of a contralateral injured knee. Future work should focus on understanding how knee function scores and bioimpedance are related, and further explore how sex and side to side anatomic differences impact the measurement
Crash Characteristics for Classic/Historic Vehicles and Comparisons to Newer Vehicles
No full textIntroduction: Older vehicles, commonly referred to as “classic,” “vintage,” or “historic” vehicles (CVH), share the roadways with newer vehicles. Older vehicles lacking safety systems likely come with an increased risk of fatality, however there is no study examining the typical conditions for crashes involving CVH. Method: This study utilized information from crashes occurring in 2012 to 2019 to estimate fatal crash rates for vehicles grouped by model year deciles. Data from crashes documented in the National Highway Traffic Safety Administration’s (NHTSA) FARS and GES/CRSS data sets were utilized to examine roadway, temporal, and crash types for passenger vehicles produced in 1970 or earlier (CVH). Results: These data show CVH crashes are rare (Conclusions and Practical Applications: Crashes involving a CVH are a rare event but have catastrophic consequences when they do occur. Regulations that limit driving to daylight hours may lower the risk of crash involvement, and safety messaging to promote belt use and sober driving may also help. Additionally, as new “smart” vehicles are developed, engineers should keep in mind that older vehicles remain on the roadway. New driving technologies will need to safely interact with these older, less safe vehicles
Modeling and Simulation of a Hybrid Energy Storage System using Li-Ion Battery and Supercapacitors for Class 2A Light Duty Pick-Up Truck
No full textThis Thesis investigates the battery pack capacity optimization problem for a full-size electric pick-up truck using a hybrid battery pack consisting of supercapacitors and Li-ion batteries. It also aims to simulate and study the thermal and aging effects on the battery pack. A simplified mathematical model of an electric pick-up truck was developed using the power consumptionbased approach which includes roadway grade, rolling resistance and wind resistance as the vehicle model along with modelling the electric powertrain. The proposed model considers the dynamic behavior of the system resulting in real time power demand by the electric motor and energy consumed by the storage system. The validation of the model is done by running the model through different US Drive Cycles which provide the second-by-second velocity and time data inputs. The energy consumed by the vehicle model is then subsequently used to simulate the battery degradation and estimate battery aging
