| 1. |
- Huang, Zhifeng, et al.
(author)
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Three-dimensional posture optimization for biped robot stepping over large ditch based on a ducted-fan propulsion system
- 2020
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In: IEEE International Conference on Intelligent Robots and Systems. - 2153-0858 .- 2153-0866. ; , s. 3591-3597
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Conference paper (peer-reviewed)abstract
- The recent progress of an ongoing project utilizing a ducted-fan propulsion system to improve a humanoid robot's ability to step over large ditches is reported. A novel method (GAS) based on the genetic algorithm with smoothness constraint can effectively minimize the thrust by optimizing the robot's posture during 3D stepping. The significant advantage of the method is that it can realize the continuity and smoothness of the thrust and pelvis trajectories. The method enables the landing point of the robot's swing foot to be not only in the forward but also in a side direction. The methods were evaluated by simulation and by being applied on a prototype robot, JetHR1. By keeping a quasistatic balance, the robot could step over a ditch with a span of 450 mm (as much as 97% of the length of the robot's leg) in 3D stepping.
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| 2. |
- Song, Kai, et al.
(author)
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An Impedance Decoupling-Based Tuning Scheme for Wireless Power Transfer System under Dual-Side Capacitance Drift
- 2021
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In: IEEE Transactions on Power Electronics. - 0885-8993 .- 1941-0107. ; 36:7, s. 7526-7536
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Journal article (peer-reviewed)abstract
- High performance of a wireless power transfer system is related to the resonance. However, the capacitance drift caused by temperature variation leads to detuning. In this article, a tuning scheme against dual-side capacitance drift using the impedance decoupling algorithm is investigated. First, the impact of the capacitance drift on transmission efficiency and output power are analyzed. Second, it is difficult to compensate for the dual-side capacitance drift quickly since the primary and secondary sides are coupled. Therefore, the impedance decoupling algorithm is introduced. The primary and secondary reactances are decoupled from the total impedance. The two independent reactances are only determined by the capacitance drift of the corresponding side. Then, by adjusting system frequency and the phase-shift angle of the semiactive rectifier, the reactances of both sides can be eliminated, respectively. Compared with the existing tuning methods focusing on total input impedance, the continuous adjustment on two sides is avoided, so the tuning time is significantly reduced. The experimental results prove that the proposed method can improve the system efficiency by 5%-40% and reduce the tuning time by 67% under different capacitance drift.
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| 3. |
- Yang, Guang, et al.
(author)
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Improved Interoperability Evaluation Method for Wireless Charging Systems Based on Interface Impedance
- 2021
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In: IEEE Transactions on Power Electronics. - 0885-8993 .- 1941-0107. ; 36:8, s. 8588-8592
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Journal article (peer-reviewed)abstract
- The interoperability between the vehicle assembly (VA) and ground assembly (GA) of wireless charging systems has been specified in international standards. SAE J2954 first proposed an interoperability evaluation method based on interface impedance. However, the impedance measurement is challenging at high frequency since the phase difference between the voltage and current is not easy to measure accurately, especially when it is close to 90. Small errors in phase angle measurement are amplified in impedance calculation due to the sine/cosine function. This letter proposes an impedance measurement method using the power decomposition algorithm. By decomposing the input power into two orthogonal components, the impedance angle can be calculated without directly measuring the phase difference between the voltage and current. Thus, the measurement results of the impedance angle do not introduce errors. With the proposal, the high-cost probe or complex high-precision phase difference measurement circuit is not needed. The experimental results show that the conventional methods maximum relative error reaches 80%, making interoperability hard to determine. Reversely, with the proposed method, the relative error of impedance measurement is reduced to less than 10%.
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| 4. |
- Cao, Wenjing, et al.
(author)
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Fuel consumption reduction effect of pre-acceleration before gliding of a vehicle with free-wheeling
- 2022
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In: Control Theory and Technology. - : Springer Science and Business Media LLC. - 2198-0942 .- 2095-6983. ; 20:2, s. 235-247
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Journal article (peer-reviewed)abstract
- Advanced fuel economy strategies are expected to reduce the fuel consumption of vehicles. An internal combustion engine (ICE) driving vehicle equipped with free-wheeling turns off the fuel injection and decouples the engine from the drivetrain when the driving force is not required. This paper proposes a method to reduce the fuel consumption of a vehicle equipped with free-wheeling. First, an optimization problem is formulated to minimize the fuel consumption of a vehicle with free-wheeling when the traveling distance, the initial and final speed are specified and the vehicle needs to glide before arriving at the end point for fuel economy. The speed profile of the vehicle, engine operating point, and engine on/off timing are obtained as the results of the optimization. The analytical and numerical analyses results demonstrate the effectiveness and the fuel-saving mechanism of the obtained speed profile. The main finding of the analyses is that rather than starting a gliding stage immediately after an acceleration or a constant speed stage, adding a pre-acceleration stage before the gliding stage is more fuel-economic under some conditions independent of the complexity of the vehicle model. The obtained speed profile including a pre-acceleration stage is applied to a driving scenario including traffic congestions. The results demonstrate the effectiveness of the pre-acceleration stage in reducing fuel consumption for a vehicle equipped with free-wheeling.
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| 5. |
- Han, Weiji, 1987, et al.
(author)
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Analysis and Estimation of the Maximum Switch Current during Battery System Reconfiguration
- 2022
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In: IEEE Transactions on Industrial Electronics. - 0278-0046 .- 1557-9948. ; 69:6, s. 5931-5941
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Journal article (peer-reviewed)abstract
- Batteries are interconnected in series and/or parallel to meet wide-range power or energy demands in various industrial applications. To pursue the benefits of multiple connection structures in one system, reconfigurable battery systems (RBSs) have recently emerged for safe and efficient operation, extended energy storage and delivery, etc. Switches are the essential elements to enable the battery system reconfiguration, but selecting appropriate switches for RBS designs has not been systematically investigated. To bridge this gap, analytical expressions are derived in this paper to estimate the maximum switch current and its upper limit to facilitate the selection of RBS switches. An RBS prototype based on H-bridges is set up and experimental results verify the effectiveness and advantage of the proposed estimation method. These analytical expressions, relying only on resistances of batteries and switches, are readily applicable to practical RBS design and much more efficient than conducting numerous circuit experiments, simulation tests, or circuit analyses, especially for large-scale systems. Moreover, the analysis framework and estimation method proposed for series-parallel mutual conversion can be adaptively extended to other complex system reconfigurations to facilitate various RBS designs.
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| 6. |
- Huang, Xiaoliang, 1985, et al.
(author)
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A Reconfigurable Battery Supercapacitor Hybrid Energy System with Active Balancing for Vehicle Applications
- 2021
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In: Proceedings - 2021 IEEE 19th International Power Electronics and Motion Control Conference, PEMC 2021. ; , s. 231-236
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Conference paper (peer-reviewed)abstract
- The concept of reconfigurable energy systems has become more and more popular in recent years for electric vehicle applications, which can largely enhance battery performance and extend battery lifetime. Active balancing is an advanced function realized by battery management systems (BMSs) to improve energy efficiencies and avoid potential over-charging risks. This paper proposed a reconfigurable hybrid energy system (HESS) that consists of one supercapacitor module, n lithium-ion modules, one DC/DC converter, and 3n switches, to enhance energy system performance with fast active balancing. The developed algorithms are to find out all possible configurations for a given lithium-ion module number and module section number, and the best configuration is selected based on the fastest balancing speed requirement. The proposed topology and algorithms are finally verified by simulations under standard vehicle driving cycles.
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| 7. |
- Huang, Xiaoliang, 1985, et al.
(author)
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Experimental evaluation of conductor insulations used in e-mobility traction motors
- 2021
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In: Proceedings - 2021 IEEE Workshop on Electrical Machines Design, Control and Diagnosis, WEMDCD 2021. ; , s. 249-253
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Conference paper (peer-reviewed)abstract
- Application of high switching frequency converters providing signals with a high level of dv/dt has resulted in an increased stress on the traction motors insulation system. This paper presents an investigation done on the insulation materials developed for traction motors used in E-mobility applications and built using form or hairpin windings. Since the high dv/dt results in a high voltage difference between the conductors, focus in this paper is placed on the conductor insulation referred as 'primary insulation'. An experimental setup is developed and test samples using different insulation materials are made. A comparison between the life-time of the non-corona resistant and corona-resistant materials are made. Additionally, influence of the temperature, voltage and thickness on the insulation system life-time is evaluated. The test results show that corona resistant Kapton® ECRC materials with different thicknesses may be considered as proper candidates for traction motors designed and produced for electrification market fed by high switching frequency converters.
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| 8. |
- Jiang, Bowen, 1993, et al.
(author)
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A New Battery Active Balancing Method with Supercapacitor Considering Regeneration Process
- 2020
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In: IECON Proceedings (Industrial Electronics Conference). - 2577-1647 .- 2162-4704. ; 2020-October:18 October 2020, s. 2364-2369
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Conference paper (peer-reviewed)abstract
- Lithium-ion batteries have been widely used in new energy vehicles (NEV) as large energy storage systems (ESS). It is necessary to balance series-connected cells to avoid over-charging or over-discharging as well as to improve the amount of usable energy. This paper starts with a comprehensive review of the existing strategies and gives a battery balancing category. A new balancing topology with its control algorithms is then introduced. A supercapacitor is used in the balancing circuit which replaces the highest state of charge (SOC) cell and is charged during the vehicle regeneration process. The supercapacitor also transfers energy to the lowest SOC cell after it is fully charged. This new strategy can not only improve the balancing efficiency due to fewer times of energy conversion but also reduce the required balancing time compared to single capacitor balancing.
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| 9. |
- Jiang, Bowen, 1993, et al.
(author)
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A Novel Approach of Electric Powertrain Co-Simulation with High Fidelity Vehicle Model
- 2022
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In: IECON Proceedings (Industrial Electronics Conference). - 2577-1647 .- 2162-4704. ; 2022-October
-
Conference paper (peer-reviewed)abstract
- This paper presents a co-simulation approach for an electric vehicle which combines dynamic models of electric machine, inverter, gearbox in PLECS with high fidelity models of driver, autobody, wheel, road and environment in CarMaker. Lumped parameter thermal networks to model heat dissipation in the electric machine and the inverter are also included. The aim is to demonstrate versatility of the co-simulation method in analyzing effects of driver behaviors on thermal performance of electric machine and inverter. Co-simulation results using two simulation tools are compared to those obtained entirely using a single tool. It is observed that performing co-simulation using low fidelity vehicle model results in underestimation of vehicle speed. Further, the impacts of three different driver models on the temperatures of electric machine windings and semiconductor junctions are analyzed. Differences of 30% and 25% in the maximum temperature are observed respectively between an aggressive and a defensive driver.
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| 10. |
- Jiang, Bowen, 1993, et al.
(author)
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Accelerated destructive experiment design of motor stator winding insulation systems
- 2021
-
In: Proceedings - 2021 IEEE Workshop on Electrical Machines Design, Control and Diagnosis, WEMDCD 2021. ; , s. 225-230
-
Conference paper (peer-reviewed)abstract
- Electric motors, being as key components in battery electric vehicles (BEVs), need to provide high power and torque to meet people's expectations on vehicles' performance. However, since the electric motors used in vehicles shall be driven by pulse width modulated (PWM) inverters, the high alternating voltages and currents applied to stator windings usually give extremely big electrical stress to their insulation systems, which may bring reductions to motors' lifetimes. Factors, such as environmental temperatures, voltage derivatives (dv/dt), insulation materials, and cover overlap percentages all affect the winding aging speeds in different degrees. To have shorter experimental time, this paper proposed a new method to do accelerated destructive experiments on insulation systems of motor stator windings. This designed method has stable measurements as well as precise detections on insulation failures and can study multiple insulation influencers. The functionalities of this insulation testing system have been finally verified by experiments using stator windings covered with Kapton® FN films.
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