| 1. |
- Boscaglia, Luca, 1991, et al.
(författare)
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Thermal Modeling and Driving-cycle Critical Temperatures Estimation of Electrically Excited Synchronous Machine for Automotive Traction
- 2023
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Ingår i: 2023 IEEE Energy Conversion Congress and Exposition, ECCE 2023. ; , s. 4501-4508
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Konferensbidrag (refereegranskat)abstract
- Electrically Excited Synchronous Machines (EESM) has garnered attention due to their outstanding performance characteristics but it presents significant thermal challenges. The rotor is embedded with active conductors resulting in a high loss density and large amount of heat that discourage the adoption of this machine in various applications. This paper investigates into the feasibility of utilizing a 60 kW EESM for a commercial vehicle application, with a specific focus on understanding its thermal behavior. Steady-state 3D Conjugate Heat Transfer (CHT) analysis is conducted to obtain the temperature response of various machine components across the torque-speed map. Based on this analysis, thermal resistances are estimated to construct a simplified Lumped Parameter Thermal Network (LPTN) and predict maximum temperatures along the Worldwide harmonized Light-duty vehicles Test Cycles (WLTC). Simulations in MATLAB Simulink show that the temperatures remain below the limits defined by the winding insulation class throughout the entire driving cycle. This finding assures the reliability and safe operation of the EESM for the considered application.
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| 2. |
- Chen, Hao, et al.
(författare)
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Electromagnetic Performance Investigation of A Brushless Electrically-Excited Synchronous Machine for Long-Distance Heavy-Duty Electric Vehicles
- 2024
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Ingår i: IEEE Transactions on Transportation Electrification. - 2332-7782. ; In Press
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Tidskriftsartikel (refereegranskat)abstract
- Long-distance heavy-duty electric vehicles, e.g., electric trucks, expect demanding requirements from the electric drive system, including high starting torque, high torque density, high power factor, high efficiency, etc. Permanent magnet synchronous machines (PMSMs) have been widely used for traction applications. However, the high cost and associated environmental issues due to the rare-earth permanent magnet material intensify researchers to explore new solutions. Accordingly, a brushless electrically-excited synchronous machine (EESM) is designed and investigated in this paper. The brushless EESM is also quantitatively compared with a PMSM candidate for the aforementioned application. Differing from conventional EESMs in which the brushes and slip rings are used for rotor field winding excitation, a contactless/brushless rotating transformer is adopted for the presented EESM to feed the rotor field winding. It is shown that the interior PMSM exhibits higher efficiency in low-speed region, but lower efficiency in high-speed region. By contrast, the brushless EESM exhibits lower efficiency in low-speed region, but much higher efficiency in high-speed region. Hence, the EESM is more suitable for long-distance heavy-duty electric vehicle applications where significant highspeed operations are required. Moreover, compared to the PMSM, the EESM is more cost-effective, sustainable, and environmentally friendly due to the absence of the rare-earth permanent magnet material. Both the PMSM and the EESM are prototyped and manufactured. Experimental results are provided to validate the effectiveness of the presented designs.
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| 3. |
- Huang, Xiaoliang, 1985, et al.
(författare)
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A Reconfigurable Battery Supercapacitor Hybrid Energy System with Active Balancing for Vehicle Applications
- 2021
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Ingår i: Proceedings - 2021 IEEE 19th International Power Electronics and Motion Control Conference, PEMC 2021. ; , s. 231-236
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Konferensbidrag (refereegranskat)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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| 4. |
- Huang, Xiaoliang, 1985, et al.
(författare)
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Experimental evaluation of conductor insulations used in e-mobility traction motors
- 2021
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Ingår i: Proceedings - 2021 IEEE Workshop on Electrical Machines Design, Control and Diagnosis, WEMDCD 2021. ; , s. 249-253
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Konferensbidrag (refereegranskat)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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| 5. |
- Jiang, Bowen, 1993, et al.
(författare)
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A Hybrid Energy Storage System with Reconfigurability and Fast Equalisation
- 2022
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Ingår i: POWER ELECTRONICS AND DRIVES. - : Walter de Gruyter GmbH. - 2543-4292 .- 2451-0262. ; 7:1, s. 68-83
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Tidskriftsartikel (refereegranskat)abstract
- With the rapid growth of electric vehicles (EVs) in recent years, the research on their energy storage systems (ESSs) has also shown great popularity. A traditional ESS normally has a fixed configuration and uses a single type of energy storage unit. However, this traditional design has some limitations, such as low flexibility and high requirements to unit consistency. To solve these problems, a new hybrid energy storage system is proposed in this paper. The proposed ESS hybridises multiple lithium-ion battery modules and one supercapacitor module. By controlling the states of switches inside the ESS topology, module level reconfiguration can be achieved. Further, a DC/DC converter is also included in the ESS topology, which is connected to the supercapacitor module and can be used to ensure correct ESS output voltage. Reconfiguration and active balancing algorithms are also given based on the proposed ESS topology. Situations with and without bypassing the lithium-ion battery modules are both discussed in the algorithms. The proposed hybrid ESS is finally verified with simulations. The system model is built in the Simulink/MATLAB environment. Simulation results show that the lithium-ion modules with a lower state of charge values have higher priorities to be connected in parallel. Reconfiguration actions are able to balance all lithium-ion battery modules within one Worldwide Harmonised Light-Duty Vehicle Test Cycle (WLTC) simulation cycle while maintaining ESS output voltage within a correct range. Furthermore, the proposed hybrid ESS control algorithms remain valid when one lithium-ion battery module is manually bypassed during simulation.
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| 6. |
- Jiang, Bowen, 1993, et al.
(författare)
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A New Battery Active Balancing Method with Supercapacitor Considering Regeneration Process
- 2020
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Ingår i: IECON Proceedings (Industrial Electronics Conference). - 2577-1647 .- 2162-4704. ; 2020-October:18 October 2020, s. 2364-2369
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Konferensbidrag (refereegranskat)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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| 7. |
- Jiang, Bowen, 1993, et al.
(författare)
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A Novel Approach of Electric Powertrain Co-Simulation with High Fidelity Vehicle Model
- 2022
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Ingår i: IECON Proceedings (Industrial Electronics Conference). - 2577-1647 .- 2162-4704. ; 2022-October
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Konferensbidrag (refereegranskat)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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| 8. |
- Jiang, Bowen, 1993, et al.
(författare)
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Accelerated destructive experiment design of motor stator winding insulation systems
- 2021
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Ingår i: Proceedings - 2021 IEEE Workshop on Electrical Machines Design, Control and Diagnosis, WEMDCD 2021. ; , s. 225-230
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Konferensbidrag (refereegranskat)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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| 9. |
- Jiang, Bowen, 1993, et al.
(författare)
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Acceleration-based wheel slip control realized with decentralised electric drivetrain systems
- 2022
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Ingår i: IET Electrical Systems in Transportation. - : Institution of Engineering and Technology (IET). - 2042-9738 .- 2042-9746. ; 12:2, s. 143-152
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Tidskriftsartikel (refereegranskat)abstract
- Traction control is one of the most important functions in vehicle drivetrain systems. When a vehicle is driven on a low-friction road surface, loss of traction force can cause the driven wheels to spin. This reduces vehicle acceleration performance and can even cause the driver to lose control of the vehicle. The high bandwidth of electric machine control in electric vehicles gives more possibilities to regulate driving torque on wheels and prevent wheel spin. An acceleration-based wheel slip control is designed and investigated. Compared to traditional slip-based traction control, the proposed method does not depend on the estimation of the vehicle speed and only relies on the driven wheel rotational acceleration. The control method is verified using the simulation of an electric vehicle with a decentralised electric drivetrain system. The vehicle and the electric drive are modelled in CarMaker and PLECS, respectively. The simulation results show that the proposed method is able to prevent the driven wheel from spinning when the vehicle is accelerated on an ice road. In addition, the control is fast enough and requires only half a second to reduce the wheel acceleration to a normal range.
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| 10. |
- Jiang, Bowen, 1993, et al.
(författare)
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Active Balancing of Reconfigurable Batteries Using Reinforcement Learning Algorithms
- 2023
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Ingår i: 2023 IEEE Transportation Electrification Conference and Expo, ITEC 2023.
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Konferensbidrag (refereegranskat)abstract
- In reconfigurable batteries, series or parallel connections among cells/modules are able to be actively changed during operations. One big advantage of reconfiguration is to achieve active balancing among cells/modules. Rule-based and greedy algorithms of reconfigurable battery control have problems of being sensitive to battery characteristic variation and requiring a lot of computing resources. Therefore, deep reinforcement learning (DRL) algorithms are used to overcome these difficulties. Very few studies related to this idea have been done previously, and the studied battery reconfiguration topologies are either too simple or too complex. Thus, in this paper, a module-level reconfigurable battery with moderate flexibilities is controlled by DRL algorithms. Two neighboring modules are connected in either parallel or series by following a well-trained optimal policy. Two battery discharging cases, constant power and variable power, are simulated. The final results prove the feasibility and great potential of utilizing DRL algorithms in reconfigurable battery control.
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