Design and Control of Electrically Excited Synchronous Machines for Vehicle Applications
Doctoral thesis, 2021
The purpose of this study is to investigate the potential application of EESMs in EVs. To achieve this aim, several topics are covered in this study. These topics are studied to confront the challenges before EESMs could become prevalent and to maximumly use the advantages of EESMs for EV applications. In control strategies, the challenge is to properly adjust the combination of stator and field currents so that high power factor and minimum copper losses can be achieved. To tackle this, control strategies are proposed so that reactive power consumption and total copper losses are minimized. With the proposed strategies, the output power is maximized along the torque-speed envelope and high efficiency in field-weakening is achieved. In dynamic current control, due to the magnetic couplings between field winding and stator winding, a current rise in one winding would induce an electromagnetic force (EMF) in the other. This introduces disturbances in dynamic current control. In this study, a current control algorithm is proposed to cancel the induced EMF and the disturbances are mitigated. In machine design, high starting torque and effective field weakening are expected to be achieved in the same EESM design. To realize this, some criteria need to be satisfied. These criteria are derived and integrated into the design procedure including multi-objective optimizations. A 48 V EESM is prototyped during the study. In experimental verification, a torque density of 10 N·m/L is achieved including cooling jacket. In field excitation, a contactless excitation technology is adopted, which leads to inaccessibility of the field winding. To realize precise control of field current in a closed loop, an estimation method of field current is proposed. Based on the estimation, closed-loop field current control is established. The field current reference is tracked within an error of 2% in experimental verifications. The cost of an EESM drive increases because of the additional converter used for field excitation. A technique is proposed in which the switching harmonics are extracted for field excitation. With this technique, both stator and field windings can be powered using only one inverter.
From all the challenges tackled in this study, it can be concluded that the application of EESMs in EVs is feasible.
Electric Machine Modeling
Electric Machine Design
Brushless Excitation
Electric Machine Control
Electric Drives
Electrically Excited Synchronous Machines
Author
Junfei Tang
Chalmers, Electrical Engineering, Electric Power Engineering
Estimation Algorithm for Current and Temperature of Field Winding in Electrically Excited Synchronous Machines with High-Frequency Brushless Exciters
IEEE Transactions on Power Electronics,;Vol. 36(2021)p. 3512-3523
Journal article
Performance Evaluation of Electrically Excited Synchronous Machine compared to PMSM for High-Power Traction Drives
2020 24th International Conference on Electrical Machines (ICEM),;(2020)p. 1793-1799
Paper in proceeding
Dynamic Current Control to Compensate for Magnetic Mutual Coupling in Electrically Excited Synchronous Machines
2020 International Conference on Electrical Machines (ICEM),;Vol. 23 August 2020(2020)p. 1779-1785
Paper in proceeding
Design of Electrically Excited Synchronous Machines to Achieve Unity Power Factor in Field Weakening for Long-Haul Electric Trucks
2020 International Conference on Electrical Machines (ICEM),;Vol. 23 August 2020(2020)p. 422-428
Paper in proceeding
Modeling and Experimental Verification of High-Frequency Inductive Brushless Exciter for Electrically Excited Synchronous Machines
IEEE Transactions on Industry Applications,;Vol. 55(2019)p. 4613-4623
Journal article
Design and Experimental Verification of a 48 V 20 kW Electrically Excited Synchronous Machine for Mild Hybrid Vehicles
International Conference on Electrical Machines,;(2018)
Paper in proceeding
Study of Voltage Spikes and Temperature Rise in Power Module Based Integrated Converter for 48 V 20 kW Electrically Excited Synchronous Machines
2018 IEEE Applied Power Electronics Conference and Exposition (APEC) ,;Vol. 2018-March(2018)p. 210-217
Paper in proceeding
Comparison of copper loss minimization and field current minimization for Electrically Excited Synchronous Motor in mild hybrid drives
2017 19th European Conference on Power Electronics and Applications (EPE'17 ECCE Europe),;(2017)
Paper in proceeding
Sensorless control of a PMSM with a transmission system including shunt branches
Proceedings - 2016 22nd International Conference on Electrical Machines, ICEM 2016. Lausanne; Switzerland; 4-7 September 2016,;(2016)p. 1160-1166
Paper in proceeding
High frequency exciter of electrically excited synchronous motors for vehicle applications
Proceedings - 2016 22nd International Conference on Electrical Machines, ICEM 2016. Lausanne; Switzerland; 4-7 September 2016,;(2016)p. 378-383
Paper in proceeding
The aim of this study is to investigate the potential of EESM applications in EVs. To tackle the challenges in machine design, machine control and magnetic field excitation is the focus in this study. In machine design, one problem is how the machine performance can be maximized. In this study, a few design criteria are concluded to maximize the torque and power density of the machine. Following these criteria, a multi-objective design procedure is formulated. In machine control, due to the magnetic mutual coupling between armature and field windings, a current rise in one winding would induce an electromotive force (EMF) in the other. This causes disturbance in dynamic control. In this study, a current control algorithm is proposed to cancel the induced EMF and the disturbances are mitigated. In field excitation, to transfer power to the rotating field winding, the traditional solution is to use brushes and sliprings. This leads to friction losses and maintenance efforts. In this study, a contactless technology is employed. Power is transferred to the field winding at 100 kHz through a 1 mm airgap in a rotating transformer. Furthermore, a control method and a circuit topology are proposed to utilize switching harmonics to do the field excitation. With this technique, the armature and field windings can be powered from only one converter.
From all the challenges tackled in this study, it can be concluded that the application of EESMs in EVs is feasible. The focus of ongoing and future studies is mainly in the mechanical and thermal topics of the EESMs.
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Subject Categories
Electrical Engineering, Electronic Engineering, Information Engineering
ISBN
978-91-7905-466-3
Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 4933
Publisher
Chalmers