An Isolated Integrated Charger for Electric or Plug-in Hybrid Vehicles

For electric and hybrid vehicles using grid power to charge the battery, traction circuit components are not normally engaged during the charging time, so there is a possibility to use them in the charger circuit to have an on-board integrated charger.In this Licentiate thesis, an isolated high power integrated charger is proposed, designed and constructed based on a special ac machine with a double set of stator windings called motor/generator.The charger is capable of unit power factor operation as well as bi-directional power operation for grid to vehicle application.The mathematical electromechanical model of the motor/generator is derived and presented. Based on the developed model, new controller schemes are developed and designed for the grid synchronization and charge control. The machine windings are re-arranged for the traction and charging by a controllable relay-based switching device that is designed for this purpose.A laboratory system is designed and implemented based on a $4$ pole $25~kW$ interior permanent magnet synchronous motor and a frequency converter considering the integrated charging features for winding re-configuration. The practical results will be added in the next step of the project. The charging power is limited to $12.5~kW$ due to the machine thermal limit (half of the motor full power in the traction mode) for this system.The whole system is simulated in Matlab/Simulink based on the developed model and controllers to verify the system operation for the charge control. Simulation results show that the system has good performance during the charging time for a load step change. The simulation results show also a good performance of the controllers leading to machine speed stability and smooth grid synchronization. Moreover, the unit power factor operation is achieved for battery charging in the simulations

An Isolated Integrated Charger for Electric or Plug-in Hybrid Vehicles

For electric and hybrid vehicles using grid power to charge the battery, traction circuit components are not normally engaged during the charging time, so there is a possibility to use them in the charger circuit to have an on-board integrated charger.In this Licentiate thesis, an isolated high power integrated charger is proposed, designed and constructed based on a special ac machine with a double set of stator windings called motor/generator.The charger is capable of unit power factor operation as well as bi-directional power operation for grid to vehicle application.The mathematical electromechanical model of the motor/generator is derived and presented. Based on the developed model, new controller schemes are developed and designed for the grid synchronization and charge control. The machine windings are re-arranged for the traction and charging by a controllable relay-based switching device that is designed for this purpose.A laboratory system is designed and implemented based on a $4$ pole $25~kW$ interior permanent magnet synchronous motor and a frequency converter considering the integrated charging features for winding re-configuration. The practical results will be added in the next step of the project. The charging power is limited to $12.5~kW$ due to the machine thermal limit (half of the motor full power in the traction mode) for this system.The whole system is simulated in Matlab/Simulink based on the developed model and controllers to verify the system operation for the charge control. Simulation results show that the system has good performance during the charging time for a load step change. The simulation results show also a good performance of the controllers leading to machine speed stability and smooth grid synchronization. Moreover, the unit power factor operation is achieved for battery charging in the simulations

A SRM-based drive system for design project course in electric power engineering master program in chalmers university of technology

The power engineering design project course is a second-year course in electric power engineering master program in Chalmers University of Technology (CTH), Sweden. Students perform and report a pre-selected project in the electric power engineering area within a group. A drive system based on a switched reluctance motor (SRM) is developed in the context of a master thesis and the system is utilized and enhanced in this course as an educational platform. The course activities, developed hardware, project results by students, and course evaluation results are presented in this paper. During a pedagogical course titled “Writing for publication and for constructive alignment” conducted by CTH, the course supervision activities are analyzed and improved. The assessment of the students individual contribution within a group is identified as the main barrier for the further involvements of the students. Changing the course grade from a pass/fail to a fail/3/4/5 system is suggested for the next round of the course to encourage the students for more engagement within the project group

Electrical failure mode and effect analysis of a 3.3 kW onboard vehicle battery charger

Reliability is one important aspect for further improvement of power electronic converters. The improvement trend is towards a higher power density, and a higher efficiency with a lower price. Those performance indices are normally in contradiction with the reliability. A failure mode and effect analysis (FMEA) of a 3.3 kW onboard battery charger is presented for the electrical part of the charger. The FMEA results are used to prioritize, investigate and analyze important fault cases in semiconductors, dc bus capacitors and sensors. Possible reasons of each fault, appropriate fault detection methods, possible mitigation algorithms and some design improvements are shortly presented. The calculated risk numbers confirm that the reliability of the charger is considerable improved consequently

Design considerations of a 50 kW compact fast charger stations using nanocrystalline magnetic materials and SiC modules

A fast charger station can charge a vehicle battery in 5-10 minutes but it is very expensive and massive. Recent advancements in the device developments and design tools enables one to have a higher power density (power divided by volume) chargers that is equivalent to a smaller size and weight. Semiconductors based on Silicon Carbide (SiC), magnetic materials based on Nanocrystalline and modern design tools like FEM simulators are examples of these advancements. Some design aspects of a 50 kW fast charger station is presented in this paper. The charger main specifications, the main topology candidates to achieve a compact design, some simulation results and constructed transformer are presented and discussed. For the DC/DC stage two designs are presented based on the full-bridge (FB) and dual active bridge (DAB) topologies. Some comparison results are described in this paper

Integrated Motor Drives and Battery Chargers for Electric or Plug-in Hybrid Electric Vehicles

Plug-in vehicles, electric vehicles or plug-in hybrid electric vehicles, use grid power to charge the battery. The components in the traction circuit, like the electric motor and the inverter, are not used during the battery charging, so there is a possibility to use them in the charger circuit to reduce the size, weight and price of the on-board charger; that is called an integrated motor drive and battery charger or simply an integrated charger which can be galvanically isolated or non-isolated from the utility grid.Different examples of integrated chargers reported by academia or industry, isolated or non-isolated, are reviewed and compared in terms of circuit configuration, control strategy, degree of integration, and efficiency. Moreover some new isolated and non-isolated solutions are presented and explained.A patented integrated motor drive and isolated battery charger based on a split-phase permanent magnet (PM) motor is described where the motor windings are reconfigured for the traction and charging mode by using a relay-based switching device. To reduce the magnetization current due to the motor airgap, the motor rotates at synchronous speed during the battery charging. So, an extra clutch is used in the system to disconnect the motor from the vehicle transmission during the charge operation. The mathematical model of the split-phase PM motor based on a double $dq$ approach, the developed controllers, and the system functionality are explained. Moreover, simulation and experimental results show that the system has a good performance in terms of system efficiency and dynamic response with two PM motor alternatives in two separate practical systems.Two new categories of integrated motor drives and non-isolated battery chargers are presented and explained. The first scheme is based on the winding\u27s reconfiguration of a split-phase PM motor which simulation and practical results are provided. The second scheme is a single-phase solution that a split-phase PM motor and two inverters enable battery charging.Based on the double $dq$ model of the split-phase PM motor that provides the theoretical framework, a modal filed-oriented controller is proposed for a drive system that utilizes two identical inverters and a split-phase PM motor. A decoupling strategy is proposed based on the eigenvalue decomposition to impart a systematic methodology for the current controllers design. Moreover, a maximum torque per ampere strategy is derived to reach an optimal torque development in the drive system. Simulation results are provided to show the system performance in the steady-state and dynamic for a speed control system. For a reference speed profile, the drive system has a fast speed response while the torque and currents are tracking the optimal trajectories

Impact of inverter switching pattern on the performance of a direct torque controlled synchronous reluctance motor drive

The synchronous reluctance motor has gained more attention recently and is a potential candidate to compete with other ac motors. The simple structure and fast torque response make the direct torque control an attractive solution for the synchronous reluctance motor drive system. Different motor, inverter and controller parameters affect the drive system performance in this method. The drive system performance is investigated for four possible inverter switching patterns in terms of the torque ripple, stator current harmonic content and inverter switching frequency in this paper. The results show that switching pattern in which a zero-voltage vector is applied to decrease the torque, regardless of increment or decrement in the flux, has a better performance in the drive system

ELECTRICAL APPARATUS COMPRISING DRIVE SYSTEM AND ELECTRICAL MACHINE WITH RECONNECTABLE STATOR WINDING

Electrical apparatus, comprising a drive system and an electrical machine for propulsion of a vehicle, wherein the electrical machine comprises at least one rotor and at least one stator winding and can be connected via a connection point to a three-phase network. The stator winding can be switched between at least a first position in which it is electrically controlled by the drive system during propulsion of the vehicle, and a second position in which it is divided into at least two separate and magnetically coupled three-phase windings for converting of a voltage level that is available in the three-phase network. One divided first three-phase winding, consisting of a first set of windings, at a rotor speed corresponding to the frequency of the three-phase network has a voltage corresponding to the voltage level at the connection point. One divided second three-phase winding, consisting of a second set of windings, is electrically matched to the drive system and the windings in the first set and the windings in the second set are each connected to each other via a switching layout