Sonja Lundmark

Grid-Connected Integrated Battery Chargers in Vehicle Applications: Review and New Solution

For vehicles using grid power to charge the battery, traction circuit components are not engaged during the charging time, so there is a possibility to use them in the charger circuit to have an onboard integrated charger. The battery charger can be galvanically isolated or nonisolated from the grid. Different examples of isolated or nonisolated integrated chargers are reviewed and explained. Moreover, a novel isolated-high-power three-phase battery charger based on a split-phase permanent-magnet motor and its winding configuration is presented in this paper. The proposed charger is a bidirectional high-power charger with a unity power factor operation capability that has high efficiency.

Integrated chargers for EV's and PHEV's: examples and new solutions

The battery is an important component in an electric vehicle (EV) or a plug-in hybrid electric vehicle (PHEV) and it should be charged from the grid in a cost efficient, preferably fast and definitely safe way. The charger could be an on board or an off board charger. For an on board charger it is possible to use available hardware of the traction system, mainly the inverter and the electric motor, in the charger circuit. This is called an integrated charger. In this paper, different examples of integrated chargers are reviewed and explained. Additionally, other possible solutions of integrated chargers are described.

An Isolated High-Power Integrated Charger in Electrified-Vehicle Applications

For electric and hybrid vehicles that use grid power to charge the battery, traction circuit components are not normally engaged during the charging time; hence, there is a possibility of using the traction circuit components in the charger circuit to have an onboard integrated charger. An isolated high-power integrated charger based on a special electrical machine with a double set of stator windings is described. Through the reconfiguration of the motor stator windings in the charging mode, a six-terminal machine is achieved. The so-called motor/generator acts as an isolated three-phase power source after synchronization with the utility grid in the charging mode. This rotary isolated power source constitutes a three-phase boost rectifier (battery charger) with full utilization of the inverter. The motor windings are reconfigured by a relay-based switching device for the charging and traction modes. This paper presents the mathematical model of the motor/generator and explains the systems functionality for the traction and charging modes. Furthermore, the charger grid synchronization and charge control are described. Finally, the simulation results are presented for a practically designed system with a traction power of 25 kW and a possible charge power of 12.5 kW.

An Integrated 20-kW Motor Drive and Isolated Battery Charger for Plug-In Vehicles

For 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 motor drive and battery charger. An isolated high-power three-phase integrated motor drive and charger based on a split-phase permanent magnet motor is presented in this paper. The motor winding connections are reversible by a relay-based switching device for traction and battery charging. In traction mode, the motor is a classical three-phase motor, but in charging mode it is a rotating isolating transformer providing a three-phase voltage source for the inverter to charge the battery. A mathematical model of the motor with six stator windings is presented for an arbitrary phase shift in windings. For the charging mode, the split-phase motor grid synchronization process and charge control are explained including the developed controller. A 20 -kW system is designed and implemented to verify the proper operation of the proposed system. Simulation and practical results are provided to show the system performance in terms of functionality, dynamic response, and efficiency. Moreover, some discussions, recommendations, and limitations are provided to give more practical insights.

An integrated charger for plug-in hybrid electric vehicles based on a special interior permanent magnet motor

For a plug-in hybrid electric vehicle (PHEV), the battery needs to be charged from the grid while the vehicle is parked. The traction system components are normally not engaged during the charging time so there is a possibility to use them in the charger system to develop an integrated charger. An innovative high power isolated three-phase bi-directional integrated charger with unit power factor operation is introduced for PHEVs based on a special configuration of the ac motor. The winding of the machine is re-arranged in charging mode to have a three-phase boost based high power battery charger. The system configuration, the device model (machine with multiple windings), traction and charging system functionality and charger control are presented in this paper.

Assessment of a Multilevel Converter for a PHEV charge and traction application

With the Plug in Hybrid Electric Vehicle (PHEV) the introduction of a charger has to be done. A standalone onboard charger will increase both weight and cost of the vehicle. A better option is the integration of the charging function into the already existing propulsion converter. The aim of this paper is to assess the multilevel converter as an integrated vehicle charge and propulsion converter. A comparison between conventional converter technology and multilevel converter technology is made both on component level and system level. The investigation, based on calculations, simulations and measurements, points to some features that can; increase the efficiency of the total system; increase the life time of the energy storage; and increase the utilization of the energy storage. However, the investigation also points to features that can increase the cost and complexity of the system and reduce efficiency in certain operation points.

Integration of plug in hybrid electric vehicles and electric vehicles - experience from Sweden

Integration of plug in hybrid electric vehicles and electric vehicles (PHEVs and EVs) includes a wide area of topics like grid effects, different charging concepts, charger designs, harmonics from the charger etc. This short paper gives an introduction to ongoing work within this field in Sweden, and shows on research work within the topic at Chalmers University of Technology.

Evaluation and comparison of a two-level and a multilevel inverter for an EV using a modulized battery topology

This paper analytically evaluates when it is suitable to use a multilevel inverter in an electrified vehicle. The multilevel inverter is compared to a classical two level inverter for different operation points and for different drive cycles.

Selecting IGBT module for a high voltage 5 MW wind turbine PMSG-equipped generating system

In this paper, a fairly high voltage generating system for a 5 MW generating system is investigated. The generating system consists of a surface mounted PMSG (Permanent Magnet Synchronous Generator) with a 2-level transistor converter. The focus is on utilizing three available high voltage IGBT-modules, and to investigate the resulting losses when using them to compose a converter, in order to observe the difference as well as the best choice. In addition, the ideal dc-link voltage for a certain module as well as for a certain main average wind speed is studied. It is found that the most suitable module to use from the loss point of view is the 1.7 kV module, the one with the lowest voltage rating. The difference towards using the 6.5 kV module is a loss increase in the converter at rated operation of 62 %. This is in spite of that a converter composed of the 6.5 kV module has less than half of the conduction losses compare to 1.7 kV module. Accordingly, it can be understood that the switching losses increase much stronger than the conduction losses decrease when using a module with higher voltage rating. When looking at the average annual energy efficiency difference, the best annual efficiency is also achieved when the converter is composed with the 1.7 kV modules.

A combined motor/drive/battery charger based on a split-windings PMSM

An integrated motor/drive/battery charger is proposed, designed and simulated for vehicles using grid power to charge the system batteries. The machine stator windings are re-configured by a relay-based switching device for charging to constitute a special grid connected generator. This rotary generator (machine with re-configured windings) provides an isolated three-phase power source for the inverter to make a three-phase boost battery charger. The system design and operation in the charging and traction modes are explained for the proposed integrated motor/drive/battery charger. The charging power is half of the traction power for the proposed system. Simulation results are provided to verify the proper operation for the proposed system.