Institute of Electric Mobility and Energy Storage Systems


One possible disadvantage of inductive charging systems compared with conductive charging systems is the fact that bidirectional operation has not yet been taken into account. For example, in many scenarios for a future electric power supply system, the vehicle battery is envisaged as a temporary storage device for the volatile feed-in of renewable energies. However, in order to make the stored energy usable again for the supply grid, bidirectional operation of the e-vehicle charging systems is essential, i.e., it must be technically possible for energy to flow in both directions. However, current inductive charging systems (only prototypes, no systems on the market yet) are only suitable for unidirectional operation, i.e. for charging the vehicle battery. The further development of unidirectional inductive charging systems into bidirectional inductive charging systems enables to combine the inductive charging process, which is convenient for the user in terms of handling, with the integration of the vehicle into a V2G infrastructure. This allows electric vehicles with inductive charging systems to enter the field of smart home system topology, as was previously only possible with vehicles that could be charged conductively.

In this project, different inductive charging systems are to be measured and evaluated with regard to their functional safety (EMC-E), their immunity to interference and their electromagnetic interference potential (EMI). For this purpose, unidirectional and bidirectional inductive charging systems were first developed and then built.

The project objective is the derivation of specified and comprehensively defined measurement systems (including test setups) for various inductive (unidirectional and bidirectional) e-vehicle charging systems to determine conformity with standards and/or laws. These measurement systems form the prototypical basis of a test service to be offered later by EMC Test for various market participants, such as OEMs, automotive suppliers or companies offering components and systems for retrofitting to motor vehicles.

Essential for the evaluation of inductive charging systems is also the recording and evaluation of the energy flows between primary and secondary side. In order to be able to conceptualize, implement and evaluate the measurement systems, the development of different inductive charging systems consisting of inductive, capacitive and power electronic components or subsystems is essential. The focus here is on realizing the highest possible average efficiency in both transmission directions. One challenge is the bidirectional design and control or the interaction of the power electronic subsystems, which, in contrast to unidirectional systems, now also have to be constructed primarily from active components (IGBT or MOSFET) on the secondary side and at the grid connection. Furthermore, the systems must comply with the legal and, if available, normative limits with regard to magnetic fields in public spaces and thus satisfy the requirements for functional safety and interference potential.

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