The present invention relates generally to electric vehicle power electronics, and more particularly, to planar EMI inductors using E-E magnetic cores that may be employed in power conditioning equipment.
The assignee of the present invention designs and develops electric vehicle propulsion systems and other power conditioning equipment. Heretofore, electric vehicle propulsion systems developed by the assignee of the present invention and others have employed a variety of different magnetic core and inductor configurations.
One implementation used E-E magnetic cores with a heavy insulated foil winding. Another implementation used E-E magnetic cores with a bent bus bar. Another implementation used C-C magnetic cores around a straight bus bar. Another implementation used toroidal magnetic cores with a straight bus bar.
The prior art approaches each have limitations that detract from their overall usefulness. For example C-C and toroidal magnetic cores are relatively expensive and require additional machining or bends. C-C cores and toroidal core magnetics used with a straight bus bar reduce the complexity of the bus bar but use higher cost cores and provide lower unit inductance. Certain of the approaches require extensive hand labor during assembly. Other limitations include trying to bend heavy gauge copper into bus bars.
It would therefore be desirable to have planar EMI inductors using E-E magnetic cores that overcome the limitations of conventional implementations.
The present invention comprises a power bus bar assembly comprising improved planar electromagnetic interference (EMI) inductors. The bus bar assembly and planar inductors may be used in electric vehicle charging systems, inverters, and other power conditioning equipment, and the like.
An exemplary power bus bar assembly or planar inductor comprises upper and lower E-E magnetic cores, and upper and lower flat bus bars that are insulated from each other and that have a plurality of core cut-outs that allow the cores to pass through them, and wherein the core cut-outs form an electrical path through the E-E cores that forms a turn that provides a predetermined amount of inductance.
The bus bars may be arranged to form turns in the same direction or opposing directions that provide for a common mode and differential mode inductors, respectively. Different core materials and stacking of multiple cores may be used to improve the frequency response of the inductor. In particular, inductance can be increased by adding additional stacked cores, or different materials can be used for each core, or both.