Coaxial Capacitor Bus Termination
Parallel plate bus structures are commonly used for high-current applications where low inductance is a requirement. Such bus structures are very well suited for inverter topologies used to convert from DC to AC power and a capacitor is needed to minimize ripple on the DC bus. However, such arrangements are not able to provide sufficiently low inductance to easily eliminate bypass capacitors which typically requires a system inductance below 10 nH nor do they provide any natural EMI suppression. The present invention utilizes that natural circular symmetry of a circular film capacitor winding by implementing a coaxial shaped bus connection from the capacitor to the switching semiconductors in the DC bus application of DC to AC inverter. The result is an achievement of lower ESL and geometry based EMI suppression without the use of external-lumped filtering components.
1 . I claim everything here noted.
2 . A low-inductance, low-resistance, and near zero field emission coaxial bus structure with an integrated wound film capacitor to be used for, but not limited to, impedance matching or filtering. This includes bus structures with more than two coaxial conductors.
3 . A means of externally cooling a wound capacitor and bus structure as required without perturbing the electro-magnetic performance of the system.
4 . An efficient means of ripple current filtering in a DC link with the best possible utilization of the bus conductor cross section. The connection between the capacitor and DC source has no sharp edges or corners such that the skin effect only acts in the radial direction.
5 . A packaging method for a single, three-phase, or n-phase inverter which provides the lowest possible inductance between the integrated annular capacitor and switch modules along with total containment of the electromagnetic fields.
6 . All of the embodiments described in the preceding claims as applied to a coaxial structure of non-circular (e.g. square, rectangular, elliptical, etc.) cross section.
7 . All of the embodiments described in claim 6 where the axis of the inner and outer conductor are not the same.