Technology
The Power Ring Film Capacitor™ provides:
- Extremely low internal losses (ESR) and low inductive properties (ESL)
- Industry Leading ESR/ESL Characteristics
- Extreme Current Pulse Survival
- Significant Capacitor Density
- Inverter Topology Design for Optimized Current Rating and Reduced Coolant Need
- High Temperature Polypropylene Film Capacitor Designs
SBE has developed the Power Ring Film Capacitor™ after years of research and experimentation on the optimum use of Polyester and Polypropylene film capacitor dielectrics.
The ring shape (annular form factor) provides extremely low internal losses (ESR) within the film and also provides for the purest form of interconnect symmetry which can dramatically lower the inductive properties (ESL). These properties drive the leading edge electrical characteristics that the designing engineer can take advantage of.
While the dimensional changes to the traditional Film Capacitor form factor are straightforward on the surface, there are many things which emerge as challenges to the ultimate success in a customer application. SBE has developed manufacturing processes which have solved these issues to produce a robust product under extreme operating conditions.
Low Losses – ESR (Low losses under heavy current loads)
The much shorter path of current between the electrodes produces the lowest ESR for Film Capacitors in the industry. The reasons for this are described in the technical paper “An Extremely Low ESR and ESL Annular Film Capacitor” (pdf link). These low losses allow for a number of greatly improved designs especially in ripple current applications. This example shows the very low temperature rise in an Automotive Hybrid Inverter DC Link application when compared with the typical capacitor bus structure used by the popular Toyota Prius.
Much more information is available in the Technical Papers and Presentations page or in the industry application sections.
Extreme Pulse Current Survival
In 2006, SBE was awarded a patent for Improved Pulse performance of a film capacitor – see paper entitled to “Just How Good is SB Electronics’ Patented Pulse Capacitor?” (pdf link). When this film design improvement is combined with the power of the shape™ that the annular form factor provides, the results can be truly outstanding. The ratio of current carrying surface area of the ring to the film loss and inductance producing distance between these end surface areas allows almost unimaginable peak pulse currents to be produced in a very efficient and cost effective device. The paper “Annular Form Factor Film Capacitors” (pdf link) is just one of many papers and presentations on the subject.
The result of this highly amplified current pulse survival feature is the new ability for a designer to optimize the design for current handling capability. Previously, he had to “bulk up” on capacitance solely for the purpose of current handling survival and lifetime requirements.
Industry Leading ESR/ESL Characteristics
No matter what your need is for an extremely low ESR and ESL characteristic in a film capacitor may be, the Power Ring Film Capacitor is industry leading in this area. The circular shape and short distance connection paths, which can be orientated symmetrically around a large current carrying area, are ideal for the lowest ESL.
The lowest possible ESR is produced by the very short film distances between the electrodes that the annular form factor provides.
There are numerous technical papers and presentations on these subjects. Please take a look at your area of interest.
Significant Capacitor Density
Since the Power Ring Film Capacitor is a continuously wound film capacitor section rather than multiple sections connected as a “bank” of capacitors, the net capacitance density per unit volume is exceptional. The calculations and explanation are available in the presentation paper “Power Ring for Embedded E-Drive applications” (pdf link).
The power of the shape means that the designer will no longer have to choose between thermal performance, lifetime characteristics, or cooling requirements and system capacitance density. With the Power Ring Film Capacitor, both can be optimized.
Inverter Topology Design for Optimized Current Rating and Reduced Coolant Need
The electric drivetrain automotive and alternative energy markets are seeking ways to increase current ratings, reduce size and cost, and eliminate additional cooling requirements. SBE has not only created IGBT switching layout topologies to best utilize the Power Ring Film Capacitor features but is also currently leading ground breaking research for the US Department of Energy in high temperature capacitor design using Polypropylene Film (pdf link).
High Temperature Polypropylene Film Capacitor Designs
SBE is leading the capacitor industry on discovering the reliable high temperature boundaries of Polypropylene film used in ripple current applications for the electric drivetrain automotive and alternative energy markets. Our goal is to produce the world’s first inexpensive DC Link capacitor utilizing Polypropylene film which can operate reliably for over 10,000 hours utilizing only 105°C engine temperature coolant. Please read the latest update on this SBIR research (pdf link).