Technical papers

NOTE: Advanced Conversion has acquired all of the technology and technical data of SBE Inc. References to SBE are now Advanced Conversion.

A. DC Link Capacitor/Bus Solutions Enabling the Highest Possible Inverter Performance

•   Highest Ampere per micro-Farad rating
•   Lowest micro-Farad per kW
•   Industry-leading ESR and ESL
1. Optimal DC Link Topologies for Best Utilization of Switch Modules (pdf)

Presented at APEC 2019

Abstract: Next-generation switch modules offer significant improvements in efficiency for power conversion systems utilized for traction drive and grid-tied applications. However, an enabling ecosystem of supporting technology including the DC link is required to fully exploit these modules. An overview of the Power Ring Film Capacitor™ is provided along with illustrations of how this building block is integrated with an optimized bus structure topology.

Powerpoint Presentation (pdf)

2. Evaluation of Infineon HybridPACK™ Drive with Optimized Integrated Capacitor/Bus DC Link for High-Performance Inverter Applications (pdf)

Presented at PCIM Europe 2018

Abstract: The Infineon HybridPACK™ Drive module was previously evaluated using the SBE 700A186 capacitor/bus DC link. This testing demonstrated the importance of low equivalent series inductance to achieve maximum efficiency with fast switching at full voltage but was test equipment limited to 50kW. Power testing up to 150kW is now performed using both 750V and 1200V IGBT versions of the HybridPACK™ Drive along with the 500V and 750V variants of the SBE capacitor/bus test kit. This work provides critical thermal data to establish a high-performance inverter baseline that can be directly compared to silicon carbide modules which are planned for the HybridPACK™ Drive package in the near future.

Technical Paper (pdf)

3. High-Performance DC Link Capacitor/Bus Sourcing Dual Infineon HybridPACK™ Drive Inverters for EV Applications (pdf)

Presented at PCIM Europe 2017

Abstract: A high performance integrated capacitor/bus for the Infineon HybridPACK™ Drive was presented previously. This foundation will now be used as the basis for evaluating a single DC link capacitor/bus to support two HybridPACK™ Drive inverters, thus enabling a significant improvement in power density, weight and cost for EV applications. Detailed knowledge of the drive cycle is required along with full thermal characterization to demonstrate the required life. Transient thermal simulation results and experimental data are provided. These results are utilized to define practical topologies and power limits for one DC link feeding two HybridPACK™ Drive modules.

Technical Paper (pdf)
Poster Presentation (pdf)

4. Optimized DC Link for Next Generation Power Modules (pdf)

Presented at PCIM Europe 2016

Abstract: The market leaders in IGBT technology are now introducing next generation “six-pack” modules to enable increased power density and reduced cost for automotive traction drive applications. However, the potential gains offered by these modules can only be harvested using an optimized DC link with integrated capacitor/bus topology. Two integrated capacitor/bus solutions have been designed to support the new Infineon HybridPACK™ Drive module with the lowest possible µF/kW ratio and minimized equivalent series inductance. Simulation and design results are presented along with third party testing data for a complete inverter.

Poster Presentation (pdf)
Technical Paper (pdf)

5. Are Snubbers the Right Choice for High Performance Inverters? (pdf)

Application note distributed in 2016

Abstract: The use of snubber capacitors across switch module terminals is a common practice, but these elements may not be effective and can limit system reliability. This application note discusses the efficacy of snubbers and provides some case studies that consider efficiency. A tightly integrated DC link approach is demonstrated to offer a better alternative.

Presentation (pdf)

6. Integrated DC Link Capacitor/Bus enables a 20% Increase in Inverter Efficiency (pdf)

Presented at PCIM Europe 2014

Abstract: Voltage overshoot at switch turn-off traditionally limits the DC operating voltage for inverter systems. Mitigation methods include snubber capacitors and intelligent gate control, which add cost and complexity while reducing efficiency. However, the fundamental first step in overshoot reduction is actually minimizing the DC link inductance. The combination of the SBE Power Ring Film Capacitor™ integrated with an optimized bus structure can achieve a DC link inductance below 10nH, which is less than typical IGBT half-bridge internal branch values. This enables safely increasing the DC voltage up to 20%, thus improving inverter cost and volume efficiency with existing IGBT’s.

Presentation (pdf)
Technical Paper (pdf)

7. Integrated DC Link Capacitor/Bus Structures to Minimize External ESL Contribution to Voltage Overshoot (pdf)

Presented at ITEC 2012 – IEEE Transportation Electrification Conference

Abstract: Voltage overshoot is defined by stray series inductance and turn‐off time and must be managed to avoid failure of IGBTs in automotive inverters. The total equivalent series inductance (ESL) is dictated by internal switch branch inductance with a significant contribution in the current path to the DC link capacitor. Using traditional topologies, external ESL dominates and by‐pass capacitors (“snubbers”) are used to mitigate overshoot. Integrated capacitor/bus designs provide an external ESL comparable to internal values for commercial IGBTs. The minimized ESL regime allows reduced switch turn‐off time with slightly increased losses to manage overshoot without the cost, space, weight, dissipation, and reliability associated with by‐pass capacitors.

Technical Paper (pdf)

8. Characterization of Equivalent Series Inductance for DC Link Capacitors and Bus Structures (pdf)

Presented at PCIM Europe 2012

Abstract: The equivalent series inductance (ESL) of the DC link capacitor and associated bus structure connecting to the switch module has important implications for optimization of electric vehicle inverters. In many cases, additional snubber (bypass) capacitors can be eliminated for sufficiently low ESL, thus reducing cost, weight and volume. This paper presents ESL measurements for realistic capacitor/bus structures using a practical method previously documented. Supporting magneto-dynamic finite element analysis results are also presented and shown to agree quite well with the measurements. The measurement and simulation results demonstrate that a 1000 μF 600V Power Ring Film Capacitor has an ESL of approximately 3 nH with a properly designed terminal structure. The bus structure is shown to dominate the total ESL for both horizontal and vertical inverter topologies when using annular form factor film capacitors with an optimal terminal configuration.

Technical Paper (pdf)

9. Electric Drive Cost Reduction by Design Simplification (pdf)

Presented at SAE 2012 Hybrid and Electric Vehicle Technology Symposium, by Jon Bereisa, President and CEO of Auto Lectrification, LLC and SBE Senior Technical Advisor.

Abstract: Jon Bereisa – a top GM Electrified Powertrain Engineer – describes how utilizing a highly integrated DC link capacitor bus is the way of the future for EV inverters.

Presentation (pdf)

10. Low Inductance – Low Temp Rise DC Bus Capacitor Properties Enabling the Optimization of High Power Inverters (pdf)

Presented at PCIM Europe 2010

Abstract: Discussion on the possible reliability improvements using the SBE Power Ring in an Automotive Inverter application.

Presentation (pdf)
Technical Paper (pdf)

B. Resonant Circuit Applications

1. System Level Considerations for Integration of Resonant Capacitors in High Power Wireless Charging (pdf)

Presented at CERV 2012

Abstract: Mass adoption of electric vehicle technology is highly dependent upon ease of recharging at the consumer level. Various strategies including battery swapping, improved battery efficiency, and wireless charging have emerged to address this issue. In the context of wireless charging, implementation options range from local hotspots in the user’s garage or public parking areas to energized roads. While a great deal of attention has been focused on the coupling coils and drive circuitry for wireless charging, the resonating capacitors are equally important components and must be carefully considered. Typical resonant frequencies range from 10 kHz to over 150 kHz which can be supported by both film and ceramic capacitor technology. However, there are significant compromises between cost and performance that remain to be clearly defined. Furthermore, capacitor performance can be significantly impacted by the hostile operating environment, which will include heating from stray magnetic fields and high-temperature coil components. An investigation of optimized hybrid film/coil capacitors has been undertaken to define the frequency and voltage operating regime where stability, cost, and graceful aging can balance dissipation losses. Test results for polypropylene film capacitors in a coupled coil resonant circuit are presented along with a discussion of system-level implementation.

Technical Paper (pdf)

C. Improving Capacitor Banks for Alternative Energy and UPS Systems

1. Next Generation Dry Film AC Filter Capacitor Eliminates Catastrophic Failures (pdf)

Presented at PCIM Europe 2015

Abstract: AC filter capacitors are a limiting factor for the reliability of power conversion systems in network power and alternative energy applications. Conventional capacitors with pressure interrupters or fuses often fail catastrophically with significant collateral damage. A next-generation annular form factor dry-film capacitor has been developed to eliminate catastrophic failures using proprietary end connection and segmentation technology. By accepting some small additional capacitance loss over life, potential failure sites are disconnected before they can transition into dangerous faults. Extreme accelerated failure prediction results at 100°C and 127% of rated voltage are presented with capacitance loss measurements under more practical operating conditions.

Technical Paper (pdf)

2. Increasing the Life of Electrolytic Capacitor Banks Using Integrated High-Performance Film Capacitors (pdf)

Presented at PCIM Europe 2013

Abstract: Inverters for wind and solar applications require DC link capacitors to provide a local reservoir of charge during switching and store energy for ride-through of grid events. Electrolytic capacitors are desirable for this application with regard to capacitance density but must be de-rated for acceptable service life. A hybrid bank combining the best features of film and electrolytic capacitors has been developed to address this problem. Advanced film capacitors supply the high-frequency components of the system ripple current to reduce electrolytic temperature rise and increase life. Simulation and laboratory test results are presented for practical DC link capacitor banks.

Presentation (pdf)
Technical Paper (pdf)