THE BENEFITS OF XILINX FPGAs
Princeton Power Systems’ algorithms required extensive calculations that can only be accomplished by floating-point DSPs, which traditionally do not have the same features as FPGAs. Some of the features of Xilinx FPGAs that particularly suited the PPS project included multi-voltage, multi-standard SelectIO I/O pins; configurable logic blocks; block RAM; and memory interfaces that can implement a large number of programmable trigger signals. These signals generate and execute pulse trains that trigger power electronic switches like IGBTs and control a large number of fast ADC channels to read important system measurements on every pulse or custom high-speed serial interfaces.
FPGAs not only allowed Princeton Power Systems to design and implement custom peripherals that matched its specific requirements, but also provided additional computational resources for the processing of input values, which otherwise would have to be done by the DSP. The Spartan-3 FPGA-based design completes several processes: It accomplishes system error checking using the values read from ADCs connected to the DSP. It implements timer-driven activities like reading ADCs precisely when necessary. And it does an averaging of ADC values.
Without the FPGA, some of these functional requirements would have been impossible to implement. Other functionalities would have required more components on the DRI’s control board or a significantly more complex software architecture. The PPS team knew it was crucial to avoid the latter, since the control board acts as the heart of the DRI system.
“While an increasing number of DSPs now offer peripherals that were previously absent, the importance of having an FPGA still remains,” said Frank Hoffmann, the R&D manager at Princeton Power Systems. “With each new generation, the amount of computational resources inside the FPGA increases—for example, from a Spartan-3 to a Spartan-6—and it has now become possible to outsource more computational work to the FPGA. And this could mean running our complex control algorithms faster and therefore improving the quality of a generated output like the one in the DRI.”
THE BOTTOM LINE
While the technical benefits of using an FPGA are clear (quick prototyping, flexible architecture, advanced support tools like Xilinx’s ChipScope™ Integrated Logic Analyzer for quick in-system debug), the decision has also affected Princeton Power Systems’ bottom line.
“Using an FPGA has made development much faster, reducing R&D expenses and time-to-market for new and innovative alternative-energy systems,” said executive vice president Darren Hammell. “The programming environment was easy to use and enabled us to rapidly develop and test our innovative software. This enabled us to complete the prototype for the demonstration much quicker than otherwise would have been possible.” The product is now shipping, and PPS has added two new customers: BMW and SuperPlug have included a DRI in new power system designs.
In fields like green power technology, engineers face new challenges, including determining how to optimize algorithm implementation while retaining necessary functionality. With the right tools, technology and team, enhancements in this field lie just within reach.
For more information on Princeton Power’s multi-terminal DRI, please visit http://www.princetonpower.com/prod_demand.shtml.
About the author:
Phillip Southard is senior design engineer at PDS Consulting, LLC. He can be reached at firstname.lastname@example.org
You can reach PDS Consulting at email@example.com
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