“They are often AC-to-AC converters that are doing things like cleaning up the power, doing power factory correction, or stabilizing the grid,” MacCleery said.
“They are very helpful for solar applications because a significant chunk of power can be coming and going, on and off the grid when clouds go over. But flexible AC transmission systems can help stabilize the grid given variability in generation and demand, plus provide voltage regulation that increases and optimizes the energy efficiency of the grid for any given condition.“
An important development for National Instruments is a single-board RIO control system that is optimized specifically for these kinds of power electronics and converter applications. Its idea is to cost-optimize and custom design an FPGA-based control platform specifically for inverter applications. The main thing to customize is the selection of the best FPGA and processor to hit the customer price point for high-volume deployment on the grid along with the right form factor mechanically and the appropriate I/O.
The goal has been to develop a GPIC (general-purpose inverter controller) platform that will be a very standardized FPGA-based design, which can be used in all kinds of applications, from the solar inverters, to wind turbine and grid storage converters, to FACTS-type systems. The overall goal is to provide an alternative to fully-custom hardware development, which is becoming increasingly expensive and risky due to the increasing internal complexity and external pin density of embedded processing devices.
What’s most important to this approach is to create a new software development process that enables the engineering teams to develop their actual FPGA software using graphical programming and within a simulation environment, and then move that code to a physical FPGA target and get identical results with little effort.
Historically, going from high-level software that intuitively captures design intent to low-level FPGA hardware meant plummeting into an abyss of text-based code that describes the design at a massively parallel hardware level. Instead, the goal of this effort is to enable designers to stay at the high level, the intuitive level, from the beginning to the end of product development. The high-level code must be able to compile down to FPGA hardware with an efficiency that’s comparable to handwritten Hardware Description Level (HDL) code. Another key advantage is a bidirectional development path, meaning that any changes made to the software at any stage automatically update anywhere that code is referenced in the tool chain.
“The power electronics circuitry must be developed in parallel with the FPGA software if you want them both to be optimal,” said MacCleery. “Most design decisions have implications that span the boundaries between the analog hardware and the digital software, and engineers need design tools which really are test tools and continuously test the design. To bring all of these things together that historically were not connected is our goal.”