Woodward IDS uses HIL400 to develop new PV inverter controller.

Woodward IDS develops new controller for PV inverters with the HIL400

“HIL400 has greatly enhanced the efficiency of our development process and will contribute greatly to Quality Assurance as the new controller covers an ever wider range of applications”.

Dr. Andreas Dittrich

Introduction

Since 1870 Woodward has been controlling speed and power and is today a world leader in turbine controls, motor drives and power management systems which includes the CON-CYCLE family of Wind Turbine Converters from 1.25 to 6MW and the SOLO family of solar in-verters from 100kW to 1MW.

The ProjectA new controller, the IPC50, was needed to achieve a more compact, more flexible and low-er cost design which would be suitable for both renewable energy applications.

The design teams were located in Switzerland for the design and in Bulgaria for testing.

ChallengeThe challenge was one of design co-ordination (different product families and power ranges), disparate locations (Switzerland, Bulgaria ...) and the rapid prototyping of a radically new and cost-reduced controller.

A key to controller design is the validation of performance over a wide range of operating conditions, all the more so when the convert-ers have different applications (Solar and Wind) and a wide power range (100kW to 6MW).

Design and testing can be a lengthy process es-pecially where different design and test teams in geographically distant locations are simulta-neously involved. Clearly, a lengthy process is not compatible with keeping costs in check.

The SolutionWoodward IDS decided at the start of the proj-ect that their development would rely on an advanced design and test tool: the Typhoon HIL400 Power Electronics emulator. This re-al-time hardware-in-the-loop tester is a desk-top box to which a developmental controller is connected in order to test control algorithms. The HIL400 thus replaces the power laboratory and allows the controls to be tested under all foreseeable operating conditions, eliminating 99% of all bugs and problems before the final, costly lab tests take place at full power.

The test “bench” is shown in the following picture taken in the Woodward design office in Zürich. In the foreground can be seen the IPC232 controller with its UFI2IO and CTR651 cards connected to the HIL400 emulator just behind it. The Tektronix oscilloscope to the left displays the analogue output signals from the HIL400 emulating the inverter while the screen to the right displays the HIL400 Control Inter-face from a PC (not shown). The HIL400 has a

“Parts of the controller design and development could be entrusted to an engineering stu-dent, since testing was at desktop level with no high voltages” says Martin Vinzens, Engineer-ing Director at Woodward IDS, Zürich. “We had our international experts and consultants around for the 20 weeks of the project and our engineering student, Alexandre Cavalier from Paris was able to work on the design of the controller and put it through extensive tests with minimal supervision”.

simple graphic user interface (GUI) as shown below, reminiscent of standard simulation soft-ware packages.

The GUI below is for the initial solar application for which different types of panel with varying degrees of insolation could be emulated, along with different filters, line impedances and grid voltages (sag, flicker, surge, harmonic content etc.).

In the case of a wind turbine, different machine characteristics can be programmed (reactanc-es, mechanical inertia etc.) which would be difficult if not impossible to replicate in a lab at rated power.

“The HIL400 allows the emulation of up to two converters with unlimited passive components around them” says Alexandre Cavalier. “If the screen gets too busy because the circuit is com-plex, you can split it with convenient ‘coupling elements’. Also, the library is really comprehen-sive with passives, converters, motors, sources, switches, meters etc.”

The ResultsThe development of the new Woodward con-troller was sped up with a minimum of involved resources. “Having the flexibility of a real-time simulator in the office meant that all those in-volved could test and modify algorithms with-out continually scheduling cumbersome tests in the Power Lab. By the time when we would be ready to go to the lab for final tests, the job then is practically done” says Martin Vinzens.

ConclusionsThe traditional approach of testing power elec-tronics controls, solely in a power lab, is too costly and incomplete to meet the quality and reliability requirements of continually evolving controller functionality. The Typhoon family of emulators addresses this paradigm and offers a revolutionary way of reducing development and QA costs in a world where power manage-ment and renewable energy production have become the Leitmotif of our age.