Danfoss Drives has a history of making frequency converters, also known as VLT® for controlling electrical motors that goes back more than 40 years. A frequency converter controls speed, torque, acceleration, synchronization, positioning, and overall performance of electrical motors. The power range spanned by the products covers voltages from 200 V to 690 V and power sizes from 0.18 kW to 1.2 MW. The frequency converters are intended for many different application areas, the main ones being the Automation drive, which is a multi-purposed industry drive, the AQUA drive used in pump and waste water systems, and the HVAC drive for heat and ventilation systems. Most of the drives developed are highly flexible and have several hundred configuration items, which allow the customers to adapt the frequency converter to their specific applications. Furthermore, additional options are offered, for instance to enable field bus communication and extended I/O. This application dedication contributes to the main variability within the drives
Before introducing software product line engineering (PLE), the previous drive series was developed and maintained following the waterfall model with reuse in a clone-and-own manner. Within this series, three drive variants existed. By 2005, there was a wish to produce a product series with an increased number of product variants while at the same time decreasing time to market and keeping development costs low. While reducing development effort on new variants, the clone-and-own approach in use would cause latency in how fast one could introduce new features and corrections across multiple products. Considering increasing number of variants requested by marketing for the new generation of drives, Danfoss Drives needed to operate differently.
When Danfoss Drives started the PLE journey, the SPLC 2005 conference in Rennes provided valuable lessons and created the basis for the current setup. One of the lessons learned was that incremental PLE adoption could be a feasible potential solution. This was a pleasant lesson to learn because some people had been under the impression that product line development had to start from scratch using domain modeling.
At the SPLC conference, it also became evident that the organizational setup also needed to be considered carefully, not only the technical parts. A major source of inspirations was the story of the LSI Logic - Engenio Storage Group from the SPLC Hall of Fame. The Engenio case very much resembled the scenario that Danfoss Drives was facing, since both had a large code base for multiple products. Hence, it appeared reasonable that Danfoss Drives should adopt the PLE approach Engenio had taken. The old drive series consisted of three main products, two fieldbus options, and an application option, which were all maintained using the clone-and-own approach. Today the product portfolio for the PLE based product family includes more than 20 main products and 60+ options. Although the number of products maintained and developed has increased almost tenfold, the number of people taking care of this work has only increased fivefold. The throughput of new features and software modules increased and quality level increased. These evaluation results show that the product line adoption journey of Danfoss Drives from single product development to platform development for both source code and non-code artifacts (e.g., requirements) has paid off.
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Krzysztof Sierszecki, Michaela Steffens, Helene H. Hojrup, Juha Savolainen, Danilo Beuche: Extending variability management to the next level. SPLC 2014: 320-329
Bo Zhang, Martin Becker, Thomas Patzke, Krzysztof Sierszecki, Juha Erik Savolainen: Variability evolution and erosion in industrial product lines: a case study. SPLC 2013: 168-177
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Thomas Fogdal, Helene Scherrebeck, Juha Kuusela, Martin Becker and Bo Zhang 2016. Ten Years of Product Line Engineering at Danfoss: Lessons Learned and Way Ahead. SPLC 2016: 252-261
About This Product Line
Danfoss was inducted into the Hall of Fame at the 20th Software Product Line Conference (SPLC 2016) .