The History of the DQ Transformation

Park’s transformation can be considered to be the single theoretical contribution that triggered the development of advanced design, control, and analysis of electrical machines (motors and generators). To most practicing engineers and researchers in this field, the story goes like this:

After Nikola Tesla invented the AC machine in the 1880s, it took the electrical engineers over 3 decades of struggling with AC circuits analysis before Robert H. Park (1902–1994) published his seminal paper, in 1929, “Two Reaction Theory of Synchronous Machines”. In that paper, the brilliant young engineer solved the problem mathemagically by introducing the dq0-transformation that has been called after him, the Park’s transformation, which transforms the natural 3-phase AC reference frame into a fictitious 2-circuit rotating reference frame.

The Park’s transformation is a brilliant idea indeed, except that it was not invented by Park… Have you ever heard of André-Eugène Blondel (1863–1938)? Here is the complete story.

Continue reading “Why is it called Park’s, not Blondel’s, Transformation?” →