enercon v. kenetech windpower inc. ben elkin uc berkeley – bioengineering 2011 ie0r 190g november...
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Enercon v. Kenetech Windpower Inc.
Ben ElkinUC Berkeley – Bioengineering 2011
IE0R 190GNovember 17, 2008
A case about variable speed wind turbines
Parties Involved
• Enercon-Third largest manufacturer of wind turbines in the world-As of November 2008, has over 13,000 turbines installed (15.5 GW power)-Tried to export their E-40 design to the U.S in 1993-1994, contracting with
New World Power Corp (NWP)
• US Int’l Trade Commission-The US ITC provides trade expertise to legislative/executive branches of
government on unfair trade practices including patent, trademark, and copyright infringement
-Independent, non-partisan federal agency
Development-1993: NWP writes Enercon to request price quote for E-40 model-August 1993, Enercon responds with specific price per turbine. States that
deal remains open until March 31, 1994, signed by Enercon officers.-February 1994, NWP submits bid for project in Texas, using E-40 turbines
-Kenetech Windpower Inc, a large US company dealing in windpower-Filed complaint with US ITC, claiming that Enercon’s E-40 turbine infringed
on its existing patent, 5,083,039 (‘039), claim 131.-Patent concerns a method of converting wind power into electrical power
that is usable by a utility company.
TechnologyBackground
-A wind turbine converts wind energy into electrical energy using a wind-driven turbine in combination with an alternating current (AC) induction generator
-In variable speed turbine, frequency of generated power waveform depends on wind speed/strength
-In North America, electrical utilities deliver power at 60 Hz
1) Variable turbine’s frequency (cycles/sec) must match grid’s for optimal power output
2) Also, the wave’s phases (max and min) must match, add constructively
-When waves for both voltage and current are in phase, all of the generator’s power is composed of “real” or usable power
-If the waveforms are out of phase, some of the power is lost, NOT ideal.-The degree to which the waves are out of phase is referred to as the “power
factor angle”
Complications-Inductive loads on a power grid can pull the current wave out of phase with
the voltage waveform. This occurs when a voltage wave reaches is peak before that of the AC current
-It is desirable to pre-correct this distortion by providing a wave that either leads or lags the waveform on the utility grid
Patent ‘039, Claim 131“131. A method for converting electricity generated by a variable speed wind turbine into fixed
frequency output electricity, wherein the wind turbine includes a generator and means for supplying generated electricity to power converter that includes a switched inverter supplying the output electricity, the method comprising the steps of:
forming a reference waveform; rotating the reference waveform by a selected power factor angle to yield a template waveform; using the template waveform to define desired output currents; and controlling the switched inverter to produce output currents corresponding to the desired output
currents.”
In English:The goal is to manipulate the current and voltage wave outputs from the
power converter. First, a reference wave is formed by sampling the waveform on the grid. Claim 131 rotates this wave by a power factor angle to generate a template, model waveform. Then, a switched inverter controls the output wave from the power converter to match the template as closely as possible
Process-Variable frequency AC from generator to direct current
(DC) using a power converter
-Power converter also switches DC back to AC, fixing frequency
-An inverter control unit supplies power to utility grid with an adjustable phase
-The power factor angle is adjusted so that the current supplied by the generator is in phase with utility voltage
-The current’s phase can be adjusted to lead or lag the voltage to compensate for inductive loads on grid
Schematic of the entire system:-Measures wind speed-Inverts current AC ---> DC ---> AC-Filters to appropriate frequency and phase-Exports energy to power grid
Case-The parties’ primary dispute was over the construction of the word “rotating”
-All parties agree that the process of “rotating” a waveform results in a phase shift in a plot against time
-Enercon argues that this term in Claim 131 is limited to a special type of phase shift – a so-called “rotational transformation”
-In trying to demonstrate what the word “rotate” means to one skilled in the art, Enercon submitted references that contain prior art to limitations of Claim 131
Decision – Oct 1996
-ITC had jurisdiction under Section 337 of the Tariff Act of 1930 (ammended 1994), based on Kenetech’s complaint. In particular, this section requires a “sale for importation” before the ITC can step in. Enercon’s involvement with NWP rendered it applicable.
-In past cases, the court has repeatedly states that while claims are construed in light of the specification, they are not necessarily limited by it
-The specification is read to use the terms “rotate” and “shift” interchangeably
-There was no evidence to indicate that the term “rotate” refers to the specialized (Kenetech) method of performing a phase shift by “rotational transformation”
Analysis-Enercon might have had a better case if they vetted their material more
closely, making sure no prior art was involved.-For all practical purposes, a phase shift and a rotation are interchangeable
when discussing sinusoidal functions. -Use more green energy!
Questions?
References• http://altlaw.org/v1/cases/1353130
• http://www.google.com/patents?id=CuIiAAAAEBAJ&printsec=abstract&zoom=4
• http://en.wikipedia.org/wiki/Enercon
• http://www.windenergy.com/news/news_Renewable_Energy_World_4-13-08.html
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