GE Dodges Mitsubishi Wind Turbine Blade Pitch Angle Patent

A previous post discussed Mitsubishi’s patent infringement action against GE in which the Japanese conglomerate fought back against multiple infringement suits (see, e.g., here and here) brought against it by GE.

Mitsubishi’s Complaint, filed in the Middle District of Florida, accused GE of infringing U.S. Patent No. 7,452,185, entitled “Blade-pitch-angle control device and wind power generator” (‘185 Patent).

Earlier this month, GE emerged victorious as the court granted GE’s motion for summary judgment on non-infringement of the ‘185 Patent.

In the suit, Mitsubishi alleged that GE’s wind turbines containing its Advanced Controls and Model-Based Controls (MBC) systems infringed independent claims 1 and 5 of the ‘185 Patent. 

Each of the claims recited a blade-pitch-angle control device comprising a memory device, an azimuth-angle detecting device, a parameter-detecting device, a command-value receiving device, and a pitch-angle-control command-value generating device. 

The decision turned on the interpretation of a key claim element reciting the functionality of the control device’s command-value receiving device:

a command value receiving device that receives the pitch-angle command values for each of the blades from the memory device, the pitch-angle command values being selected on the basis of the azimuth angle of each blade detected by the azimuth-angle detecting device and the predetermined parameters detected by the parameter-detecting device

Mitsubishi identified two GE pitch values that it alleged satisfied the limitations of the claims – the “Aerobalance” value and the “Lower Pitch Limit.” 

GE countered that its turbines do not infringe claims 1 or 5 of the ‘985 Patent because the pitch-angle control values in Advanced Controls and MBC are calculated rather than received and selected from a memory device.

In particular, with respect to the Aerobalance value, GE asserted that the pitch offet values are not selected on the basis of azimuth angle and predetermined parameters.  Rather, GE said they are stored in memory for twenty minutes and continuously applied to a specific blade, if needed, regardless of the blade’s azimuth angle.

The court agreed with GE on the Aerobalance value, relying upon Mitsubishi’s expert testimony:

Dr. Van Schoor [Mitsubishi’s expert] acknowledged in his deposition that the AeroBalance value is applied for twenty minutes to a blade – as the blade rotates around and around – and is used regardless of that blade’s azimuth angle.  Thus, it cannot be said that the AeroBalance value is selected on the basis of azimuth angle as required by the claim limitation.

As to the Lower Pitch Limit - a value below which the pitch angles are not set - the court found that, though azimuth angle is used to calculate a command value for pitch angle, that is not sufficient to meet the claim limitation at issue:

The use of azimuth angle in calculating an individual pitch-angle command value that is then compared to the Lower Pitch Limit – followed by selection of the Lower Pitch Limit – does not amount to selecting a pitch-angle command value based on azimuth angle.  The Lower Pitch Limit is chosen over the other, calculated pitch-angle command value – if at all – based on a numerical comparison between the two, not based on a blade’s position….The fact that azimuth angle might be an input into the calculation of the comparator pitch-angle command values does not satisify the “selected on the basis of” limitation.

This is the second recent federal court victory for GE over Mitsubishi.  In March a Texas jury found that Mitsubishi infringed GE’s U.S. Patent No. 7,629,705 and awarded GE $170 million.



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Eric Lane

Eric Lane, the founder and principal of Green Patent Law, is an intellectual property lawyer and registered U.S. patent attorney in New York and is a member of the bar in New York and California. Eric has more than two decades of experience working with wind, solar PV, CSP, biofuels, and geothermal, energy storage technologies, carbon capture and sequestration, medical devices, data communications, mechanical, chemical, internet and software.