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General Electric Company v. International Trade Commission

February 29, 2012


Appeal from the United States International Trade Commission in Investigation No. 337-TA-641.

The opinion of the court was delivered by: Newman, Circuit Judge.

Before RADER, Chief Judge, NEWMAN, and LINN, Circuit Judges.

The General Electric Company appeals the decision of the United States International Trade Commission, holding that certain variable speed wind turbines imported by Mitsubishi Heavy Industries, Ltd. and Mitsubishi Power Systems Americas, Inc. (together "Mitsubishi") do not violate section 337 of the Tariff Act, 19 U.S.C. §1337.*fn1 The patents at issue were General Electric's United States Patents No. 7,321,221 (the '221 patent), No. 5,083,039 (the '039 patent), and No. 6,921,985 (the '985 patent).


On General Electric's complaint, the Commission conducted an investigation and the Administrative Law Judge held an evidentiary hearing on all of the issues raised by General Electric as complainant, by Mitsubishi as respondent, and by the Commission's investigators. By Final Initial Determination, including 126 pages of findings of fact and conclusions of law, the ALJ held that section 337 is violated by the imported Mitsubishi turbines. The ALJ determined that the '221 patent is not invalid by reason of obviousness; that the '039 patent is not invalid by reason of obviousness, written description, or enablement; and that the '985 patent is not invalid by reason of obviousness or best mode. The ALJ also determined that the three patents are infringed by the imported Mitsubishi wind turbines, and that the intent element of inequitable conduct as to the '985 patent was not established. The ALJ also determined that the domestic industry requirement is not met as to the '221 patent, but is met as to the '039 and '985 patents.

Each participant requested review by the full Commission of the ALJ's adverse rulings. The Commission "noticed" review of the Final Initial Determination except for

(1) the issue of importation and (2) the intent finding of inequitable conduct.*fn2 The Commission received briefing and argument on all of the other issues, and held by Final Determination that the '039 patent is not invalid by reason of obviousness or written description, that the '039 and '221 patents are not infringed by the Mitsubishi turbines, and that the domestic industry requirement is not met as to any of the patents. The Commission took no position on any other issue in the Final Initial Determination, and held that section 337 is not violated by the Mitsubishi imported turbines. This appeal followed.

The '039 patent expired on February 1, 2011, and this court dismissed that portion of the appeal as moot, vacating the Commission's rulings as to the '039 patent.*fn3 We now affirm the Commission's ruling that the '221 patent is not infringed. We reverse the Commission's determination of no domestic industry as to the '985 patent, and remand for further proceedings with respect to the '985 patent.


Electric power is generated from energy sources such as coal, natural gas, nuclear fission, flowing water, and wind, whereby the energy causes the rotation of magnets or electromagnets in association with coils of wire, producing an electric current. See the parties' joint tutorial of the technology presented to the ALJ, Hr'g Tr. Apr. 29, 2009.

The electric current generated by wind turbines is usually fed to a centralized power grid, where electricity from various facilities is combined, stored, and distributed. Although wind is an advantageous source of energy, wind activity tends to be extremely irregular, whereas uniform electric current of fixed frequency is required to be fed to the power grid. This led to the development of variable speed wind turbines, which convert the irregular product of wind energy into the fixed-frequency alternating current (AC) required by the power grid. The General Electric '221 and '985 patents are directed to structure and circuitry that protect the turbine components from the effects of irregu- larities caused by emergency events such as lightning strikes, downed power lines, short circuits, and the like.

The products whose importation is charged with violation of section 337 are variable speed wind turbines designated as Mitsubishi models MWT 92 and MWT 95. As products of the domestic industry, General Electric designated its models SLE, XLE, and SE. The Mitsubishi and General Electric turbines have the structure and circuit configuration called a "doubly-fed induction generator," illustrated as follows:

Gen. Elec. Br. 17 (from J.A. 2222). In operation, the wind turns the blades and causes the shaft to rotate, thereby spinning the rotor and producing a magnetic field in the winding coils, generating electric current. To produce AC electricity of uniform and fixed frequency, in doubly-fed induction generators a second magnetic field is imposed by current drawn from the grid and, by operations not here at issue, the system produces electricity of the desired uniform frequency. Testimony of Dr. Collins, Hr'g Tr. 46-48 (Apr. 29, 2009), J.A. 2746-48.


The '221 patent relates to protective circuitry for variations in grid supply voltage in doubly fed induction generator wind turbines. The patent explains that the problem arises that large voltage differences between grid and stator coils occur on variations of the supply voltage amplitudes caused in the grid by, e.g., short circuits. These differences cause, in turn, a strong current rise in the stator coils directly coupled to the grid. These strong current rises in the stator coils are caused because the induction generator is usually fully excited at the variation of the grid frequency amplitude and mechanical energy is permanently supplied by the rotor. The strong current rise occurring in the stator coils on variations of the supply voltage leads to high induction voltages in the rotor windings, which can, in turn, cause damages on the converters used for feeding the rotor current.

'221 patent, col.1 ll.45-57. The '221 patent employs a protective circuit called a "crowbar circuit," which decouples the current feed-in unit from the rotor windings when large current variations occur, thereby protecting the circuitry. Both the imported Mitsubishi and the domestic General Electric wind turbines employ a system of protective decoupling of the rotor windings from the feed-in converter, but the turbines differ in the method by which operation is restored. In the General Electric turbines recoupling of the circuitry occurs when the emergency-induced elevation in current has declined to a predetermined value as measured in the turbine, and in the Mitsubishi turbines recoupling occurs after a pre-set period of time.

A. Claim Construction

The issue of infringement of the '221 patent was determined based on the Commission's construction of the '221 claims with respect to the method of restoring operation after an emergency-induced decoupling. The claim construction question is the meaning of the term "predetermined value" in the '221 patent claim 5 (emphases added):

5. A wind turbine, comprising: a rotor with at least one rotor blade, the rotor being rotatably arranged with regard to a substantially horizontal rotor axis; an induction generator whose rotor windings are coupled to the rotor and whose stator coils can be coupled to a voltage grid; a feed-in unit for feeding currents into the rotor windings; a control unit for controlling the frequency of the fed-in currents depending on the rotor rotation frequency, and an emergency unit which can be operated to electrically decouple the feed-in unit from the rotor windings in case of variations of the grid voltage amplitude, wherein the emergency unit comprises a release arrangement for releasing the rotor current feed-in after decoupling, when the currents generated in the rotor windings by variation of the grid voltage amplitude triggering the decoupling are declined to a predetermined value.

The Commission held that the claim's release arrangement "requires the wind turbine to measure current or an ade- quate proxy for current to determine whether the current has declined to a level previously decided upon." Final Determination, at 26. The Commission held that a pre-set period of time is not such a proxy for current.

General Electric argues that the term "predetermined value," construed in light of the specification, includes not only a value of current, but also a predetermined period of time, for the '221 patent states that turbine operation can be resumed "under consideration of a predetermined time constant." '221 patent, col.3 ll.5-6. General Electric points out that the '221 patent recognizes and recites time periods for externally-caused fluctuations in current, and argues that the Commission incorrectly construed the claims as excluding a predetermined time constant from "predetermined value." General Electric cites several supporting statements in the '221 specification:

Basically, resuming the feeding of rotor current can be accomplished under consideration of a predetermined time constant. In view of an increase in plant safety, it has been shown particularly expedient that when the rotor current is sensed as a two or three-phase signal or the rectified current is sensed as a single-phase signal and the current that was sensed drops to a pre-determined value, the feeding of the rotor current is resumed. Current transformers (e.g. current-compensated transformers) can be used for sensing the currents.

. . . When the amplitude of the rotor current has dropped sufficiently after 100 to 200 msec [milliseconds], the feeding of the rotor current can be resumed on recurrence of the supply voltage within the framework of the method according to the invention.

. . . As is explained above, in this case the rotor and the starter current diminish within 50 to 150 msec ...

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