PTAB

IPR2026-00023

Generac Power Systems Inc v. J Carl Cooper

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: POWER SOURCE LOAD CONTROL
  • Brief Description: The ’857 patent discloses methods for controlling backup power sources by altering the AC power frequency in response to the electrical load. The system determines remaining available power and, if an overload is imminent, changes the frequency to signal and manage the load.

3. Grounds for Unpatentability

Ground 1A: Obviousness over Lasseter and Lopes - Claims 17-23, 25, and 27-38 are obvious over Lasseter in view of Lopes.

  • Prior Art Relied Upon: Lasseter (Application # 2006/0208574) and Lopes (J.A. Peças Lopes et al., Defining Control Strategies for MicroGrids Islanded Operation, IEEE Transactions on Power Systems, May 2006).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner asserted that Lasseter discloses a distributed energy resource (DER) system with microsources that control their output frequency based on power demand. In Lasseter’s system, a controller reduces the operating frequency to increase power output up to a maximum rated power (Pmax). Petitioner argued that exceeding Pmax constitutes an “overload” under the patent’s definition. While Lasseter acknowledges situations where generation capacity is insufficient for the total load, it provides only a preemptive load disconnection solution and does not detail a responsive strategy for overload conditions. Lopes addresses this exact problem, teaching a control strategy for islanded microgrids that uses responsive, frequency-based load shedding to manage overloads. Lopes discloses using under-frequency relays to temporarily disconnect less important loads when a high imbalance between load and generation causes large frequency deviations.
    • Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would combine Lasseter and Lopes to solve the problem Lasseter identifies but does not adequately address—managing loads when generation capacity is insufficient. Lopes provides a well-known, responsive load-shedding technique that is a direct solution. Combining them would improve system efficiency by avoiding the need for excess generation capacity, protect critical loads by shedding non-critical ones only when necessary, and avoid the drawbacks of Lasseter’s preemptive disconnection, which unnecessarily powers down loads during periods of low demand.
    • Expectation of Success: A POSITA would have a high expectation of success, as the combination involves applying Lopes’s well-known, frequency-responsive load-shedding technique to Lasseter’s frequency-controlled power system. This integration uses familiar elements for their intended purposes to achieve the predictable result of a more robust and efficient power management system.

Ground 1B: Obviousness over Lasseter, Lopes, and Baldassarre - Claims 24 and 26 are obvious over the combination of Lasseter and Lopes in view of Baldassarre.

  • Prior Art Relied Upon: Lasseter (Application # 2006/0208574), Lopes (J.A. Peças Lopes et al., Defining Control Strategies for MicroGrids Islanded Operation, IEEE Transactions on Power Systems, May 2006), and Baldassarre (Application # 2010/0019574).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that the combination of Lasseter and Lopes teaches a system that automatically sheds loads based on frequency deviations. Baldassarre supplements this by disclosing a processor-based control system with a user interface that allows a user to program load priorities and define sequences for load shedding and reconnection. Baldassarre also teaches an alternative method for detecting overloads by monitoring sine wave distortion, which is asserted to be an additional parameter for the coupling circuit (under-frequency relays) to respond to.
    • Motivation to Combine: A POSITA would be motivated to add Baldassarre’s teachings to the Lasseter-Lopes system to provide user-configurability. While Lasseter-Lopes provides the automatic control logic, it lacks a mechanism for users to specify which loads are more critical. Baldassarre provides an obvious solution by adding a user interface for priority programming, allowing for a more flexible and intelligent load-shedding system. This would also enable real-time adjustment of priorities, a feature not addressed by Lasseter-Lopes.
    • Expectation of Success: Success would be expected because integrating Baldassarre’s user interface and priority logic into the microcontroller-based system of Lasseter-Lopes involves combining known hardware and software elements to predictably yield a system with user-definable, frequency-responsive load management.

Ground 1C: Obviousness over Lasseter, Lopes, and Tsukida - Claims 35-36 are obvious over the combination of Lasseter and Lopes in view of Tsukida.

  • Prior Art Relied Upon: Lasseter (Application # 2006/0208574), Lopes (J.A. Peças Lopes et al., Defining Control Strategies for MicroGrids Islanded Operation, IEEE Transactions on Power Systems, May 2006), and Tsukida (Application # 2007/0222294).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner asserted that while Lopes teaches the general concept of under-frequency load shedding, Tsukida provides a specific and detailed implementation algorithm. Tsukida discloses a system that sheds loads based on the degree of underfrequency, the duration of the state, and the output voltage. Critically, Tsukida’s logic distinguishes between under-frequency caused by a true overload versus an "out-of-step condition," preventing false-positive load sheds. It also provides exemplary staggered time intervals for shedding different loads.
    • Motivation to Combine: A POSITA would look to Tsukida to implement the general strategy taught by Lopes. Tsukida provides a concrete, sophisticated algorithm that enhances the base system by improving selectivity and avoiding unnecessary load shedding. This would make the Lasseter-Lopes system more reliable and robust.
    • Expectation of Success: A POSITA would reasonably expect success because Tsukida provides a specific, detailed control strategy that directly implements the general load-shedding concept from Lopes. It is a predictable improvement that adds precision and reliability to the combined Lasseter-Lopes system.

4. Key Claim Construction Positions

  • Petitioner asserted that the Challenged Claims are obvious under their plain and ordinary meaning but highlighted that several key terms are expressly defined in the ’857 patent’s specification.
  • "Overload": Defined as "a load that if not disconnected or otherwise prevented will either cause a departure from specifications for the power output from the power source," including deviations in AC voltage or frequency.
  • "Parameter": Defined as "a quantity of one or more property or attribute...which is treated as a constant," though it may at times be adjusted. Examples include voltage and current.
  • "Timely": Defined as "instant, real time, close to real time or a suitable time."
  • "Known": Defined as "to have been previously stored in a memory and available."

5. Relief Requested

  • Petitioner requests the institution of an inter partes review and the cancellation of claims 17-38 of the ’857 patent as unpatentable under 35 U.S.C. §103.