PTAB

IPR2019-01225

SolarEdge Technologies Ltd v. SMA Solar Technology AG

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Inverter with a Housing Having a Cooling Unit
  • Brief Description: The ’631 patent discloses a two-chambered housing for an inverter. The design separates sensitive electronic components, which are placed in a sealed first chamber with a high protection grade, from less-sensitive components and a heat sink, which are located in a second chamber that is open to and cooled by ambient air.

3. Grounds for Unpatentability

Ground 1: Claims 1, 3-4, 6-13, and 15-18 are obvious over Kramer in view of Birger

  • Prior Art Relied Upon: Kramer (European Patent Publication No. 1283589) and Birger (European Patent Publication No. 0900621).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Kramer taught an inverter module where sensitive power semiconductors were hermetically separated by a wall from less-sensitive components, such as a transformer and heat sink cooling fins, which were cooled by the same ambient airflow. While Kramer described its module as intended for a housing cabinet, it did not explicitly show the housing. Birger was argued to supply this missing element, teaching a two-chambered power supply housing with one sealed circuit chamber and one open cooling chamber, separated by a wall through which a heat sink extends. The combination of Kramer’s inverter module within Birger’s housing allegedly met all limitations of independent claims 1 and 9. For example, Kramer’s sensitive semiconductors would reside in Birger’s sealed chamber (first chamber), while Kramer’s transformer and heat sink fins would reside in Birger’s open, fan-cooled chamber (second chamber).
    • Motivation to Combine: A POSITA would combine Kramer with Birger because Kramer’s inverter module was designed to be placed in a housing, and Birger provided the exact type of two-chambered housing needed to implement Kramer’s design philosophy: protecting sensitive electronics from contamination while efficiently cooling less-sensitive components with ambient air. Petitioner asserted this was a combination of known prior art elements to obtain a predictable result.
    • Expectation of Success: A POSITA would have a reasonable expectation of success because incorporating Kramer’s module into Birger’s housing was a simple mechanical integration of compatible systems to achieve the known benefits of segregated cooling.

Ground 2: Claims 2 and 14 are obvious over Kramer and Birger in view of Shinohara

  • Prior Art Relied Upon: Kramer, Birger, and Shinohara (Japanese Patent Publication No. 11234963).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground built upon the combination of Kramer and Birger to address claims 2 and 14, which required the second chamber to have vent slots at an end opposite the cooling system. Petitioner asserted that Shinohara explicitly taught this configuration. Shinohara disclosed a two-chamber power supply cabinet where the fan (cooling system) and exhaust vents were positioned on opposite walls of the cooling chamber.
    • Motivation to Combine: A POSITA would be motivated to modify the Kramer/Birger combination with the teachings of Shinohara to improve cooling efficiency. Shinohara explicitly touted the benefit of its opposed-vent design, which allows air to travel directly across the cooling fins without changing direction. This modification represented applying a known technique to a similar device to achieve an expected improvement.
    • Expectation of Success: Success would be expected, as repositioning fans and vents was a simple mechanical modification well within the skill of a POSITA.

Ground 3: Claims 1 and 3-8 are obvious over Kramer/Birger in view of Brinkmann

  • Prior Art Relied Upon: Kramer, Birger, and Brinkmann (German Patent Publication 29607354).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground addressed claim 5, which required the sealed chamber to have an IP grade rating of IP65. Petitioner argued that the base Kramer/Birger combination already taught a sealed chamber for sensitive electronics. Brinkmann was cited as explicitly teaching an inverter in a sealed chamber with an IP65 rating to protect the electronics against moisture and dust.
    • Motivation to Combine: A POSITA would be motivated to ensure the sealed chamber of the Kramer/Birger combination met the IP65 standard taught by Brinkmann to provide robust protection for electronics in harsh environments where inverters are often used (e.g., outdoors, construction sites). Brinkmann’s express teaching of an IP65-rated chamber for an inverter provided a clear motivation to apply this known protection standard.
    • Expectation of Success: Petitioner argued that constructing a sealed chamber to meet a specific, well-known IP grade was a routine task for a POSITA, ensuring a high expectation of success.
  • Additional Grounds: Petitioner asserted an additional obviousness challenge (Ground D) for claim 2 based on the combination of Kramer, Birger, and Shinohara, further in view of Brinkmann.

4. Key Claim Construction Positions

  • "first chamber... which has a higher IP grade rating for protection... than the electrical components mounted in said second chamber" (Claim 1): Petitioner argued this phrase should be construed to mean the first chamber protects against dust and moisture to a greater degree than the second chamber does. The comparison, according to Petitioner, is between the two chambers, not between the first chamber and the components in the second chamber.
  • "at least one of a choke and a transformer" (Claim 1): Petitioner contended this phrase should be construed disjunctively as "at least one choke or transformer," meaning the presence of either one would satisfy the limitation. This construction was supported by the prosecution history, where the Patent Owner distinguished prior art for lacking "a choke or transformer."
  • "component of a high protection grade" (Claims 9, 17): Petitioner proposed this term means a "component of a protection grade sufficient to be insensitive to contamination from exposure to ambient air." This links the "high grade" to the component's ability to function properly in the open, air-cooled second chamber.

5. Relief Requested

  • Petitioner requested institution of an inter partes review and cancellation of claims 1-18 of the ’631 patent as unpatentable.