PTAB

IPR2019-01224

SolarEdge Technologies Ltd v. SMA Solar Technology AG

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Petition
petition Intelligence

1. Case Identification

2. Patent Overview

  • Title: INVERTER WITH A HOUSING HAVING A COOLING UNIT
  • Brief Description: The ’631 patent describes an inverter housing with two separate chambers. A first, sealed chamber protects sensitive electronic components from dust and moisture, while a second, open chamber houses less-sensitive components (e.g., transformers, chokes, heat sinks) and a cooling unit that uses ambient air.

3. Grounds for Unpatentability

Ground 1: Claims 1-7, 9-15, and 17 are obvious over Rodi in view of Brinkmann.

  • Prior Art Relied Upon: Rodi (European Patent Application No. 0297308) and Brinkmann (German Patent Publication 29607354).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Rodi discloses nearly every limitation of the independent claims. Rodi teaches a two-chamber power supply cabinet where a first sealed chamber (rated IP54) houses sensitive circuit boards, and a second open chamber (rated IP20) contains less-sensitive components like transformers, chokes, and heat sinks. A fan in the second chamber cools these components and the heat sinks, which are thermally coupled to the electronics in the sealed chamber. Petitioner contended the only significant limitation not explicitly shown in Rodi is a heat sink that includes a "heat exchange structure extending through said wall." This limitation, Petitioner asserted, is taught by Brinkmann, which discloses an inverter with a sealed chamber (rated IP65) where a heat sink projection extends through the chamber wall to make direct thermal contact with internal power components.
    • Motivation to Combine: A POSITA would combine Brinkmann's heat sink design with Rodi's overall system to improve a similar device using a known technique. Both references address the same problem of cooling electronics in a sealed enclosure. A POSITA would have recognized the benefit of Brinkmann's through-wall heat sink for providing more efficient thermal transfer and would have been motivated to apply it to Rodi's two-chamber design to achieve the predictable result of improved cooling while maintaining a sealed, protected environment for sensitive electronics. Further motivation stemmed from the desire to improve dust and moisture protection, as Brinkmann's design explicitly achieves a higher IP65 rating.
    • Expectation of Success: Petitioner asserted a high expectation of success, as incorporating Brinkmann's heat sink into Rodi's housing would be a simple mechanical modification, combining known elements for their intended purposes to achieve a predictable outcome.

Ground 2: Claims 8, 16, and 18 are obvious over Rodi and Brinkmann, further in view of Birger.

  • Prior Art Relied Upon: Rodi (European Patent Application No. 0297308), Brinkmann (German Patent Publication 29607354), and Birger (European Patent Application No. 0900621).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground addresses the additional limitation in claims 8, 16, and 18 that "the first chamber excludes an air flow movement device." Petitioner argued that Rodi discloses a fan as an optional feature, and its omission would be an obvious design choice if its function was not desired. To bolster this, Petitioner introduced Birger, which also discloses a two-chamber power supply with a sealed circuit chamber and an open cooling chamber. Crucially, Birger expressly teaches against using a forced airflow device within the sealed circuit chamber to "entirely prevent the problem...of dust in the circuit chamber."
    • Motivation to Combine: A POSITA would be motivated to apply Birger's explicit teaching to the Rodi/Brinkmann combination for the stated purpose of enhancing protection against dust contamination. Since the primary goal of the sealed chamber in all cited references is to protect sensitive electronics, a POSITA would find Birger's caution against internal fans compelling and would readily omit any such device from the sealed chamber of Rodi/Brinkmann to improve reliability and reduce complexity and cost.
    • Expectation of Success: Petitioner argued success would be reasonably expected, as it involves either removing an optional component or applying an explicit teaching from analogous art to achieve the well-understood benefit of reduced contamination risk.

4. Key Claim Construction Positions

  • "first chamber ... which has a higher IP grade rating ... than the electrical components mounted in said second chamber": Petitioner argued this phrase should be construed to mean the first chamber has a higher IP rating than the second chamber. Petitioner contended that comparing a chamber's protection rating to a component's rating is technically improper, and the patent's specification and prosecution history emphasize that the "important point" is the difference in protection levels between the two chambers themselves.
  • "at least one of a choke and a transformer": Petitioner asserted this term should be interpreted disjunctively as "at least one choke OR transformer." This construction was supported by the prosecution history, where an earlier version of the claim recited "at least one of a choke or one of a transformer," and the Patent Owner argued against prior art by referring to "a choke or transformer."
  • "component of a high protection grade": Petitioner proposed this term means a "component of a protection grade sufficient to be insensitive to contamination from exposure to ambient air." The argument was that the specification links this characteristic to the ability of components to function properly in the open, air-cooled second chamber, rather than requiring a specific numerical IP rating.