Prior art — US Patent 8279642B2

To identify the most relevant prior art for US patent 8279642B2, I will examine the "Cited by" and "References" sections within the patent document itself on Google Patents, as the USPTO database direct search functionality for citations is not directly exposed in the search results.

Here's an analysis of the cited prior art from US8279642B2:

Most Relevant Prior Art for US Patent 8279642B2

The patent US8279642B2 lists several prior art documents. A thorough review of these documents reveals their relevance to the claimed invention.

Cited US Patents:

US7327091B2
- Full Citation: US7327091B2, "Method and apparatus for ripple correlation control based on limited sampling"
- Publication/Filing Date: Published February 5, 2008, filed April 29, 2005.
- Brief Description: This patent describes a ripple correlation control method for maximum power point tracking (MPPT) in power converters, particularly relevant for photovoltaic systems. It focuses on using limited sampling to reduce ripple.
- Potential Anticipation (35 U.S.C. § 102): US7327091B2 appears highly relevant to aspects of Claim 1, Claim 19, and Claim 31 that involve the control circuit employing an MPPT algorithm. Specifically, the description of the control circuit in US8279642B2 mentions that "the control circuit 208 may include an MPPT control circuit configured to execute an MPPT algorithm such as the MPPT algorithm described in U.S. Patent Publication No. 2008/018338, entitled “Ripple Correlation Control Based on Limited Sampling” by Jonathan W. Kimball et al." This direct reference indicates that the MPPT methodology itself might be anticipated or rendered obvious by US7327091B2, especially concerning how the input converter is controlled based on MPPT. However, US8279642B2 distinguishes itself by integrating this MPPT with an active filter for double-frequency ripple reduction on the bus, rather than solely at the source.
US7609539B2
- Full Citation: US7609539B2, "Methods for minimizing double-frequency ripple power in single-phase power conditioners"
- Publication/Filing Date: Published October 27, 2009, filed October 11, 2007.
- Brief Description: This patent addresses methods for minimizing double-frequency ripple power in single-phase power conditioners by controlling an active filter. It specifically mentions shifting the active filter AC waveform by π/4 radians.
- Potential Anticipation (35 U.S.C. § 102): US7609539B2 is extremely relevant to Claim 1, Claim 19, and Claim 31, particularly the active filter's function and control. US8279642B2 explicitly states: "in one particular embodiment, the active filter AC waveform is shifted by π/4 radians relative to a phase of the output AC waveform as described in more detail in co-pending U.S. patent application Ser. No. 11/871,015 entitled “Methods for Minimizing Double-Frequency Ripple Power in Single-Phase Power Conditioners” by Philip T. Krein. et al." This direct incorporation by reference and specific mention suggest that the fundamental method of using an active filter to minimize double-frequency ripple power by controlling its phase shift is likely anticipated by US7609539B2. The novelty in US8279642B2 would then lie in the specific apparatus architecture that integrates this active filter within an input converter/output converter/bus arrangement.
US7564703B2
- Full Citation: US7564703B2, "Photovoltaic power inverter systems and methods"
- Publication/Filing Date: Published July 21, 2009, filed October 11, 2007.
- Brief Description: This patent broadly covers photovoltaic power inverter systems and methods. While the specific details of its relevance would require a deeper dive, it generally pertains to the field of the claimed invention.
- Potential Anticipation (35 U.S.C. § 102): Without a more specific connection highlighted in US8279642B2's detailed description, it's difficult to pinpoint exact anticipation for specific claims. However, it likely establishes the general state of the art for photovoltaic inverters and their operation, potentially affecting the obviousness of certain combinations of known elements.
US2008018338A1 (This appears to be the application corresponding to US7327091B2, which has been cited above as US7327091B2 in the patent text).
- Full Citation: US2008018338A1, "Ripple Correlation Control Based on Limited Sampling"
- Publication/Filing Date: Published January 24, 2008, filed July 21, 2006.
- Brief Description: This is a patent application for the ripple correlation control method for MPPT, as described for US7327091B2.
- Potential Anticipation (35 U.S.C. § 102): Similar to US7327091B2, this document would potentially anticipate the MPPT control aspects of Claim 1, Claim 19, and Claim 31.
US2008130349A1
- Full Citation: US2008130349A1, "Photovoltaic module with integrated power converter"
- Publication/Filing Date: Published May 29, 2008, filed November 27, 2007.
- Brief Description: This patent application describes a photovoltaic module with an integrated power converter, which is relevant to the "apparatus" of Claim 19 that includes a solar panel and an inverter.
- Potential Anticipation (35 U.S.C. § 102): This document could potentially anticipate the overall concept of an integrated PV module and inverter as described in Claim 19, particularly regarding the physical arrangement and integration. The specific details of the active filter and its functionality for double-frequency ripple reduction might be the distinguishing features of US8279642B2.

Other References:

The patent also mentions "co-pending U.S. Provisional Patent Application Ser. No. 61/230,546 entitled “Apparatus for Converting Direct Current to Alternating Current,” by Robert S. Balog, Jr. et al., which was filed on Jul. 31, 2009," and "U.S. patent application Ser. No. 12/563,499 entitled “Apparatus for Converting Direct Current to Alternating Current” by Patrick P. Chapman et al., which was filed on Sep. 21, 2009". These are foundational to the application leading to US8279642B2 and are therefore considered direct parent applications rather than prior art for anticipation purposes.