News Column

Patent Application Titled "Master Slave Architecture for Distributed Dc to Ac Power Conversion" Published Online

May 23, 2014



By a News Reporter-Staff News Editor at Energy Weekly News -- According to news reporting originating from Washington, D.C., by VerticalNews journalists, a patent application by the inventors POTHARAJU, Suryanarayana (San Jose, CA); Jayaraman, Vijay Shankar (San Jose, CA), filed on December 31, 2012, was made available online on May 8, 2014.

The assignee for this patent application is SunEdison Microinverter Products LLC.

Reporters obtained the following quote from the background information supplied by the inventors: "The present disclosure generally relates to integrated circuits. More particularly, the present disclosure provides a method and system for a master circuit and a slave circuit architecture configured for a solar module. Merely by way of example, the inverter device can be coupled to a backplane of a solar module, including a plurality of solar cells. Of course, there can be other variations, modifications, and alternatives.

"Since the discovery of the photoelectric effect, solar inverters have been designed to convert direct current (DC) electricity produced by solar cells or panels into alternating current (AC). The circuits termed inverters originally refer to the process of constantly inverting the incoming signal from a DC source have been performing the DC to AC conversion from watts to megawatts. Since the resurgence of the PV solar panel technologies in the early 2000's, inverters have become the point of focus as they defined the cost, performance and reliability of solar installations. Clubbed with other components as part of the Balance-of-System (BOS) components the inverter plays a significant role in defining the lifetime of the installation.

"As an example, the US Department of Energy has launched the SunShot.TM. initiative to achieve the goal of an installed cost of $1/watt (DC) for solar systems for residential, commercial and utility-scale photovoltaic (PV) solar installations. With panel costs rapidly falling, the inverter, BOS costs and installation costs have been the focus for the PV industry. In addition the lower system efficiencies (Solar-panel to grid/end point of load), hovering around 80%, have been an area of concern as they contribute to significant capital expenditure and O&M costs. Efficient power conversion topologies that would lower the cost, improve system efficiency and performance have been sought to achieve the goal of grid parity for Leveraged cost of electricity (LCOS) for PV Solar power."

In addition to obtaining background information on this patent application, VerticalNews editors also obtained the inventors' summary information for this patent application: "The present disclosure generally relates to integrated circuits. More particularly, the present disclosure provides a method and system for a master circuit and slave circuit architecture configured for a solar module. Merely by way of example, the inverter device can be coupled to a backplane of a solar module, including a plurality of solar cells. Of course, there can be other variations, modifications, and alternatives.

"In a specific embodiment, the present invention provides a distributed power converter for a solar module. The system has a plurality of slave circuits, each if which is coupled to a solar cell group. Each of the slave circuits has an input comprising a DC input from a solar cell group. The slave circuit has a preliminary boost circuit coupled to the input. The preliminary boost circuit is configured to boost an input voltage from the input from the solar cell group to an intermediary voltage. The slave circuit has a DC boost circuit coupled to the preliminary boost circuit and is configured to boost the intermediary voltage to an AC RMS peak voltage. The slave circuit has a rectifier circuit coupled to the DC boost circuit and configured to wave shape the DC output to a half wave rectified DC waveform and is preferably configured to reduce a diode recovery loss in the rectifier circuit.

"In an example, the system has an output coupled to a DC bus structure and a master circuit. The master circuit is coupled to each of the slave circuits via the DC bus structure. The master circuit is configured to generate a timing signal to synchronize each of the slave circuits, which generate a synchronized half wave rectified DC waveform. The plurality of slave circuits output a resulting half wave rectified DC waveform having a amplitude characterized by a combination of each of the amplitudes from each of the slave circuits.

"In an alternative embodiment, a solar module device with the master circuit generates the timing signal to synchronize each of the synchronized half wave rectified DC waveform generated by each of the slave circuits to a grid AC signal or a reference AC signal to allow the DC-AC power conversion of a plurality of solar cell groups provided in a module in an on-grid application and an off-grid application.

"In an example, the master circuit is configured for at least one house-keeping operation to regulate a performance of each of the slave circuits in response to a changes in an external condition on the grid AC signal when configured in the on-grid mode. In an example, the master circuit is configured for at least one house-keeping operation to regulate a performance of each of the slave circuits in response to a change in an external conditions on the reference AC signal when configured in the off-grid mode. In an example, the synchronized half-wave rectified DC waveform is converted into an AC voltage and a current waveform to feed power into a utility grid for an on-grid operation or a micro-grid for an off-grid application through a selection of an AC un-folding circuit provided per a feature of a configured application. In an example, the master circuit and the un-folding circuit uses a combination of a sense circuit to monitor the grid AC signal or reference AC signal to generate a reference signal of the slave circuit to generate the synchronized half-wave rectified DC waveform to add up a power output from each cell group.

"In an example, the present invention provides a method of using a distributed power converter for a solar module. The method includes generating a DC output from a solar cell group from a plurality of solar cell groups provided in a module and receiving the DC output at an input of a preliminary boost circuit coupled to the input. The method includes boosting, using the preliminary boost circuit, an input voltage from the input from the solar cell group to an intermediary voltage. The method includes boosting, using the DC boost circuit, the intermediary voltage to an AC RMS peak voltage. The method includes wave-shaping the DC output to a half wave rectified DC waveform while reducing a diode recovery loss in the rectifier circuit and generate a timing signal from a master circuit to synchronize the half wave rectified DC waveform to generate a synchronized half wave rectified DC waveform. The method includes combining the synchronized half wave rectified DC waveform with a plurality of other synchronized half wave rectified DC waveforms to output a resulting half wave rectified DC waveform having an amplitude characterized by a combination of each amplitude from each of synchronized half wave rectified DC waveforms. Further details of the present method can be found throughout the present specification and more particularly below.

"Many benefits are achieved by ways of present invention. For example, the present invention uses an integrated solar inverter device, having a master/slave architecture, on a back plane coupled to a solar module. The present solar module is efficient and less costly than conventional solar modules with external inverters connected through a junction box. Additionally, the inverter device comprises a slave circuit and master circuit. Depending on the embodiment, one or more of the benefits can be achieved. These and other benefits will be described in more detailed throughout the present specification and particularly below.

BRIEF DESCRIPTION OF THE DRAWINGS

"FIG. 1 is a simplified top view diagram of a solar module comprising a plurality of cells and associated inverters according to an embodiment of the present disclosure;

"FIG. 2 is a simplified top view diagram of a module backplane coupled to a slave inverter according to an embodiment of the present disclosure;

"FIG. 3 is a simplified diagram of a master chip module according to an embodiment of the present disclosure.

"FIG. 4 is a simplified diagram of a slave chip module according to an embodiment of the present disclosure.

"FIG. 4A is a simplified flow diagram of a master chip module and slave chip module operation according to an embodiment of the present invention.

"FIG. 4B is a simplified flow diagram of a master chip module and slave chip module operation according to an embodiment of the present invention.

"FIG. 5 is a more detailed of the slave circuit of FIG. 4, including filter, phase shifter, RERC, and boost circuit (including phase shifter and RERC) according to an embodiment of the present disclosure.

"FIGS. 6, 7, and 8 are examples of inverter circuits according to an embodiment of the present disclosure.

"FIG. 9 is a waveform derived from a slave circuit according to an embodiment of the present disclosure.

"FIG. 10 is an overall diagram of a master circuit coupled to a plurality of slave circuits according to an embodiment of the present disclosure.

"FIG. 11 illustrates each of the voltage and current wave forms from each of the slave circuits and an aggregation of each of the voltage and current wave forms according to an embodiment of the present disclosure.

"FIG. 12 illustrates solar cell elements, including a glass member, a plurality of cells, a backplane, and an inverter according to an embodiment of the present disclosure.

"FIGS. 13 and 14 illustrate waveforms with switching voltages across rectifier bridge diodes with and without the RERC circuitry according to an embodiment of the present disclosure.

"FIG. 15 illustrates a voltage/current plotted against time for the circuitry of FIGS. 13 and 14.

"FIG. 16 illustrates waveforms of a wave shaper circuit according to an embodiment of the present disclosure."

For more information, see this patent application: POTHARAJU, Suryanarayana; Jayaraman, Vijay Shankar. Master Slave Architecture for Distributed Dc to Ac Power Conversion. Filed December 31, 2012 and posted May 8, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=5589&p=112&f=G&l=50&d=PG01&S1=20140501.PD.&OS=PD/20140501&RS=PD/20140501

Keywords for this news article include: Energy, Solar Cell, SunEdison Microinverter Products LLC.

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Source: Energy Weekly News