PV Inverter Control for Shared PV and Battery DC/DC Conversion

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Solution Overview

Problem

Existing systems for solar energy harvesting and energy storage are not cost-effective due to the need for two separate power electronic converters, which also lack real-time information sharing between PV panels and energy storage devices, leading to suboptimal power flow and inefficiencies, and the use of bulky low-frequency transformers for higher power applications is not scalable or efficient.

Innovation Solution

A unified control system manages multiple DC/DC converters coupled to renewable energy sources and energy storage devices, automatically detecting modes to perform maximum power point tracking or control discharge, eliminating the need for separate converters and transformers by using DC/DC converters for isolation, thus optimizing power flow and reducing component costs and bulkiness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If two separate power electronic converters are used for PV panels and energy storage devices, then each converter can be optimized for its specific function, but the system cost increases and real-time information sharing between components is lost

Engineering Contradiction:

Improvefunctional optimizationVSAvoidsystem cost

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines two separate power electronic converters (PV inverter and battery inverter) into a single unified inverter that handles both PV panel conversion and energy storage device conversion. This merging eliminates the need for two separate devices, reducing system cost while maintaining real-time information sharing between PV and battery components through a common control system.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The unified inverter is designed to perform multiple functions: it acts as both a PV inverter for maximum power point tracking and a battery inverter for charge-discharge control. The single device universally handles power conversion for both energy sources, eliminating the need for separate specialized converters and enabling real-time coordination between PV and battery operations.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If a low frequency transformer is used to increase voltage and provide galvanic isolation, then isolation and voltage transformation are achieved, but the transformer becomes bulky, heavy, and causes significant power losses

Engineering Contradiction:

Improvegalvanic isolationVSAvoidpower losses

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent replaces the traditional low frequency transformer (a bulky mechanical/electromagnetic device) with a high frequency transformer. By operating at high frequency, the transformer achieves the same galvanic isolation and voltage transformation functions with much smaller size, reduced weight, and significantly lower power losses due to reduced core losses and copper losses.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If the DC/DC converter is designed to provide isolation and high voltage operation, then power density and efficiency improve, but the voltage range of energy storage devices becomes limited and reliability decreases

Engineering Contradiction:

Improvepower densityVSAvoidvoltage range compatibility

Core Design Contradiction:

ProductivityVSAdaptability or versatility

Solution Approach 1:

The patent employs a DC/DC converter stage before the inverter that dynamically adapts to different battery voltage levels. This converter can operate across a wide voltage range, allowing the system to accommodate various battery types and states of charge. The DC/DC converter adjusts its operation to maintain optimal power transfer while protecting the inverter from voltage variations, thus enabling high power density without limiting adaptability to different energy storage devices.

Inventive Principle:

Principle #15Dynamics

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The unified control system enhances efficiency and scalability by optimizing power conversion and storage operations, reducing component costs and power losses, and enabling the use of a wider range of energy storage devices, while maintaining high power handling capabilities.

Implementation Method 1

A plurality of DC/DC converters, each DC/DC converter being directly coupled between an energy source and said DC/AC inverter

Methodology Applied

Scientific EffectElectrical energy conversion:

Implementation Method 2

A DC/AC inverter; wherein said DC/AC inverter is coupled between said power grid and said plurality of DC/DC converters

Methodology Applied

Scientific EffectElectrical energy conversion:

Data Source

PatentUS11777336B2PV inverter apparatus with energy storage capability

Publication Date: 2023.10.03 SPARQ SYST INC

AI summary

Systems and methods for providing AC power to a power grid using renewable energy sources as well as energy storage devices. A control system controls multiple DC/DC converters that are coupled to renewable energy sources as well as to one or more energy storage devices. The control system also controls the charge/discharge of the energy storage devices. Each DC/DC converter control block in the control system automatically detects whether to perform MPPT on the renewable energy source or to control the discharge of the energy storage devices. Each DC/DC converter control block ensures that power from the renewable energy source or from the energy storage device is converted and provided to the power grid.