Partial Power DC-DC Converter for PV String Efficiency

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Solution Overview

Problem

Traditional PV power generation systems suffer from reduced efficiency due to the 'efficiency compounding effect' of central DC to DC converters and are prone to failures, leading to increased costs and weight, with full-power conversion reducing overall DC to AC conversion efficiency by 1% to 2% and requiring additional safety measures.

Innovation Solution

Implementing a DC to DC partial power converter system that processes only a fraction of the total power output, distributing converters throughout the system to minimize losses and maximize power extraction, while using semiconductor switches to control current flow and maximize power output, thereby reducing converter size, cost, and weight.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a central DC to DC converter is used to convert the entire power output of the PV array, then the system can provide stable DC voltage, but the efficiency is reduced by 1% to 2% due to the compounding of converter efficiency and inverter efficiency

Engineering Contradiction:

Improvepower lossVSAvoidconverter configuration

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The patent divides the PV array into multiple independent strings, each with its own DC to DC converter. This segmentation allows each converter to process only a portion of the total power, reducing the compounding efficiency loss while maintaining stable DC voltage conversion for each string independently.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements partial power conversion by having each DC to DC converter process only a fraction of the total PV array power output. This partial action approach reduces the efficiency compounding effect while still providing necessary voltage regulation and power management for the overall system.

Inventive Principle:

Principle #16Partial or excessive action

2Reliability

If a full-power rated central DC to DC converter is used, then the entire PV array power can be converted, but a fault in the converter may cause failure of the entire PV array

Engineering Contradiction:

Improvesystem reliabilityVSAvoidconverter configuration

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the PV array into multiple independent strings with individual converters. This segmentation ensures that a fault in one converter affects only its associated string rather than the entire array, significantly improving system reliability through fault isolation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent incorporates protective diodes and fuses in each string configuration to prevent converter failures from propagating throughout the entire system. These protective measures are built into the design beforehand to cushion against potential failures and maintain operation of healthy strings.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If additional array series diodes and fuses are used to isolate converter failure, then PV array failure can be prevented, but the system cost and complexity increase

Engineering Contradiction:

Improvefault isolationVSAvoidsafety measures

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent uses segmentation to naturally isolate faults within individual strings. Each string with its dedicated converter and protective devices forms an independent unit, so fault isolation is achieved through the modular architecture itself rather than requiring extensive cross-string protective measures.

Inventive Principle:

Principle #1Segmentation

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

This approach increases the overall efficiency of the PV power generation system, enhances reliability, and reduces costs by allowing for simpler power management and arc fault detection, while maintaining high energy yield even under conditions like shading or module mismatch.

Implementation Method 1

Photovoltaic (PV) cells generate direct current (DC) power with the level of DC current being dependent on solar irradiation

Methodology Applied

Scientific EffectPhotovoltaic effect: Photovoltaic Effect

Implementation Method 2

using semiconductor switches to control current flow and maximize power output

Methodology Applied

Scientific EffectElectromagnetic field control: Electromagnetic Induction

Data Source

PatentUS8330299B2DC to DC power converters and methods of controlling the same

Publication Date: 2012.12.11 GE GRID SOLUTIONS LLC

AI summary

A power generation system configured to provide direct current (DC) power to a DC link is described. The system includes a first power generation unit configured to output DC power. The system also includes a first DC to DC converter comprising an input section and an output section. The output section of the first DC to DC converter is coupled in series with the first power generation unit. The first DC to DC converter is configured to process a first portion of the DC power output by the first power generation unit and to provide an unprocessed second portion of the DC power output of the first power generation unit to the output section.