DC-DC Converter Control Circuit Using Half-Voltage Reference

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Solution Overview

Problem

Conventional maximum power point tracking (MPPT) circuits for DC-DC converters, especially those used with thermogenerators and solar cells, face challenges in minimizing power consumption and complexity, particularly in applications with limited power availability, where existing solutions like digital signal processors or analog multipliers are not optimized for low-power consumption and stability.

Innovation Solution

A control circuit for DC-DC converters comprising a series connection of a differentiator, a comparator unit with an inverting amplifier, and an integrator, which compares an input signal to a reference signal at half the voltage level of the DC-DC converter's output, allowing for reduced power consumption and drift, and enabling operation on both sides of the maximum power point with a single positive voltage supply.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If digital signal processors or micro-controllers are used for MPPT control, then measurement precision and control accuracy are improved, but power consumption and device complexity increase

Engineering Contradiction:

Improvepower measurement accuracyVSAvoidcontrol circuit power consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent replaces digital signal processors and micro-controllers with an analog control circuit consisting of operational amplifiers, multipliers, and integrators. This substitution eliminates the need for digital processing while maintaining measurement precision through analog signal processing, thereby significantly reducing power consumption in low-power applications

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent extracts and removes the power-consuming digital processing components (DSP, micro-controllers) from the MPPT control system, retaining only the essential analog circuitry needed for power measurement and control signal generation, thus achieving low-power operation while preserving control accuracy

Inventive Principle:

Principle #2Taking out (Extraction)

2Use of energy by moving object

If analog circuits are used for MPPT control, then power consumption is reduced, but complexity and drift increase

Engineering Contradiction:

Improvecontrol circuit power consumptionVSAvoidcircuit complexity

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent merges multiple functions into a unified analog control architecture where operational amplifiers perform both signal conditioning and comparison functions, multipliers handle power calculation, and integrators provide control signal generation. This functional integration reduces the number of discrete components and simplifies the overall circuit complexity while maintaining low power consumption

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The analog circuit components are designed to perform multiple functions: operational amplifiers serve as both signal amplifiers and comparators, the multiplier circuit simultaneously calculates instantaneous power and generates control signals, and integrators provide both filtering and control signal integration. This multi-functionality reduces component count and circuit complexity

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Device complexity

If conventional comparator circuits are used, then device simplicity is maintained, but response time and precision deteriorate

Engineering Contradiction:

Improvecircuit simplicityVSAvoidfeedback signal generation speed

Core Design Contradiction:

Device complexityVSSpeed

Solution Approach 1:

The patent changes the operating parameters of the comparator by using an operational amplifier configured as a comparator with optimized gain and bandwidth parameters. This allows the circuit to maintain simplicity while achieving faster response times and improved precision in detecting power signal crossings and generating control signals

Inventive Principle:

Principle #35Parameter changes

4Device complexity

If single-sided voltage supply is used, then device simplicity is improved, but adaptability to operate on both sides of MPP deteriorates

Engineering Contradiction:

Improvepower supply configurationVSAvoidoperation range around MPP

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent introduces asymmetry in the reference voltage configuration by using a virtual ground at half the supply voltage (Vcc/2) rather than a symmetric ground reference. This asymmetric biasing allows the single-sided power supply to accommodate both positive and negative excursions of the power signal around the maximum power point, enabling operation on both sides of MPP while maintaining circuit simplicity

Inventive Principle:

Principle #4Asymmetry

Data Source

PatentUS8749218B2Control circuit for a DC-DC converter using a reference signal that is half a voltage level of a voltage of a battery to be charged

Publication Date: 2014.06.10 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV

AI summary

A control circuit according to an embodiment of the present invention for a DC-DC converter which has an input, an output and a series connection of a differentiator, a comparator unit, and an integrator. The series connection is coupled in between the input and the output. The comparator unit has an inverting amplifier.