Synchronous Voltage-Doubling Rectifier for Low-Voltage Energy Harvesting

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Solution Overview

Problem

Existing step-up DC-DC converters for energy harvesting from low voltage sources, such as thermo-electric generators (TEGs), operate at relatively low efficiencies and require significant overhead power for switch control, making them inefficient for low-power applications like wireless sensor networks and IoT devices.

Innovation Solution

A DC-DC converter system that includes an oscillator with a voltage-sensitive low-power transistor and a voltage-insensitive high-power transistor, a transformer for voltage amplification, and an autonomous, synchronous voltage-doubling rectification circuit controlled by current through a transformer, minimizing overhead power and maximizing efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If synchronous rectification with sophisticated controllers is employed, then switching timing control is improved, but overhead power consumption increases significantly

Engineering Contradiction:

Improveswitching timing controlVSAvoidoverhead power consumption

Core Design Contradiction:

Ease of operationVSUse of energy by moving object

Solution Approach 1:

The patent implements self-driven synchronous rectification where the rectification switches are controlled by the voltage applied to them during normal operation, eliminating the need for external controllers. The MOSFET switches automatically turn on and off based on the voltage polarity across them, achieving precise timing control without consuming overhead power for control circuits.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent removes the sophisticated controller component entirely from the synchronous rectification circuit. By extracting the control function and embedding it directly into the passive voltage-dependent behavior of the MOSFET switches, the system eliminates the power-hungry control electronics while maintaining accurate switching timing.

Inventive Principle:

Principle #2Taking out (Extraction)

2Device complexity

If conventional rectification is used, then device complexity is reduced, but efficiency decreases due to diode voltage drops

Engineering Contradiction:

Improverectification circuit complexityVSAvoidrectification efficiency

Core Design Contradiction:

Device complexityVSLoss of energy

Solution Approach 1:

The patent inverts the traditional rectification approach by using active MOSFET switches instead of passive diodes. Rather than allowing current to flow through diodes with fixed voltage drops, the system uses voltage-controlled switches that can be turned on to create low-resistance paths, thereby reducing voltage drops and improving efficiency while maintaining relatively simple circuit topology.

Inventive Principle:

Principle #13The other way round (Inversion)

3Power

If step-up DC-DC conversion is implemented for low voltage sources, then usable voltage level is improved, but conversion efficiency remains low

Engineering Contradiction:

Improveoutput voltage levelVSAvoidconversion efficiency

Core Design Contradiction:

PowerVSLoss of energy

Solution Approach 1:

The patent changes the operating parameters of the rectification stage by using synchronous switching with MOSFETs having very low on-resistance compared to diode forward voltage drops. This parameter change in the rectification mechanism directly improves the overall conversion efficiency of the step-up DC-DC converter while maintaining the required voltage boosting function.

Inventive Principle:

Principle #35Parameter changes

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 proposed solution achieves a peak efficiency of 56% and a 10-20 percentage point gain in efficiency over prior art converters, while consuming minimal overhead power, effectively addressing the inefficiencies and power consumption issues of existing systems.

Implementation Method 1

a first transformer for converting the AC signal produced by the oscillator to a higher voltage AC signal

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

an autonomous, synchronous voltage-doubling rectification circuit for converting the higher voltage AC signal to the higher voltage DC output

Methodology Applied

Scientific EffectSynchronous rectification:

Data Source

PatentUS12348149B2Synchronous rectification to improve efficiency of electricity conversion for harvesting energy from low voltage sources

Publication Date: 2025.07.01 NAT RES COUNCIL OF CANADA

AI summary

A DC-DC converter for converting a low voltage DC input to a higher voltage DC output, the DC-DC converter comprising: an oscillator comprising a first relatively voltage sensitive and relatively low power transistor and a second relatively voltage insensitive and relatively high power transistor, the oscillator producing an AC signal from the low voltage DC input; a first transformer for converting the AC signal produced by the oscillator to a higher voltage AC signal; an autonomous, synchronous voltage-doubling rectification circuit for converting the higher voltage AC signal to the higher voltage DC output, wherein the autonomous, synchronous voltage-doubling rectification circuit comprises a second transformer, a first shunt switch and a second shunt switch; and wherein current through the second transformer controls the synchronous rectification.