Adaptive RF-to-DC Rectifier Stage Control for Variable Input Power
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Solution Overview
Problem
Existing energy harvesting solutions for wireless sensor networks and IoT applications face inefficiencies due to unpredictable variations in input power, leading to substantial energy losses and reduced performance, especially in scenarios where input power is not constant.
Innovation Solution
A self-adaptive energy harvesting circuit with a dynamically optimized RF-to-DC transducer that adjusts the number of active stages based on input power levels, utilizing a miniaturized sensing circuit to maintain efficient power transfer and minimize energy inefficiencies, allowing continuous operation and reduced power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a fixed architecture RF-to-DC converter is used to maximize efficiency at a given input power level, then efficiency is improved at that specific power level, but efficiency degrades when input power varies
Solution Approach 1:
The patent implements a dynamic reconfiguration mechanism that automatically adjusts the number of active voltage multiplication stages based on the detected input power level. The system transitions from a fixed architecture to a dynamic one where the converter adapts its structure in real-time, maintaining optimal efficiency across varying input power conditions by activating or deactivating specific stages through control signals.
Solution Approach 2:
The system changes the operational parameters of the RF-to-DC converter by varying the number of active voltage multiplication stages according to the input power level. When input power is high, fewer stages are activated to prevent saturation and maintain efficiency; when input power is low, more stages are activated to maximize voltage output, thus optimizing performance across different power conditions.
2Loss of energy
If reconfiguration is performed statically during constant input power periods, then efficiency is improved during those periods, but efficiency is reduced when input power is varying
Solution Approach 1:
The patent incorporates a feedback mechanism where the system continuously monitors the input power level and automatically adjusts the number of active stages accordingly. The detection circuit provides real-time feedback about the input power condition, and the control logic responds by reconfiguring the converter architecture, ensuring the system adapts dynamically to power variations without manual intervention or delay.
3Adaptability or versatility
If the converter is designed for wide input power range operation, then adaptability is improved, but efficiency may be reduced at specific power levels
Solution Approach 1:
The patent divides the voltage multiplication converter into multiple independent stages that can be selectively activated. Each stage represents a segment of the overall conversion process, and the system activates only the necessary number of segments based on the input power level. This segmentation allows the converter to maintain peak efficiency at each power level by using only the required number of stages, rather than operating a single fixed architecture across the entire power range.
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 solution enhances energy efficiency and flexibility over a wide range of input power values, enabling continuous energy flow and improved data update rates in battery-free systems, particularly suitable for ultra-low power applications like Bluetooth low-energy radio and IoT devices.
Implementation Method 1
an RF-to-DC transducer circuit configured to operate with a self-adaptive maximum power transfer method
Data Source
AI summary
A first RF-to-DC circuit receives a radiofrequency signal and produces a first converted signal delivered to an energy storage circuit. A second RF-to-DC circuit, which is a down-scaled replica of the first RF-to-DC circuit, produces a second converted signal from the radiofrequency signal that is indicative of an open-circuit voltage of the first RF-to-DC circuit. The first RF-to-DC section includes N sub-stages, with a sub-set of sub-stages being selectively activatable. A window comparison of the second converted signal generates a first signal and a second signal indicative of whether the second converted signal is within a range of values proportional to a voltage reference signal. The sub-set of sub-stages is selectively deactivated, respectively activated, when the performed window comparison has a first result, respectively, a second result.