Dual-Capacitor Energy Harvesting Voltage Management
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Solution Overview
Problem
Existing energy harvesting systems face limitations in maximizing storage efficiency and voltage output due to constraints on the design of components like DC-DC converters, especially when dealing with intermittent mechanical energy sources and varying power demands.
Innovation Solution
The system employs a dual-capacitor configuration with a switch controlled by hysteretic logic to manage voltage within the allowed range of standard DC-DC converters, allowing for efficient storage and supply of electrical energy to multiple loads without specific design constraints on other components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a standard DC-DC converter is used with fixed input voltage range constraints, then the converter design is simplified and more readily available, but the maximum storable electrical charge is limited and voltage management becomes constrained
Solution Approach 1:
The system divides the storage function into two separate capacitors: a first capacitor dedicated to energy storage and a second capacitor dedicated to voltage regulation for the DC-DC converter. This segmentation allows the first capacitor to be optimized for maximum charge storage without being constrained by the voltage range requirements of the converter, while the second capacitor handles the voltage management. The switch selectively connects these capacitors to maximize stored energy while maintaining converter operation within its specified input voltage range.
2Device complexity
If the scavenging interface directly supplies power to the DC-DC converter without intermediate storage management, then the system complexity is reduced, but efficiency is lost due to inability to optimize for intermittent energy sources
Solution Approach 1:
The system performs preliminary energy storage in the first capacitor before supplying power to the DC-DC converter. The control logic monitors the energy level in the first capacitor and proactively transfers energy to the second capacitor or directly to the converter when optimal conditions are detected. This preliminary action allows the system to accumulate energy during periods when the DC-DC converter is not operating or when energy availability is low, thereby maximizing the utilization of intermittent environmental energy sources and reducing energy loss.
3Device complexity
If the system operates continuously without switching between storage modes, then the control logic is simplified, but the system cannot optimize for varying power demands and intermittent energy sources
Solution Approach 1:
The system dynamically switches between different operational modes based on real-time conditions: (1) charging the first capacitor from the scavenging interface when energy is available, (2) transferring energy from the first to the second capacitor when the converter input voltage is out of range, and (3) supplying power from the second capacitor to the DC-DC converter when energy is needed. The control logic implements this dynamic behavior by monitoring voltage levels and power demands, enabling the system to adapt to intermittent energy sources and varying load requirements, thereby maximizing energy utilization efficiency without excessive complexity.
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 maximizes the storage of electrical charge and maintains high efficiency by optimizing voltage management and reducing power loss, enabling the system to operate independently of external energy peaks and temporary energy absences.
Implementation Method 1
a transducer (2), for example of an electromagnetic or piezoelectric type, subjected in use to environmental mechanical vibrations and configured for converting mechanical energy into electrical energy
Implementation Method 2
a transducer (2), for example of an electromagnetic or piezoelectric type, subjected in use to environmental mechanical vibrations and configured for converting mechanical energy into electrical energy
Implementation Method 3
a first storage element (12), for example one or more capacitors; a second storage element (16), for example one or more capacitors
Data Source
AI summary
A transducer converts energy coming from an energy source into an electrical signal for storage as electrical energy on a first storage element. A switch is selectively actuated to pass electrical energy from the first storage element to a second storage element. The selective actuation of the switch is driven by sensing electrical energy stored in the second storage element. The switch is closed when electrical energy in the second storage element is sensed to fall below a first threshold. The switch is opened when electrical energy in the second storage element is sensed to rise above a second threshold.