EAP Energy Conversion Continuous Current Mode
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electromechanical energy conversion systems using Electro Active Polymers (EAP) face inefficiencies due to high series resistance, leading to energy losses exceeding converted energy, especially in charging and discharging processes with small deformations, where discontinuous current increases losses significantly.
Innovation Solution
The EAP-based device is positioned in the step-down converter on the load side during charging and in the step-up converter on the source side during discharging, allowing for continuous current mode, reducing the ratio of effective to average current and minimizing losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If discontinuous current mode is used in EAP charging/discharging, then the switching operation is simpler, but energy losses increase significantly due to high effective current
Solution Approach 1:
The patent applies continuous current mode operation in the DC/DC converter to maintain continuous power flow to the EAP device, avoiding the discontinuous current pulses that cause high effective current and energy losses. This is achieved by proper sizing of the inductor and control of the switching duty cycle to ensure the inductor current never reaches zero, thereby maintaining continuous energy transfer and reducing I²R losses in the EAP's series resistance.
2Adaptability or versatility
If EAP device operates with small deformations, then the application range is broader, but conversion efficiency decreases because losses exceed converted energy
Solution Approach 1:
The patent changes the electrical operating parameters by implementing continuous current mode operation with optimized duty cycle control. This parameter change ensures that even during small deformation cycles, the power transfer remains efficient by maintaining continuous current flow and avoiding the high effective current penalties of discontinuous mode, thereby preserving conversion efficiency across the full range of deformation amplitudes.
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 configuration significantly reduces energy losses and enhances conversion efficiency by minimizing the ratio of effective to average current, leading to a 50% loss reduction and improved performance in EAP electromechanical energy conversion.
Implementation Method 1
Electro Active Polymers (EAP) in electromechanical energy conversion applications require active excitation in each electrical or mechanical cycle
Implementation Method 2
An electromechanical energy conversion system using an EAP based device is for example disclosed in WO 2010/146457. Such an EAP based device can be considered as a variable capacitor of which the capacitance changes as a function of the amount of deformation exerted on a layer of EAP material
Implementation Method 3
The step-up converter L1, S1, D1 comprises a boost inductor L1, a boost switching element S1 and a boost diode D1
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An electromechanical energy conversion system includes a variable capacitor, an electronic charging/discharging unit and a power source/sink; the power source/sink being coupled to the electronic charging/discharging unit; the electronic charging/discharging unit being coupled to the variable capacitor; the variable capacitor comprising first and second electrodes that are separated by an intermediate medium providing a gap distance between the first and second electrodes; the gap distance of the variable capacitor being adjustable between a minimal distance and a maximal distance as a function of an externally applied mechanical force; the electronic charging/discharging unit being arranged for charging the variable capacitor from the power source/sink at substantially a state of the variable capacitor when the gap distance is minimal and the area of the elastically deformed body maximal, and for discharging the variable capacitor to the power source/sink at substantially a state of the variable capacitor when the gap distance is maximal and the area of the elastically deformed body minimal.