Electrostatic Vibrational Energy Harvester with Variable Force Factor
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Solution Overview
Problem
Conventional vibrational energy harvester devices of the electrostatic type face inefficiencies in rectifying and charging electricity due to fixed output impedance, which prevents optimal utilization of electric current at varying excitation vibration accelerations, leading to losses at both low and high acceleration conditions.
Innovation Solution
A vibrational energy harvester device with a movable part and a fixed part, where the surfaces are designed with alternating recessed portions and salients, and an electret film is formed on at least one of the parts, allowing the force factor to adjust with vibration amplitude, thereby dynamically changing output impedance and optimizing electric current and voltage output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the output impedance of the vibrational energy harvester device is increased to enable rectifying diode conduction at low excitation vibration acceleration, then the voltage exceeds the threshold voltage of the rectifier diode, but great electric current at high excitation vibration acceleration cannot be utilized efficiently due to increased loss
Solution Approach 1:
The patent applies the dynamics principle by making the output impedance variable rather than fixed. The output impedance changes dynamically based on the vibration amplitude through the variable force factor. At low acceleration, the force factor is smaller resulting in higher output impedance that enables rectifier diode conduction. At high acceleration, the force factor increases resulting in lower output impedance that allows efficient utilization of great electric current, thus resolving the contradiction between reliable conduction at low acceleration and energy efficiency at high acceleration.
Solution Approach 2:
The patent applies parameter changes by varying the force factor (electromechanical conversion factor) which directly affects the output impedance. The force factor changes with vibration amplitude, causing the output impedance to adapt to different operating conditions. This parameter change enables the system to optimize both voltage output at low acceleration and current utilization at high acceleration, resolving the energy loss contradiction.
2Productivity
If the output impedance of the vibrational energy harvester device is decreased to efficiently utilize great electric current at high excitation vibration acceleration, then energy utilization is improved, but the voltage cannot exceed the threshold voltage of the rectifier diode preventing operation at low excitation vibration acceleration
Solution Approach 1:
The dynamics principle resolves this contradiction by making the output impedance adaptive. At high acceleration conditions, the variable force factor produces lower output impedance that maximizes electric current utilization efficiency. At low acceleration conditions, the same variable force factor produces higher output impedance that ensures voltage exceeds the rectifier diode threshold. This dynamic adaptation eliminates the need to choose between current efficiency and reliable conduction.
Solution Approach 2:
The parameter changes principle is applied through the variable force factor that modifies the output impedance based on operating conditions. This parameter variation enables the system to achieve both high current utilization at high acceleration and sufficient voltage output at low acceleration, resolving the contradiction between productivity and reliability.
3Device complexity
If a fixed output impedance is used in the vibrational energy harvester device, then the device structure is simple, but the device cannot efficiently rectify and charge electricity across varying acceleration levels from low to high
Solution Approach 1:
The patent applies the self-service principle by enabling the output impedance to self-adjust according to the vibration amplitude without external control mechanisms. The variable force factor automatically modifies the output impedance based on the operating conditions, allowing the device to efficiently rectify and charge electricity across varying acceleration levels. This self-adjusting capability improves productivity while maintaining relatively simple device structure, resolving the contradiction between complexity and efficiency.
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 device efficiently rectifies and charges electricity across a wide range of acceleration levels, ensuring effective power generation and charging regardless of low or high excitation vibration acceleration.
Implementation Method 1
Vibrational energy harvester device of electrostatic type with an electret to convert mechanical vibrational energy into electricity by electrostatic induction action
Data Source
AI summary
Provided is an electrostatic-type vibrational energy harvester device that makes it possible to efficiently rectify and charge power from low acceleration to high acceleration of vibrational energy applied from the exterior. The vibrational energy harvester device is provided with: a movable part capable of vibrating in a vibration direction as a result of mechanical vibrational energy, said movable part being provided with a first surface along the vibration direction; and a fixed part provided with a second surface facing the first surface of the movable part with a gap therebetween so that it is possible for the movable part to vibrate in the vibration direction. A plurality of recessed portions and protruding sections are formed in an alternating manner in the vibration direction on the surfaces of each of the first surface of the movable part and the second surface of the fixed part. An electret film is formed on at least one of the fixed part and the movable part. The vibrational energy harvester device is configured so that a force factor (electromechanical conversion factor) having a value that corresponds to the gap between the first surface of the movable part and the second surface of the fixed part becomes small when the vibration amplitude of the movable part is small and large when the vibration amplitude of the movable part is large.