Piezo Actuator Phase Control for Vibration Energy Harvesting
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Solution Overview
Problem
Existing devices for generating electrical energy from mechanical excitation vibrations face inefficiencies due to incorrect assumptions about excitation amplitude, continuous operation during resonance frequency search, and unclear direction for re-initiating the search, leading to energy loss and reduced efficiency.
Innovation Solution
Incorporating a measuring device to generate a phase difference signal between the holder and deflection point vibrations, with a phase controller adjusting the resonant frequency to match the excitation frequency, utilizing sensors for displacement or velocity measurements and a PID controller to optimize phase regulation, and employing a piezo element for actuation and control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the resonant frequency is adjusted by continuously operating the actuator during search, then the resonance frequency can be found, but energy is lost due to continuous actuator operation
Solution Approach 1:
The actuator operates periodically rather than continuously. The control device activates the actuator only when needed to adjust the resonant frequency based on phase difference measurements, then stops operation. This periodic activation eliminates continuous energy consumption while maintaining the ability to track resonance frequency changes.
Solution Approach 2:
A feedback mechanism using phase difference measurement between excitation vibration and resonator response enables intelligent actuator control. The control device measures the phase difference and only activates the actuator when the phase difference indicates the resonant frequency has shifted, creating a feedback-driven, energy-efficient adjustment system.
2Measurement precision
If the search for maximum output power is started in the wrong direction, then unnecessary energy is consumed to correct the search direction
Solution Approach 1:
The phase difference measurement provides directional feedback information. By analyzing whether the phase difference is positive or negative, the control device determines the correct adjustment direction for the resonant frequency, eliminating random or wrong-direction searches and reducing energy waste.
3Productivity
If the resonant frequency search is performed cyclically, then the maximum output power can be maintained, but the actuator must operate constantly consuming energy
Solution Approach 1:
The system performs resonance frequency tracking periodically based on phase difference triggers rather than continuously. The actuator operates only when phase difference measurements indicate a resonance shift has occurred, converting continuous cyclic searching into event-driven periodic adjustment.
Solution Approach 2:
The system uses the phase difference signal from the resonator's own operation to trigger adjustments only when needed. The resonator effectively signals when it requires frequency realignment, eliminating the need for external continuous scanning and enabling self-regulated, energy-efficient operation.
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 allows for efficient conversion of mechanical vibrations into electrical energy by accurately determining the resonant frequency and direction, reducing energy loss and improving overall efficiency.
Implementation Method 1
The actuator has a piezo element which is connected to the spring in such a way that the spring constant of the spring can be adjusted by applying an electrical voltage to the electrodes of the piezo element
Implementation Method 2
The deflection point being in drive connection with an electrical generator
Data Source
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AI summary
The invention relates to a device (1) for generating electric energy from mechanical excitation oscillation, comprising a mechanical resonator (2) that has at least one resonance element and a support (5) to which the excitation oscillations can be transmitted. Said resonance element is connected to the support (5) on the fixing point (4) and can be elastically deflected in relation to the fixing point (4) on a deflection point (6) which is arranged at a distance from the fixing point (4). An actuating element is provided for adjusting the resonance frequency of the resonance element. Said deflection point (6) is drivingly connected to an electric generator (8). Said device (1) comprises a measuring device for producing a phase differential signal (Up) for the difference between the phase position of the oscillation of the support (5) and the phase position of the oscillation of the deflection point (6). An outlet of the measuring device is connected to the actuating element via a phase controller (21) in order to adapt the resonance frequency of the resonance element to the frequency of the mechanical oscillations of the support (5).