Active Rectifier Circuit for Voice Coil Energy Harvesting
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing voice coil energy harvesting circuits experience significant power losses due to the use of diodes below their knee point, leading to inefficient conversion of alternating current (AC) to direct current (DC) from the low AC output generated by voice coils.
Innovation Solution
An energy harvesting circuit with a hybrid acoustic absorber and active rectifier, where a diaphragm made of piezoelectric material generates a voltage equal to or greater than the gate drive voltage to drive active switching elements, and a voice coil attached to the diaphragm produces a lower AC voltage that is converted to DC, reducing power losses and improving energy transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If passive diodes are used in the rectifier, then the circuit structure is simple, but significant power losses occur when converting low AC voltage to DC
Solution Approach 1:
The patent replaces passive diode-based rectification with an active switching element-based rectifier. The active switching elements (such as MOSFETs or transistors) are controlled by gate drive signals to perform rectification, substituting the passive mechanical/electrical diode system with an actively controlled electronic system that can operate efficiently at low voltages without knee-point losses.
Solution Approach 2:
The patent changes the operating parameters of the rectifier by using active switching elements that can be controlled to operate in their linear region rather than relying on the non-linear knee-point operation of diodes. The gate drive voltage and switching timing are adjusted to optimize performance for low-voltage AC input, fundamentally changing how the rectification process operates.
2Productivity
If the gate drive voltage is increased to drive active switching elements, then rectification efficiency improves, but the piezoelectric material must generate higher voltage which increases device complexity
Solution Approach 1:
The patent merges two energy harvesting mechanisms into a single hybrid acoustic absorber device: piezoelectric material for generating gate drive voltage and voice coil for generating power output. This combination allows the device to simultaneously produce the higher voltage needed for active switching control and the power output for electrical loads, resolving the complexity issue by integrating multiple functions into one structure.
Solution Approach 2:
The hybrid acoustic absorber structure serves multiple functions: the piezoelectric material generates both structural support and electrical voltage for gate control, while the voice coil attached to the same diaphragm generates the power output. This multi-functionality reduces overall system complexity by eliminating the need for separate voltage generation and power generation subsystems.
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 solution significantly reduces AC to DC conversion losses and enhances energy transfer, providing a greater amount of electrical power at similar sound pressure levels compared to conventional devices.
Implementation Method 1
a diaphragm constructed at least in part of a piezoelectric material, wherein the piezoelectric material is configured to generate a diaphragm voltage in response to sound waves deforming the diaphragm
Implementation Method 2
a voice coil attached to the diaphragm and configured to generate a voice coil voltage... The voice coil voltage comprises an alternating current (AC) output that is converted into a DC output by the rectifier
Data Source
AI summary
An energy harvesting circuit is disclosed and comprises one or more electrical loads that consume direct current (DC) power, a rectifier, and a hybrid acoustic absorber. The rectifier comprises one or more active switching elements that are driven by a gate drive voltage. The hybrid acoustic absorber comprises a diaphragm and a voice coil. The diaphragm is constructed at least in part of a piezoelectric material. The piezoelectric material is configured to generate a diaphragm voltage in response to sound waves deforming the diaphragm. The diaphragm voltage is at least equal to the gate drive voltage to drive the one or more active switching elements of the rectifier. The voice coil is attached to the diaphragm and configured to generate a voice coil voltage that is less than the gate drive voltage of the one or more active switching elements.