Differential Drive Amplifier for Wireless Power Noise Reduction
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Solution Overview
Problem
Long-range and alignment-insensitive wireless power systems face challenges with high levels of conducted and radiated noise due to the use of high voltages and large, unshielded primary coils, leading to electromagnetic interference with other electronic devices.
Innovation Solution
A differential drive amplifier is employed, utilizing a single switching device to generate differential output signals that are equal in magnitude but opposite in polarity, which are used to reduce common-mode noise by co-locating high and low voltages within tightly coupled coils, minimizing noise emissions and interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high voltages and large primary coils are used in wireless power systems, then power transmission capability and operating range are improved, but conducted and radiated noise levels increase
Solution Approach 1:
The primary winding is divided into multiple separate windings (first primary winding and second primary winding) that are spatially separated and independently controlled. This segmentation allows each winding to operate at lower individual voltages while collectively providing the required power transmission capability, thereby reducing noise emissions from any single winding.
Solution Approach 2:
The patent transitions from a single-plane coil arrangement to a three-dimensional configuration where primary windings are distributed in space around the secondary winding. This spatial distribution in multiple dimensions enables effective noise cancellation through differential signaling while maintaining power transmission capability.
2Reliability
If high voltages are used to overcome weak coupling between primary and secondary coils, then wireless power transmission effectiveness is improved, but common-mode noise increases
Solution Approach 1:
Instead of using high voltage to overcome weak coupling, the patent inverts the approach by using differential signaling with equal and opposite voltages on multiple primary windings. This creates a noise cancellation effect that allows effective power transmission at lower voltage levels by exploiting the differential mode signal path while canceling common-mode noise.
Solution Approach 2:
The patent converts the potentially harmful common-mode noise generated by high-voltage operation into a beneficial cancellation mechanism. By deliberately creating equal and opposite voltages on adjacent windings, the common-mode noise components cancel each other out, transforming what would be interference into a noise-reduction mechanism.
3Length of moving object
If large unshielded primary windings are used to transmit power over long distances, then transmission range is improved, but electromagnetic interference with surrounding electronics increases
Solution Approach 1:
The large primary winding is segmented into multiple smaller windings distributed in space. Each segment operates at lower voltage and produces reduced electromagnetic interference individually, while collectively maintaining the required transmission range through coordinated differential operation.
Solution Approach 2:
The patent introduces differential signaling as an intermediary mechanism between the power transmission requirement and the electromagnetic interference problem. The differential mode acts as a mediator that enables power transmission while the common-mode noise cancellation suppresses electromagnetic interference with surrounding electronics.
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 effectively reduces common-mode noise emissions and interference while maintaining efficient wireless power transfer, maximizing efficiency and minimizing component requirements, thus reducing costs and electromagnetic interference with other electronic devices.
Implementation Method 1
A differential drive amplifier is employed, utilizing a single switching device to generate differential output signals that are equal in magnitude but opposite in polarity
Implementation Method 2
which are used to reduce common-mode noise by co-locating high and low voltages within tightly coupled coils
Implementation Method 3
co-locating high and low voltages within tightly coupled coils
Implementation Method 4
minimizing noise emissions and interference
Data Source
AI summary
Exemplary embodiments are directed to differentially driving a load. An apparatus includes a differential drive amplifier including a switching device coupled with a first output node and a second output node. The first output node and the second output node drive a load network including primary coils. The differential drive amplifier also includes a drive circuit configured to drive the switching device. The drive circuit may be configured to provide a drive signal to the switching device to alter a conductive state of the switching device to produce a first output signal at the first output node and a second output signal at the second output node. The first and second output signals may be substantially equal in magnitude but opposite in polarity relative to a reference voltage.