Wireless Power Transmitter Coil Clamping Circuit
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Solution Overview
Problem
Conventional wireless power transmitters with multiple coils face efficiency reduction due to parasitic coupling, which leads to energy loss and requires higher voltage-rated components to prevent damage, especially when only one coil is actively transmitting while others are unused.
Innovation Solution
Incorporating a switching circuit with clamp elements across each transmit coil to enable and disable coils dynamically, allowing energy from unused coils to be recycled into the active coil's loop, thereby reducing parasitic coupling and improving efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple transmit coils are used in a wireless power transmitter, then the wireless power receiver has multiple locations to draw power from, but parasitic coupling into adjacent unused coils generates high voltages and reduces efficiency
Solution Approach 1:
The patent converts the harmful parasitic coupling effect into a beneficial feature by using the induced voltage in unused coils to generate recoverable energy. Clamp elements (diodes) are placed across switches in parallel paths to capture the energy from parasitically coupled coils and redirect it to the load, transforming energy loss into useful power output.
Solution Approach 2:
The patent recovers energy that would otherwise be discarded as loss. When one transmit coil is active and another is unused, the unused coil still experiences parasitic coupling that generates voltage. The clamp elements capture this energy and redirect it to the load through the bridge inverter, preventing energy waste and improving overall system efficiency.
2Power
If high current is used to deliver power at suitable levels, then power delivery is sufficient, but it results in stronger magnetic fields that couple into adjacent unused coils and generate high voltages
Solution Approach 1:
The patent converts the harmful high voltages generated by parasitic coupling into beneficial recovered energy. By placing clamp elements across the switches in parallel paths, the system captures the voltage spikes from unused coils and redirects them to the load, transforming a harmful effect into a useful energy source.
Solution Approach 2:
The clamp elements (diodes) act as intermediaries between the parasitically coupled unused coils and the load. These diodes provide a controlled path for the high voltages generated in unused coils, directing them to the load through the bridge inverter rather than allowing them to damage sensitive electronic subsystems.
3Reliability
If components with higher voltage ratings are used to prevent damage, then component protection is improved, but system cost and complexity increase
Solution Approach 1:
The patent eliminates the need for expensive high-voltage-rated components by converting the harmful parasitic voltage into useful energy. The clamp elements capture and redirect the voltage spikes, allowing standard voltage-rated components to be used while maintaining system reliability and reducing cost.
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 solution enhances power transfer efficiency by minimizing energy loss and allowing the use of lower voltage-rated components, similar to a single coil system, while maintaining flexibility in coil usage.
Implementation Method 1
Wireless power transmission using inductive coils is one method considered as an un-tethered method for transferring power wirelessly through a coupled wireless power signal. In wireless power transmission, power is transferred by transmitting a wireless power signal through a transmit coil.
Implementation Method 2
High current results in a stronger magnetic field (B-field), which in turn can couple (i.e., parasitic coupling) into an adjacent unused coil, which may generate high voltages and current in portions of the circuits that are not being used.
Data Source
AI summary
A wireless power transmitter may include a bridge inverter and a plurality of parallel paths operably coupled to the bridge inverter. Each path includes a resonance tank including a transmit coil coupled with at least one resonance capacitor, a first switch serially coupled with the resonance tank and switching node A of the bridge inverter, a first clamping element in parallel with the first switch, a second switch serially coupled with the resonance tank and switching node B of the bridge inverter, and a second clamping element in parallel with the second switch. A method includes generating a wireless power signal through a used coil in a first parallel path, and clamping a parasitic voltage generated in at least one unused coil in at least one additional parallel path through a clamp element across a switch in the at least one parallel path for the at least one unused coil.