Inductive Charging Switching Circuit for Leakage Current Reduction
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Solution Overview
Problem
Inductive charging systems experience significant power loss due to leakage current, which is exacerbated by the generation of common mode voltage when the resonant tank is shorted or maintained at a medium voltage, leading to increased energy waste and reduced efficiency.
Innovation Solution
Implementing a switch control circuit that toggles an H bridge or stacked half bridge circuit between high and low voltage configurations without intermediate medium voltage states, maintaining unbalanced duty cycles to reduce common mode voltage and leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the resonant tank is shorted or maintained at medium voltage, then the switching circuit can operate, but leakage current increases and energy efficiency decreases
Solution Approach 1:
The switching circuit alternates between high voltage and low voltage states in periodic cycles, avoiding sustained medium voltage operation. This periodic switching reduces the time the resonant tank spends at medium voltage, thereby minimizing leakage current while maintaining continuous power transfer capability
Solution Approach 2:
The system dynamically adjusts the voltage state of the resonant tank by toggling between discrete high and low voltage configurations rather than maintaining a static medium voltage state. This dynamic operation allows the circuit to achieve reliable switching while reducing energy loss through minimized medium voltage exposure
2Ease of operation
If the resonant tank is maintained at medium voltage, then the switching circuit functions, but electromagnetic interference and radiative emissions increase
Solution Approach 1:
By implementing periodic switching between high and low voltage states, the system limits the duration of medium voltage conditions, thereby reducing the cumulative electromagnetic interference and radiative emissions generated during operation while preserving switching functionality
Solution Approach 2:
The invention extracts or eliminates the sustained medium voltage state from the switching cycle, retaining only the high and low voltage configurations. This removal of the problematic medium voltage state reduces electromagnetic interference while maintaining the essential switching 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 reduces energy consumption, minimizes electromagnetic interference, and decreases conducted and radiative emissions by effectively managing leakage current, thereby enhancing energy transfer efficiency in wireless charging systems.
Implementation Method 1
Inductive charging uses electromagnetic induction to generate, or otherwise provide, electricity to devices without necessarily requiring physical electrical connectivity
Data Source
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AI summary
A method of wireless power transfer can include toggling a switching circuit of a ground pad alternately and sequentially between a first switch configuration and a second switch configuration with an unbalanced duty cycle, and causing wireless power transfer from the ground pad to a vehicle pad of a vehicle using a voltage. The voltage across a resonant tank electrically connected to the switching circuit can be different from a medium voltage for both the first switch configuration and the second switch configuration. The switching circuit can be configured to provide a high voltage, a low voltage, or the medium voltage across the resonant tank. Related wireless charging pads and methods of operating a vehicle pad are also disclosed.