Inductive Charging Switch Control to Cut Leakage Current
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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 consumption and electromagnetic interference.
Innovation Solution
A switch control circuit controls the H bridge or stacked half bridge circuit to toggle between high and low voltage configurations without transitioning to a medium voltage, maintaining an unbalanced duty cycle to reduce leakage current and common mode voltage, thereby minimizing energy waste and electromagnetic interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the resonant tank is shorted or maintained at medium voltage, then the switching circuit can operate, but leakage current increases and energy is lost
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the switching duty cycle of the H-bridge circuit to maintain the resonant tank voltage at either high or low levels, avoiding the medium voltage range that causes leakage current. This parameter optimization resolves the contradiction by changing the voltage parameter to eliminate energy loss while maintaining operational capability.
2Stability of the object's composition
If the resonant tank is shorted to maintain operation, then the switching circuit remains stable, but common mode voltage is generated causing electromagnetic interference
Solution Approach 1:
The patent changes the voltage parameter of the resonant tank to avoid medium voltage levels that generate common mode voltage and electromagnetic interference. By maintaining the tank at high or low voltage through duty cycle adjustment, the system achieves stable operation without generating harmful electromagnetic emissions.
3Power
If medium voltage is maintained across the resonant tank, then the switching circuit can regulate power, but energy consumption increases
Solution Approach 1:
The patent employs periodic action through pulsed width modulation (PWM) control, where the switching circuit alternates between high and low voltage states with optimized duty cycles. This periodic switching enables power regulation capability while avoiding continuous medium voltage operation that would increase energy consumption, thus resolving the contradiction between power control and energy efficiency.
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 leakage current, enhances energy transfer efficiency, and minimizes electromagnetic interference by avoiding shorting the resonant tank, allowing for higher voltage charging capabilities.
Implementation Method 1
Inductive charging uses electromagnetic induction to generate, or otherwise provide, electricity to devices without necessarily requiring physical electrical connectivity
Data Source
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.