Overvoltage Clamping Circuit for Inductive Power Transfer
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Solution Overview
Problem
Inductive power transfer systems face challenges in protecting against overvoltages, which can damage components like synchronous rectifiers and linear chargers due to high voltages and power levels, especially at resonance frequencies, leading to inefficiencies and potential component damage.
Innovation Solution
The implementation of a clamping circuit using a capacitor and a switch, controlled by an overvoltage detector and switch driver, that selectively couples the capacitor to reduce overvoltages by redirecting energy away from the output, preventing damage and maintaining efficient power transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a clamping circuit is added to protect against overvoltages, then component reliability is improved, but device complexity increases
Solution Approach 1:
The patent introduces a capacitor as an intermediary energy storage element that temporarily absorbs overvoltage energy, and a switch as a mediator that controls the coupling between the capacitor and the circuit. This intermediary approach protects components without requiring complex active protection circuits, thereby improving reliability while limiting the increase in device complexity.
2Reliability
If overvoltage protection is implemented, then component damage is prevented, but manufacturing cost increases
Solution Approach 1:
The patent employs passive components (capacitor and switch) that are inexpensive and simple to manufacture compared to complex active protection circuits. The capacitor can be a standard electronic component, and the switch can be implemented with simple transistors or even diodes, making the overall protection circuit cost-effective while providing reliable overvoltage protection.
3Reliability
If the capacitor is continuously coupled to reduce overvoltages, then component protection is improved, but power transfer efficiency deteriorates
Solution Approach 1:
The patent implements periodic action by using a switch that selectively couples the capacitor to the circuit only when overvoltage conditions are detected. The overvoltage detector monitors the circuit voltage and triggers the switch to couple the capacitor only during overvoltage events, rather than keeping it continuously coupled. This periodic engagement provides component protection while minimizing interference with normal power transfer efficiency during standard operating conditions.
4Productivity
If a switch is added to selectively couple the capacitor, then power transfer efficiency is maintained, but device complexity increases
Solution Approach 1:
The patent implements self-service by using an overvoltage detector that automatically monitors circuit conditions and triggers the switch to couple the capacitor when overvoltage is detected. The system serves itself by detecting its own overvoltage condition and activating the protection mechanism without requiring external control or complex management circuitry, thereby maintaining efficiency while limiting the increase in device complexity.
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 effectively limits overvoltages, preventing damage to components while maintaining efficient power transfer, allowing for smaller, less expensive circuit implementations and reduced exposure to high current and voltage spikes, thus enhancing the reliability and cost-effectiveness of inductive power transfer systems.
Implementation Method 1
a capacitor in circuit with the first terminal, a switch in circuit with the capacitor and the first terminal configured to selectively electrically couple the capacitor to the first terminal based on an overvoltage detection signal to reduce an overvoltage on the second signal
Implementation Method 2
The transmitting unit generates a magnetic field via an inductive coil. When the receiving unit, which includes another inductive coil, is placed within the magnetic field, the magnetic field causes the receiving unit to generate an electrical current proportional to the magnetic field generated by the transmitting unit
Data Source
AI summary
Methods and apparatus to clamp overvoltages for inductive power transfer systems are described herein. An example overvoltage protection circuit is described, including a first terminal configured to receive an alternating current signal for conversion to a second signal, a capacitor, a first switch configured to selectively electrically couple the capacitor to the first terminal based on an overvoltage detection signal to reduce an overvoltage on the second signal, and an overvoltage detector. The example overvoltage detector is configured to determine a signal level of the second signal and, in response to determining that the signal level of the second signal is greater than a threshold, to output the overvoltage detection signal to cause the switch to electrically couple the capacitor between the first terminal and a second terminal.