Converter Control for Inductive Power Transfer
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Solution Overview
Problem
Inductive power transfer systems face inefficiencies due to varying resonant frequencies caused by load changes and manufacturing tolerances, leading to diminished power throughput and increased complexity in converter control.
Innovation Solution
A method for controlling converters with a resonant circuit where control switches are switched based on dependent variables, such as zero-voltage events, and fixed time intervals, ensuring a constant switching frequency regardless of resonant frequency changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the converter operates at resonant frequency to maximize power throughput, then efficiency is improved, but the resonant frequency varies with load changes causing loss of efficiency
Solution Approach 1:
The patent applies parameter changes by deliberately varying the switching frequency of the converter away from the resonant frequency. This is achieved through control circuitry that adjusts the switching frequency based on operating conditions, allowing the system to maintain stable operation despite load variations. The frequency deviation is controlled to prevent excessive current while ensuring reliable power transfer.
Solution Approach 2:
The patent implements dynamics by making the switching frequency adjustable and adaptive rather than fixed. The control system dynamically modifies the switching frequency in response to load changes and system conditions, transforming a static resonant system into a dynamic one that can adapt to varying operational requirements while maintaining efficiency.
2Productivity
If the switching frequency is increased to improve power throughput, then efficiency is improved, but current through the transmitting coil increases causing potential overheating
Solution Approach 1:
The patent applies parameter changes by adjusting the switching frequency to an optimized value that balances power throughput and current levels. Rather than simply maximizing frequency, the control system selects a frequency that achieves adequate power transfer while keeping coil current within safe thermal limits, preventing overheating.
Solution Approach 2:
The patent implements feedback mechanisms where the control circuitry monitors system parameters such as current and temperature, and adjusts the switching frequency accordingly. This closed-loop control ensures that power throughput is maximized only when safe operating conditions are maintained, automatically reducing frequency when thermal limits are approached.
3Adaptability or versatility
If multiple control layers are added to adapt to resonant frequency changes, then system adaptability is improved, but device complexity and cost increase
Solution Approach 1:
The patent applies universality by designing a control circuit that performs multiple functions: it monitors resonant frequency, determines frequency deviation, and adjusts switching frequency all within a single integrated control layer. This multi-functional approach eliminates the need for separate control circuits for each function, reducing overall system complexity while maintaining adaptability.
Solution Approach 2:
The patent merges multiple control functions into a single integrated control mechanism. Rather than having separate control layers for frequency detection, analysis, and adjustment, the patent combines these functions into one unified control system that handles all frequency adaptation tasks, thereby simplifying the overall control architecture.
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 maintains a constant operating frequency, adapting to parameter variations while preventing energy losses and maintaining efficiency in inductive power transfer systems, eliminating the need for receiver retuning and ensuring efficient wireless energy transfer.
Implementation Method 1
a primary side generates a time-varying magnetic field from a transmitting coil or coils. This magnetic field induces an alternating current in a suitable receiving coil
Implementation Method 2
In some instances, it is possible to add capacitors around the transmitter coil to create a resonant circuit. Similarly, capacitors can be added around the receiver coil(s) to create a resonant circuit. Using a resonant circuit can increase power throughput and efficiency at the corresponding resonant frequency.
Data Source
AI summary
A method for controlling a converter including a resonant circuit, where the converter is controlled such that control switches are switched into a first state at the occurrence of an event that is related to a dependent variable of the converter and are switched into a second state at the occurrence of an event that is not related to a dependent variable of the converter, and the method may be employed in a converter or an inductive power transfer transmitter.