Wireless Power Transmitter Driver with Adaptive Switching Intervals
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Solution Overview
Problem
Current wireless power transfer systems using Qi Specifications face challenges such as suboptimal operation, high EMI, communication errors, and overvoltage issues due to the limitations of half or full bridge inverter topologies, particularly when the drive frequency is near the resonance frequency, leading to inefficient power transfer and potential damage to electronic components.
Innovation Solution
A power transmitter with a parallel resonance circuit and a driver generating cyclic drive signals to control switch elements, allowing for adaptive operation by adjusting the duration of time intervals to match the effective resonance frequency with the drive frequency, thereby reducing peak voltages, improving EMI performance, and facilitating quick adaptation to changes in operating conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If half or full bridge inverter topology is used with drive frequency near resonance frequency, then wireless power transfer capability is achieved, but peak voltages increase and EMI performance deteriorates
Solution Approach 1:
The patent implements dynamic switching control where the driver adaptively adjusts the switching timing of the first and second switch elements based on real-time operating conditions. The third time interval allows the parallel resonance circuit to naturally oscillate and settle, enabling the system to dynamically adapt to varying load conditions and maintain optimal performance while reducing peak voltages and EMI.
Solution Approach 2:
The driver generates cyclic drive signals with periodic time intervals including a third interval where both switch elements are closed. This periodic switching pattern synchronizes with the resonance frequency of the parallel resonance circuit, enabling efficient power transfer while the periodic nature allows for controlled voltage peaks and reduced EMI through predictable switching behavior.
2Loss of energy
If drive frequency is operated near resonance frequency, then power transfer efficiency is improved, but system adaptability to changing operating conditions deteriorates
Solution Approach 1:
The system employs dynamic control where the driver continuously adjusts the switching pattern in response to changing operating conditions such as load variations or receiver positioning. The inclusion of the third time interval provides the system with dynamic adaptability to maintain efficient power transfer across varying conditions by allowing the resonance circuit to naturally respond to changes.
Solution Approach 2:
The patent implements a feedback mechanism where the driver monitors the operating conditions and adjusts the drive signal accordingly. The third time interval serves as a feedback period where the system can detect changes in the resonance circuit behavior and adapt the subsequent switching pattern to maintain optimal power transfer efficiency under changing conditions.
3Speed
If switch elements are switched rapidly to achieve high frequency power transfer, then power transfer speed is improved, but overvoltage risk and component stress increase
Solution Approach 1:
The third time interval acts as a cushioning period before the next switching cycle begins. During this interval, both switch elements are closed, allowing the parallel resonance circuit to naturally oscillate and dissipate energy, thereby preventing excessive voltage buildup and reducing stress on the switch elements and other components before the next high-speed switching event.
Solution Approach 2:
The periodic inclusion of the third time interval creates a rhythm in the switching pattern that allows the system to handle high-frequency power transfer while periodically reducing stress on components. This periodic action provides regular intervals for voltage normalization and energy dissipation, maintaining reliability during high-speed 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 enhances power transfer efficiency, reduces the risk of overvoltage, improves communication, and provides a more flexible and adaptive wireless power transfer system with reduced EMI, allowing for efficient operation across varying conditions.
Implementation Method 1
power is inductively transferred from a transmitter coil in a power transmitter device to a receiver coil in the individual devices
Implementation Method 2
a parallel resonance circuit comprising at least a capacitive impedance and an inductive impedance
Data Source
AI summary
A power transmitter (501) for a wireless power transfer system includes a parallel resonance circuit (601) comprising at a transmitter coil (503) for generating the power transfer signal. A power source (605) has a current sink terminal and a power source terminal providing current to the parallel resonance circuit (601) with a limited rate of change of the current drawn. A first switch element (607) is coupled between a first end of the parallel resonance circuit (601) and the current sink terminal. A second switch element (609) is coupled between the other end and the current sink terminal. A driver (611) generates a cyclic drive signal such that each cycle comprises a two time intervals in which one switch element (607, 609) is closed and the other (607, 609) is open; and a third time interval in which both the first switch element (607) and the second switch element (609) are closed, the third time interval being between the other two intervals.