Wireless Charging Inverter Impedance Control for ZVS
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Solution Overview
Problem
Existing wireless charging systems face inefficiencies due to the challenge of ensuring zero-voltage switching (ZVS) for controllable switching transistors in DC-AC inverters across various phase shift angles and output voltages, leading to increased switching losses and potential damage.
Innovation Solution
Incorporating an impedance adjustment circuit with inductive branches and a controller that adjusts the impedance by connecting or disconnecting inductive branches based on phase shift angles and output powers to maintain ZVS for the lagging bridge arm, reducing power consumption and preventing damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the input voltage of H1 is adjusted to implement ZVS in all working conditions, then wireless charging efficiency is improved, but the size and costs of the wireless transmitting apparatus increase due to additional direct current conversion circuit
Solution Approach 1:
The patent applies dynamics by making the impedance adjustment circuit configurable and adaptable to different working conditions. The circuit can dynamically adjust its impedance characteristics based on the operating phase shift angle, allowing ZVS to be achieved across various conditions without requiring a completely different circuit configuration for each scenario.
Solution Approach 2:
The patent changes physical parameters by adjusting the impedance of the adjustment circuit according to different phase shift angles. By varying the impedance parameter dynamically, the system maintains ZVS conditions across different operating points without adding complex voltage conversion circuits.
2Power
If the output voltage of H1 is adjusted by changing phase shift, then voltage regulation is achieved, but ZVS cannot be ensured for all controllable switching transistors under various output voltages
Solution Approach 1:
The patent implements feedback by using the controller to detect the phase shift angle and automatically adjust the impedance of the adjustment circuit accordingly. This closed-loop control ensures that ZVS conditions are maintained for the lagging bridge arm transistors across different output voltage conditions, improving reliability.
Solution Approach 2:
The adjustment circuit acts as an intermediary element between the DC power supply and the lagging bridge arm. By controlling the impedance of this intermediate circuit, the system can influence the operating conditions of the switching transistors to achieve ZVS without directly modifying the main power conversion path.
3Productivity
If controllable switching transistor loses ZVS, then wireless charging efficiency decreases, but switching loss increases and H1 may be damaged
Solution Approach 1:
The patent applies preliminary action by proactively adjusting the impedance of the adjustment circuit before the switching events occur. The controller predicts the phase shift angle and pre-configures the adjustment circuit to ensure ZVS conditions are met, preventing switching losses and potential damage before they can occur.
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 enhances wireless charging efficiency by reducing switching losses, improving stability, and ensuring reliable operation across different operating conditions without interrupting power transmission.
Implementation Method 1
The transmitting coil is configured to: receive the alternating current and generate an alternating current magnetic field
Implementation Method 2
The receiving coil Cr is configured to receive, in an alternating current magnetic field, electromagnetic energy emitted by the transmitting coil Ct
Data Source
AI summary
This application discloses wireless charging apparatuses, methods, and systems. One apparatus includes: a direct current to alternating current (DC-to-AC) inverter circuit configured to invert a DC output by a DC power supply to an AC; a compensation circuit configured to compensate the AC output by the DC-to-AC inverter circuit and send the AC obtained after the compensation to a transmitting coil; the transmitting coil configured to receive the AC and generate an AC magnetic field; an impedance adjustment circuit comprising one or more inductive branches; and a controller configured to control on or off of the switch in the inductive branch to change a current flowing out of the lagging bridge arm to enable a controllable switching transistor of the lagging bridge arm to implement zero-voltage switching.