Resonance Converter for Wireless EV Charger
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Solution Overview
Problem
Current wireless charging technologies face inefficiencies in magnetic coupling and switching losses, particularly in achieving zero phase angle conditions for constant-current and constant-voltage charging in electric vehicles, leading to complex implementations and increased costs.
Innovation Solution
A resonance converter with a full bridge inverter, a resonance tank comprising primary and secondary resonators with intermediate resonators, and a rectification bridge, which operates under fixed frequency conditions to achieve zero phase angle conditions for soft switching and efficient voltage conversion, along with a control circuit for stable charging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a 3-coil system is used to improve magnetic coupling, then coupling efficiency is improved, but zero phase angle condition cannot be achieved and switching loss increases
Solution Approach 1:
The patent divides the resonance tank into multiple independent resonators (first resonator, second resonator, third resonator, fourth resonator) that can be independently controlled. This segmentation allows each resonator to be tuned to achieve zero phase angle condition at different stages, thereby reducing switching loss while maintaining manageable system complexity through modular design.
Solution Approach 2:
The patent dynamically adjusts the resonance frequency of each resonator during operation. By changing the resonance frequency of the resonance tank according to operating conditions, the system can maintain zero phase angle condition across different power levels and load conditions, minimizing switching loss dynamically rather than being fixed.
2Loss of energy
If high permeability material such as ferrite is used to increase magnetic coupling, then coupling efficiency is improved, but size, weight and cost of the electric vehicle increase
Solution Approach 1:
The patent replaces the mechanical/material-based approach (using high permeability ferrite materials) with an electrical/control-based approach. By using multiple resonators with adjustable resonance frequencies and controlling their operating points, the system achieves high magnetic coupling efficiency without relying on heavy ferrite materials, thereby reducing vehicle weight while maintaining coupling efficiency.
3Ease of operation
If pulse frequency modulation method is used for constant-voltage charging, then voltage control is achieved, but wide frequency change is required and zero phase angle condition cannot be satisfied
Solution Approach 1:
The patent dynamically adjusts the resonance frequency of the resonance tank during charging operations. By changing the resonance frequency according to the charging stage (constant current or constant voltage mode), the system can maintain zero phase angle condition while achieving the required voltage control, avoiding the energy losses associated with wide frequency changes in PFM methods.
Solution Approach 2:
The patent employs feedback control mechanisms that monitor the operating conditions and adjust the resonance frequency accordingly. This feedback ensures that the system maintains zero phase angle condition while achieving the desired voltage control, preventing the energy losses that would occur with open-loop frequency modulation methods.
4Ease of operation
If resonance frequency is changed for constant-current and constant-voltage charging, then charging control is achieved, but switching loss increases due to narrow soft switching range
Solution Approach 1:
The patent segments the resonance tank into multiple resonators that can be independently controlled. This allows the system to maintain a narrow overall frequency change range while achieving both constant-current and constant-voltage charging control through coordinated adjustment of individual resonators, thereby preserving soft switching conditions and minimizing switching loss.
Solution Approach 2:
The patent dynamically adjusts the operating points of individual resonators rather than changing the overall resonance frequency widely. By controlling each resonator's contribution to the total output, the system achieves the required charging control modes while maintaining operation within a narrow frequency range that preserves soft switching and minimizes switching loss.
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
Enables simple control and stability for constant-current and constant-voltage charging, reducing switching losses and manufacturing costs while maintaining high efficiency.
Implementation Method 1
perform voltage conversion in an inductive power transfer manner among four resonators of the primary resonance tank and the secondary resonance tank
Implementation Method 2
a resonance converter for a wireless charger to perform constant-current and constant-voltage charging
Implementation Method 3
a full bridge inverter connected to an input power source that supplies an input voltage
Implementation Method 4
a rectification bridge configured to rectify an output voltage sent from the resonance tank and transfer the rectified output voltage to a battery
Data Source
AI summary
Provided is a resonance converter for a wireless charger, which includes a full bridge inverter connected to an input power source that supplies an input voltage and having first to fourth switches, a resonance tank having a plurality of resonators composed of capacitors and coils connected in series and configured to receive the input voltage from the full bridge inverter and perform voltage conversion in an inductive power transfer manner among the plurality of resonators, and a rectification bridge configured to rectify an output voltage sent from the resonance tank and transfer the rectified output voltage to a battery.