Wireless Power Transfer Circuit With Switchable Secondary Windings
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Solution Overview
Problem
The variability in the distance between wireless power transfer (WPT) primary and secondary pads due to factors like vehicle clearance and load variations poses challenges in maintaining efficient power transfer in electric vehicles.
Innovation Solution
A variable wireless power transfer system is implemented using a secondary pad with parallel windings and rectification sections, along with a controller that intermittently switches the windings to control voltage and current, and a primary pad with a full-bridge topology and transformer, allowing for adjustable power transfer across varying distances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the distance between primary and secondary pads is increased to accommodate vehicle clearance and load variations, then the adaptability of the wireless power transfer system is improved, but the power transfer efficiency deteriorates
Solution Approach 1:
The patent applies dynamics by making the winding configuration changeable during operation. The secondary pad windings can be dynamically reconfigured between series and parallel connections based on the coupling conditions, which vary with distance. This dynamic adaptation allows the system to maintain optimal performance across varying distances while accommodating vehicle clearance and load variations.
Solution Approach 2:
The patent changes the electrical parameters of the secondary pad by altering the winding configuration. By switching between series and parallel connections, the system changes the equivalent inductance and impedance parameters, thereby adapting to different coupling conditions and distance variations while maintaining power transfer efficiency.
2Reliability
If the windings are reconfigured to maintain power transfer at varying distances, then the reliability of power transfer is improved, but the device complexity increases
Solution Approach 1:
The patent uses dynamic switching between series and parallel winding configurations to maintain reliable power transfer across varying distances. The controller automatically detects coupling conditions and switches the winding configuration accordingly, ensuring continuous reliable operation without requiring complex manual intervention or multiple independent systems.
Solution Approach 2:
The secondary pad windings serve multiple functions through a single configurable structure. The same windings can operate in series for certain distance conditions and in parallel for other conditions, making the system universal and adaptable to various operating scenarios without requiring separate dedicated windings for each condition.
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 system ensures reliable and efficient wireless power transfer across varying distances by dynamically adjusting voltage and current, maintaining effective coupling between the primary and secondary pads.
Implementation Method 1
a resonant frequency of the primary pad matches a resonant frequency of the secondary pad
Implementation Method 2
The secondary pad includes a first winding and a second winding in parallel with the first winding
Implementation Method 3
a first rectification section that receives power from the first winding and a second rectification section that receives power from the second winding
Data Source
AI summary
In one example, an apparatus for wireless power transfer may include a resonant section of a wireless power transfer converter, a first switching section having a full-bridge topology, a second switching section including bidirectional switches in a full-bridge topology, and a transformer with N turns having a first side and a second side. The first switching section may include a first leg and a second leg, each having a center point. The resonant section may include a first connection and a second connection. The second switching section may include a first leg and a second leg, each having a center point. A first connection of the first side of the transformer may be connected in series with the second connection of the resonant section. The first connection of the resonant section and a second connection of the first side of the transformer may be connected to the center points of the first switching section, respectively. The second side of the transformer may be connected between the center points of the second switching section. Other examples may be described and claimed.