PRSS Resonant Tank Tuning for Misalignment-Tolerant Wireless Power
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Solution Overview
Problem
Misalignment between primary and secondary coils in wireless inductive power transfer systems leads to a decrease in coupling, resulting in a drop in power transfer, and existing solutions often require complex coil structures and additional converters to maintain constant output power.
Innovation Solution
A parallel resonant series-series (PRSS) tuning method is introduced, which includes a loosely coupled transformer with specific capacitor and inductor configurations to maintain nearly constant power transfer across a range of coupling coefficients without external controls, utilizing a parallel resonant tank to adjust impedance and current to compensate for misalignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If misalignment occurs between primary and secondary coils, then coupling decreases, but power transfer drops
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the resonant frequency of the parallel resonant tank circuit to compensate for coupling variations. When misalignment occurs and coupling coefficient decreases, the system changes the resonant frequency parameter of the parallel LC circuit to maintain optimal power transfer conditions, thereby resolving the contradiction between power transfer stability and coupling coefficient variation
Solution Approach 2:
The patent implements dynamics by making the resonant frequency of the parallel resonant tank adjustable rather than fixed. This dynamic adjustment capability allows the system to adapt to changing coupling conditions caused by misalignment, enabling the system to maintain reliable power transfer across varying coupling coefficients through real-time frequency tuning
2Reliability
If complex coil structures and additional converters are used to maintain constant output power, then power transfer stability improves, but device complexity increases
Solution Approach 1:
The patent merges the power transfer stabilization function into the existing parallel resonant tank circuit of the IPT system. Instead of adding separate complex coil structures or additional converters, the invention combines the compensation mechanism with the existing resonant circuit by adjusting its resonant frequency, thereby achieving output power constancy without increasing device complexity
Solution Approach 2:
The patent applies self-service by enabling the parallel resonant tank circuit to automatically compensate for coupling variations through frequency adjustment. The system uses its own existing resonant circuit components to maintain constant output power, eliminating the need for external complex control systems or additional converters, thus resolving the contradiction between reliability and device complexity
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
The PRSS tuning method ensures a relatively constant output power by adjusting impedance and current, effectively maintaining power transfer despite misalignment, simplifying coil design and eliminating the need for external controls.
Implementation Method 1
The primary series capacitor Cps is chosen to be at a resonant frequency ωr with the primary inductance Lp and the secondary series capacitor Css is chosen to be at the resonant frequency ωr with the secondary inductance Ls
Implementation Method 2
The tuning section includes a primary parallel capacitor Cpp, of a parallel resonant tank connected in parallel with the primary series capacitor Cps and the primary winding
Implementation Method 3
The tuning section includes a loosely coupled transformer with a primary inductance Lp and a secondary inductance Ls
Data Source
AI summary
A power converter includes switching section, tuning section, and rectification section. The tuning section includes transformer with a primary inductance and a secondary inductance and a primary series capacitor connected in series with a primary winding and a secondary series capacitor connected in series with a secondary winding. The primary series capacitor is selected with a resonant frequency with the primary inductance and the secondary series capacitor is selected with the resonant frequency with the secondary inductance. The tuning section includes a resonant tank with a primary parallel capacitor connected in parallel with the primary series capacitor and the primary winding and a primary resonant inductor connected between the switching section and a connection to the primary parallel capacitor. An input impedance of the resonant tank at a switching frequency is below a frequency intersecting an open circuit input impedance and a short circuit input impedance of the resonant tank.