Switching Frequency Adjusting Circuit for Wireless Charging

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Solution Overview

Problem

In wireless charging systems, the resonant frequency of the compensation network deviates due to manufacturing tolerances in inductance and capacitance, causing the inverter switch to operate away from the optimal resonant frequency, leading to inefficient energy transfer and high switching losses.

Innovation Solution

A switching frequency adjusting circuit that determines the phase difference between output voltage and current signals, using a phase difference determination circuit, average determination circuit, and loop compensator to adjust the switching frequency and implement soft switching, thereby aligning the inverter operation with the resonant frequency of the compensation network.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the switching frequency is set according to nominal inductance and capacitance values, then the circuit design is simple, but the actual resonant frequency deviates significantly causing inefficient operation

Engineering Contradiction:

Improvecircuit design simplicityVSAvoidenergy transfer efficiency

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

The patent implements a feedback mechanism by detecting the phase difference between output voltage and current signals. The phase difference determination circuit continuously monitors the phase relationship, and the loop compensator adjusts the switching frequency based on this feedback to maintain operation at the actual resonant frequency, resolving the contradiction between simple design and efficient operation.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent dynamically changes the switching frequency parameter based on detected phase difference. Instead of using a fixed nominal frequency, the system continuously adjusts the frequency parameter to match the actual resonant conditions, thereby maintaining high efficiency despite manufacturing tolerances in inductance and capacitance values.

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If the inverter operates away from resonant frequency due to parameter tolerances, then manufacturing is easier with standard components, but switching losses increase significantly

Engineering Contradiction:

Improvecomponent tolerance acceptanceVSAvoidswitching loss

Core Design Contradiction:

Manufacturing precisionVSLoss of energy

Solution Approach 1:

The feedback mechanism detects phase difference between voltage and current, which indicates deviation from resonant frequency. The loop compensator uses this information to adjust the switching frequency, ensuring the inverter operates at the actual resonant frequency despite component tolerances, thereby minimizing switching losses.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system transitions from a static fixed-frequency design to a dynamic frequency-adjustment system. The switching frequency is no longer fixed but dynamically adapted based on real-time phase difference detection, allowing the system to maintain optimal operation despite manufacturing variations in components.

Inventive Principle:

Principle #15Dynamics

3Productivity

If analog phase detection is used to identify resonant frequency, then frequency adjustment is achieved, but signal interference and oscillations increase

Engineering Contradiction:

Improveresonant frequency identificationVSAvoidsignal interference

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces traditional analog phase detection methods with a digital signal processing approach. By using digital techniques to process the phase difference between voltage and current signals, the system achieves resonant frequency identification while filtering out analog noise and interference, thereby reducing signal oscillations.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces an intermediary processing stage between the phase detection and frequency adjustment. The phase difference determination circuit acts as an intermediary that processes the voltage and current signals to extract phase information in a noise-resistant manner, preventing direct transmission of analog interference to the frequency control loop.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS20240364235A1Switching frequency adjusting circuit and device comprising the same

Publication Date: 2024.10.31 OMNION POWER TECHNOLOGY GMBH

AI summary

In one embodiment, a switching frequency adjusting circuit includes an inverter circuit, a phase difference determining circuit, an average determination circuit, and a loop compensator. The inverter circuit includes an inverter switch configured to switch on and off at a switching frequency. The phase difference determination circuit is configured to obtain a first signal related to an output voltage of the inverter circuit and a second signal related to an output current of the inverter circuit. The average determination circuit is configured to determine a first average value of a first output signal and a second average value of a second output signal, and the loop compensator is configured to compare the first average value or the second average value with a reference value and adjust the switching frequency of the inverter switch based on the comparison result.