Resonant Wireless Power Transmitter Phase Detection

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Solution Overview

Problem

Resonant wireless power transmitter circuits face power loss due to off-resonance issues, which are not effectively controlled, especially when there are multiple receivers or receiver misalignment, leading to phase differences between current and voltage in reactive components, resulting in inefficient power transmission.

Innovation Solution

A resonant wireless power transmitter circuit with a phase detection and control system that uses a current sensing device within a power conversion circuit to detect voltage differences during a dead time period, generating impedance and frequency control signals to adjust the impedance matching circuit and operating frequency, thereby regulating the load current phase difference and maintaining resonance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a current transformer is used for phase detection, then phase detection capability is achieved, but bandwidth is limited and manufacturing cost increases

Engineering Contradiction:

Improvephase detection capabilityVSAvoidbandwidth

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent extracts the phase detection function from the traditional current transformer and implements it directly using the MOSFET's inherent characteristics. The MOSFET's on-resistance serves as the sensing element, eliminating the need for external current transformers and their associated bandwidth limitations.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the electromagnetic transformation mechanism of current transformers with a direct electronic sensing approach using MOSFET voltage measurements. This substitution enables broader bandwidth operation by removing the electromagnetic coupling limitations of transformer-based systems.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Device complexity

If impedance matching is fixed, then circuit simplicity is maintained, but operation efficiency decreases under off-resonance conditions

Engineering Contradiction:

Improvecircuit simplicityVSAvoidpower loss

Core Design Contradiction:

Device complexityVSLoss of energy

Solution Approach 1:

The patent implements dynamic impedance matching by continuously adjusting the impedance matching circuit based on real-time phase detection. The system transitions from fixed to variable impedance, allowing optimal power transfer under varying load and resonance conditions while maintaining relatively simple circuit architecture.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent establishes a feedback loop where the detected phase difference information is used to control the impedance matching circuit adjustment. This feedback mechanism enables automatic optimization of power transfer efficiency without requiring complex manual tuning or multiple fixed impedance circuits.

Inventive Principle:

Principle #23Feedback

3Ease of operation

If phase difference is not controlled, then circuit operation is simple, but power transmission efficiency decreases

Engineering Contradiction:

Improvecircuit operation simplicityVSAvoidpower transmission efficiency

Core Design Contradiction:

Ease of operationVSProductivity

Solution Approach 1:

The patent enables the system to self-regulate the phase difference through automatic detection and control. The MOSFET's inherent characteristics and the control circuit work together to automatically maintain optimal phase alignment, eliminating the need for external phase adjustment mechanisms while improving transmission efficiency.

Inventive Principle:

Principle #25Self-service

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 operation efficiency by adjusting impedance matching and frequency, reducing power loss and maintaining efficient wireless power transmission across a wider range of frequencies, including high frequencies like 6.78 MHz and 13.56 MHz, without the need for transformers and with fewer components.

Implementation Method 1

the resonant circuit and the impedance matching circuit cooperate to convert the output power VSW into a wireless output power by resonance effect

Methodology Applied

Scientific EffectResonance: Resonance

Implementation Method 2

a phase detection and control circuit, configured to operably detect a voltage difference between a current inflow terminal and a current outflow terminal of the current sensing device within a dead time period

Methodology Applied

Scientific EffectVoltage detection:

Data Source

PatentUS10601252B2Resonant wireless power transmitter circuit and control method thereof

Publication Date: 2020.03.24 RICHTEK TECH

AI summary

The present invention provides a resonant wireless power transmitter circuit, including: a load circuit, a power conversion circuit which is coupled between an input power supply and the load circuit, and a phase detection and control circuit. The power conversion circuit includes plural power switches and a current sensing device. The plural power switches operate with an operating frequency to convert the input power supply to an output power for driving the load circuit, wherein the load circuit has a load current. The load current has a load current phase difference from the switching frequency. The phase detection and control circuit detects a voltage difference between the current inflow terminal and the current outflow terminal of the current sensing device within a dead time in which the plural power switches are not conductive. The voltage difference corresponds to the load current phase difference.