Class-E Rectifier Resonant Tuning for Stable Input Reactance

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Solution Overview

Problem

Existing Class-E rectifiers face challenges with varying input reactance as the dc load changes, leading to inefficiencies and the need for additional energy storage components and external circuitry, which increase system size and cost.

Innovation Solution

Designing a Class-E rectifier with a resonant frequency ratio (A r ) between 1.75 and 3, allowing for low input reactance deviation and inherent output voltage regulation, eliminating the need for external circuitry and energy storage components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If existing Class-E rectifiers are used, then rectification function is provided, but input reactance varies significantly as dc load changes, requiring additional energy storage components and external circuitry

Engineering Contradiction:
Improveinput reactance stabilityVSAvoidsystem complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent changes the resonant frequency ratio parameter (Ar) to a specific range (1.75-3) to achieve low input reactance deviation. By adjusting this key parameter, the rectifier maintains stable input reactance across varying dc load conditions without requiring additional external circuitry or energy storage components.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The rectifier circuit provides inherent output voltage regulation and maintains low input reactance deviation through its own internal resonant network design, eliminating the need for external regulation circuitry. The system self-regulates by utilizing the resonant characteristics of its internal components rather than requiring separate control mechanisms.

Inventive Principle:
Principle #25Self-service

2Reliability

If additional energy storage components and external circuitry are added to compensate for reactance variation, then input reactance stability is improved, but system size and cost increase

Engineering Contradiction:
Improveinput reactance stabilityVSAvoidsystem size
Core Design Contradiction:
ReliabilityVSVolume of stationary object

Solution Approach 1:

The resonant network in the rectifier performs multiple functions simultaneously: it provides the necessary rectification operation, maintains low input reactance deviation, and delivers inherent output voltage regulation. By making the resonant network multi-functional, the patent eliminates the need for separate energy storage components and external circuitry, thereby reducing system size while maintaining reliability.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Reliability

If additional energy storage components and external circuitry are added to compensate for reactance variation, then input reactance stability is improved, but manufacturing cost increases

Engineering Contradiction:
Improveinput reactance stabilityVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent extracts and eliminates the unnecessary external circuitry and energy storage components from the system by incorporating their functions directly into the resonant network of the rectifier. This extraction reduces component count, simplifies manufacturing, and lowers cost while maintaining the required input reactance stability through the optimized resonant frequency ratio.

Inventive Principle:
Principle #2Taking out (Extraction)

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 solution achieves low input reactance deviation and inherent output voltage regulation, improving efficiency and reducing system size and cost by eliminating the need for additional components.

Implementation Method 1

A resonant network is arranged in parallel with the switching device between the power source and ground, the resonant network having a resonant frequency which is a non-integer multiple of the switching frequency, such that, in operation, a substantially constant current passes through the load resistance

Methodology Applied
Scientific EffectResonance: Resonance

Implementation Method 2

an alternating current passes through a transmitter coil. This causes the transmitter coil to produce a time-varying magnetic field. When a receiver coil is placed in the time-varying magnetic field, the magnetic field induces an alternating current in the receiver coil

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP3549250B1Wireless power transfer system
Publication Date: 2023.09.27 IMPERIAL COLLEGE INNVOATIONS LTD
  • EP3549250B1 patent drawingFigure 1a~1b
  • EP3549250B1 patent drawingFigure 2a~2b
  • EP3549250B1 patent drawingFigure 2c~2d

AI summary

Disclosed herein is a rectifier circuit for receiving an AC signal from a receiver coil in an inductive power transfer system. The circuit is configured to operate at an operating frequency. The circuit comprises a Class-E rectifier; an AC signal supplier configured to supply an AC signal to the rectifier circuit; and a resonant network having an inductor and a capacitor. The resonant network has a resonant frequency, and the ratio of the resonant frequency to the operating frequency is within the range of 1.75 to 3.