Inductive Energy Transfer Assembly with Switchable Resonant Circuit

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Solution Overview

Problem

Existing inductive energy transmission systems lack flexibility and effective overvoltage protection when transmitting electrical energy from a stationary primary conductor to a movable device, limiting their adaptability and reliability.

Innovation Solution

A modular arrangement with a switch-controlled resonant circuit that adjusts resonant frequency and voltage detection for optimal energy transfer, incorporating pulse width modulation for precise voltage regulation and overvoltage protection by switching between two distinct resonant frequencies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a fixed resonant frequency is used in the inductive energy transmission system, then the system structure is simple, but the adaptability to different operating conditions and frequency variations is poor

Engineering Contradiction:
Improveadaptability to frequency variationsVSAvoidsystem structure complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent implements a dynamic resonant frequency adjustment mechanism by introducing a switchable capacitor arrangement that can change capacitance values based on operating conditions. The controller dynamically selects between different capacitance configurations (first and second capacitance values) to match varying frequencies from the feed unit, transforming a static system into an adaptive one without requiring complete system redesign

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the electrical parameter (capacitance) of the resonant circuit to adapt to frequency variations. By switching between different capacitance values in the resonant circuit, the system can tune its resonant frequency to match the feed unit's operating frequency, achieving frequency adaptation through parameter modification rather than structural complexity

Inventive Principle:
Principle #35Parameter changes

2Reliability

If overvoltage protection mechanisms are added to the inductive energy transmission system, then the reliability is improved, but the device complexity increases

Engineering Contradiction:
Improveovervoltage protectionVSAvoidsystem structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements feedback-based overvoltage protection by continuously monitoring the voltage across the capacitor arrangement and using this information to control the switch. When the voltage exceeds a predetermined threshold, the feedback mechanism triggers the switch to change state, thereby adjusting the resonant frequency to reduce voltage. This closed-loop control provides reliable protection without requiring separate protection circuits

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system performs self-protection against overvoltage conditions by using its own operational parameters (voltage across capacitor) to trigger protective action. The controller automatically detects overvoltage and switches the resonant circuit configuration accordingly, enabling the system to protect itself without external intervention or additional complex protection hardware

Inventive Principle:
Principle #25Self-service

3Productivity

If the resonant frequency is continuously adjusted to match the feed unit frequency, then the energy transmission efficiency is maximized, but the risk of overvoltage increases

Engineering Contradiction:
Improveenergy transmission efficiencyVSAvoidovervoltage risk
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent employs periodic monitoring of voltage levels during resonant operation and uses discrete switching actions between two capacitance states. Rather than continuous adjustment, the system periodically checks voltage conditions and makes stepped frequency adjustments, maintaining efficiency while introducing safety thresholds that prevent continuous voltage escalation

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The system prepares for potential overvoltage conditions by establishing a predetermined voltage threshold before dangerous levels are reached. The switchable capacitor arrangement provides a pre-configured safety mechanism that automatically activates when voltage approaches hazardous levels, cushioning against overvoltage damage before it occurs rather than reacting after the problem arises

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

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

Enables efficient and adaptable inductive energy transmission with enhanced overvoltage protection, ensuring high power transfer efficiency while preventing damage from excessive voltages.

Implementation Method 1

energy is transmitted via the inductive coupling between the primary conductor and the secondary winding

Methodology Applied
Scientific EffectInductive coupling: Electromagnetic Induction

Implementation Method 2

the resonant frequency can be controlled by means of appropriate activation of the switch. In a first switch position, the resonant circuit has a different resonant frequency than in a second switch position

Methodology Applied
Scientific EffectResonance: Resonance

Data Source

PatentEP3323186B1Assembly for the inductive transfer of electrical energy from a stationary primary conductor to a device that can move relative to same, and method for operating the assembly
Publication Date: 2020.03.18 SEW EURODRIVE GMBH & CO KG
  • EP3323186B1 patent drawingFigure 1

AI summary

The invention relates to an assembly for the inductive transfer of electrical energy from a stationary primary conductor to a device that can move relative to same, such as a vehicle, mobile part or similar, wherein the moveable device has a secondary winding, in particular on the underside thereof, which can be inductively coupled to the primary conductor, and wherein a capacitor assembly is connected in parallel with the secondary winding or the series connection formed from the secondary winding and a first capacitor C1, which capacitor assembly has a second capacitor C2, to which a third capacitor C3 can be connected in parallel via a controllable switch S.