Inductive Charging Return Conductor Grounding via Inductance
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Solution Overview
Problem
Existing inductive energy transmission systems face challenges in ensuring safety and reducing losses, particularly in grounding low-frequency currents while preventing dissipation of medium-frequency currents.
Innovation Solution
A system with a primary-conductor loop having a feed and return conductor, where the return conductor is connected to ground through inductance, allowing low-frequency grounding without medium-frequency dissipation, and featuring a U-shaped ferrite core for high coupling efficiency, and using multistrand wire and aluminum continuous casting profiles to suppress electromagnetic waves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the return conductor is directly connected to ground, then safety is improved through grounding, but medium-frequency currents dissipate to ground causing energy losses
Solution Approach 1:
An inductance element is introduced as an intermediary between the return conductor and ground. This inductance acts as a frequency-selective mediator that allows low-frequency grounding currents to pass while blocking medium-frequency currents from dissipating to ground, thus resolving the contradiction between safety grounding and energy loss prevention
Solution Approach 2:
The inductance value is specifically chosen to create different impedance characteristics at different frequencies. At low frequencies (power line frequency), the inductance presents low impedance allowing grounding, while at medium frequencies (inductive energy transmission frequency), it presents high impedance preventing current dissipation. This parameter-based frequency differentiation resolves the contradiction
2Productivity
If the primary conductor is arranged as an elongated loop with multiple line sections, then multiple vehicles can be supplied simultaneously, but the system complexity increases
Solution Approach 1:
The primary conductor system is segmented into multiple line sections, each capable of independently coupling with vehicles. This segmentation allows multiple vehicles to be supplied simultaneously at different locations along the conductor loop while maintaining a relatively simple overall structure that avoids the need for multiple separate transmission systems
3Reliability
If the return conductor surrounds the feed conductor in the circumferential direction, then coupling factor is improved, but the vehicle movement freedom is restricted
Solution Approach 1:
The return conductor surrounds the feed conductor only partially in the circumferential direction, rather than completely. This partial surrounding provides sufficient coupling factor for effective inductive energy transmission while leaving gaps that allow vehicles to move freely back and forth and along curves without restriction
Solution Approach 2:
The return conductor is positioned to provide optimal coupling in the critical coupling region between feed and return conductors, while being open in other areas to permit vehicle movement. This local optimization of conductor arrangement achieves both good coupling and movement freedom
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 system enhances safety and efficiency by maintaining medium-frequency currents within the system for inductive energy transmission, enabling simultaneous supply to multiple vehicles and reducing electromagnetic interference.
Implementation Method 1
an alternating current is able to be applied to a primary-conductor system in inductive energy transmissions and that electrical energy can thereby be transmitted to a secondary winding that is provided to be inductively coupled with the primary-conductor system
Implementation Method 2
the secondary winding in particular being provided around a U-shaped ferrite core, the legs of the U in each case projecting or extending into the space region between the feed conductor and the return conductor
Data Source
AI summary
In a system for an inductive energy transmission from a primary-conductor system, in particular a stationary primary conductor system, to a vehicle having a secondary winding, the secondary winding is inductively coupled with the primary-conductor system. The primary conductor is installed as a primary-conductor loop installed in elongated form, which has a feed conductor and a return conductor in a line section, in particular a return conductor that is installed parallel thereto, and the return conductor is electrically grounded in that at least one inductance is disposed between the return conductor and the electrical ground.