Inductive Energy Transfer Secondary Freewheeling State
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Solution Overview
Problem
Existing inductive energy transmission systems face inefficiencies and safety concerns due to variable coupling factors and the need for precise positioning, leading to suboptimal operating points and potential hazards from high magnetic fields.
Innovation Solution
The introduction of an additional freewheeling state on the secondary side, enabled by replacing diodes with active switches, allows for targeted control of the inductive energy transmission, optimizing efficiency across a wide range of coupling factors and preventing excessive magnetic field strengths by periodically short-circuiting the secondary coil during each half cycle of the AC voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If wireless inductive charging is used to eliminate cable connections, then ease of operation is improved, but positioning precision requirements increase and coupling factor stability deteriorates
Solution Approach 1:
The patent applies dynamics by making the operating frequency variable rather than fixed. The control unit dynamically adjusts the operating frequency of the primary coil based on the detected coupling factor, allowing the system to adapt to changing positioning conditions and maintain optimal charging efficiency across different vehicle positions.
Solution Approach 2:
The patent changes the parameter of operating frequency to resolve the contradiction. By varying the frequency in response to coupling factor changes, the system maintains effective charging without requiring precise positioning, thus improving ease of operation while compensating for positioning variations.
2Device complexity
If operating frequency is kept constant for simple control, then device complexity is reduced, but adaptability to varying coupling factors deteriorates
Solution Approach 1:
The patent implements feedback by using the control unit to continuously detect the coupling factor and adjust the operating frequency accordingly. This closed-loop control enables the system to adapt to varying coupling conditions while maintaining relatively simple hardware architecture, resolving the contradiction between complexity and adaptability.
Solution Approach 2:
The system transitions from static frequency operation to dynamic frequency adjustment. The operating frequency becomes a variable parameter that automatically adapts to coupling factor changes, providing high adaptability without requiring complex hardware modifications.
3Power
If high primary current is used to ensure sufficient power transfer, then power is improved, but energy losses increase
Solution Approach 1:
The patent changes the frequency parameter to optimize the balance between power transfer and energy losses. By adjusting the operating frequency to match the resonant frequency of the coil system under varying coupling conditions, the system achieves efficient power transfer at lower currents, thereby reducing I²R losses while maintaining sufficient power delivery.
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 approach enhances efficiency and safety by allowing efficient energy transfer even with unfavorable coupling factors, reducing system losses, and preventing overheating hazards, while also providing a protective function against uncontrolled load shedding.
Implementation Method 1
a primary coil arrangement (12), which is designed to provide an alternating magnetic field (H1)
Implementation Method 2
an alternating magnetic field (H1), in which a secondary coil arrangement (22) is designed to couple
Data Source
Figure 1
Figure 2
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AI summary
The invention relates to inductive energy transmission from a primary coil (12) to a secondary coil (22) having an additional operating state. By means of this two-sided regulation, a primary-side and secondary-side control of the power electronics is performed in accordance with a predetermined operational strategy. Thus, even in the case of unfavorable coupling factors, for example, the efficiency of the inductive energy transmission can be increased, the magnetic field in the air gap between the primary coil (12) and the secondary coil (22) can be minimized, and the inductive energy transmission can be optimized. This optimized operational strategy is enabled by means of a newly introduced idle state, which permits periodic short-circuiting of the secondary side by means of switches on the secondary side (S5, S6) of the inductive energy transmission system. The invention is preferably used in the charging of the battery of an electric vehicle (4), but other applications are also possible.