Inductive Power Transfer Compensation for Resonance Shift Losses
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Solution Overview
Problem
Existing contactless energy transmission systems, particularly inductive systems for transport systems like linear motors, face challenges in achieving efficient and low-loss energy transfer due to relative movements between primary and secondary parts, which can shift resonance frequencies and increase blind power, leading to reduced transferable activity.
Innovation Solution
The introduction of a secondary compensation current to the reception coil on the secondary part creates a second magnetic field that induces a compensation voltage in the transmission coil on the primary part, modifying the phase shift between the voltage and current, thereby increasing the transferred activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If resonant coupling is used to increase magnetic coupling between transmitting and receiving coils, then energy transfer efficiency is improved, but the system becomes sensitive to resonance frequency shifts caused by relative movements between primary and secondary parts
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the excitation frequency to track the resonant frequency of the coupled system. The control unit continuously monitors the impedance of the transmitting coil and adjusts the excitation frequency accordingly to maintain resonance conditions despite relative movements between primary and secondary parts, thereby maintaining high energy transfer efficiency while adapting to changing system conditions
2Device complexity
If the supply voltage is limited by physical limitations of power electronic devices, then device complexity is reduced, but the available electrical power for energy transmission is limited
Solution Approach 1:
The patent employs periodic action by using high-frequency alternating current to generate time-varying magnetic fields for inductive energy transmission. The periodic switching of power electronic devices at high frequencies enables effective energy transfer while operating within voltage limitations, as the rapid oscillations create sufficient magnetic coupling without requiring continuously high voltage levels
Solution Approach 2:
The system changes parameters by operating power electronic devices at high switching frequencies rather than relying on high voltage levels. This parameter change allows the system to transmit adequate power through increased frequency of operation, compensating for the limited voltage capability of the power electronic devices while maintaining manageable device complexity
3Adaptability or versatility
If relative movements occur between primary and secondary parts during operation, then transport system functionality is enabled, but resonance frequencies shift and negatively impact energy transfer
Solution Approach 1:
The patent implements feedback control by continuously monitoring the impedance characteristics of the transmitting coil and using this information to adjust the excitation frequency. The control unit processes impedance measurements in real-time and modifies the operating frequency to maintain resonance conditions despite changes in coupling caused by relative movements, thereby preventing energy transfer degradation
Solution Approach 2:
The system applies dynamics by making the excitation frequency adjustable and adaptable rather than fixed. The frequency of the excitation signal is dynamically modified in response to changing coupling conditions caused by relative movements, allowing the system to maintain optimal resonance conditions throughout the range of motion between primary and secondary parts
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 the transferred activity by up to several thousand percent compared to uncompensated systems, while also reducing blind power and improving the robustness of energy transmission, especially in systems with limited supply voltage and large scatter inductivity.
Implementation Method 1
an electrical primary current is introduced from a supply unit into a transmitting coil arranged on the primary part to build up a first alternating magnetic field for energy transmission, whereby an electrical alternating voltage is induced in a receiving coil arranged on the secondary part
Implementation Method 2
The introduction of a secondary compensation current to the reception coil on the secondary part creates a second magnetic field that induces a compensation voltage in the transmission coil on the primary part
Implementation Method 3
the usual goal of resonant coupling at this point is to select the frequency of the supply voltage applied to the transmitting coil, often referred to as the excitation frequency, as close as possible to a resonant frequency of the resonant electrical circuit. This primarily increases the magnetic coupling between the transmitting and receiving coils
Data Source
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AI summary
The invention relates to an improved method for inductive energy transmission between a primary part (I) and a secondary part (II), wherein a primary current (i s ) is introduced into a transmitting coil (L 1 ) arranged on the primary part (I) in order to create a first magnetic field which induces an electrical AC voltage (u i ) in a receiving coil (L 2 ) arranged on the secondary part (II), which electrical AC voltage causes an electrical secondary current (i v ) at the secondary part (II) and thus a power flow to at least one load (V) connected to the receiving coil (L 2 ), which power flow comprises an uncompensated active power (P N ). According to the invention, a compensation unit (K) introduces a compensation current (i K ) into a secondary-side coil (L K ), which compensation current generates a second magnetic field which is superimposed on the first magnetic field and induces a compensation voltage (u K ) in the transmitting coil (L 1 ). The compensation voltage (u K ) changes the phase shift between the primary voltage (u L1 ) that drops across the transmitting coil (L 1 ) and the primary current (i s ) that flows through the transmitting coil (L 1 ) in such a way that the transmitted active power (P R ) increases.