Variable-Inductance Resonant Circuit for Low-Frequency EV Charging
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Solution Overview
Problem
Existing contactless power transmission systems for vehicles require high frequencies and short distances, necessitating expensive components like soft ferrites and Litz wire, limiting operational flexibility and cost-effectiveness.
Innovation Solution
A resonant circuit design that amplifies current and voltage using a variable magnetic reluctance assembly and electronic voltage inverter, allowing operation at lower frequencies and greater distances with cost-effective components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high frequency operation is used to transmit satisfactory power levels, then power transmission capability is improved, but component cost increases due to expensive soft ferrites and Litz wire
Solution Approach 1:
The patent changes the operating frequency parameter from high frequency (85 kHz or more) to low frequency (below 85 kHz), which fundamentally alters the system requirements. This parameter change allows the use of conventional, cost-effective components instead of expensive soft ferrites and Litz wire, while still achieving satisfactory power transmission levels through the resonant coupling mechanism
Solution Approach 2:
The patent employs variable inductors that can dynamically adjust their inductance values to maintain resonant conditions at lower frequencies. This dynamic adjustment capability enables the system to operate effectively at reduced frequencies without sacrificing power transmission capability, thereby avoiding the need for expensive high-frequency components
2Power
If high frequency operation is used, then power transmission is improved, but operating distance is limited to short distances
Solution Approach 1:
By changing the operating frequency parameter to lower values and utilizing resonant coupling, the patent extends the effective operating distance beyond the short distances limitation of high-frequency systems. The resonant interaction between transmitter and receiver circuits at matched low frequencies enables power transmission over extended distances
3Ease of manufacture
If low frequency operation is used, then component cost is reduced, but power transmission capability deteriorates
Solution Approach 1:
The patent uses dynamically adjustable variable inductors that can modify their inductance to maintain optimal resonant conditions at low frequencies. This dynamic adaptation compensates for the potential power transmission reduction at lower frequencies, enabling the system to achieve satisfactory power levels while using cost-effective components
Solution Approach 2:
The patent employs periodic tuning and adjustment of the resonant circuits to maintain optimal power transfer at low frequencies. By periodically adjusting the variable inductors to maintain resonant conditions, the system overcomes the natural tendency for reduced power transmission at lower frequencies
4Length of stationary object
If low frequency operation is used, then operating distance is extended, but power transmission capability is reduced
Solution Approach 1:
The variable inductors provide dynamic adjustment capability that maintains resonant coupling efficiency over extended distances at low frequencies. By dynamically adapting the inductance values, the system compensates for the increased distance, thereby maintaining satisfactory power transmission capability while achieving extended operating range
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 power transmission up to 500 kW at lower frequencies and extended distances, reducing component costs and improving operational flexibility.
Implementation Method 1
contactless power transmission by inductive resonance coupling
Implementation Method 2
resonant inductive coupling for charging or recharging a motor vehicle
Implementation Method 3
magnetically coupled remote electrical circuits tuned to the same frequency. The magnetically coupled circuits each comprise at least one resonant LC element
Data Source
Figure 1~2
Figure 3~4
Figure 5~7
AI summary
The invention relates to a transmitting or receiving resonant circuit (2) for transmitting power contactlessly through inductive resonant coupling with a transmitting receiving resonant circuit (1), having a first capacitance (C1) and a first winding (E1), the first winding (E1) having an inductance (L1) and a first resistance (R1), the transmitting resonant circuit (2) having a second capacitance (C2) of value C2' and a second winding (E2), the second winding (E2) having a second inductance (L2) of value L2', a second resistance (R2) of value R2', the transmitting resonant circuit (2) having an eigenpulse u>2 such that w2 = 1/V (L2' x C2') and an eigenfrequency f2 such that f2 = w2/(2-rr), characterised in that the inductance value of the second inductance (L2) varies in a predetermined manner.