Inductive Power Transmitter Tuning for K-Coefficient Compensation
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Solution Overview
Problem
High-power inductive power transfer systems face challenges with heat dissipation and power efficiency, particularly in applications like wireless charging of electric vehicles, where existing techniques struggle to adequately address these issues.
Innovation Solution
The design incorporates a tuned circuit with a plurality of components, including a transmitting coil, inductors, capacitors, and additional components arranged to remodel the circuit as series tuned, allowing for independent control of inverter sub-circuit output current and transmitting coil current, reducing power loss and improving power factor and EMI performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high-power inductive power transfer is implemented, then power delivery capability is improved, but heat dissipation and power efficiency deteriorate
Solution Approach 1:
The patent segments the current path by introducing a parallel resonant circuit with additional inductor and capacitor components. This creates separate current pathways: one through the transmitting coil and another through the parallel resonant circuit, allowing the inverter sub-circuit current to be less than the transmitting coil current and reducing power loss in the inverter
Solution Approach 2:
The patent changes the circuit configuration parameters by adding reactive components (inductor and capacitor) to create a parallel resonant circuit. This transforms the circuit from a simple series configuration to a more complex parallel resonance configuration, enabling independent control of inverter output current and transmitting coil current, thereby improving power efficiency
2Device complexity
If simple tuned circuit is used, then device complexity is reduced, but ability to compensate for K coefficient variations deteriorates
Solution Approach 1:
The patent divides the tuning function into two separate networks: a first tuning network (series LC circuit) and a second tuning network (parallel resonant circuit with additional inductor and capacitor). This segmentation allows each network to perform specific functions - the first for basic resonance and the second for current compensation and power factor improvement
Solution Approach 2:
The parallel resonant circuit serves multiple functions simultaneously: it provides current compensation for K coefficient variations, improves power factor, reduces EMI, and enables independent control of inverter and coil currents. This multi-functionality achieves reliable compensation without proportionally increasing complexity
3Loss of energy
If inverter output current is made independent of transmitting coil current, then power loss in inverter is reduced, but device complexity increases
Solution Approach 1:
The patent segments the current pathways by introducing a parallel resonant circuit, creating distinct current loops. The inverter sub-circuit connects to the first tuning network which then connects to the transmitting coil through the parallel resonant circuit, allowing independent current control in each segment
Solution Approach 2:
The parallel resonant circuit acts as an intermediary between the inverter sub-circuit and the transmitting coil. It mediates the current relationship by providing an additional current path, allowing the inverter to operate at lower current while still delivering sufficient power to the coil through the resonant circuit's current amplification effect
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 enables efficient power transfer with reduced inverter sub-circuit power loss and improved EMI performance, effectively compensating for variations in the magnetic coupling coefficient and maintaining constant power delivery to the load.
Implementation Method 1
The system uses a magnetic field to transfer electrical power wirelessly from the primary coil to a secondary coil. The magnetic field is created by inputting an AC current at the primary coil.
Implementation Method 2
a first tuning network comprising: an inductor, and a capacitor... arranged such that the tuned circuit can: vary current through the transmitting coil to compensate for variations in K coefficient
Implementation Method 3
A typical inductive power transfer transmitter is driven by an electric power source, and comprises an inverter, a primary tuning network, and a primary coil... generates an electromagnetic field, and which is used to transfer electric power across space
Data Source
AI summary
An inductive power transfer transmitter comprising: an inverter sub-circuit comprising at least one inverter, and a tuned circuit comprising a plurality of components including at least: a transmitting coil; a first tuning network comprising: an inductor, and a capacitor; a second tuning network comprising a first additional component wherein the plurality of components are arranged such that the tuned circuit can: vary current through the transmitting coil to compensate for variations in K coefficient, provide an output current from the inverter sub-circuit independent of a transmitting coil current.