Polyphase Coil Assembly With Resonant Balancing for EV Charging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Polyphase wireless power transfer systems face limitations in power transfer capability due to non-zero interphase mutual-inductance and unbalanced phases, which restricts high-power charging for electric vehicles and requires improvements in power density and specific power.
Innovation Solution
A three-phase inductive power transfer system with independent bipolar or unipolar phases, featuring a coil assembly with coils of opposite polarities on different layers and a compensating network that allows for balanced self and mutual inductance, along with a controller that adjusts switching pairs based on receiver type and alignment for optimized power transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single phase coil system is used for wireless power transfer, then the system design is simpler, but power transfer capability is limited by electromagnetic field emissions requirements and foreign object heating limits
Solution Approach 1:
The patent divides the single-phase system into multiple independent phases (three-phase system). Each phase has its own coil assembly with separate control, allowing power to be distributed across multiple channels. This segmentation enables higher total power transfer while maintaining simpler individual phase designs that meet emissions and safety limits.
2Power
If polyphase wireless transfer systems are designed to increase power transfer for electric vehicles, then power transfer capability increases, but non-zero interphase mutual-inductance causes unbalance between phases which compromises power transfer capability
Solution Approach 1:
The patent applies different compensation characteristics to different phases based on their specific needs. Each phase can have independently tuned compensation networks that account for local variations in mutual inductance and coupling conditions. This localized optimization ensures each phase operates at its optimal performance point despite variations in the polyphase system.
Solution Approach 2:
The patent adjusts key parameters including compensating capacitance values, switching frequencies, and coil configurations for each phase to achieve balanced operation. By dynamically tuning these parameters, the system compensates for non-zero mutual inductance effects and maintains phase balance, enabling reliable high-power transfer.
3Productivity
If there is non-zero interphase mutual-inductance in polyphase systems, then phase coupling occurs, but unbalance between phases reduces power transfer capability
Solution Approach 1:
The patent incorporates control systems that monitor phase balance and mutual inductance effects in real-time. Based on feedback signals, the controller adjusts switching patterns and compensation parameters to maintain balanced operation. This closed-loop control ensures high power transfer efficiency while compensating for mutual inductance-induced imbalances.
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 achieves balanced inductance and efficient power transfer, enabling higher power density and specific power, and is compatible with various receivers, enhancing charging speed and efficiency while meeting electromagnetic field emission and safety standards.
Implementation Method 1
Single phase designs work by pulsing the flux produced by the primary coil with time. Part of this time-varying flux couples with the secondary coil and induces a voltage.
Implementation Method 2
The coil assembly may comprise one or more layers of coils stacked on a ferrite.
Implementation Method 3
The compensating network may have an LCC configuration. The value of the compensating capacitance determined, for each phase, such that the receiver has at least two independently excitable resonant modes at the resonant frequency.
Data Source
Figure 1
Figure 2A~3B
Figure 4A~4B
AI summary
Polyphase wireless power transfer systems are provided. The transfer system may be used for charging hybrid and electric vehicles. The systems are capable of transferring over 50KW over an air gap of 15 cm. The systems use a rotating magnetic field to transfer power. The system may comprise transmitter coil assembly. The coil assembly may be one or more layers. The system may employ either unipolar or bipolar coils. The transmitter also comprises compensating capacitance connected in series with at least one coil for each phase. A value of the compensating capacitance for each phase is determined such that the transmitter has at least two independently excitable resonant modes at a resonant frequency. The transmitter is compatible with a plurality of different receivers including three-phase, single phase with a circular coil and single phase with DD coils.