Polyphase Inductive Power Transfer System Phase Control
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Solution Overview
Problem
Existing IPT systems are inefficient and costly due to the need for multiple dedicated systems for selective charging and discharging of electric vehicles, with high ripple currents and standby losses, and lack flexibility and control in polyphase applications.
Innovation Solution
A polyphase IPT system with individually operable primary and pick-up conductors, allowing selective energization of primary conductors only when needed, and using phase control to minimize peak currents and improve magnetic coupling, enabling efficient bi-directional power transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple dedicated IPT systems are used for selective charging and discharging of EVs, then reliability and safety are improved, but cost and device complexity increase significantly
Solution Approach 1:
The primary winding is divided into multiple independently controllable phases (e.g., three phases), each capable of being selectively energized. This segmentation allows the system to activate only the necessary phases for each charging/discharging operation, providing dedicated control for multiple EVs without requiring multiple complete IPT systems, thus improving reliability while reducing overall device complexity and cost.
2Reliability
If primary windings are continuously energized to enable selective charging, then readiness and reliability are improved, but energy loss and efficiency deteriorate due to standby losses
Solution Approach 1:
The system employs periodic or on-demand energization of primary windings based on detection of EV presence and charging/discharging requirements. Instead of continuous energization, phases are activated periodically or as needed, significantly reducing standby energy losses while maintaining system readiness through rapid response capability when vehicles are detected.
3Device complexity
If single-phase IPT systems are used for multiple EVs, then cost is reduced, but efficiency and ripple current performance deteriorate
Solution Approach 1:
The system transitions from single-phase to polyphase (e.g., three-phase) configuration, changing the electrical parameters of the IPT system. This parameter change fundamentally alters the current waveform characteristics, reducing ripple currents and improving efficiency while maintaining cost-effectiveness through shared infrastructure. The polyphase operation provides smoother power transfer and reduced electromagnetic interference compared to single-phase systems.
4Loss of energy
If polyphase IPT systems are implemented, then efficiency and ripple current reduction are improved, but control complexity and device complexity increase
Solution Approach 1:
The polyphase IPT system is designed with multi-functional capability to handle various operating modes: charging multiple EVs simultaneously, discharging multiple EVs, bidirectional power flow, and selective phase activation. This universal design consolidates multiple functions into a single system framework, reducing overall control complexity compared to implementing separate dedicated systems for each function while maintaining high efficiency and reduced ripple currents.
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 reduced ripple currents, improved efficiency, and cost-effectiveness by allowing individual control of primary windings and minimizing peak currents, making it suitable for high-power applications like EV charging.
Implementation Method 1
a primary power supply comprising a plurality of primary conductors, the primary conductors being individually selectively operable to provide or receive a magnetic field for inductive power transfer
Implementation Method 2
at least one pick-up comprising one or more pick-up conductors, the one or more pick-up conductors each being individually selectively operable to magnetically couple with a primary conductor to control power transfer between the primary power supply and a load
Data Source
AI summary
The present invention provides a polyphase inductive power transfer (IPT) system comprising a primary power supply comprising a plurality of primary conductors, the primary conductors being individually selectively operable to provide or receive a magnetic field for inductive power transfer; and at least one pick-up comprising one or more pick-up conductors, the one or more pick-up conductors each being individually selectively operable to magnetically couple with a primary conductor to control power transfer between the primary power supply and a load coupled or coupleable with the respective pick-up. The polyphase primary power supply may be used to power a plurality of single-phase pick-ups, one or more polyphase pick-ups, or a combination thereof. Also disclosed are polyphase primary and secondary converters for use in such a system.