Wireless EV Charger Reactive Power Control
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Solution Overview
Problem
Wired charging solutions for electric vehicles are inconvenient and prone to mechanical wear, safety hazards, and vandalism, while existing wireless charging technologies face inefficiencies due to variations in coupling and alignment.
Innovation Solution
A wireless power transfer system using a transmitter with an inverter and controller to adjust the load angle and reactive power, ensuring constant output power by measuring and comparing the load angle to a reference, and adjusting the inverter's operating characteristics to maintain efficient energy transfer via a magnetic field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wired charging connections are used, then power transfer reliability is improved, but ease of operation deteriorates due to cable inconvenience and mechanical wear
Solution Approach 1:
The patent replaces the mechanical cable connection system with a wireless electromagnetic field-based power transfer system. The transmitter generates a magnetic field that inductively couples with the receiver coil to transfer power without physical contact, eliminating mechanical wear and improving ease of operation while maintaining power transfer reliability through controlled electromagnetic coupling.
Solution Approach 2:
The patent introduces a magnetic field as an intermediary medium between the power source and the load. The transmitter converts electrical energy to a magnetic field, which then inductively couples with the receiver to transfer power. This intermediary field-based approach eliminates the need for direct mechanical cable connections while ensuring reliable power transfer.
2Ease of operation
If wireless power transfer is used, then ease of operation is improved, but power transfer efficiency deteriorates due to coupling variations and alignment sensitivity
Solution Approach 1:
The patent employs dynamic control of the transmitter's output power based on real-time monitoring of the magnetic coupling conditions. The controller adjusts the inverter duty cycle and switching frequency dynamically to optimize power transfer efficiency as coupling conditions change, thereby reducing energy losses while maintaining ease of operation.
Solution Approach 2:
The patent implements a feedback control system that monitors the magnetic coupling between transmitter and receiver, and adjusts the transmitter output accordingly. The controller receives feedback about coupling conditions and modifies the inverter operation to maintain optimal power transfer efficiency, compensating for variations in alignment and coupling strength.
3Loss of energy
If inverter duty cycle is increased to compensate for coupling losses, then power transfer efficiency is improved, but reactive power injection increases causing grid instability
Solution Approach 1:
The patent changes the operating parameters of the inverter, specifically adjusting the switching frequency in addition to the duty cycle. By modifying the switching frequency, the system can achieve the desired power transfer efficiency while controlling the reactive power injection, thus maintaining grid stability without sacrificing efficiency.
Solution Approach 2:
The patent dynamically adjusts both the duty cycle and switching frequency of the inverter based on real-time operating conditions. This dynamic parameter adjustment allows the system to optimize power transfer efficiency while simultaneously managing reactive power injection to prevent grid instability, adapting to changing load and coupling conditions.
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 provides efficient, safe, and convenient wireless charging with reduced mechanical wear and increased reliability, allowing for Vehicle-to-Grid operations by stabilizing the power distribution grid.
Implementation Method 1
a transmitter configured to provide wireless power via a magnetic field sufficient to power or charge a load
Data Source
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AI summary
Systems, methods, and apparatus are disclosed for wirelessly charging an electric vehicle. In one aspect, a method for transferring power via a magnetic field in a wireless power transfer system is provided. The method includes outputting an alternating electric current to a wireless power transmitter, generating, at the wireless power transmitter, the magnetic field in response to being driven with the alternating electrical current, receiving a value indicative of an electrical characteristic of the wireless power transmitter, and adjusting an operating characteristic of the wireless power transmitter to trigger a change in an electrical current in the receiver, the amount of adjustment selected to cause adjustment of an amount of reactive power in the wireless power transfer system based on changes in the receiver that automatically occur to maintain the output power substantially constant in response to the change in the electrical current in the receiver.