Wireless Power Transfer Frequency and Duty Ratio Control
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Solution Overview
Problem
Wireless power transfer for plug-in electric vehicles faces challenges in interoperability, safety, and bidirectional communications, particularly in maximizing power transfer efficiency and ensuring the integrity and economical charging of regenerative energy storage systems.
Innovation Solution
A system that monitors the state of charge and temperature of the regenerative energy storage system to calculate an optimal frequency for the grid converter, adjusting the duty ratio to optimize power transfer, and employs bidirectional communication for safe and efficient charging, using a primary and secondary coil configuration with a battery management system and vehicle-side communication for effective power management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the grid converter operates at nominal frequency and fixed duty ratio, then the system operation is simple, but the power transfer efficiency is not maximized and RESS pack integrity cannot be ensured
Solution Approach 1:
The patent implements dynamic adjustment of the grid converter's operating frequency and duty ratio based on real-time monitoring of RESS pack state of charge and temperature. The frequency is dynamically tuned to cancel the imaginary component of input impedance, while the duty ratio is dynamically adjusted according to charge rate requirements, transforming a static system into an adaptive one that maximizes efficiency under varying conditions.
Solution Approach 2:
The system employs feedback control by continuously monitoring the RESS pack's state of charge and temperature, then using this information to adjust the grid converter's frequency and duty ratio. This closed-loop control ensures that power transfer efficiency is optimized while preventing overheating and preserving battery integrity through real-time parameter adjustment.
2Productivity
If the power transfer rate is increased to reduce charging time, then the productivity improves, but the RESS pack temperature increases and integrity is compromised
Solution Approach 1:
The patent changes operating parameters (frequency and duty ratio) based on RESS pack temperature and state of charge. When the battery approaches full charge or temperature increases, the duty ratio is reduced to lower the power transfer rate, preventing thermal runaway and preserving battery integrity while still achieving efficient charging during appropriate conditions.
Solution Approach 2:
The system dynamically adjusts the power transfer rate by modulating the grid converter's duty ratio in response to real-time battery conditions. This dynamic control allows the system to operate at high power levels when safe and efficient, then automatically reduce power when temperature or charge level thresholds are approached, balancing speed and safety.
3Productivity
If the grid converter duty ratio is increased to maximize power transfer, then the productivity improves, but the RESS pack may overheat and safety is compromised
Solution Approach 1:
The system uses feedback from temperature sensors and state of charge monitoring to control the grid converter's duty ratio. When temperature rises or charge level increases, the feedback loop automatically reduces the duty ratio to prevent overheating, ensuring safe operation while maintaining maximum efficient power transfer under normal conditions.
Solution Approach 2:
The system implements preventive control by monitoring battery temperature and state of charge before dangerous conditions occur. By anticipating thermal buildup and adjusting the duty ratio in advance, the system prevents overheating rather than reacting to it, ensuring safety margins are maintained throughout the charging process.
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 maximizes power transfer efficiency, ensures safety, and provides economical charging by optimizing the power transfer rate and integrity of the regenerative energy storage system, while addressing interoperability and bidirectional communication needs.
Implementation Method 1
a primary circuit including a grid converter and a primary coil located in a primary pad... A vehicle is provided, which includes a secondary circuit that includes a secondary coil
Implementation Method 2
an optimal frequency that cancels the imaginary component of the input impedance for the output signal from a grid converter is calculated from the load of the RESS pack, and a frequency offset f* is made to the nominal frequency f0 of the grid converter output based on the resonance frequency of a magnetically coupled circuit
Data Source
AI summary
Power transfer rate at a charging facility can be maximized by employing a feedback scheme. The state of charge (SOC) and temperature of the regenerative energy storage system (RESS) pack of a vehicle is monitored to determine the load due to the RESS pack. An optimal frequency that cancels the imaginary component of the input impedance for the output signal from a grid converter is calculated from the load of the RESS pack, and a frequency offset f* is made to the nominal frequency f0 of the grid converter output based on the resonance frequency of a magnetically coupled circuit. The optimal frequency can maximize the efficiency of the power transfer. Further, an optimal grid converter duty ratio d* can be derived from the charge rate of the RESS pack. The grid converter duty ratio d* regulates wireless power transfer (WPT) power level.