Bridgeless Rectifier Resonance Frequency Control for EV Wireless Charging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Wireless power transfer systems for electric vehicles face inefficiencies due to resonance frequency fluctuations caused by changes in the alignment and coupling coefficients between the transmission and reception pads, leading to ineffective power transfer and increased phase differences.
Innovation Solution
A method and apparatus using a bridgeless rectifier to detect phase differences and predict resonance frequency changes, controlling switching time points and duty to compensate for these fluctuations by setting target resonance frequencies based on minimum, maximum, or median coupling coefficients, ensuring efficient power transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the WPT system is operated at the transmission-side resonance frequency, then power transfer can be maintained, but power transfer becomes ineffective when resonance frequency changes due to positional variation
Solution Approach 1:
The patent implements dynamic resonance frequency tracking by continuously monitoring the phase difference between transmission and reception sides, and adjusting the switching duty cycle of the bridgeless rectifier in real-time to maintain optimal power transfer conditions despite positional variations
Solution Approach 2:
The system uses phase difference detection as a feedback mechanism to sense resonance frequency deviations, then adjusts the rectifier switching parameters accordingly to compensate for changes in coupling coefficient and inductance caused by EV positional variations
2Reliability
If the WPT system is operated at the reception-side resonance frequency, then power transfer can continue, but a phase difference between input voltage and current increases, causing rated output to increase
Solution Approach 1:
The patent changes the operating parameters of the bridgeless rectifier (switching duty cycle and switching frequency) to optimize the phase difference between voltage and current, thereby controlling the rated output power while maintaining continuous power transfer at reception-side resonance frequency
3Productivity
If the switching frequency is increased to compensate for resonance frequency changes, then power transfer efficiency improves, but device complexity and control difficulty increase
Solution Approach 1:
The patent pre-configures the bridgeless rectifier with predetermined switching duty cycles corresponding to different resonance frequency conditions, allowing the system to quickly adapt to frequency changes without complex real-time calculations, thus improving efficiency while limiting control complexity
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 improves charging efficiency by synchronizing transmission-side and reception-side resonance frequencies, reducing control complexity, and effectively compensating for resonance frequency variations, even under large changes.
Implementation Method 1
a reception coil in a vehicle assembly (VA) mounted in the EV forms an inductive resonant coupling with a transmission coil in a group assembly (GA) located in a charging station or a charging spot. Electric power is then transferred from the GA to the VA to charge the high-voltage battery of the EV through the inductive resonant coupling.
Implementation Method 2
a method and an apparatus for controlling wireless power transfer to an electric vehicle, and more specifically, to a method and an apparatus for compensating for resonance frequency fluctuations occurring in an alignment process for electric vehicle charging by controlling a switching duty and a switching time point of a bridgeless rectifier.
Data Source
AI summary
A method for controlling wireless power transfer to an EV using a bridgeless rectifier may include detecting a phase difference between an input voltage of a transmission-side resonance circuit and an output voltage of a reception-side resonance circuit; after detecting the phase difference, predicting a resonance frequency change direction according to a preconfigured design condition; and controlling switching time points of switches included in the bridgeless rectifier in a direction compensating for the predicted change direction.