Inverter Control for Contactless EV Charging
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Solution Overview
Problem
Contactless battery charging systems for electric or hybrid vehicles face inefficiencies due to the need for precise positioning and the risk of current saturation when charging high voltage batteries, which can lead to power supply faults.
Innovation Solution
A method for controlling the inverter in a contactless charging system using closed-loop regulation of the supply current and voltage, with setpoints for maximum current and power, and adaptive pulse width modulation to maintain efficient power transfer while avoiding saturation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the inverter is controlled at resonant frequency to maximize efficiency and positioning tolerance, then charging efficiency is improved, but current saturation occurs causing power supply faults
Solution Approach 1:
The patent applies dynamics by making the inverter switching frequency variable rather than fixed at resonant frequency. The control system dynamically adjusts the switching frequency based on real-time monitoring of current levels, allowing the system to operate near resonance for high efficiency while preventing current saturation that would cause power supply faults.
Solution Approach 2:
The patent implements feedback control by continuously monitoring the current drawn from the power supply and using this information to adjust the inverter switching frequency. This closed-loop control ensures the system operates at optimal efficiency points while preventing current saturation, thus maintaining power supply reliability.
2Loss of energy
If precise positioning is required for contactless charging, then coupling efficiency is improved, but system complexity and positioning tolerance increase
Solution Approach 1:
The patent changes the operating parameter (switching frequency) to compensate for positioning variations. By adjusting the frequency dynamically, the system maintains optimal coupling efficiency even when positioning is not perfectly precise, thereby reducing the complexity requirements of the positioning system.
3Power
If high current is drawn to charge high voltage batteries, then charging power is improved, but current saturation occurs leading to fault mode
Solution Approach 1:
The system dynamically adjusts the switching frequency based on load conditions and current levels. This allows the system to deliver high charging power when needed while automatically reducing current draw when approaching saturation limits, maintaining power supply reliability throughout the charging process.
Solution Approach 2:
The control system uses feedback from current sensors to monitor power supply load and adjusts operating parameters accordingly. This ensures high charging power delivery while preventing current saturation that would trigger fault modes, thus maintaining system reliability.
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
Enables fine control of power injection, maximizing efficiency and tolerance to positioning variations, and prevents current saturation by dynamically adjusting the duty cycle and phase of control signals, ensuring reliable charging.
Implementation Method 1
an inverter supplied by an inverter power generator connected to the sector and, on the other hand, arranged in the vehicle, an energy receiving terminal, intended to be placed above the inductor, so as to allow a transfer of energy by inductive coupling
Implementation Method 2
controlling the inverter bridge of the power generator at a frequency substantially equal to the value of the resonant frequency of the load formed by the inductor and the receiving terminal, regardless of the positioning of the vehicle relative to the energy emitting terminal. Resonance increases efficiency by concentrating the magnetic field on the receiving terminal.
Data Source
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AI summary
The invention relates to a method for controlling the charging of a battery of an electric drive motor vehicle or a hybrid motor vehicle, in a non-contact charging system wherein a power generator (10) comprising a direct current source (11) followed by an inverter (12) feeds a load comprising an inductor (ID1) arranged in series with the inverter, said method comprising a step of controlling said inverter (12) at a working frequency (f) slaved to the load resonance frequency by the transmission of first and second pulse-width modulation command signals respectively to first and second switching arms of said inverter, characterised in that a closed-loop regulation is performed on the intensity of the supply current of said inverter, a supply current set value being defined according to the maximum current (Imax_dc) that can be supplied by said direct current source.