EV Charging Device Using DC/DC Boost Converter for Voltage Matching
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Solution Overview
Problem
High-voltage electric vehicles with batteries exceeding the charging station's voltage cannot be reliably charged due to asymmetry and incorrect insulation resistance calculations by ISO guards, leading to premature charging interruptions.
Innovation Solution
A method and charging device that utilize a DC/DC boost converter to match the charging station's voltage with the vehicle's battery voltage, combined with current draining to establish PE symmetry, ensuring safe and efficient charging by controlling the voltage and current through an electronic control unit and insulation monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a DC/DC boost converter is used to convert charging station voltage to match battery voltage, then the electric vehicle can be charged at charging stations with lower voltage, but an asymmetry and shift of electrical potential occurs between the high-voltage side and protective earth, causing the insulation voltage range to be exceeded and the ISO guard to calculate wrong insulation resistance
Solution Approach 1:
The method performs preliminary actions by actively balancing the electrical potential between the high-voltage side and protective earth before charging begins. The control unit monitors potential differences and adjusts the connection state of switching elements to equalize potentials, preventing asymmetry from developing during charging operation.
Solution Approach 2:
The patent introduces switching elements (transistors or thyristors) as intermediary components between the high-voltage side and protective earth. These switching elements act as controllable intermediaries that can be selectively connected or disconnected to balance electrical potential and maintain symmetry in the charging circuit.
2Reliability
If the ISO guard monitors insulation resistance between protective earth and high-voltage side, then safety is ensured, but the asymmetry caused by DC/DC conversion is interpreted as faulty insulation resistance, causing the charging process to be interrupted
Solution Approach 1:
The system performs preliminary potential balancing before charging starts, ensuring that the electrical potential between high-voltage sides and protective earth is equalized. This preliminary action prevents the ISO guard from detecting false insulation faults during normal charging operation.
Solution Approach 2:
The patent implements equipotentiality by actively maintaining equal electrical potential between the high-voltage side of the charging station and the high-voltage side of the battery. By using switching elements to balance potentials, the system ensures that the potential difference remains within valid ranges, preventing false insulation resistance readings.
3Adaptability or versatility
If charging voltage is lower than nominal battery voltage, then charging at more charging stations becomes possible, but the voltage asymmetry exceeds the valid range of insulation voltage and causes incorrect insulation resistance calculation
Solution Approach 1:
The system maintains equipotential conditions by actively balancing the electrical potential between high-voltage sides using controllable switching elements. This ensures that voltage asymmetry remains within valid measurement ranges, allowing the ISO guard to accurately measure insulation resistance even when charging from a lower voltage station.
Solution Approach 2:
The patent dynamically changes the state parameters of switching elements (connected or disconnected) based on monitored potential differences. By adjusting these parameter states, the system maintains optimal electrical conditions for both charging operation and insulation monitoring accuracy.
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
Facilitates reliable, safe, and efficient charging of high-voltage batteries at charging stations with lower voltages, increasing the compatibility of electric vehicles with various charging stations by preventing incorrect insulation resistance interpretations and ensuring continuous charging operations.
Implementation Method 1
it is also common to use a DC/DC boost converter to convert the voltage provided by the charging station to match with the nominal voltage of the high-voltage battery
Implementation Method 2
draining current between the first battery terminal and the protective earth terminal such that the DC voltage between the first battery terminal and the protective earth terminal essentially matches with the DC voltage between the first charging terminal and the protective earth terminal
Data Source
AI summary
A method for charging a high-voltage battery of an electric vehicle, comprising: providing the high-voltage battery having a nominal battery voltage; providing a charging station outputting a DC charging voltage less than the nominal battery voltage; draining current between a first battery terminal and a protective earth terminal such that the voltage between the first battery terminal and the protective earth terminal essentially matches with the voltage between a first charging terminal and the protective earth terminal, and boosting the voltage at a second charging terminal of the charging station to match the charging voltage with the nominal battery voltage.