EV Charging Control Device Maintaining Constant Load Resistance
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Solution Overview
Problem
Existing wireless power transmission systems for electric vehicles face inefficiencies in charging due to varying load resistance and state of charge (SOC) of the battery, leading to reduced power transmission efficiency when switching between constant current and constant voltage control modes.
Innovation Solution
An electric vehicle charging system that includes a control device with a battery voltage detecting unit and a charging current value setting unit, which adjusts the charging current to maintain a constant load resistance during charging, switching to constant-power mode when the SOC or battery voltage is below a threshold, ensuring high efficiency throughout the charging process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If constant voltage control is used to charge the battery, then the battery voltage is maintained at a stable level, but the charging power is reduced leading to lower power transmission efficiency
Solution Approach 1:
The patent applies dynamics by switching from static constant voltage control to dynamic constant resistance control. The charging current is continuously adjusted based on real-time battery voltage feedback to maintain constant resistance, enabling the system to adapt to changing battery conditions while maintaining high power transmission efficiency throughout the charging process
Solution Approach 2:
The patent changes the control parameter from voltage (constant voltage mode) to resistance (constant resistance mode). By controlling the charging current to maintain constant resistance rather than constant voltage, the system achieves both high power transmission efficiency and appropriate charging rates across different battery states
2Power
If constant current control is used to charge the battery, then the charging power is maintained at high levels, but the battery voltage becomes unstable and may lead to overcharging
Solution Approach 1:
The patent implements feedback control by continuously monitoring battery voltage and adjusting the charging current accordingly. The control device uses the detected battery voltage to calculate the required charging current that maintains constant resistance, ensuring both high charging power and voltage stability through closed-loop control
Solution Approach 2:
The system transitions from static constant current control to dynamic constant resistance control. The charging current is continuously adjusted based on real-time battery voltage feedback, allowing the system to maintain high power while adapting to changing battery conditions and preventing overcharging
3Loss of time
If the charging current is increased to charge the battery faster, then the charging time is reduced, but the load resistance decreases leading to lower power transmission efficiency
Solution Approach 1:
The patent changes the control approach from fixed current or voltage to dynamic resistance-based control. By maintaining constant resistance through continuous adjustment of charging current based on battery voltage, the system optimizes the balance between charging speed and power transmission efficiency
Solution Approach 2:
The system uses dynamic control where the charging current is continuously adjusted to maintain constant resistance. This allows the charging rate to adapt to battery conditions, achieving fast charging when appropriate while maintaining high efficiency, rather than using fixed high current that would reduce efficiency
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 maintains high charging efficiency by keeping the load resistance constant, preventing efficiency drops and extending battery life, while also allowing for user-controlled or automated switching between charging modes based on battery state.
Implementation Method 1
a reception coil configured to receive, by wireless power transmission, AC power transmitted from an electrical transmission circuit outside of the vehicle
Implementation Method 2
The battery is charged with power obtained by rectifying the AC power received by the reception coil
Data Source
AI summary
An electric vehicle includes a charging circuit and a control device. The control device is configured to set a charging current value by increasing the charging current value over time while a voltage of a battery of the charging circuit increases so that a load resistance value of the charging circuit is constant in a constant-resistance charging mode, at the time of continuing charging of the battery. The control device is configured to initiate the constant-resistance charging mode based on a determination by the control device that an SOC of the battery or the voltage of the battery is at or above a predetermined threshold value, or based on an input from a user. The control device is configured to initiate a constant-power control charging mode in which charging power of the charging circuit is constant.