On-Board Charger Current Control for Battery Heating and Charging
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Solution Overview
Problem
In-vehicle charging devices face challenges in charging batteries at high power without causing an overcurrent state, especially when simultaneously adjusting battery temperature, due to varying current limits and load variations in battery temperature adjustment devices.
Innovation Solution
An in-vehicle charging device and method that control the output current of the charging circuit to match the total allowable value of the battery's charging current and the current consumption of the battery temperature adjustment device, identified using battery and heater characteristic information, ensuring safe and efficient high-power charging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If charging is executed at high power while simultaneously adjusting battery temperature, then charging time is reduced, but overcurrent state occurs in the battery causing deterioration and damage
Solution Approach 1:
The charging current is dynamically adjusted based on real-time temperature measurements. As the battery temperature increases during charging, the system automatically reduces the charging current to prevent overcurrent damage, while still maintaining efficient charging overall. This dynamic control allows the system to operate at high power when safe and reduce power when temperature thresholds are approached.
Solution Approach 2:
The system continuously monitors battery temperature and uses this feedback to control the charging current. Temperature sensors provide real-time data to the control unit, which then adjusts the charging power accordingly. This closed-loop feedback mechanism ensures that high-power charging is maintained only when temperature conditions permit, preventing overcurrent states while maximizing charging efficiency.
2Productivity
If charging current is increased to maximize charging speed, then charging efficiency improves, but the allowable current limit varies with battery temperature and charging rate making control difficult
Solution Approach 1:
The system pre-establishes temperature thresholds and corresponding charging current limits based on battery characteristics. Before actual charging begins, the control unit is configured with knowledge of how current limits vary with temperature and charging rate. This preliminary preparation simplifies real-time control by providing predetermined guidelines for current adjustment based on temperature measurements.
Solution Approach 2:
The system changes the charging current parameter based on temperature parameter changes. As temperature increases, the allowable current parameter is automatically adjusted downward according to pre-determined relationships. This parameter-based control approach simplifies the complexity by using temperature as the primary control variable rather than attempting to directly manage the complex interrelationships between current, temperature, and charging rate.
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 high-power battery charging without generating an overcurrent state, thereby preventing battery deterioration and damage, while optimizing charging time.
Implementation Method 1
supplying power to a battery temperature adjustment device (e.g., a resistive heater, or PTC heater or the like) as well, after raising the temperature of the battery or while raising the temperature of the battery
Data Source
AI summary
Provided is a vehicle-mounted charging device in which a charging circuit subjects power supplied from an external power supply to power conversion and supplies power to a battery and a PTC heater in parallel. The vehicle-mounted charging device is provided with a control device which, when temperature adjustment of the battery by the PTC heater and charging of the battery are carried out at the same time, controls an output current of the charging circuit so as to approach a total value of an allowable value of charging current for the battery and a current consumption of the PTC heater at each time point during charging. The allowable value of charging current for the battery and the current consumption of the PTC heater are specified on the basis of battery characteristic information of the battery and heater characteristic information of the PTC heater which are stored in advance.