Propulsion Battery Charging Logic for EV Maintenance Battery Reliability
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Solution Overview
Problem
Maintenance battery packs in electric vehicles are often over-dimensioned to handle long periods without charging, leading to potential discharging issues that can prevent vehicle startup, even with sufficient energy in the propulsion battery pack, resulting in larger and heavier battery packs that negatively affect vehicle load capacity.
Innovation Solution
A method for charging maintenance battery packs involves continually measuring battery voltage, current, and temperature, calculating State Of Charge (SOC) and State Of Health (SOH), and using predetermined threshold values to initiate and terminate charging, ensuring the maintenance battery pack is not excessively discharged and that the propulsion battery pack remains sufficient for vehicle operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the maintenance battery pack is over-dimensioned to handle long periods without charging, then the reliability of vehicle startup is improved, but the weight of the battery pack increases
Solution Approach 1:
The propulsion battery pack serves a dual function: it provides energy for vehicle propulsion and simultaneously charges the maintenance battery pack during vehicle operation. This self-service approach eliminates the need for external charging infrastructure and allows the maintenance battery to be smaller since it only needs to bridge short periods between propulsion battery availability and vehicle startup, not long stationary periods.
Solution Approach 2:
The propulsion battery pack performs multiple functions: it acts as both the primary propulsion energy source and as a charging source for the maintenance battery pack. By making the propulsion battery multi-functional, the system eliminates the need for separate charging equipment and reduces the maintenance battery capacity requirements, thereby reducing weight while maintaining startup reliability.
2Reliability
If the maintenance battery pack is over-dimensioned to ensure sufficient energy availability, then the reliability of vehicle operation is improved, but the load capacity of the vehicle decreases
Solution Approach 1:
The propulsion battery pack automatically charges the maintenance battery pack during vehicle operation without requiring external charging infrastructure. This self-service mechanism ensures the maintenance battery is replenished regularly, allowing it to be smaller in capacity while still maintaining sufficient energy for vehicle startup and operation reliability.
Solution Approach 2:
The maintenance battery pack is charged in advance during vehicle operation before the vehicle is parked or the propulsion battery is deactivated. This preliminary charging action ensures the maintenance battery has sufficient energy ready for vehicle startup, allowing it to be smaller in capacity while maintaining operational reliability.
3Duration of action of moving object
If the maintenance battery pack is sized for long periods without charging, then the duration of vehicle inactivity without startup failure is improved, but the weight of the battery system increases
Solution Approach 1:
The propulsion battery pack automatically recharges the maintenance battery pack during each vehicle operation cycle. This self-service charging eliminates the need for the maintenance battery to store energy for extended stationary periods, allowing both batteries to be optimized to smaller, lighter capacities while maintaining the ability to handle reasonable periods of vehicle inactivity.
Solution Approach 2:
The maintenance battery pack is charged periodically during each vehicle operation cycle rather than requiring a single large capacity to cover extended stationary periods. This periodic recharging allows the maintenance battery to be smaller and lighter, as it only needs to bridge the period between the last propulsion battery operation and the next expected startup.
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 solution minimizes the risk of discharging the maintenance battery pack, allowing for a reduction in battery pack size and weight, thereby enhancing vehicle load capacity and ensuring reliable vehicle startup even when inactive for extended periods.
Implementation Method 1
The electric machine unit is arranged to activate the battery handling unit for the propulsion battery pack to charge the maintenance battery pack
Data Source
AI summary
The application relates to charging a maintenance battery pack of a vehicle, which also comprises a propulsion battery pack, comprising, when the vehicle is inactive: providing a predetermined threshold SOC/SOH1Threshold value when charging is activated and a predetermined threshold SOH2Threshold value when charging is terminated; continually measuring maintenance battery pack voltage, current, and temperature; calculating State Of Charge SOC, as number of ampere hours possible to discharge before the maintenance battery pack is discharged; calculating State of Health SOH, as number of ampere hours possible to discharge if the maintenance battery pack was fully charged; calculating a battery charge quota SOC/SOH; comparing SOC/SOH with the SOC/SOH1Threshold value; if SOC/SOH<SOC/SOH1Threshold, checking the condition of the propulsion battery pack, and if condition is satisfactory, activating the propulsion battery pack to charge the maintenance battery, comparing SOC/SOH with the SOC/SOH2Threshold value; and terminating charging when SOC/SOH≥SOC/SOH2Threshold.