EV Battery Charging Control Under Cooling Capacity Limits
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Solution Overview
Problem
The challenge is to shorten the charging time of vehicle-mountable power storage devices while minimizing power loss during quick charging, as excessive heat generation can exceed the cooling capacity of the cooling device, leading to prolonged charging times and potential battery deterioration.
Innovation Solution
A vehicle system that includes a power storage device, a cooling device, and a controller to manage charging conditions by maintaining a constant current or power, allowing the battery temperature to reach an upper limit, thereby balancing heat generation and cooling capacity, and adjusting cooling capabilities based on air-conditioning operations to optimize charging efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If quick charging with maximum current is performed, then charging time is shortened, but heat generation exceeds cooling capacity and charging time becomes longer due to current suppression
Solution Approach 1:
The cooling device is activated before quick charging begins to pre-cool the power storage device. This preliminary cooling action ensures that the device can withstand the heat generation from maximum current charging without immediately exceeding temperature limits, thereby maintaining high charging current for longer periods and reducing total charging time.
Solution Approach 2:
The controller continuously monitors the temperature of the power storage device during charging and dynamically adjusts the charging current based on real-time temperature feedback. When temperature approaches the upper limit, the controller reduces current to prevent overheating; when temperature is lower, the controller maintains maximum current to minimize charging time. This closed-loop control optimizes the balance between charging speed and temperature management.
2Temperature
If charging current is suppressed to prevent temperature rise, then temperature is controlled, but charging time becomes excessively long
Solution Approach 1:
The charging current is made dynamic rather than static. The controller continuously adjusts the charging current based on real-time temperature conditions, allowing the system to operate at maximum current when safe and reduce current only when necessary. This dynamic adjustment prevents prolonged operation at suppressed current levels, minimizing charging time while maintaining temperature control.
Solution Approach 2:
The cooling device operates continuously throughout the charging process, not just when temperature limits are approached. This continuous cooling action maintains the power storage device within the optimal temperature range, allowing the charging current to remain at maximum levels for extended periods without interruption, thereby reducing total charging time.
3Quantity of substance
If power storage device capacity is increased, then EV traveling distance is extended, but charging time becomes excessively long
Solution Approach 1:
The system employs quick charging with maximum current to rapidly charge the high-capacity power storage device, effectively 'skipping' through the charging process at high speed. Combined with pre-cooling and continuous temperature monitoring, this approach enables the system to sustain maximum charging current throughout most of the charging cycle, reducing the time required to charge large-capacity batteries.
Solution Approach 2:
The system changes the charging parameter from conventional charging current to maximum quick charging current. By adjusting the charging current parameter to its maximum feasible value and maintaining it through dynamic control and continuous cooling, the system achieves fast charging of high-capacity power storage devices, extending traveling distance without proportionally increasing charging time.
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 approach reduces heat generation and allows for faster charging while minimizing power loss, allowing the battery to reach the upper limit temperature, thus shortening charging time without compromising battery health.
Implementation Method 1
a cooling device that cools the power storage device
Implementation Method 2
a power loss (Joule heat) produced in the power storage device
Data Source
AI summary
A vehicle includes: a battery that is chargeable with electric power supplied from a charger provided outside the vehicle; and an air-conditioning and cooling system that cools the battery. An ECU controls a charging operation for the battery such that the battery is charged under a charging condition of a constant current which is constant over a charging period from start of charging to satisfaction of a completion condition. The ECU sets the charging condition such that a battery temperature when the completion condition is satisfied becomes an upper limit temperature, based on an amount of heat generation in the battery caused by charging and an amount of cooling of the battery by the air-conditioning and cooling system.