Auxiliary Battery Charging in Plug-in Electric Vehicles
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Solution Overview
Problem
The existing systems for charging auxiliary batteries in plug-in electric vehicles reduce the driving range and efficiency by using onboard energy to recharge the secondary battery, which decreases its state of charge and affects the overall performance of the vehicle.
Innovation Solution
A system and method that utilize an external power source to charge the auxiliary battery to a predetermined upper charge level, reducing the energy usage from the onboard charging system, and allowing it to discharge to a lower level during drive mode, while charging the high-voltage battery using the external power source, thereby minimizing energy consumption from the onboard system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the auxiliary battery is recharged using onboard energy from the high-voltage storage battery or engine-driven generator, then the auxiliary battery charge level is maintained, but the driving range and overall efficiency of the vehicle are reduced
Solution Approach 1:
The patent extracts the auxiliary battery charging function from the onboard energy system by introducing an external power source. The auxiliary battery is charged externally during vehicle storage or idle periods, separating this charging operation from the vehicle's propulsion energy supply and eliminating the energy trade-off.
2Ease of operation
If the auxiliary battery is charged using onboard energy, then the auxiliary battery can provide power for low-voltage loads, but the state of charge of the high-voltage storage battery decreases
Solution Approach 1:
The patent extracts the charging operation from the high-voltage storage battery by using an external power source. This separation allows the high-voltage battery to retain its charge for propulsion purposes while the auxiliary battery receives independent external charging, eliminating the energy transfer between the two battery systems.
3Reliability
If the auxiliary battery charge level is maintained at a high level using onboard charging, then the battery is ready to support loads, but the overall energy efficiency of the vehicle is reduced
Solution Approach 1:
The patent applies preliminary action by charging the auxiliary battery in advance during vehicle storage or idle periods using external power. This preliminary charging ensures the auxiliary battery is ready to support loads when needed, while avoiding continuous or frequent onboard charging operations that would reduce overall energy 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
This approach extends the electric-only driving range of the vehicle by reducing energy usage from the onboard charging system and optimizing the state of charge of both the auxiliary and high-voltage batteries, enhancing overall vehicle efficiency.
Implementation Method 1
The auxiliary battery is allowed to be charged to the upper charge level using an external power source
Implementation Method 2
The secondary battery can provide electric power to drive various low-voltage loads in the HEV
Implementation Method 3
The high-voltage storage battery has a state of charge (SOC). However, the SOC of the battery decreases when the high-voltage storage battery provides electric power for the vehicle
Data Source
AI summary
A system and method is provided for charging an auxiliary battery in a plug-in electric vehicle with an onboard charging system. The auxiliary battery has a predetermined operating range of charge levels. The auxiliary battery is charged to an upper charge level using an external power source thereby reducing energy used from the onboard charging system to charge the auxiliary battery during a drive mode of the vehicle. The upper charge level may be substantially similar to an upper level of the predetermined operating range of charge levels or greater than the predetermined operating range of charge levels. The auxiliary battery may be allowed to discharge to a lower charge level, which may be substantially similar to a lower level of the predetermined operating range of charge levels or less than the predetermined operating range of charge levels.