Battery Control Apparatus Managing Parallel Switching for Charge Optimization
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Solution Overview
Problem
In micro hybrid electric vehicles (HEVs), the use of batteries with different properties, such as lead acid and lithium ion batteries, leads to inefficiencies in energy recovery due to cross currents when connected in parallel, resulting in a suboptimal total charge capacity.
Innovation Solution
A battery system control apparatus that estimates charging currents for each battery based on internal resistance and switches between batteries to maximize the total charge by selectively connecting the battery with the higher charging current during regenerative charging, ensuring efficient energy distribution and storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If batteries with different OCV are connected in parallel to recover regenerative energy, then the charging capacity increases, but cross current occurs causing energy loss
Solution Approach 1:
A DC-to-DC converter is introduced as an intermediary device between the lead acid battery and the sub battery. This converter acts as a mediator that enables charging of both batteries with different OCV without allowing direct current exchange between them, thus preventing cross current loss while maintaining increased charging capacity.
Solution Approach 2:
The charging system is segmented into separate charging paths for the lead acid battery and the sub battery. By dividing the charging system and using independent control for each battery, the patent prevents direct interaction between batteries of different OCV, eliminating cross current while allowing both to be charged effectively.
2Loss of energy
If a DC-to-DC converter is inserted between batteries to prevent cross current, then energy loss is reduced, but system cost increases
Solution Approach 1:
The DC-to-DC converter serves as a cost-effective intermediary solution that prevents cross current loss. While it adds device complexity, it avoids the need for more expensive alternatives such as sophisticated switch control systems or batteries with matched OCV characteristics.
3Device complexity
If switch control is used to prevent cross current without DC-to-DC converter, then system cost is reduced, but charging efficiency decreases
Solution Approach 1:
The switch control system dynamically adjusts the connection state of switches based on real-time battery voltage and current measurements. By implementing dynamic control strategies, the system achieves effective prevention of cross current while maintaining high charging efficiency, avoiding the need for static or overly complex control mechanisms.
Solution Approach 2:
The switch control system incorporates feedback mechanisms that continuously monitor battery parameters and adjust switch states accordingly. This feedback-based control ensures optimal charging efficiency while preventing cross current, achieving a balance between system simplicity and charging performance.
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 solution enhances the total charge capacity by effectively managing the switching between batteries with different properties, preventing cross currents and optimizing energy recovery during regenerative charging.
Implementation Method 1
A battery system control apparatus connectable to a first battery and a second battery in parallel through switches, including: an estimator which estimates a charging current of the first battery at least from an internal resistance of the first battery; and an estimator which estimates a charging current of the second battery at least from an internal resistance of the second battery.
Data Source
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AI summary
In a battery system that connects a plurality of types of batteries through a switch SW, when the switch SW is switched at a voltage (charge rate), it has been possible to increase a stored charge during charging, depending on the DC resistance of the battery. An object of the present invention is to provide switch SW switching control so that the stored charge can further be increased. A first feature of the present invention is to provide a battery system in which a first battery and a second battery are connected in parallel through the switch SW, including an estimator which estimates the charging current by measuring the resistance and OCV of each battery. The battery system can further increase the stored charge by switching to a switch SW combination that can increase the stored charge.