Battery Cell Bypass Control for Full Discharge Output Duration
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Solution Overview
Problem
Existing battery discharge systems struggle to efficiently utilize all battery cells without leaving discharge capacity, leading to a shortened duration of desired output due to varying discharge current limit values and system minimum current requirements.
Innovation Solution
A battery control device that includes a bypass circuit to manage battery discharge by prioritizing cells with lower remaining capacity, ensuring all cells are discharged efficiently by equalizing their remaining capacity through sequential bypassing and connection strategies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If discharge is performed sequentially by bypassing battery cells that reach discharge termination voltage, then all battery cells can be discharged without leaving discharge capacity, but time for which a desired output is obtained is shortened
Solution Approach 1:
The control device calculates remaining discharge quantities in advance and determines the optimal bypass sequence before actual discharge occurs. By pre-planning which cells to bypass and when, the system avoids the time loss associated with real-time decision-making and sequential bypassing, thereby extending the duration of desired output while still achieving complete discharge capacity utilization.
Solution Approach 2:
The system dynamically adjusts the bypass strategy based on real-time monitoring of discharge currents and remaining capacities. Rather than following a fixed sequential bypass pattern, the control device continuously optimizes which cells are bypassed and when, adapting to changing battery conditions to maintain desired output levels for extended periods.
2Reliability
If discharge current limit value is set according to battery remaining quantity, then battery safety is ensured, but it becomes difficult to discharge all battery cells without leaving discharge capacity
Solution Approach 1:
The control device segments the battery pack into individual cell groups that can be discharged independently or in parallel. By dividing the battery system into manageable segments, the controller can apply different discharge strategies to different groups, allowing some cells to be discharged to lower voltages while others are bypassed, thereby achieving complete discharge capacity utilization without compromising overall battery safety.
Solution Approach 2:
The system changes discharge parameters dynamically based on battery state. Instead of applying a uniform discharge current limit to all cells, the control device adjusts discharge currents, voltages, and bypass timing for different cells based on their individual remaining quantities and health states, enabling complete discharge while maintaining safety constraints.
3Loss of energy
If sequential bypassing is performed to discharge all battery cells, then discharge capacity is fully utilized, but discharge current limit value decreases causing system minimum current requirements to not be met
Solution Approach 1:
The control device merges multiple discharge paths by operating different battery cell groups in parallel. Instead of sequentially bypassing cells one by one, the system combines several cells or groups of cells to discharge simultaneously, maintaining higher discharge currents for longer periods and meeting system minimum current requirements while still achieving complete discharge capacity utilization.
Data Source
AI summary
A battery control device controls a battery system including a plurality of battery cells connected in series and a bypass circuit that bypasses each of the battery cells. Discharge is performed from each of the battery cells until remaining quantity of the battery cell decreases to a predetermined value. When the remaining quantity of the battery cell is decreased to the predetermined value, each of the battery cells is bypassed by the bypass circuit. When the remaining quantity of all of the plurality of battery cells is decreased to the predetermined value, discharge is performed from all of the plurality of battery cells.