Battery Cell Voltage Equalization via Segmented Discharge
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing charge condition adjusting apparatuses for hybrid electric vehicles require extensive time to equalize voltages between unit cells, necessitating complex calculations and increased costs due to sequential discharging of unit cells.
Innovation Solution
The apparatus segments unit cells into blocks, using a first equalizing unit to discharge cell blocks until the smallest unit cell reaches a target voltage, followed by a second unit discharging individual cells until all reach the target voltage, with narrower criteria for judging voltage equality, thereby reducing overall equalization time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If unit cells are discharged step-by-step by connecting the discharge resistor to the unit cell in sequence, then the voltage between both ends of each unit cell can be equalized, but it requires much time to equalize the each unit cell
Solution Approach 1:
The battery pack is divided into multiple cell blocks, each containing several unit cells. The equalization process is segmented into two stages: first equalizing all cell blocks simultaneously by connecting discharge resistors to each cell block, then performing individual cell equalization only where needed. This segmentation allows parallel processing of multiple cells, significantly reducing the overall equalization time while maintaining voltage accuracy.
Solution Approach 2:
Before individual cell equalization, a preliminary equalization stage is performed where all cell blocks are discharged simultaneously to a common reference voltage (the minimum voltage among all cells). This preliminary action brings most cells close to the target voltage, reducing the number of cells requiring subsequent individual equalization and thereby shortening the total equalization time.
2Productivity
If the adjust discharge time is determined based on the adjust target value and the voltage between the both ends of the unit cell, then the each unit cell can be discharged in the adjust target time, but calculating the adjust target values for respective unit cells is required, so that complicated calculation is required and the cost is increased
Solution Approach 1:
The system uses the inherent voltage differences among cells to drive the equalization process without requiring complex external calculations. By connecting discharge resistors and using the natural voltage discharge characteristics, the system automatically equalizes cells based on their own voltage levels relative to the minimum voltage cell, eliminating the need for complicated adjust target value calculations.
Solution Approach 2:
The invention changes the control parameter from individual cell-specific target voltages to a single common reference voltage (minimum voltage among all cells). This parameter change simplifies the control logic: all cells are discharged to the same reference point, and the discharge time is determined by the voltage difference between each cell and the reference, rather than requiring separate calculated target values for each cell.
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 significantly shortens the equalization time by discharging multiple unit cells simultaneously and eliminating the need for complex calculations, enhancing the efficiency and speed of voltage equalization.
Implementation Method 1
a discharging resistor for discharging the unit cell
Data Source
AI summary
Providing a charge condition adjusting apparatus, which can shorten a time for equalization of each charge in unit cells, a low-voltage CPU selects each smallest unit cell in the each cell block, which has each smallest voltage between the both electrodes, from among plural unit cells structuring the cell blocks. The low-voltage CPU controls ON/OFF of a block-discharging switch to connect the both electrodes of each cell block and each block-discharging resistor for discharging the each cell block until the each voltage between the both electrodes of the selected smallest unit cell reaches the target voltage. Successively, the low-voltage CPU controls ON/OFF of a selecting switches and a cell-discharging switch to connect the both electrodes of each unit cell and each cell-discharging resistor to discharge the each unit cell until the each voltage between the both electrodes of the unit cells reaches the target voltage.