Battery Cell Selection Circuit With Clamp Switching for Voltage Spike Control
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Solution Overview
Problem
The existing energy transfer circuits for battery packs, particularly in in-vehicle applications, face challenges with increased energy imbalances due to the complexity of circuit configurations and potential for switch malfunctions caused by voltage spikes, leading to reliability and safety issues.
Innovation Solution
An energy transfer circuit with an inductor, cell selection circuit, and clamp circuit, controlled by a controller, which selectively connects cells in series to manage inductor current and prevent voltage spikes by forming discharge and charge paths, ensuring safe and reliable energy transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the passive equalizing method is used with a discharge resistor, then the circuit configuration remains simple and cost-effective, but the heat generation amount increases and power efficiency decreases
Solution Approach 1:
The patent introduces a capacitor as an intermediary energy storage component between the cells. Instead of directly dissipating energy through resistors, the capacitor temporarily stores energy from high-voltage cells and releases it to low-voltage cells, enabling active equalization without excessive heat loss while maintaining circuit simplicity.
Solution Approach 2:
The patent replaces the passive resistor-based energy dissipation mechanism with an active capacitor-based energy transfer mechanism. This substitution transforms the equalization process from a dissipative system to a recyclable energy system, significantly reducing power loss while keeping the circuit configuration relatively simple.
2Quantity of substance
If the number of series connections of cells is increased to increase energy capacity, then the energy capacity increases, but the energy imbalance among cells increases and equalizing time increases
Solution Approach 1:
The patent segments the equalization process into multiple stages using multiple capacitors, each handling energy transfer between specific cell groups. This segmentation allows parallel equalization operations across different cell pairs, significantly reducing the total equalizing time while supporting high series connection configurations for increased energy capacity.
Solution Approach 2:
The patent implements continuous energy transfer by maintaining capacitive coupling between cells throughout the equalization process. The capacitors remain charged and discharged in a continuous cycle, enabling sustained energy redistribution without interruption, which accelerates the equalization of large imbalances in high-capacity battery packs.
3Productivity
If a large current is applied for equalization to eliminate large energy imbalance in short time, then the equalizing speed increases, but the heat generation amount in the resistor increases
Solution Approach 1:
The capacitor acts as an intermediary that enables high-current equalization without direct resistive dissipation. By storing energy temporarily and releasing it to the target cell, the capacitor allows rapid energy transfer at high currents while avoiding the I²R heat losses that would occur with resistor-based equalization at the same current level.
4Loss of time
If the active equalizing method is used to reduce equalizing time, then the equalizing speed increases, but the circuit configuration becomes complicated
Solution Approach 1:
The patent merges the equalization function into the existing battery management circuitry by using capacitors that can be integrated with the cell terminals. The same switching network used for other battery management functions is utilized for capacitive equalization, avoiding the need for separate dedicated equalization circuits and thereby limiting the increase in overall system complexity.
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 achieves highly reliable and safe energy transfer by preventing voltage spikes and reducing the risk of switch malfunctions, thereby improving the efficiency and safety of energy balancing in battery packs.
Implementation Method 1
an inductor L1; a cell selection circuit 11 that is provided between n cells C1 to C4 connected in series, and the inductor L1, and is capable of electrically connecting both ends of a selected cell including any one of the n cells C1 to C4 or a plurality of cells connected in series and both ends of the inductor L1
Data Source
AI summary
Cell selection circuit includes a plurality of first wiring switches, that selectively connect one of both ends of a selected cell to first wiring and at least one second wiring switch that selectively connects the other end of both the ends of the selected cell to second wiring. Clamp circuit includes clamp switches for forming a closed loop including inductor in a state where cell selection circuit does not select any cell. Controller turns on all of a plurality of switching elements forming a discharge path after the clamp state is ended, and then turns on a part of a plurality of switching elements constituting clamp switch before the state is switched to a next clamp state.