Battery Unit Switch Control for Sneak Current Suppression
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Solution Overview
Problem
Existing battery units with parallel-connected cell assemblies face issues of sneak currents due to electrical state differences, leading to potential excessive current flow and reduced power efficiency, with diode-based solutions causing significant power loss.
Innovation Solution
A battery unit configuration using switch sections and a control section to selectively manage current paths between cell assemblies, preventing simultaneous activation and employing a simultaneous on-suppression section to block sneak currents without diodes, utilizing switches with lower voltage drop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If diodes are used to block sneak currents between parallel-connected cell assemblies, then sneak current is prevented, but power loss increases and heat generation occurs
Solution Approach 1:
The patent changes the electrical parameter of the blocking component from a diode with high forward voltage drop to a switch with low on-resistance. By controlling the switch to remain in the off-state during normal operation, sneak currents are blocked while minimizing power loss when the switch is on during charging/discharging operations.
Solution Approach 2:
The patent employs dynamically controllable switches instead of static diodes. The switches can be turned on or off based on operational conditions (charging/discharging vs. normal operation), allowing the system to adapt its electrical characteristics to minimize power loss while maintaining sneak current prevention when needed.
2Power
If multiple cell assemblies are connected in parallel to increase power output, then power supply capability is improved, but sneak currents between assemblies occur due to electrical state differences
Solution Approach 1:
The patent segments the parallel-connected cell assemblies by inserting individually controllable switches in series with each assembly's positive electrode connection. This segmentation allows independent control of each cell assembly's electrical connection, enabling the system to maintain high power capability while preventing unwanted current paths between assemblies.
Solution Approach 2:
The patent introduces switches as intermediary components between the cell assemblies and the common positive electrode connection terminal. These switches act as mediators that can selectively connect or disconnect individual assemblies, preventing direct parallel connection that would allow sneak currents while maintaining the ability to supply high power when needed.
3Loss of energy
If switches are used instead of diodes to control current paths, then power loss is reduced, but device complexity increases due to control requirements
Solution Approach 1:
The patent makes the control section perform multiple functions: it controls the switching elements to connect/disconnect cell assemblies, prevents simultaneous conduction of multiple switches, monitors cell assembly states, and manages charging/discharging operations. This multi-functionality reduces the need for separate dedicated components, offsetting the complexity increase from using controllable switches.
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
Effectively suppresses sneak currents between cell assemblies while minimizing power loss, enhancing reliability and efficiency by using switches with lower on-resistance compared to diodes, and detecting short-circuit faults to prevent abnormality propagation.
Implementation Method 1
switches with lower on-resistance compared to diodes
Data Source
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AI summary
A battery unit (1; 70) in one aspect of an embodiment of the present disclosure includes a plurality of cell assemblies (10, 20, 30), a positive electrode connection terminal (91), a negative electrode connection terminal (92), a plurality of switch sections (40, 50, 60; 71, 72, 73), a control section (2; 6), and a simultaneous on-suppression section (A; B). When an on-command signal is output from the control section (2, 6) to at least two of the plurality of the switch sections (40, 50, 60; 71, 72, 73), the simultaneous on-suppression section (A; B) performs one of enabling the on-command signal to one of the at least two switch sections and disabling the on-command signal to all of the at least two switch sections, so as to suppress the at least two switch sections from being turned on at the same time.