Power Storage Module Hot Swap Control via Voltage Assessment
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Solution Overview
Problem
Existing power storage systems face challenges in performing hot swaps of modules without causing deterioration or failure, particularly with lithium-ion batteries, due to excessive current flow during the process, and require complex circuit configurations with DC-DC converters, leading to increased costs.
Innovation Solution
A power storage device and control method that manage the hot swap process by switching on a charging switch when excessive charging current is not expected, using a configuration with charging and discharging switches controlled by a module controller to prevent excessive current flow, and allowing modules to be swapped while maintaining system stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If modules are swapped during operation (hot swap), then system availability is improved, but excessive current flow causes deterioration or failure of the module
Solution Approach 1:
The module controller performs preliminary assessment of voltage difference between the operating module and the resting module before enabling hot swap. By calculating the voltage difference in advance and comparing it against a predetermined threshold, the system determines whether hot swap can proceed safely, preventing excessive current flow before it occurs
Solution Approach 2:
The module controller continuously monitors voltage levels of both operating and resting modules, using this feedback to make real-time decisions about permitting hot swap. The controller adjusts its permission status based on the current voltage difference, creating a closed-loop control system that prevents harmful current flow while enabling safe hot swap operations
2Stability of the object's composition
If DC-DC converters are used to adjust voltage during hot swap, then voltage matching is improved, but circuit complexity and cost increase
Solution Approach 1:
The patent extracts the voltage adjustment function from complex DC-DC converter circuits and implements it through a simplified controller-based assessment mechanism. By removing the need for active voltage conversion hardware and replacing it with a controller that evaluates voltage difference and permits or prohibits hot swap accordingly, the system achieves voltage matching without the complexity and cost of DC-DC converters
Solution Approach 2:
The module controller acts as an intermediary that mediates the hot swap process by assessing voltage compatibility and controlling the switching operation. Instead of using complex circuitry to actively adjust voltages, the controller serves as a intelligent mediator that permits hot swap only when voltage conditions are safe, simplifying the overall system architecture
Data Source
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AI summary
There is provided a power storage device including a plurality of modules each including secondary batteries, a charging switch that controls charging to the secondary batteries, a discharging switch that controls discharging of the secondary batteries, and a voltage measuring unit that measures a voltage of the module, and a switch control unit that controls one or both of the charging switch and the discharging switch. The modules are connected in parallel. The switch control unit maintains an on state of the discharging switch for at least one of the modules for a predetermined period, and controls the charging switch of the module in which a maximum module charging current estimated based on the voltage of the module is a predetermined value or less, to be in an on state.