Main Line Switch Control for Battery Rack Overcurrent Timing

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Solution Overview

Problem

In energy storage systems with multiple battery racks, the timing of overcurrent protection control varies, leading to potential damage to the last contactor blocking the main line current due to inconsistent timing, and existing methods either prolong overcurrent flow or increase costs.

Innovation Solution

A method and apparatus that introduces a time delay from overcurrent detection to contactor opening and uses a disconnect switch unit controlled by a switch controller based on overcurrent detection signals from each rack, ensuring the disconnect switch unit blocks the main line current before the last contactor opens.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a time delay is set in the overcurrent protection control unit of each rack to safely open the contactor, then the contactor can be protected from damage, but the overcurrent flows for a longer time causing safety risks

Engineering Contradiction:

Improvecontactor protectionVSAvoidovercurrent flow time

Core Design Contradiction:

ReliabilityVSDuration of action of moving object

Solution Approach 1:

The disconnect switch unit is activated in advance based on overcurrent detection signals from battery racks before the contactor opens. This preliminary action ensures that when the contactor opens after the time delay, the main line current has already been blocked by the disconnect switch unit, preventing damage to the disconnect switch unit while allowing the contactor to open safely.

Inventive Principle:

Principle #10Preliminary action

2Duration of action of moving object

If a short time delay is set from overcurrent detection to main line current blocking, then the overcurrent is quickly blocked improving safety, but the contactor may be damaged due to timing differences

Engineering Contradiction:

Improveovercurrent flow timeVSAvoidcontactor protection

Core Design Contradiction:

Duration of action of moving objectVSReliability

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

3Speed

If a large shunt resistor is used to detect main line current and quickly block overcurrent, then the response time is reduced, but the system cost increases

Engineering Contradiction:

Improveovercurrent detection speedVSAvoidsystem cost

Core Design Contradiction:

SpeedVSEase of manufacture

Solution Approach 1:

The overcurrent detection function is segmented and distributed to each battery rack's overcurrent protection control unit rather than using a centralized detection system with a large shunt resistor. Each rack independently detects overcurrent conditions and sends detection signals to the switch controller, which then activates the disconnect switch unit. This segmentation eliminates the need for expensive large shunt resistors while maintaining fast response times.

Inventive Principle:

Principle #1Segmentation

4Reliability

If individual overcurrent protection control is implemented in each rack, then each rack can be protected independently, but the blocking timing of each rack cannot be completely the same causing the last contactor to block the same current as main line current

Engineering Contradiction:

Improveindividual rack protectionVSAvoidblocking timing synchronization

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The switch controller acts as an intermediary that receives overcurrent detection signals from individual rack protection control units and coordinates the activation of the disconnect switch unit. Instead of each rack independently controlling its contactor opening timing, the switch controller centralizes the decision-making process, ensuring that the disconnect switch unit is activated at the appropriate time based on signals from any rack experiencing overcurrent.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS20260074533A1Apparatus and method for controlling main line switch

Publication Date: 2026.03.12 SAMSUNG SDI CO LTD

AI summary

An apparatus for controlling a main line switch mounted on an energy storage system is provided. The energy storage system includes a plurality of battery racks and a disconnect switch unit. The apparatus includes: a battery connection unit respectively on each of the battery racks, the battery connection unit being configured to measure a current of a corresponding one of the battery racks by using a built-in current measurement unit and to generate an overcurrent detection signal when the current of the corresponding one of the battery racks exceeds an overcurrent protection level; and a switch controller configured to open the disconnect switch unit to block a main line current flowing to the energy storage system in response to the overcurrent detection signal from a reference number or more of battery connection units.