Battery Control System Effective Current Windowing

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Solution Overview

Problem

Existing battery control methods fail to accurately assess battery degradation when current is continuously changing, leading to unreliable prevention of performance decreases in batteries.

Innovation Solution

A battery control system that calculates effective current values in multiple time windows and imposes charge/discharge restrictions based on these values, with a second phase of restriction triggered by cumulative time exceeding thresholds, ensuring reliable prevention of performance degradation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an evaluation value is integrated based on discharge current and time elapsed to restrict battery discharge, then battery degradation due to continuous discharge is prevented, but the method fails to accurately assess degradation when current continuously changes

Engineering Contradiction:
Improvebattery degradation assessment accuracyVSAvoidevaluation value calculation accuracy
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The patent divides the continuous current monitoring into discrete time windows (e.g., 10 minutes, 30 minutes, 1 hour, 3 hours, 6 hours, 12 hours). Within each time window, the effective current is calculated separately, allowing accurate assessment of degradation under varying current conditions. This segmentation enables the system to capture current characteristics at different time scales without being overwhelmed by continuous variation.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent dynamically adjusts the effective current calculation based on the actual current waveform within each time window. Rather than using a fixed threshold or simple integration, the system calculates the effective current (RMS value) that adapts to the actual current profile, whether it's steady, pulsating, or continuously varying. This dynamic approach ensures accurate degradation assessment under any current condition.

Inventive Principle:
Principle #15Dynamics

2Device complexity

If charge/discharge current is restricted based on simple evaluation value integration, then implementation is simple, but battery performance decrease cannot be reliably prevented under continuous current changes

Engineering Contradiction:
Improvecontrol system complexityVSAvoidbattery performance protection reliability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent segments the control approach into multiple time windows with different effective current thresholds. Each time window has its own threshold value stored in memory, allowing the system to apply appropriate restrictions based on the specific time scale being monitored. This segmented approach maintains relative simplicity while significantly improving reliability compared to single-threshold methods.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements a feedback mechanism where the calculated effective current in each time window is compared against the corresponding threshold value. When the effective current exceeds the threshold, charge/discharge restriction is applied. This feedback loop continuously monitors and adjusts the restriction level based on actual battery conditions, ensuring reliable performance protection while maintaining clear control logic.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP3032690B1Battery control system and vehicle control system
Publication Date: 2021.02.24 HITACHI AUTOMOTIVE SYST LTD
  • EP3032690B1 patent drawingFigure 1
  • EP3032690B1 patent drawingFigure 2
  • EP3032690B1 patent drawingFigure 3

AI summary

A battery control system connected to a battery, which controls charge/discharge at the battery, includes: a current detection unit that measures a current value by detecting a charge/discharge current flowing through the battery; a voltage detection unit that detects a voltage at the battery; a temperature detection unit that detects a temperature at the battery; an effective current value calculation unit that calculates, based upon the current value measured by the current detection unit, an effective current value in a predetermined time window; and a charge/discharge restriction unit that imposes a first charge/discharge restriction so as to restrict the charge/discharge current based upon the effective current value calculated by the effective current value calculation unit.