Adaptive Charging Circuit for Battery Pack Overcharge Prevention

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Solution Overview

Problem

Conventional charging circuits fail to prevent overcharging of battery packs in degraded or abnormal temperature states without prolonging charging time, leading to reduced battery life and safety concerns.

Innovation Solution

A charging circuit with a changing unit that adapts charging data based on the battery pack's temperature and degradation state, allowing for real-time adjustments to control voltage and current supply to prevent overcharging, even when stored charging data is insufficient or outdated.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a large amount of electric current is supplied immediately after starting charging to shorten charging time, then charging speed is improved, but the risk of overcharging increases when the battery is already in full or near-full charge condition

Engineering Contradiction:
Improvecharging speedVSAvoidovercharge prevention
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The control unit performs preliminary detection of the battery's charge state before initiating high-current charging. By checking the charged voltage against the control voltage threshold in advance, the system determines whether the battery is already full or near-full, and only then allows large current supply. This preliminary action prevents overcharging while enabling fast charging when safe.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The voltage monitoring unit continuously monitors the charged voltage of the secondary batteries and provides real-time feedback to the control unit. This feedback mechanism allows the control unit to adjust the charging current dynamically, reducing current when the battery approaches full charge and preventing overcharging while maintaining high charging speed during the charging process.

Inventive Principle:
Principle #23Feedback

2Adaptability or versatility

If charging data is stored in the battery pack for adaptability to different battery kinds, then versatility is improved, but the charging data may become outdated or insufficient for degraded batteries

Engineering Contradiction:
Improvecharging data adaptabilityVSAvoidcharging accuracy for degraded batteries
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The control unit dynamically changes charging parameters such as control voltage and charging current based on real-time detection of the battery's charge state and degradation level. Instead of relying solely on pre-stored charging data, the system adjusts parameters adaptively during charging, using detection results to modify charging settings and ensure accurate charging even for degraded batteries.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The battery pack's storage unit stores charging data that enables the battery itself to provide information about its characteristics and degradation state. The control unit uses this self-provided information from the battery to determine appropriate charging parameters, allowing the battery to serve its own charging needs while enabling the system to adapt to degradation over time.

Inventive Principle:
Principle #25Self-service

3Device complexity

If charging control uses fixed control voltage threshold to determine full charge, then simplicity is maintained, but overcharging occurs when battery characteristics change due to degradation or temperature

Engineering Contradiction:
Improvecharging control simplicityVSAvoidovercharge prevention under varying conditions
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The control unit dynamically adjusts the control voltage threshold based on detected battery temperature and degradation state. Instead of using a fixed control voltage, the system modifies the threshold adaptively - lowering it for degraded batteries or high-temperature conditions to prevent overcharging. This dynamic adjustment maintains reliability while the overall control structure remains relatively simple.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP2290781B1Charging circuit
Publication Date: 2020.02.26 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD
  • EP2290781B1 patent drawingFigure 1
  • EP2290781B1 patent drawingFigure 2~3
  • EP2290781B1 patent drawingFigure 4

AI summary

A charging circuit includes a battery pack (4) provided with one or more secondary batteries (5) and a battery charger (1) for charging the secondary batteries, (5) the battery pack (4) being detachably attachable to the battery charger (1). The charging circuit further includes a control unit (2) for performing a charging control, a monitoring unit (6) for detecting charged voltage of the secondary batteries (5) to determine completion of charging, a storage unit (7) storing charging data for use in the charging control of the control unit (2) and determination of the charging completion of the monitoring unit (6) and a changing unit (9) for changing the charging data. The monitoring unit (6) and the storage unit (7) are arranged in the battery pack (4), and the changing unit (9) and the control unit (2) are arranged in the battery charger (4).