Battery Charge Current Control Circuit for Modulated Loads
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Solution Overview
Problem
Existing battery charging methods inaccurately determine the end of charge condition due to distortion from system loads, as they measure average charge current over long integration periods, which is not suitable for precise end of charge detection.
Innovation Solution
A control circuit is introduced that includes a current limited power source connected in parallel to the battery and load, with means to indicate overload conditions and measure battery current, allowing for accurate determination of charge current by selecting values from intervals without overload, and compensating for offset errors through signal commutation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the power supply current limit is reduced to protect the battery, then battery safety is improved, but the ability to supply required charge current deteriorates during high load conditions
Solution Approach 1:
The patent applies preliminary action by setting a predetermined current limit before overload occurs. The control circuit is pre-configured with safety thresholds and automatically activates protection mechanisms when approaching the limit, preventing battery damage before it can occur while maintaining normal operation below the threshold.
Solution Approach 2:
The patent implements feedback by continuously monitoring the sum of load current and charge current against the predetermined limit. The control circuit uses this feedback to detect overload conditions and adjust measurements accordingly, ensuring battery safety while optimizing charge current utilization during normal operating conditions.
2Reliability
If the system load has priority over battery charging, then system operation reliability is improved, but charge current measurement accuracy deteriorates due to current stealing
Solution Approach 1:
The patent extracts and isolates the valid measurement portions from the distorted total current. By identifying intervals where no current stealing occurs, the control circuit separates accurate charge current measurements from the distorted signal caused by load priority, enabling precise measurement without compromising system reliability.
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
This method ensures accurate measurement of real battery charge current, unaffected by system loads, thereby improving the precision of end of charge detection and maintaining accuracy even during overload conditions.
Implementation Method 1
The analog-to-digital converter may be configured to measure a voltage drop over the resistor
Data Source
AI summary
This application relates a method and a control circuit for determining a charge current of a battery connected to a modulated load, wherein a current limited power source is connected in parallel to the modulated load and the battery for supplying a load dependent current up to a predetermined current limit to the modulated load and the battery. The control circuit comprises means for measuring a current flowing through the battery; means for indicating an overload condition of the current limited power source; and means for determining the charge current of the battery. The means for indicating an overload condition are configured to indicate an overload condition when a sum of a current drawn by the modulated load and a current flowing into the battery exceeds the predetermined current limit of the current limited power source.