Battery Current Estimation via Switchable Load Impedance
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Solution Overview
Problem
Portable electronic devices face inaccuracies in estimating available battery current due to voltage slumps caused by varying current draws from components, leading to premature low battery indications and unnecessary power conservation actions, which degrade user experience and battery life.
Innovation Solution
A system and method that utilize an auxiliary supply rail, a switchable load, current and voltage sensors, and an electronic processor to calculate an accurate current budget for the battery by measuring unloaded and loaded voltages, impedance, and adjusting operating parameters based on the current budget.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voltage measurements are taken during normal operation, then power level monitoring is continuous, but voltage slumps cause inaccurate battery current estimates
Solution Approach 1:
The system performs preliminary actions by switching off the load before taking voltage measurements to obtain accurate battery voltage readings. This preliminary step eliminates the voltage slump effect caused by load operation, ensuring that voltage measurements reflect the true battery state rather than transient voltage drops during operation.
Solution Approach 2:
The system applies preliminary anti-action by temporarily removing the load (switching it off) before measurement. This counteracts the harmful voltage slump effect that would otherwise occur during normal operation, allowing accurate voltage and current estimates to be obtained without the distorting influence of active load consumption.
2Measurement precision
If the load is switched off for voltage measurements, then voltage readings are accurate, but device operation is interrupted
Solution Approach 1:
The system implements periodic action by switching the load on and off at regular intervals. The load is switched off only briefly during measurement periods and then restored for normal operation. This periodic cycling allows continuous monitoring while minimizing disruption to device functionality and maintaining overall operational continuity.
Solution Approach 2:
The system applies dynamics by making the load switching state changeable and time-dependent. The load switching controller dynamically adjusts the load state based on measurement requirements, transitioning between on and off states as needed. This dynamic control enables the system to adapt between measurement mode (load off) and operation mode (load on) seamlessly.
3Reliability
If battery voltage is monitored continuously, then power level is tracked, but voltage slumps cause premature low battery indications
Solution Approach 1:
The system implements feedback by using the measured voltage and calculated current to continuously update the battery state information. The processor calculates available battery current based on voltage measurements and load characteristics, then uses this feedback to provide accurate battery status indications. This feedback loop ensures that the displayed battery level reflects true remaining capacity rather than transient voltage slump conditions.
Solution Approach 2:
The system performs preliminary measurement actions by acquiring voltage readings during periods when the load is switched off, before returning to normal operation. This preliminary measurement ensures that the battery voltage is captured at its true value without the influence of ongoing load consumption, providing reliable data for accurate battery status indication.
4Speed
If measurements are taken during high current draw, then real-time monitoring is achieved, but voltage slumps distort the readings
Solution Approach 1:
The system uses periodic action by implementing regular measurement cycles where the load is temporarily switched off and voltage is measured, then the load is restored. This periodic measurement approach maintains real-time monitoring capability while ensuring that each individual measurement is taken under controlled, slump-free conditions, thus preserving both speed and precision.
Solution Approach 2:
The system applies preliminary action by switching off the load before taking measurements. This preliminary step creates the optimal measurement condition by eliminating the voltage slump effect, ensuring that voltage readings are accurate even though the measurement process is brief and frequent.
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 approach provides accurate available current estimates, reducing unnecessary power conservation actions and improving user experience by accounting for voltage slumps, thereby extending battery life and maintaining consistent power readings.
Implementation Method 1
acquire, from a voltage sensor configured to measure a voltage of the battery, a unloaded voltage measurement for the battery
Implementation Method 2
a current sensor configured to sense a current level of the auxiliary supply rail
Implementation Method 3
activating a switchable load coupled between the battery and a ground
Data Source
AI summary
Systems and methods for determining available current for a battery in a portable electronic device. One method includes, in response to determining that a received current level of an auxiliary supply rail is equal to or below a predetermined threshold, acquiring a plurality of unloaded voltages for the battery and calculating an unloaded voltage based on the unloaded voltages. The method includes activating a switchable load coupled between the battery and ground, acquiring a plurality of loaded voltages for the battery, and calculating a loaded voltage based on the loaded voltages. The method includes calculating an impedance for the battery based on the unloaded and loaded voltages and an impedance for the switchable load. The method includes determining a current budget based on the impedance, a minimum operating voltage, and a maximum allowable current draw, and adjusting an operating parameter of the portable electronic device based on the current budget.