External Battery Charger with Offset Compensator for Impedance Loss
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Solution Overview
Problem
The design of mobile computing devices faces challenges in reducing size and weight while managing heat generation and ensuring safe battery charging, as internal charging circuitry adds weight and generates waste heat, and existing battery chemistries require carefully managed charging regimes to prevent unsafe conditions.
Innovation Solution
An external charging unit with an offset compensator that applies an offset voltage to compensate for impedance loss between the charger and the battery, allowing charging to proceed according to a predefined profile, switching between constant current and constant voltage modes based on measured battery voltage and current, and continuously applying the offset voltage to maintain the charger in the first mode until the threshold voltage is reached.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If internal charging circuitry is included in mobile computing devices, then battery charging safety and control are ensured, but device weight increases and heat generation occurs
Solution Approach 1:
The charging control circuitry is extracted from the mobile computing device and placed in an external charging unit. This allows the device to gain battery charging safety and control capabilities while avoiding the weight penalty of including the charging circuitry internally. The external unit handles all charging management functions, leaving the mobile device with only the necessary battery and minimal interface components.
2Reliability
If internal charging circuitry is included in mobile computing devices, then battery charging safety and control are ensured, but heat generation increases
Solution Approach 1:
The charging control circuitry is extracted from the mobile computing device and placed in an external charging unit. This relocation transfers the heat-generating charging operations outside the device, allowing safe battery charging without the heat generation burden affecting the device's thermal management and user comfort.
3Productivity
If higher charging currents are used, then charging speed increases, but impedance loss and voltage drop become more significant
Solution Approach 1:
The external charging unit incorporates feedback mechanisms that continuously monitor the charging current and voltage. Based on this feedback, the system dynamically adjusts the charging parameters to optimize the balance between charging speed and energy efficiency. The feedback loop allows the system to compensate for impedance losses and maintain optimal charging performance throughout the charging process.
Solution Approach 2:
The charging system dynamically changes operating parameters such as current and voltage levels during the charging process. By adjusting these parameters based on battery state and impedance characteristics, the system achieves high charging speeds while minimizing energy loss due to impedance. The ability to vary parameters allows optimization at different stages of charging.
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 solution reduces the weight and heat generation of mobile computing devices by externalizing charging circuitry, allowing for higher charging currents and flexibility in battery types, while ensuring safe and efficient battery charging by maintaining the desired threshold voltage despite impedance losses.
Implementation Method 1
an offset compensator to apply an offset voltage to the charger to compensate for impedance loss between the charger and the at least one battery
Implementation Method 2
a charger configured for providing a charge to the at least one battery
Data Source
AI summary
A system and method for externally controlling the charging of a battery powered mobile computing device includes a charging unit configured to be electrically coupled to the mobile computing device to charge a battery therein. The charging unit comprises a charger configured to operate in a first mode to provide a constant charge current to the battery to be charged and to operate in a second mode to provide a constant charge voltage to the battery to be charged and where the switch from the first mode to the second mode occurs when the voltage at the battery a predefined threshold voltage. The charger including an offset compensator configured for applying an offset voltage to the measured output of the charger to maintain the charger in the first mode to compensate for voltage drops between the charger and the battery thereby allowing the battery voltage to reach the threshold voltage.