Dynamic Current Limiting for Portable LMR Devices
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Solution Overview
Problem
Portable battery-powered communication devices face challenges in managing excessive transient current demands, which can lead to device resets and communication loss, especially when incorporating non-mission critical features like LTE, WiFi, and GPS alongside mission critical LMR functions.
Innovation Solution
A method and apparatus for dynamically adjusting current limiting using a bank of comparators and logic gates managed by a master processor to control high current loads, prioritizing mission critical functions during high power events, and implementing a finite state machine to monitor and limit current draw based on battery profiles and events like PTT presses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple features (LTE, WiFi, GPS) are added to expand functionality, then adaptability is improved, but transient current demands increase causing device resets
Solution Approach 1:
The patent implements dynamic current limiting that adjusts in real-time based on battery conditions and function priority. The system continuously monitors battery voltage and dynamically scales current delivery to non-mission-critical functions during high-demand events, while maintaining stable power to mission-critical LMR functions. This dynamic adjustment prevents device resets caused by excessive transient current while preserving expanded functionality.
2Use of energy by moving object
If more battery cells are added to handle increased power demands, then power capacity is improved, but size, cost, and weight increase
Solution Approach 1:
The patent changes the operational parameters of existing battery cells by implementing intelligent current limiting and load management. Instead of adding more battery cells, the system modifies how current is distributed and limited across different functions based on real-time battery state. This allows the existing battery to handle transient demands of multiple features without exceeding safe operating limits, avoiding the need for additional battery cells that would increase weight.
3Reliability
If current limiting is increased to prevent device resets, then reliability is improved, but current available to mission critical functions is reduced
Solution Approach 1:
The patent applies different current limiting strategies to different functions based on their criticality. Mission-critical LMR functions are exempt from aggressive current limiting and maintain priority access to battery current, while non-mission-critical functions (LTE, WiFi, GPS) are subject to dynamic current scaling. This localized differentiation ensures device stability through current limiting while preserving adequate power delivery to mission-critical functions.
Data Source
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AI summary
A battery operated portable communication device provides converged functionality while avoiding resets to the device. Composite logic circuitry formed of at least one comparator and a logic interface controls current limiting to a primary load formed of high power land mobile radio (LMR) devices and programming to secondary loads formed of non-LMR peripherals. At least one current limit control signal is used to control current to the primary load under high current mode operations. Another control signal provides an interruption alert to a slave processor for controlled programming of the secondary loads during the high current operations of the primary load. Current to the primary load is restored while the secondary load is interrupted. Operation of secondary load processes is resumed when the primary load ceases high power operation.