TRU Battery Charger Offset Current Feedback for Dynamic Load Compensation
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Solution Overview
Problem
Transport refrigeration unit (TRU) battery chargers face inaccuracies in output current due to dynamically changing loads, leading to potential battery depletion and failure to restart under certain conditions, as they do not account for the offset current drawn during null-mode voltage measurements.
Innovation Solution
A system and method that dynamically characterize the load connected to the TRU battery charger by measuring and communicating the offset current through a programmable TRS Controller, allowing the smart battery charger to adjust its output current and transition between charging modes accurately, using a predetermined current path and communication interfaces like CAN bus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the battery charger uses a fixed charging algorithm without dynamic load characterization, then the device complexity is reduced, but the charging accuracy and reliability deteriorate due to unaccounted offset currents
Solution Approach 1:
The system implements feedback by measuring the offset current drawn during null-mode voltage measurements and using this information to dynamically adjust the charging algorithm. The battery charger controller continuously monitors load conditions and modifies charging parameters accordingly, ensuring accurate charging despite varying load conditions.
Solution Approach 2:
The system performs self-characterization by automatically measuring its own offset current during normal operation. The controller uses internal measurements of voltage and current to dynamically determine load characteristics without requiring external testing equipment or manual intervention.
2Reliability
If the battery charger does not dynamically characterize load conditions, then the ease of operation is maintained, but the reliability deteriorates due to potential battery depletion and failure to restart
Solution Approach 1:
The system continuously monitors offset current and battery voltage to dynamically adjust charging parameters. This feedback mechanism ensures the battery is charged correctly under varying load conditions, preventing depletion and ensuring reliable restart capability without requiring user intervention.
Solution Approach 2:
The charging system transitions from a static, fixed algorithm to a dynamic system that automatically adapts to changing load conditions. The controller modifies charging current and voltage based on real-time measurements, ensuring reliable operation across different operating scenarios.
3Loss of energy
If the battery charger operates without offset current compensation, then the productivity is maintained with simpler charging processes, but the loss of energy increases due to inefficient charging algorithms
Solution Approach 1:
The system uses feedback from offset current measurements to optimize charging efficiency. By compensating for offset currents in real-time, the system ensures that charging current is delivered effectively to the battery, minimizing energy losses and improving overall charging efficiency.
Data Source
AI summary
A transport refrigeration unit (TRU) battery charging system includes a programmable transport refrigeration system (TRS) Controller, a TRU battery and a programmable battery charger (BC) programmed to transfer electrical current to the TRU battery via a predetermined current path through the programmable TRS Controller in response to a value of offset current drawn from the TRU battery by the programmable TRS Controller and subsequently communicated to the programmable BC by the programmable TRS Controller. The programmable TRU battery charger allows for a dynamic load characterization of the programmable TRS Controller and accessory loads based on programmable TRU battery charger internal shunt current measurements and programmable TRS Controller internal shunt current measurements to allow the programmable TRU battery charger to function properly with all intended modes of operation.