Grid-Shielded Electrical System for TRU Phase Imbalance Detection
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Solution Overview
Problem
Transportation refrigeration units (TRUs) face shutdowns due to unbalanced or loose phases in three-phase grid power during ship transportation, leading to potential cargo losses, as existing technologies lack the ability to detect and mitigate these issues.
Innovation Solution
A grid-shielded electrical system with a three-phase bus, voltage sensors to detect voltage conditions, and a controller to identify root cause issues such as unbalanced phases or phase loss, which automatically shuts down and restarts electrical components, and includes current sensors to detect non-grid issues like low or high amperage conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If TRUs operate in standby mode with grid power during ship transportation, then power is provided without diesel operation, but unbalanced or loose phases cause shutdowns and cargo losses
Solution Approach 1:
The voltage sensor continuously monitors voltage conditions on each phase before shutdowns occur. The controller detects unbalanced phases or loose phases in advance and triggers protective shutdown sequences, preventing cargo losses by acting before the harmful effect completes its damage
Solution Approach 2:
The system implements continuous feedback through voltage sensors monitoring each phase of the three-phase grid power. The controller receives real-time voltage readings and adjusts operation accordingly, shutting down when imbalances are detected and restarting when conditions normalize, creating a closed-loop protection system
2Measurement precision
If voltage sensors and controllers are added to detect grid issues, then root cause detection is improved, but device complexity increases
Solution Approach 1:
The electrical system performs self-diagnosis through integrated voltage sensors and controllers that automatically monitor grid power conditions, detect unbalanced or loose phases, and execute protective shutdowns without external intervention. The system shields itself from grid issues through autonomous detection and response
Solution Approach 2:
The controller serves multiple functions: it manages normal standby operation, detects voltage imbalances, determines root causes of issues, executes protective shutdowns, and automatically restarts when conditions improve. This multi-functionality reduces the need for separate dedicated components for each function
Data Source
AI summary
A grid-shielded electrical system for a transportation refrigeration system is provided. The grid-shielded electrical system includes a bus to deliver three-phase grid power, which is received from a grid, to electrical components of the transportation refrigeration system, a voltage sensor disposed to sense a condition of voltage on the bus and configured to generate voltage readings accordingly and a controller disposed in signal communication with the voltage sensor and configured to detect a root cause issue with the grid based on the voltage readings.