Train Auxiliary Power Supply Cross-Unit Redundancy via Isolation Contactor
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Solution Overview
Problem
Conventional multiple-unit train power supply systems fail to provide continuous power during a three-phase bus ground fault, rendering traction equipment, air conditioners, and air compressors inoperable and leaving the train out of service.
Innovation Solution
An auxiliary power supply device comprising a three-phase isolation contactor, alternating current relays, control circuits, and power supply circuits for both units, where the three-phase isolation contactor connects the power supply between units, allowing one unit to power the other in case of a fault, ensuring continuous power to the entire train.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a three-phase bus ground fault occurs in one unit, then the auxiliary power supply system fails and the train is out of service, but the system lacks redundancy to maintain power supply
Solution Approach 1:
The patent merges the power supply systems of the first and second units by introducing a cross-unit power supply path. When a ground fault occurs in one unit's three-phase bus, the other unit can supply power through the isolation contactor and circuit breaker, enabling inter-unit power sharing to maintain auxiliary equipment operation throughout the train.
Solution Approach 2:
The patent changes the operational state of the isolation contactor and circuit breaker based on fault detection. When a ground fault is detected in one unit, the system activates the cross-unit power supply path by closing the isolation contactor and circuit breaker, thereby changing from a isolated to a connected power supply configuration.
2Adaptability or versatility
If the train uses separate power supply systems for each unit, then each unit can operate independently, but the system lacks the capability to provide continuous power during faults
Solution Approach 1:
The patent makes the power supply system universal by enabling each unit to serve dual functions: normal independent operation and emergency cross-unit power supply. The isolation contactor and circuit breaker facilitate this multi-functionality, allowing the system to adapt between independent and interconnected operational modes based on fault conditions.
3Reliability
If cross-unit power supply is enabled through isolation contactor and circuit breaker, then continuous power can be maintained during faults, but the system complexity increases
Solution Approach 1:
The patent introduces an intermediary control mechanism comprising detection circuits, isolation contactors, and circuit breakers that mediate between the two power supply units. This intermediary system automatically detects ground faults and activates the cross-unit power supply path without requiring complex manual intervention or centralized control.
Solution Approach 2:
The patent segments the power supply system into independent controllable units with clear boundaries. Each unit has its own detection circuit, isolation contactor, and circuit breaker, allowing fault isolation and selective activation of cross-unit power supply paths without affecting the entire system.
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
Enables simultaneous power supply to both units of the train, ensuring all compartments remain operational even during a three-phase bus ground fault, thereby maintaining the train's functionality.
Implementation Method 1
the three-phase isolation contactor includes a normally-open main contact of the three-phase isolation contactor and a coil of the three-phase isolation contactor
Implementation Method 2
two terminals of a coil of the alternating current relay of the first unit are respectively connected to one phase and a neutral line of the bus of the first unit
Data Source
Figure 1
Figure 2
AI summary
A motor train unit auxiliary power supply apparatus. A normally open three-phase isolation contactor main contact is connected in series between a first unit three-phase four-wire system bus bar and a second unit three-phase four-wire system bus bar. A coil of the three-phase isolation contactor is connected in series between a first unit power supply circuit and a second unit power supply circuit. Two ends of a coil of a first unit alternating current relay are respectively connected to a one-phase bus bar (U101, V101, W101) and a neutral conductor (N100) of the first unit. Two ends of a coil of a second unit alternating current relay are respectively connected to a one-phase bus bar (U101A, V101A, W101A) and a neutral conductor (N100A) of the second unit. When the first unit three-phase four-wire system bus bar supplies power, the first unit control circuit controls the first unit power supply circuit to be powered on, the coil of the three-phase isolation contactor to get power, and the normally open three-phase isolation contactor main contact to be closed. When the second unit three-phase four-wire system bus bar supplies power, the second unit control circuit controls the second unit power supply circuit to be powered on, the coil of the three-phase isolation contactor to get power, and the normally open three-phase isolation contactor main contact to be closed. Any unit in the apparatus supplies power, and the three-phase isolation contactor is closed to realize power supply for the whole train.