Segmented HVIL Safety Circuit for Fault Isolation in Traction Systems
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Solution Overview
Problem
In high-voltage electrical systems with multiple machines, existing safety circuits often require shutting down the entire system due to a single fault, which is undesirable as it can disrupt critical functions like steering in marine vessels.
Innovation Solution
A safety circuit comprising a primary high voltage interlock loop connected to a battery and secondary interlock loops for each machine, where switch units can break the secondary loops and trigger the primary loop to disconnect power in case of a fault, allowing selective machine disconnection and ensuring safety during maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single fault in an electrical machine is detected, then the entire power system must be shut down for safety, but this causes loss of critical functions and reduced system availability
Solution Approach 1:
The HVIL system is segmented into multiple independent circuits: a primary HVIL circuit connected to the battery and secondary HVIL circuits connected to individual electrical machines. Each machine has its own switch unit that can open its secondary circuit independently. This segmentation allows fault isolation to a single machine without affecting the entire system, resolving the contradiction between safety and availability.
2Reliability
If the primary HVIL circuit is broken to ensure safety during maintenance, then all electrical machines are disconnected, but this prevents selective maintenance and reduces operational flexibility
Solution Approach 1:
The switch units are segmented into individual components associated with each electrical machine. Each switch unit can open its secondary HVIL circuit independently, allowing selective disconnection of a single machine for maintenance while leaving other machines operational. The trigger device provides an additional layer by enabling controlled breaking of the primary circuit when needed, giving operators flexibility to choose the appropriate disconnection level.
Solution Approach 2:
The system transitions from a static all-or-nothing disconnection approach to a dynamic selective disconnection approach. The switch units and trigger device enable the system to adapt its disconnection level based on operational needs, allowing maintenance personnel to isolate only the necessary components while maintaining power to critical systems.
3Reliability
If manual shutdown procedures are used to disconnect high-voltage systems, then the system can be safely shut down, but this requires human intervention and is prone to human error
Solution Approach 1:
The HVIL system implements self-service through automatic detection and response to faults. When a fault is detected in an electrical machine, the corresponding switch unit automatically opens its secondary HVIL circuit, and the trigger device can automatically break the primary circuit if needed. This eliminates the need for manual intervention in fault response, reducing human error and ensuring consistent safety protocols are followed.
Data Source
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AI summary
The invention relates to a safety circuit (100) for a high-voltage electrical traction system comprising a plurality of electric machines (102a-b). The safety circuit comprises: a primary high voltage interlock loop, HVIL, circuit (104) configured to be connected to a battery (106); and for each of the plurality of electric machines, a secondary high voltage interlock loop, HVIL, circuit (108a-b), wherein each secondary HVIL-circuit is controlled by a corresponding switch unit (110a-b) configured to break the secondary HVIL-circuit if a fault in a corresponding electric machine is detected, and wherein the switch unit comprises a trigger device (114a-b) configured to break the primary HVIL-circuit if the switch unit is opened.