DC Auxiliary Safety Circuit for Continuous Safe Turn-Off Testing
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Solution Overview
Problem
Existing power electronic devices face challenges in testing the functionality of safe turn-off circuitry without interrupting device operation, as traditional methods of switching off auxiliary voltage disrupt continuous processes.
Innovation Solution
A safety circuit arrangement that allows separate disconnection of each DC auxiliary voltage pole, with energy storage maintaining output voltage above a limit, and feedback signals indicating component states, enabling regular testing without operation interruption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the auxiliary voltage is switched off to ensure safe turn-off functionality, then the safety function is achieved, but the device operation is interrupted
Solution Approach 1:
The DC auxiliary voltage is segmented into separate poles (positive and negative), allowing independent disconnection of each pole. This enables testing of safe turn-off functionality by disconnecting one pole at a time while maintaining the other, thus avoiding complete operation interruption
Solution Approach 2:
Energy storage devices (capacitors) are pre-charged during normal operation to maintain output voltage above the limit value during testing. This preliminary energy storage enables the safety circuit to remain functional during pole disconnection tests without interrupting device operation
2Reliability
If the auxiliary voltage is switched off to test safety functionality, then the functionality can be tested, but normal operation is disrupted
Solution Approach 1:
The safety circuit functionality is tested through periodic disconnection of individual DC voltage poles during normal operation. The energy storage devices maintain voltage levels during these periodic tests, enabling continuous functionality verification without operational disruption
Solution Approach 2:
The safe turn-off circuit generates feedback signals indicating the operating states of critical components. This feedback enables monitoring and verification of safety functionality during operation, allowing continuous testing without interrupting device operation
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 reliable and continuous testing of safe turn-off functionality in power electronic devices, ensuring compliance with safety standards like IEC61508 without disrupting normal operation.
Implementation Method 1
When only one DC pole is disconnected, an energy storage device maintains the output voltage of the safety circuitry above a limit value for at least a predefined time period
Data Source
AI summary
A safety circuit coupled between a first direct current (DC) circuit and a second DC circuit, wherein the first DC circuit supplies power to the second DC circuit. The safety circuit comprises a first series connection between positive poles of the first and second DC circuits (the first series connection comprising a first diode, a second diode and a first controllable switch), a second series connection between negative poles of the first and second DC circuits (the second series connection comprising a third diode, a fourth diode and a second controllable switch), a first energy storage device (coupled between the positive pole of the second DC circuit and the first terminal of the second controllable switch), and a second energy storage device (coupled between the negative pole of the second DC circuit and the first terminal of the first controllable switch). The safety circuit further comprises a first feedback circuit for indicating an active state of the first controllable switch and a second feedback circuit for indicating an active state of the second controllable switch.