Inverter Shutdown Test via External Trigger Signal
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Solution Overview
Problem
Existing methods for performing shutdown tests on inverters are cumbersome and unsafe due to the need for internal access to high-voltage trigger signals, requiring expensive and high-resolution oscilloscopes, which complicates the determination of shutdown duration and increases safety risks.
Innovation Solution
A method that uses a defined period before applying a fault signal, allowing precise determination of the shutdown duration by measuring AC current or voltage, which can be synchronized to zero crossings, enabling automatic and safer shutdown testing without additional hardware or expensive equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a trigger output is provided internally in the inverter to signal the moment of fault signal application, then the shutdown duration can be determined precisely, but the inverter must be opened to access the trigger signal which exposes operators to high voltages greater than 50V safety extra low voltage
Solution Approach 1:
The patent introduces an intermediary signal - a trigger signal that is coupled to the switching arrangement and can be detected externally through standard I/Os. This trigger signal acts as a mediator that conveys the moment of fault signal application without requiring direct access to high-voltage internal circuits. The trigger signal is generated by the control unit and transmitted through safe I/O interfaces, allowing external systems to synchronize fault detection and measure shutdown duration without exposing operators to dangerous voltages.
Solution Approach 2:
The patent replaces the mechanical/electrical approach of physically opening the inverter to access trigger signals with an electronic signal transmission approach. Instead of requiring physical access to internal high-voltage circuits, the trigger signal is transmitted through standard I/O interfaces that operate at safe voltage levels. This substitution eliminates the need for physical opening of the inverter while maintaining precise timing capability for shutdown duration measurement.
2Measurement precision
If a separate trigger output is provided on the inverter hardware to enable precise shutdown timing measurement, then the shutdown duration can be determined accurately, but the circuit becomes more complex and expensive
Solution Approach 1:
The patent makes the existing I/O interfaces multi-functional by enabling them to serve both normal operational functions and shutdown test functions. The same I/Os that are used for standard inverter control and monitoring are also utilized to detect the trigger signal and measure shutdown duration. This eliminates the need for dedicated separate trigger outputs while maintaining precise measurement capability, thereby avoiding increased circuit complexity and cost.
Solution Approach 2:
The inverter's existing control unit and I/O system serve the additional function of generating and transmitting the trigger signal for shutdown testing. Instead of requiring external or separate trigger generation hardware, the inverter's own control unit generates the trigger signal and the existing I/O infrastructure handles its transmission. This self-service approach eliminates the need for additional hardware components while achieving precise shutdown timing measurement.
3Measurement precision
If high resolution oscilloscopes are used to record relevant signals for shutdown testing, then precise measurement of shutdown duration is possible, but the testing becomes expensive
Solution Approach 1:
The patent replaces expensive high-resolution oscilloscopes with standard, lower-cost I/O interfaces and measurement systems. By providing a clean digital trigger signal through standard I/Os, the system enables accurate shutdown duration measurement using conventional measurement equipment rather than requiring expensive high-resolution oscilloscopes. This substitution of expensive measurement tools with cheaper alternatives maintains measurement precision while significantly reducing testing costs.
Data Source
AI summary
In order to be able to perform a shutdown test on an inverter with little expenditure, a trigger signal is modulated to the AC current or the AC voltage at a first moment, and the inverter is used at a second moment, which occurs a defined duration after the start of the trigger signal at the first moment, to generate an AC current or an AC voltage with a fault signal that is detected by the inverter and which triggers a shutdown of the inverter, and the shutdown moment of the AC current or the AC voltage is determined. A shutdown duration of the inverter is determined from the difference between the shutdown moment and the second moment.