Inverter Switch-Off Device for Safe Electric Machine Shutdown
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Solution Overview
Problem
Existing electric machine control systems face challenges in safely switching off the machine, especially when the control device is defective or not connected, leading to potential short circuits due to unclear valve closure determination.
Innovation Solution
An inverter configuration with a switch-off device that can dynamically close all first or second current valves based on a switch-off signal, independent of the control device's signals, ensuring a safe state by controlling the electric machine's current flow, even in fault conditions, and integrating the switch-off device with the inverter for redundant control paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If control terminals of current valves are connected to fixed potential via pull-up or pull-down resistors to enable active short circuit in case of control device defect, then the machine can be switched off even with control device failure, but it is unclear which current valves close and a short circuit in the link circuit may occur
Solution Approach 1:
The patent applies preliminary action by pre-configuring the switch-off device to autonomously determine and execute the correct valve closure sequence before a fault occurs. The switch-off device is designed with predetermined logic to identify which current valves should close based on the operational state, ensuring that the safe state transition follows a pre-planned path that avoids link circuit short circuits even when the control device fails.
Solution Approach 2:
The switch-off device acts as an intermediary between the control device and the current valves. It receives the switch-off signal and independently determines which valves to close, mediating the control signal to ensure safe state transition without directly relying on the potentially defective control device signals. This intermediary function prevents harmful short circuits while maintaining the ability to switch off the machine.
2Reliability
If all first current valves are closed to bring machine to safe state, then machine shutdown is achieved, but current may flow through unintended paths causing short circuit
Solution Approach 1:
The patent applies local quality by making the valve closure action selective rather than uniform. The switch-off device determines locally which specific current valves should close based on the operational state and safety requirements, rather than closing all valves indiscriminately. This localized control ensures that shutdown is achieved while preventing unintended current paths that could cause short circuits.
Solution Approach 2:
The switch-off device performs preliminary analysis to determine the correct valve closure configuration before executing the shutdown. By pre-determining which valves should close based on the current operational state, the system ensures that the shutdown path is safe and does not create unintended current paths, while still achieving reliable machine shutdown.
3Ease of operation
If control device signals are used to determine valve closure, then normal control functionality is maintained, but in case of control device defect the determination of which valves to close becomes uncertain
Solution Approach 1:
The switch-off device serves as an intermediary that processes the switch-off signal independently of the control device's operational signals. It mediates between the external switch-off request and the current valve control, using its own internal logic to determine valve closure rather than relying on control device signals. This maintains normal control functionality while ensuring reliable valve determination in fault conditions.
Solution Approach 2:
The switch-off device performs self-service by autonomously determining which valves to close without requiring signals from the control device. It uses its own internal logic and the switch-off signal to make the determination, making the system self-sufficient in fault conditions while maintaining compatibility with normal control operations when the control device is functional.
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
The solution enables safe and reliable shutdown of the electric machine by autonomously determining which current valves to close, preventing short circuits and ensuring the machine is in a non-operational state, even if the control device is faulty, with high processing speed and resistance to interference.
Implementation Method 1
Each first current valve (120) is configured to control current between the high electrical potential and the assigned terminal, and each second current valve (125) is configured to control current between the assigned terminal and the low electrical potential
Implementation Method 2
A kinetic energy of the machine can then be converted into electrical energy and the latter can be converted into heat by way of the short circuit
Implementation Method 3
the latter can be converted into heat by way of the short circuit
Data Source
AI summary
The invention relates to an inverter for controlling an electric machine on a voltage source having a first and a second potential. The inverter comprises a plurality of bridge circuits which each comprise a first flow control valve, a second flow control valve and a connector for the electric machine, and a first interface for receiving individual control signals for the flow control valves and a second interface for detecting a switch-off signal. Each first flow control valve is configured to control current between the high electrical potential and the associated connector, and each second flow control valve is configured to control current between the associated connector and the low electrical potential. A switch-off device is configured to close either all first or all second flow control valves as a function of the shut-off signal and independently of signals on the first interface.