Converter Failure Detection via Power Disconnection
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Solution Overview
Problem
Conventional methods for detecting failures in power transistors within converter apparatuses risk causing short circuits when power devices are turned on in a powered state, potentially damaging the converter apparatus.
Innovation Solution
A converter apparatus and method that includes a DC link capacitor, a charging circuit, current and voltage detectors, a switch for connecting/disconnecting the power supply, and a failure detector that compares currents after disconnecting the power supply to determine the presence of failures using threshold values, preventing damage by assessing currents post-disconnection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If power devices are turned on in a powered state to detect failure, then failure detection capability is improved, but short circuit risk increases causing potential damage to the converter apparatus
Solution Approach 1:
The patent applies preliminary action by disconnecting the power supply before turning on the power devices for failure detection. The control device first opens the switch to disconnect the AC power supply, then turns on the power devices in a powered-off state to perform resistance value measurement. This sequence prevents short circuits during the detection process while maintaining effective failure detection capability.
Solution Approach 2:
The patent applies preliminary anti-action by preemptively disconnecting the power supply before the failure detection process begins. The control device opens the switch to eliminate the harmful effect of powered state during detection, preventing potential short circuits. This counter-action ensures that the detection process occurs in a safe, powered-off condition while still achieving reliable failure detection.
2Object-affected harmful factors
If power supply is disconnected before failure detection, then safety is improved preventing short circuits, but detection timing complexity increases
Solution Approach 1:
The patent applies feedback by using the control device to monitor and manage the switching state of the power supply connection. The control device receives feedback from the switch position and automatically adjusts the detection sequence accordingly - only initiating failure detection when the power supply is disconnected. This feedback mechanism simplifies the overall control logic by creating a clear conditional sequence rather than complex simultaneous control.
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
Effectively detects open-circuit and short-circuit failures in power devices without causing damage, ensuring safe operation and preventing re-powering of faulty components.
Implementation Method 1
a DC link capacitor connected to an output side of the converter
Implementation Method 2
a voltage detector configured to detect the voltage of the DC link capacitor
Implementation Method 3
a current detector configured to detect a current flowing between the converter and the DC link capacitor
Data Source
AI summary
A converter apparatus includes: a converter for converting an AC voltage into a DC voltage; a DC link capacitor connected to the converter; a voltage detector for DC link voltage; a charging circuit for the DC link capacitor; a charging circuit controller for a switch connected with a charging resistor; a current detector for detecting a current of the converter; a turn-on controller for controlling the turning-on of power devices; a switch for connecting or disconnecting a power supply; a power supply monitor for monitoring a connection state of the power supply; a threshold value setter for setting a first or second threshold value; and a failure detector for determining the presence or absence of the failure of the power devices by a comparison between a current flowing upon turning on the power device, immediately after disconnection of the power supply, and the first or second threshold value.