Converter Contactor Current Detection for Overvoltage Shutdown
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Solution Overview
Problem
Existing converter systems fail to promptly stop operation when a contactor open failure occurs, leading to excessive output voltage and potential damage to electronic components due to delayed voltage regulation.
Innovation Solution
A converter system with dual contactors and current sensors that detect contactor drive current, allowing the controller to immediately stop the converter operation upon detection of an open failure, thereby preventing excessive output voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the converter output is stopped after the output voltage exceeds the overvoltage threshold, then the converter can be protected from damage, but there is a stop delay that causes the output voltage to become higher than the overvoltage threshold
Solution Approach 1:
The system performs preliminary detection of contactor drive current status before the overvoltage condition develops. By monitoring whether the contactor drive current is present, the control unit can detect contactor open failure in advance and stop the converter immediately, preventing the voltage from rising to dangerous levels.
Solution Approach 2:
The system uses feedback from the current sensor to continuously monitor the contactor drive current status. This feedback mechanism allows the control unit to detect when the contactor has opened due to failure and respond by stopping the converter, eliminating the delay inherent in threshold-based voltage monitoring.
2Object-affected harmful factors
If a capacitor with large capacitance is provided to prevent excessive voltage, then electronic components can be protected, but the system complexity and cost increase
Solution Approach 1:
The system replaces the passive mechanical/electrical approach of using a large-capacitance buffer with an active control approach. Instead of relying on the capacitor's physical properties to absorb voltage spikes, the control unit actively monitors contactor current and stops the converter immediately upon detecting open failure, eliminating the need for oversized capacitors.
Solution Approach 2:
The system uses its own control system and current sensing capability to protect itself from overvoltage damage. Rather than relying on external passive components like large capacitors, the converter monitors its own operating conditions and takes corrective action autonomously.
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
Prevents excessive output voltage by promptly stopping the converter when an open failure is detected, reducing the risk of component failure.
Implementation Method 1
a contactor (6) provided between the converter and the load in the first power supply path, the contactor including a normally open movable contact (13) for selectively establishing/interrupting the first power supply path and an electromagnetic coil (14) for driving the movable contact
Data Source
AI summary
A converter system includes: a first power supply path connecting a power supply and a load; a converter provided on the first power supply path; a contactor provided between the converter and the load, the contactor including a normally open movable contact for selectively establishing/interrupting the first power supply path and an electromagnetic coil for driving the movable contact; a contactor driving circuit electrically connected to the electromagnetic coil to drive the contactor; a current sensor for detecting a contactor drive current flowing from the contactor driving circuit to the electromagnetic coil; and a controller for controlling the converter and the contactor driving circuit. The controller stops operation of the converter in a case where the contactor drive current becomes undetected by the current sensor during operation of the converter.