Vehicle Control Device Inrush Current Suppression
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Solution Overview
Problem
Voltage oscillations due to mechanical vibrations can lead to erroneous power supply determination in electric railway vehicles, causing unnecessary disconnection from the overhead line and preventing power delivery to load devices.
Innovation Solution
A vehicle control device with a power converter, first and second voltage detectors, and a contactor controller that closes or opens contactors based on voltage differences to accurately suppress inrush currents by determining when the voltage decreases exceed specific thresholds, ensuring accurate power supply assessment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If voltage threshold detection is used to determine power supply status, then inrush current suppression can be achieved, but measurement accuracy deteriorates due to voltage oscillations from mechanical vibrations
Solution Approach 1:
The voltage detection function is segmented into two independent detection paths: first voltage detection (power supply line voltage) and second voltage detection (power converter output voltage). This segmentation allows each detector to monitor specific voltage points, and the control unit compares both voltages to determine power supply status, preventing erroneous judgments caused by oscillations at a single detection point.
Solution Approach 2:
The control unit acts as an intermediary that processes and compares voltages from both detectors. Instead of relying on a single voltage threshold comparison, the control unit evaluates the relationship between first voltage (from power supply line) and second voltage (from power converter), using this intermediate comparison to accurately determine power supply status even when voltage oscillations occur.
2Ease of operation
If single voltage threshold comparison is used, then detection simplicity is maintained, but determination accuracy deteriorates under vibration conditions
Solution Approach 1:
The detection system is segmented into two independent voltage detection channels with separate detectors monitoring different voltage points. This segmentation transforms the simple but inaccurate single-threshold method into a dual-channel comparison system that maintains operational simplicity while significantly improving determination accuracy under vibration conditions.
Solution Approach 2:
The control unit continuously monitors both first and second voltages and uses feedback from this dual-voltage information to determine power supply status. By comparing the relationship between the two voltages rather than relying on a single static threshold, the system provides accurate feedback-based determination that adapts to voltage oscillations caused by mechanical vibrations.
Data Source
AI summary
A vehicle control device includes a power converter that converts supplied direct current power and supplies the converted direct current power to a load device. A first voltage detector detects a first voltage that is a voltage of the power supply line. A second voltage detector detects a second voltage that is a voltage of the power converter on a side where a power supply source is provided. When a first contactor is closed and brought into a state allowing current to flow through the first contactor, if a decreasing amount of the first voltage from a first time ago to a present time is greater than or equal to a first threshold and a decreasing amount of the second voltage from a second time ago to the present time is greater than or equal to a second threshold, a contactor controller opens the first contactor.