AC Electric Vehicle Controller Power Failure Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional techniques for detecting power failures in AC overhead contact lines face challenges in accurately and promptly identifying balanced power failures, leading to decreased detection accuracy and potential erroneous stops during normal operations.
Innovation Solution
The controller employs a power failure detection system that uses specific-frequency settings to enhance sensitivity and accuracy by comparing main-transformer output currents and voltages with set values, extracting and subtracting specific-frequency components to determine power failures, thereby preventing erroneous detections and delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the power-failure detection set value is set small to detect balanced power failures with small fluctuation ranges, then power failure detection sensitivity is improved, but power failure detection accuracy decreases leading to erroneous detections
Solution Approach 1:
The patent applies dynamics by making the power-failure detection set value variable rather than fixed. The control unit dynamically adjusts the set value based on the absolute value of the deviation between the detected current and the extracted current component. When the deviation is large, a smaller set value is used for high sensitivity; when the deviation is small, a larger set value is used to prevent erroneous detections. This dynamic adjustment resolves the contradiction between detection sensitivity and detection accuracy.
2Ease of operation
If conventional power failure detection methods are used, then simple detection is possible, but detection accuracy decreases during balanced power failures due to small current and voltage fluctuations
Solution Approach 1:
The patent applies parameter changes by modifying the detection threshold parameter (power-failure detection set value) based on the operating conditions. Instead of using a fixed threshold, the system changes the threshold parameter dynamically according to the magnitude of current deviation. This allows the detection system to maintain high accuracy across different operating conditions, including balanced power failures where fluctuations are minimal, while preserving operational simplicity through automated parameter adjustment.
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
To improve power failure detection accuracy, while increasing power failure detection sensitivity as compared to that in conventional techniques, in a controller of an AC electric vehicle having a power failure detection function in an overhead contact line. The controller includes a first specific-frequency-current computation unit 14a that extracts a current component corresponding to a first specific frequency set value Fset1 from a main-transformer output current IS and outputs the current component as a first specific-frequency current I1, a subtractor 16 that subtracts the first specific-frequency current I1 from the main-transformer output current IS and outputs a subtraction result as a current deviation DI1, a second specific-frequency-current computation unit 15a that extracts a current component corresponding to a second specific frequency set value Fset2 from the current deviation DI1 and outputs the current component as a second specific-frequency current I2, and a power-failure detection unit 19a that compares the second specific-frequency current I2 with a predetermined power-failure detection-current set value Iset and outputs a power-failure detection signal when the second specific-frequency current I2 is larger than the power-failure detection-current set value Iset.