DC Voltage Detection in Thyristor Power Converters
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing thyristor starters are bulky and expensive due to the need for a separate DC voltage detector to prevent excessive DC voltage and monitor ripples, which increases size and cost.
Innovation Solution
A power converter that integrates a DC voltage detector functionality within the existing AC voltage detection system, using the control circuit to determine DC voltage based on detected AC voltages, eliminating the need for a separate DC voltage detector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate DC voltage detector is provided to detect DC voltage and prevent overvoltage breakdown, then the reliability of the power converter is improved, but the device size and manufacturing cost increase
Solution Approach 1:
The patent merges the DC voltage detection function with the existing AC voltage detector by adding a holding circuit that maintains the detected AC voltage signal during the rectification period. This allows the single detector to provide both AC voltage detection and DC voltage monitoring capabilities without requiring a separate DC voltage detector, thereby improving reliability while avoiding increased device size.
Solution Approach 2:
The existing AC voltage detector is made multi-functional by incorporating a holding circuit that preserves the AC voltage signal. This enables the same detector to serve dual purposes: detecting AC voltage for control purposes and deriving DC voltage information for overvoltage protection, thus eliminating the need for a dedicated DC voltage detector and reducing overall device complexity.
2Reliability
If a separate DC voltage detector is provided to monitor DC voltage ripples, then the reliability of the power converter is improved, but the manufacturing cost increases
Solution Approach 1:
The patent combines the DC voltage monitoring function with the existing AC voltage detector through the holding circuit. The holding circuit maintains the AC voltage signal level, which corresponds to the DC voltage level after rectification. This allows the single detector to monitor both AC input voltage and DC output voltage ripples, improving reliability without adding extra detection components and keeping manufacturing costs low.
Solution Approach 2:
The AC voltage detector is enhanced to perform multiple functions including AC voltage detection, DC voltage level monitoring, and ripple detection. By using the holding circuit to preserve the AC voltage signal representation, the same detector circuitry can identify DC voltage anomalies and ripples, eliminating the need for separate DC detection hardware and reducing manufacturing complexity and cost.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
In a thyristor control device which converts a first AC voltage to a DC voltage and converts the DC voltage to a second AC voltage to be supplied to a synchronous motor (11), a DC voltage detector (7, 40) is configured to detect the DC voltage, and is provided with an AC voltage detector (7) configured to detect the second AC voltage and an arithmetic circuit (40) configured to determine the DC voltage on the basis of the second AC voltage detected by the AC voltage detector (7). As a result, there is no need to separately provide a DV voltage detector, which makes it possible to make the device compact in size and cheap in price.