Reverse Converter Voltage Correction for DC Component Elimination
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Solution Overview
Problem
Power conversion devices face challenges in accurately controlling reverse converters when voltage division ratios of voltage dividers are not identical, leading to residual DC components in three-phase AC voltages, which can cause asymmetrical excitation in transformers.
Innovation Solution
A power conversion device comprising a reverse converter, voltage dividers, detectors, a storage unit, and a correction unit that detects and removes DC components resulting from errors in voltage division ratios, ensuring accurate control of the reverse converter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If voltage division ratios of the first to third voltage dividers are not identical, then the device structure can be simpler or manufacturing easier, but DC components resulting from errors of voltage ratios are included in the third three-phase AC voltages, making the reverse converter unable to be controlled accurately
Solution Approach 1:
The patent applies preliminary action by detecting voltage division ratio errors in advance and storing correction values before control operations. The correction unit uses these pre-stored error values to compensate for DC components in real-time, allowing accurate control without requiring precisely matched voltage dividers during manufacturing
Solution Approach 2:
The patent implements feedback by detecting the actual voltage division ratios, storing the error information, and using this feedback to correct control signals. The correction unit continuously compensates for DC components based on the stored error data, creating a closed-loop system that maintains control accuracy despite manufacturing variations
2Device complexity
If the reverse converter is controlled to eliminate DC components of the third three-phase AC voltages without correction, then the control process is simpler, but when voltage division ratios are not identical, DC components cannot be eliminated accurately
Solution Approach 1:
The patent introduces an intermediary correction unit that mediates between the voltage detectors and the reverse converter control. This correction unit processes the detected voltage errors and generates corrected control signals, serving as an intermediary layer that improves control reliability without significantly increasing overall system complexity
Solution Approach 2:
The correction values are determined and stored in advance before actual control operations. This preliminary preparation of correction data allows the control system to reliably eliminate DC components during operation without complex real-time calculations, maintaining simplicity while improving reliability
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
The device effectively eliminates DC components from three-phase AC voltages, enabling precise control of the reverse converter even when voltage division ratios are not identical, thereby preventing asymmetrical excitation in transformers.
Implementation Method 1
a reverse converter that converts DC voltage into three-phase AC voltage
Implementation Method 2
the first to third voltage dividers divide the first three-phase AC voltages to generate second three-phase AC voltages
Implementation Method 3
The first to third voltage detectors detect third three-phase AC voltages that are line-to-line voltages of the second three-phase AC voltages. The fourth voltage detector detects a neutral point voltage of the first three-phase AC voltages
Data Source
AI summary
In this power conversion device, first three-phase AC voltages generated by an inverter and an AC filter are divided by first to third voltage dividers to generate second three-phase AC voltages, and third three-phase AC voltages that are line-to-line voltages of the second three-phase AC voltages and a neutral point voltage of the first three-phase AC voltages are detected. Then, DC components of the third three-phase AC voltages resulting from errors of voltage ratios of the first to third voltage dividers are obtained based on the detection results and contents in a storage unit, the DC components are removed from the third three-phase AC voltages to generate fourth three-phase AC voltages, and the inverter is controlled such that DC components of the fourth three-phase AC voltages are eliminated.