Single-Type Converter Pole Fault Voltage Control
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Solution Overview
Problem
Conventional single-type converters for DC distribution struggle to maintain normal DC power supply when a fault occurs at a pole, especially during short circuits or overloads, due to difficulties in applying current limits for protection coordination.
Innovation Solution
An apparatus and method for controlling output voltage in a single-type converter, which includes a power input/output unit, an output voltage and current measurement unit, a controller, and a switching unit, allowing for current limit control and voltage control across both poles to maintain steady-state output voltage during faults, using capacitors and switching units to manage power transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single-type converter is used for DC distribution, then the converter is economical and compact, but it has difficulty providing normal DC power supply when a fault occurs at a pole
Solution Approach 1:
The patent implements dynamic control of the converter operation mode based on real-time detection of pole fault conditions. The controller switches between different operational states: normal bipolar operation, single-pole operation during faults, and current limiting modes. This dynamic adaptability allows the single-type converter to maintain reliability during pole faults while remaining economical and compact in normal operation.
Solution Approach 2:
The patent changes operational parameters (current limits, voltage references, switching patterns) based on the detected pole condition. During a pole fault, the controller modifies current limiting parameters and voltage control parameters to prevent damage while maintaining power supply to the healthy pole. This parameter adaptation resolves the contradiction by enabling the converter to handle fault conditions without requiring a more complex dual-converter architecture.
2Reliability
If current limit control is applied for protection coordination at a faulty pole, then protection is provided, but output voltage unbalance occurs between the two poles
Solution Approach 1:
The patent intentionally applies asymmetric control to the two poles based on their respective conditions. The healthy pole receives full voltage control while the faulty pole receives current-limited control. This asymmetric treatment resolves the voltage unbalance issue by allowing each pole to operate according to its actual condition, rather than forcing symmetric control that would compromise either protection or voltage stability.
Solution Approach 2:
The patent segments the control strategy into independent control loops for each pole. The controller separately manages voltage control for the healthy pole and current limiting for the faulty pole, allowing independent optimization of each pole's performance. This segmented approach enables simultaneous achievement of protection coordination and voltage balance.
3Reliability
If a bipolar method is used for DC distribution, then supply capacity and reliability are increased, but the converter becomes more complex and costly
Solution Approach 1:
The patent makes the single-type converter universal by enabling it to perform multiple functions: normal bipolar power conversion, single-pole power supply during faults, and protective current limiting. This multi-functionality allows one converter to replace what would traditionally require two separate converters, reducing complexity while maintaining the reliability benefits of bipolar distribution.
Solution Approach 2:
The patent implements dynamic reconfiguration capability that allows the converter to adapt its topology and control strategy based on operational conditions. During normal operation, it functions as a standard bipolar converter; during pole faults, it dynamically reconfigures to provide single-pole operation with appropriate protection. This dynamic versatility achieves high reliability without the permanent complexity of a dual-converter system.
Data Source
AI summary
The present invention relates to an apparatus for controlling an output voltage for a single-type converter and a method therefor, the apparatus including: a power input/output unit connected in parallel to both poles of the single-type converter, respectively, thereby receiving and outputting output voltages, respectively; an output voltage and current measurement unit measuring output currents and the output voltages output from the power input/output unit; a controller performing a current limit control for a protection coordination for a first pole and performing a voltage control for a second pole following a checking of a state of the first pole of the both poles of the single-type converter using the measured output currents; a switching unit being switched according to a control performed on the both poles; and a power transfer unit transferring the output voltages of the single-type converter according to switching of the switching unit.