Power Converter Voltage Control With Overcurrent Suppression
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Solution Overview
Problem
Power conversion devices with voltage-controlled operations are prone to generating overcurrents due to abrupt changes in system voltage, which can lead to component failure.
Innovation Solution
A power conversion device and its control system that include measurement devices for line currents and phase voltages, and a control device with a command value calculation part and an overcurrent suppression controller. The control device calculates instantaneous voltage output command values to suppress overcurrents by using input information from both the power conversion part and the major circuit part.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a voltage source voltage-controlled power conversion device is used to enable seamless transition between system-connected and isolated operation, then adaptability is improved, but the risk of generating overcurrent due to abrupt system voltage changes increases
Solution Approach 1:
The control device calculates instantaneous voltage output command values in advance by using measured phase voltages and line currents from both the power conversion part and major circuit part. This preliminary calculation allows the system to proactively suppress overcurrent before it occurs during abrupt system voltage changes, enabling reliable voltage-controlled operation during seamless transitions between operation modes
Solution Approach 2:
The system continuously measures phase voltages and line currents at multiple points (power conversion part output and major circuit part output) and feeds this information back to the control device. The control device uses this real-time feedback to dynamically adjust voltage output command values, suppressing overcurrent while maintaining the adaptability of voltage-controlled operation for seamless mode transitions
2Adaptability or versatility
If voltage-controlled operation is performed to improve system adaptability, then operational flexibility is improved, but instantaneous potential differences may generate overcurrent causing component failure
Solution Approach 1:
The control device acts as an intermediary between the power conversion part and the major circuit part. It receives measured values from both sides, calculates appropriate voltage output command values that account for instantaneous potential differences, and generates control signals that suppress overcurrent while maintaining voltage-controlled operation capability
Solution Approach 2:
The control device dynamically changes voltage output parameters (instantaneous voltage command values) based on real-time measured phase voltages and line currents. By adjusting these parameters in response to system conditions, the system maintains voltage-controlled operation flexibility while suppressing harmful overcurrent effects
Data Source
AI summary
A power conversion device is provided, and includes a major circuit part, and a control device; the major circuit part includes a power conversion part converting, into AC power, power that is input, and a filter circuit causing the AC power output from the power conversion part to approach a sine wave; the control device controls power conversion by the major circuit part by controlling an operation of the power conversion part; the control device includes an overcurrent suppression controller; the overcurrent suppression controller calculates instantaneous value voltage output command values of the phases of the AC power output from the power conversion part to suppress an overcurrent at the output end of the major circuit part. Accordingly, a power conversion device and a control device of the power conversion device are provided in which the generation of an overcurrent can be suppressed even when a voltage-controlled operation is performed.