Inverter DC-Link Voltage Control for Capacitor Protection
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Solution Overview
Problem
Inverters face operational shutdowns and capacitor damage due to overvoltage faults caused by large input voltage fluctuations, which exceed the rated voltage of the direct current-link capacitor, leading to frequent overvoltage faults and reduced capacitor lifespan.
Innovation Solution
A method for controlling the inverter that monitors the direct current-link voltage and accumulates a cumulative value based on voltage and time, blocking output when the voltage exceeds predefined thresholds, and updates the value when within the rated voltage range, thereby preventing overvoltage faults and extending capacitor lifespan without hardware changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the inverter operates with large input voltage fluctuations, then the operable region is expanded, but the direct current-link voltage exceeds the rated voltage causing overvoltage faults and capacitor damage
Solution Approach 1:
The control method performs preliminary detection of direct current-link voltage before overvoltage damage occurs. By continuously monitoring the voltage and comparing it against the rated voltage threshold, the system takes preventive action before the capacitor is damaged, allowing expanded operable region while protecting capacitor lifespan
Solution Approach 2:
The system implements feedback control by detecting the direct current-link voltage and using this information to control the inverter operation. When the voltage exceeds the rated voltage, the system provides feedback to stop operation, preventing capacitor damage while allowing normal operation within safe voltage ranges
2Reliability
If the inverter stops operation when direct current-link voltage exceeds rated voltage, then capacitor damage is prevented, but continuous operation is reduced
Solution Approach 1:
The control method detects overvoltage conditions preliminarily and stops the inverter before capacitor damage occurs. This preliminary detection and protective stopping prevents capacitor damage while minimizing operational interruption, as the system can resume operation once voltage returns to safe levels
Solution Approach 2:
The system uses feedback from voltage detection to control inverter operation dynamically. When overvoltage is detected, operation is stopped to protect the capacitor; when voltage returns to normal range, operation can resume, enabling continuous operation while maintaining capacitor protection
Data Source
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AI summary
The present disclosure provides a method for controlling an inverter in an inverter system including the inverter, wherein the inverter includes a direct current-link capacitor, and an inverting unit including a plurality of switching elements, wherein the inverter system includes a control unit for controlling the inverting unit, wherein the method comprises: checking whether a direct current-link voltage of the direct current-link capacitor is equal to or greater than a predefined first voltage; checking whether the direct current-link voltage is greater than or equal to a second voltage greater than the first voltage; when the direct current-link voltage is greater than or equal to the first voltage and is smaller than the second voltage, calculating a value using the direct current-link voltage and a time, and accumulating the calculated value over time to generate a cumulative value; when the cumulative value is greater than or equal to a predefined first value, blocking an output of the inverting unit; and when the direct current-link voltage is smaller than the first voltage, obtaining a value by subtracting a second predefined value from the cumulative value, and updating the cumulative value as the obtained value.