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VFD DC Link System (DC-BANK)
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Product Overview:
Generally, the Variable Frequency Drives (VFDs) are equipped with over-voltage, under-voltage, and momentary power-off protection functions. When a VFD experiences undervoltage or a power outage, the inverter element, which uses IGBT technology, will allow the VFD to continue operating for a predefined period (td). If the undervoltage or power interruption lasts for less than td (to < td), the VFD will smoothly recover and continue running. However, if the duration exceeds td (to > td), the VFD will activate its protection mechanism and stop operation. There-fore, significant AC power fluctuations or prolonged undervoltage conditions can cause the VFD to cease operation. Currently, most common VFDs are AC-DC-AC voltage-source inverters, where the intermediate DC circuit is generated through three-phase AC rectification, resulting in a voltage of approximately 510-620V. Therefore, supplying a VFD with a DC power source in the range of 510-620V will enable the it to operate continuously. Based on this principle, we have developed the LD/DC-BANK, an uninterrupted power supply system that provides DC support for VFDs.
Product Composition:
- Circuit breaker.
- VFD drive module, composed of rectifier, inverter, and control unit.
- Rectifier, composed of diodes or thyristors, filter capacitors, and control units.
- Voltage sag protection module.
- Energy storage unit, which is necessary to address short interruptions. Usually, it is composed of standard energy storage batteries or super capacitors.