The cascaded H-bridge topology is the most common design used in the Medium Voltage variable frequency drive industry. Rockwell/Allen Bradley has been transitioning customers to their voltage-source medium voltage drive: The Powerflex6000. This replaces the older current-source Powerflex7000 medium voltage variable frequency drive. The Powerflex 6000 design is similar to many other cascaded H-bridge topology drives, like the Robicon/Siemens perfect harmony variable frequency drive. EMA has experience in repair and service of the Powerflex7000 and Powerflex6000.
Unlike low voltage VFDs, medium voltage VFD designs differ from one manufacturer to another. Manufacturers vary in switching schemes in the inverter section, and also use different internal components. For example: some manufacturers use oil filled bus capacitors, some use self-healing film capacitors, while others use electrolytic capacitors. In general, oil filled capacitors in MV VFDs last longer than the film capacitors, while film capacitors last longer than electrolytic capacitors.
The Rockwell Powerflex6000 MV VFD is a voltage source drive, unlike its predecessor, the Powerflex7000, which is a current source drive. It uses electrolytic bus capacitors in the DC link section. Electrolytic bus capacitors have a useful life of roughly 7 seven years, and although we have not seen any Powerflex6000’s that need bus capacitor replacement yet (because they are all relatively new) we expect to see the need for this soon.
The experience we have gained while working on both voltage-source and current-source medium voltage variable frequency drives allows us to help our customers on the Powerflex series variable frequency drives, and also on many other types of MV Drives such as: ABB ACS2000, ABB ACS1000, WEG MVW01, WEG MV3000, Toshiba T300MVi and MV2 Series, and the Siemens/Robicon Perfect Harmony Series Drives. We would appreciate an opportunity to work for you in getting your medium voltage variable frequency drives up and running. Contact us via email, call us, or click the chat to your right. Let us prove to you that No One ANYWHERE, Is Better At Drives Than We Are.