Medium voltage variable speed drives double rated power



More than twice the previous rated maximum power is delivered with the air-cooled MVW01 medium voltage variable speed drives, says WEG.

The air-cooled drives meet the needs of medium voltage three-phase induction and synchronous motors across a broader power range and range from 6.5 to 16MW for voltages from 2.3 to 4.16kV. The company's entire range now covers 2.3 to 6.9kV and the rated power range from 400kW to 16MW.

A water-cooled version is also available, offering up to 40% higher rated power than the air-cooled model. With efficiency levels of more than 99%, the drive achieves the best efficiency of any medium voltage drive currently available on the market, according to the company, meaning customers can increase energy efficiencies, while reducing the environmental footprint and making associated cost savings.

The drive is suitable for a pumps, fans, mills and agitators in the oil and gas, mining, minerals and metals, chemical, paper, plastics and rubber, and water and wastewater sectors.

A voltage source inverter (VSI) topology has a three-phase rectifier, DC link and multi-level output converter using Neutral Point Clamped (NPC) technology with three or five voltage level for output from 2.3 to 4.16kV or five or nine voltage levels for output of 6.0 to 6.9kV. Specifically designed for the harsh conditions of traction applications, the frequency inverter is equipped with the IGBTs (insulated-gate bipolar transistors) for voltages up to 6.5kV, and a DC link with a 12-pulse bridge rectifier, with 18-, 24- or 36-pulse rectifiers available as an option.

Multi-pulse diode configuration of the input rectifier offers a power factor over 97%, which translates into lower demand for incoming current, reducing costs. Driven by the company's Optimised Pulse Pattern (OPP) clocking method, the output stage topology of the inverter (multi-level NPC) enables optimal switching behaviour that minimises motor current harmonics.

Maintenance is simplified by plug-in inverter power modules (one per phase), while the NPC inverter topology with multi-level technology offers a relatively low number of power components.

A fibre optic interface is used for the inverter drive signals and signal feedback to the CPU to reliably isolate the medium-voltage components from the control circuit and the control interfaces. In addition, the variable speed drives are housed in IP41-rated cabinets and support all commonly used network protocols, including DeviceNet, Modbus, Profibus DP and Ethernet. Flow-through ventilation with top-mounted fans provides extremely effective heat dissipation and a low noise level (less than 75dB A).