Energy-saving PM torque motors challenge DC drives

At the recent SPS/IPC/Drives show in Germany, the French motor-maker Parvex — part of Parker SSD Drives — unveiled a permanent magnet synchronous torque motor aimed at low-speed, high-torque applications.

Michel Bernard, the company`s commercial director, says that the brushless machines could replace asynchronous or DC motors, avoiding the need for a gearbox, and cutting energy consumption by around 10%. They are also smaller and quieter than conventional motors in these applications and should not need any maintenance.

The fanless TM series torque motors — which can be cooled using air or water — cover ratings from 132-800kW in three sizes with diameters from 360-762mm. They are designed to deliver 635Nm-22kNm of torque, at speeds from 100-400 rpm.

The motors are aimed at applications such as extrusion machines, paper mills and winders. They could also be used as lift drives, where their low noise and compact dimensions could be attractive characteristics.

Parvex calculates that one of these motors driving a 100kW extruder operating for 7.200 hours a year, could cut energy costs by around €1,800 (£1,190) a year (based on electricity costing €0.05/kWh). Avoiding the need for maintenance could result in further savings.

Bernard suggests that the motors could be combined with indexers to provide servo performance. The current generation of machines operate with an efficiency of 92%, but he expects this to be raised in the next generation.

The Parvex motors can be driven by Parker SSD`s AC890PX modular extruder drives.