High Efficiency Machines

"60-65% of generated electrical energy in the United States is consumed in motor drives"

Source: B.K. Bose, Power electronics machines and drives advances and trends, quoting an EPRI Report.

22kW calorimeter being prepared for test

Improving energy efficiency in motor drives should be a priority for carbon reduction. However, reducing losses, without increasing material costs, requires a good understanding of the loss mechanisms and accurate measurements to validate these loss models. Getting reliable power measurements on switched power converters and mechanical pulsating loads can be challenging.

The calorimeter measures system losses directly as heat, for losses up to 4kW, on motors up to a 184 frame size. The power dissipated by the system under test is calculated as the product of the temperature difference between the coolant (air) at the inlet and outlet, the airflow rate and the specific heat capacity. A LabView data acquisition system controls temperatures and flow rate and monitors electrical, mechanical, and environmental variables. The calorimeter has been used to evaluate manufacturing methods to reduce rotor inter-bar losses and is currently being used to test energy saving strategies in aircraft drives.

Active work packages


  • Validating loss models for aircraft drives
  • Improving the efficiency of low-cost industrial drives


For further details please contact Dr Judith Apsley


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