MS student Samith Sirimanna with advisor K. Haran

Typically, HVAC systems consume 36% of the total energy requirement for commercial buildings in the USA. Since the major power consumption in an HVAC system lies in the compressor motor, the requirement for having a high-efficiency motor is significant. This project, funded by Johnson Controls International PLC, is focused on designing and developing a 100kW high-efficiency motor for compressor applications and includes three main phases.
The first phase is a trade study on various motor types used in this application. Motor-drive system efficiency and cost are the two main selection criteria. Table 1 gives the Trade Study Summary of the chosen motor types. The second phase is to create a feasible design, build the prototype and test it. Several aspects are considered, including ac losses, mechanical stability at higher speeds and integrating the motor into a hermetic refrigerant environment. A cross-coupled electro-magnetic and mechanical optimization is implemented using Flux 12.1 and Creo software to find the optimum design. A number of motor dimensions, including slot geometry and bridge geometry of the interior permanent magnet rotor, are taken as variables and modified to find the best performance.

Table 1: Final Summary of Trade Study

  PMSM 2 pole PMSM 4 pole Induction 2 pole PM assisted SynRM (NdFeB) PM assisted SynRM (Ferrite)
IPLV Motor % 96.0% 95.8% 94.5% 96.1% 96.2%
IPLV VSD % 97.6% 97.0% 97.6% 97.0% 97.0%
IPLV Integrated % 93.6% 92.9% 92.2% 93.2% 93.3%
Motor Material Cost Index 0.303 0.233 0.089 0.126 0.088
Motor + VSD Material Cost Index 1.164 1.180 1.000 1.167 1.129