Evaluation of induction and permanent-magnet synchronous machines using drive-cycle energy and loss minimization in traction applications

This paper presents a comparative study of induction machines (IMs) and interior permanent-magnet synchronous machines (IPMSMs) in traction applications. Machines are chosen to have similar ratings to operate in the same vector-controlled drive system and to achieve a fair comparison. Due to the dynamic nature of traction applications, static efficiency maps are not used. Instead, energy consumption is evaluated for both IMs and IPMSMs during typical drive cycles. Machine efficiency is also evaluated during the drive cycle to account for steady-state and transient conditions. The results of these comparisons show that the IPMSM can have higher efficiencies for most conditions. After comparing IMs and IPMSMs, loss minimization is integrated into the IM drive. Optimal flux commands are dynamically set, and then, energy and efficiency are compared with those of the IPMSM. Results show that IMs can achieve efficiencies comparable to the IPMSMs when loss minimization is applied. The efficiency gap between the IM and IPMSM is thus reduced, and these results are verified in both a hybrid electric vehicle simulator and a hardware-in-the-loop experimental setup.