Maximum Efficiency Per Ampere Control of Permanent-Magnet Synchronous Machines

High-efficiency electric drive systems claim not only optimally designed electric machines but also efficiency-oriented control strategies. Taking machines and drives into synergetic consideration, this paper proposes a novel vector control algorithm named maximum efficiency per ampere (MEPA) control, aiming to maximize the efficiency of permanent-magnet synchronous machines (PMSMs) during operation. Different from conventional i_d = 0 or maximum torque per ampere control, MEPA fully considers the cross effect and iron loss from which the full-order loss model of PMSMs is built. Due to the proposed concise and accurate analytical approach to iron loss calculation, the optimal current phasor angle for MEPA can be quickly found, and the estimation of efficiency is consistent with measurement. Comparison among different control algorithms is drawn from both analytical and experimental results, from which the effectiveness of MEPA is verified.