On the true maximum efficiency operations of synchronous motor drives

Abstract

Energy efficient AC drives for synchronous machines are key components in modern mechatronic systems, including applications of renewable energy and transportation. It is possible that the next generation of synchronous motors may be of the reluctance-prevalent type, due to the ecological footprint and cost of permanent magnet materials. When a reluctance torque is available, the torque is usually regulated according to the maximum torque per ampere principle which minimises the copper losses for a given torque request. However, iron and additional losses also contribute to the total machine losses, although their influence on the best current vector trajectory for total loss minimisation is not clear yet. The aim of this paper is to discuss and quantitatively evaluate the effect of iron and additional losses on the efficiency of different synchronous machines, looking for the true maximum efficiency. An extended batch of measurements performed on different types of machines with low power rating are discussed in detail.

Online MTPA Control of IPM Motor Using NN-Based Perturb and Observe Algorithm

“…Voltage equations, electromagnetic torque equation and mechanical motion equation of IPM motor in dq rotating coordinate frame can be defined as (1), ( 2) and (3), separately. The relationship between mechanical angular speed and electrical angular speed is shown in (4).…”

“…In synchronous motors, copper losses typically dominate over iron losses, and the evaluation of iron losses is frequently overlooked [4]. Therefore, in IPM motor control technologies, maximum torque per ampere (MTPA) control methods are often used to improve the efficiency of IPM motors and provide maximum torque or minimum stator current to minimize copper losses.…”