Evaluation of the Efficiency of Line-Start Permanent-Magnet Machines as a Function of the Operating Temperature

Abstract

Abstract-The standard squirrel-cage induction machine has nearly reached its maximum efficiency. In order to further increase the energy efficiency of electrical machines, the use of permanent magnets in combination with the robust design and the line start capability of the induction machine is extensively investigated. Many experimental designs have been suggested in literature, but recently, these line-start permanent-magnet machines (LSPMMs) have become off-the-shelf products available in a power range up to 7.5 kW. The permanent magnet flux density is a function of the operating temperature. Consequently, the temperature will affect almost every electrical quantity of the machine, including current, torque, and efficiency. In this paper, the efficiency of an off-the-shelf 4-kW three-phase LSPMM is evaluated as a function of the temperature by both finite-element modeling and by practical measurements. In order to obtain stator, rotor, and permanent magnet temperatures, lumped thermal modeling is used.

Research on the Temperature Field of High-Voltage High Power Line Start Permanent Magnet Synchronous Machines with Different Rotor Cage Structure

“…n is the Steinmetz constant. According to [16], the joule losses in the stator windings can be calculated by:…”

“…According to [16], friction and windage losses, that is, Pw, mainly depend on the size of the fan and the mechanical speed of the machine. Besides, with the electromagnetic losses (the stator core loss, the stator copper loss and the rotor loss) obtained from the above analyses, the loss distribution in LSPMSM under rated operating is determined, as shown in Table 2, which are taken as the distributed heat generation sources in the fluid-thermal coupling analysis.…”

“…Recently, a number of works have been published about permanent magnet synchronous machines (PMSMs) [14][15][16][17][18][19][20][21][22][23]. However, most of these studies are focused on the electromagnetic design and performance analyses, but ignoring the thermal investigation.…”

Performance Variation of Ferrite Magnet PMBLDC Motor With Temperature

“…However, authors did not evaluate the performance variation with temperature. In [17], the authors used manufacturer supplied temperature coefficient of B r and H c of ferrite magnet to evaluate the performance of a line-start PM machine for different operating temperatures. This paper uses laboratory measured BH characteristics of a ferrite magnet to evaluate the margin of safety to irreversible demagnetization in a segmented axial torus (SAT) PMBLDC motor.…”

Thermal model of totally enclosed water-cooled permanent magnet synchronous machines for electric vehicle applications

“…Taking advantages of the flexibility of the thermal circuit method and the accuracy of the temperature field method, the transient temperature-rise of a tubular linear motor with short and movable primary was discussed in [6]. The efficiency of an off-the-shelf 4-kW three-phase line-start permanent-magnet machine (LSPMM) was evaluated as a function of the temperature by both the TRN and practical measurements in [7]. An extended survey on the evolution and the modern approaches in the thermal analysis of electric machines was presented in [8], in which the thermal analysis method of TRN, FEA and CFD were comparative discussed.…”