Determination of heat transfer coefficient of finned housing of a TEFC variable speed motor

Abstract

This paper proposes the analytical calculation of the heat transfer coefficient from the housing of a totally enclosed fan cooled (TEFC) machine during the active cooling. A particular focus is on the calculation of the heat transfer coefficient from the machine's housing for different fan rotational speeds. The paper describes the challenges and provides solutions to dominate them during the analytical calculation of the heat transfer coefficient a TEFC electrical machine. Finally, the proposed method is validated experimentally on a totally enclosed fan cooled synchronous reluctance motor (SynRM), and good correspondence between the analytical and experimental results is obtained.

Challenges in Winding Design and Thermal Calculations: Physical Model of Permanent Magnet Synchronous Machine

“…The empirically calculated heat transfer coefficients are α st in = 44 Wm −2 K −1 for the inner stator surface and α rot out = 24 Wm −2 K −1 for the rotor outer surface. These coefficients are based on the formulas from literature [14,16,17]. These values are confirmed by the 3D computational fluid dynamics (CFD) simulation of the rotating machine (see Figure 14).…”

“…The dimensionless quantities are used in the analytical and numerical calculations to quantify the thermal convection; the Reynold's (Re) and Nusselt (Nu) numbers are used in this paper. The formulas used for estimation of the heat transfer coefficient α are different, empirical, and defined differently in every literature [16,28,29]. Individual empirical relations have to be used for every part of the machine.…”

“…The most complicated situation appears in the round-wired coils with random placement of the conductors in the slot area. The equivalent thermal parameters (thermal conductivity [14,15] heat transfer coefficients [16,17]) are often historically defined as empirical values based on the comparison of the calculation and measurement. The same methodology is also used in [18,19].…”

Additive Manufacturing of Prototype Axial Flux Switched Reluctance Electrical Machine

“…However, to achieve cost-effectiveness and lightweight demand metrics, the automotive company starts to manufacture EV motors with compact structures that generate a few dozen kilowatts. Therefore, the standard aircooling method [6], [7], and [8] and cannot provide sufficient cooling conditions for the high-power density and compact motors; and, there is a need for novel cooling methods.…”

Design and additive manufacturing of brushless electric motor components

“…Due to its capacity for direct digital manufacturing of end products AM opens new avenues for design solutions that are otherwise challenging or impossible to achieve when using conventional manufacturing techniques. Therefore, the evolution of AM has been recognized as a key enabling technology in a wide range of applications, some of which include the medical, aerospace, and automotive industries [4,5]. Another advantage of the AM relates to its low material waste and its very high flexibility.…”