Motors in semi-hermetic compressor drives are mostly fed from line. Because of good cooling conditions, the motors are heavily loaded, and employ a specific rotor structure with ŽCŽ bore. In the field of semi-hermetic drives the use of induction motors (IMs) is still dominant, although different motor types with line-starting capabilities, as for example linestart interior permanent magnet synchronous motors (LSIPMSMs), can be used. This work presents the direct performance comparison of a family of commercially available three-phase four-pole IMs for semi-hermetic compressor drives with the equal size prototypes of LSIPMSMs. The motors were rated as 1, 2.5, 3.8, 5.5, 7.5 and 20 Hp. Presence of ''C'' bore in rotor structure can degrade LSIPMSM steady-state performance, therefore the LSIPMSM designs steady-state performances are evaluated by FEA as well by the experimental method. The motorsʼ dynamic performance is experimentally evaluated as well. The ultimate goal of this study is to reveal the improvement of LSIPMSMs characteristics in comparison to IMs characteristics and to check the possibility for the immediate replacement of existent IMs with LSIPMSMs in the target semi-hermetic compressor application.
COBISS.SI-ID: 72594433
This paper presents an in-depth comparative analysis of the variable speed drive (VSD) performance between an IEC frame size 90 four-pole three-phase induction motor (IM) and the equal line-start interior permanent magnet synchronous motor (LSIPMSM). Employing measurement data from no-load tests, load tests, and temperature-rise tests of the aforementioned motors and different cage materials as well, the motors’ no-load and load characteristics are first examined in detail and then the drives’ characteristics are analyzed in open-loop volts per hertz (V/f) control by using the same voltage-source inverter and the aforementioned IM or LSIPMSM in both constant torque and constant power operation. It has been established that particularly the motors’ current and power factor characteristics have distinct impact on the consequent VSD performance in terms of loss and efficiency. Furthermore, it has been shown that the lower loss of the LSIPMSM enables a significant increase of the VSD’s constant power range.
COBISS.SI-ID: 16458518
This paper shows the use of FEM for a second order time dependent electromagnetic field problem, around grounding systems (GS). Twenty-node isoparametric quadratic 3D finite element, three-node quadratic 1D finite element and a spatial transformation of the infinite space into the finite space are all applied to achieve better accuracy. Time integration is conducted with the Newmark algorithm. The applied program solution is suitablefor any GS and isotropic/anisotropic soil properties as well as time-varying fault current.
COBISS.SI-ID: 15836438