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Examoogle • User • info@examoogle.com • EE-2024-8821
Chapter 1 of 12 • Page 1 of 248🔒 Protected PDF • Watermarked
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In three-phase induction motor design, Flux density in the Stator core is depended on the ___________.
Tooth Width
Tooth Height
Stator Core Length
Stator Core Depth
Stator Core Depth
In a three-phase induction motor, the stator core flux density is inversely proportional to the stator core depth. The stator core depth is defined as the radial thickness of the iron portion behind the stator slots, which carries the flux.
In a three-phase induction motor, the stator core flux density is inversely proportional to the stator core depth. The stator core depth is defined as the radial thickness of the iron portion behind the stator slots, which carries the flux.
Bc=2⋅Li⋅dc⋅ksΦ — Flux density in stator core
dc=2⋅Bc⋅Li⋅ksΦ — Required core depth calculation
The flux per pole divides equally into two paths in the stator core as it returns from the teeth. Therefore, the flux in the core is half of the flux per pole (2Φ). The core depth (dc) is determined by the requirement to keep the flux density (Bc) within limits to prevent core saturation, according to the relation Bc=2⋅Li⋅dc⋅ksΦ, where Li is net iron length and ks is stacking factor.
Flux density in the stator core is maintained at a specific value (typically 1.2 to 1.5 Tesla) to minimize iron losses.
Increasing stator core depth reduces flux density, thereby reducing hysteresis and eddy current losses.
Excessive core depth increases the overall machine diameter and cost, leading to an optimized design trade-off.
Reduces magnetizing current requirement
Minimizes iron core losses (hysteresis and eddy current)
Increased core depth results in a larger machine frame
Adds significant weight and material cost to the stator
Design of industrial poly-phase induction motors
Optimization of magnetic circuit dimensions in rotating electrical machines
Stator core depth is specifically the distance between the bottom of the slots and the outer periphery of the stator lamination.
Option A (Tooth Width) affects the tooth flux density, not the back-iron (stator core) flux density.
D is correct — The stator core depth is the cross-sectional area through which the pole flux passes, directly determining the magnetic flux density in the yoke of the stator.
Always remember that flux density in the teeth is determined by tooth width, while flux density in the back-iron (yoke) is determined by the core depth.