OTHER: Electrical - Motor - Stator - Sheet-metal Lamellae

• The stator core is laminated to reduce eddy current losses.
• The thickness varies accordingly to the frequency of operation. In machines for 60 Hz lamination thickness is typically 0.014" (0.355 mm).
• Ferromagnetic material
• It appears that the plane of the laminations normal to the axis of the rotor's rotation. Is this always the case? And if so, why?
• Can the sheet metal pieces have one or more bends put in them to provide a 3-dimentional aspect to the flow of the flux similar to that which can be done with Soft Magnetic Composite (SMC)?
• "Too reduce the core loss, lamination thickness of 0.1 mm has been used [Source ~ PMMT p.370] 0.1mm thick laminations is mentioned on a number of pages. For reference; the laminations on the furnace motors are 0.5 mm.
• Since the rotation of the motor is always in one direction could an increase in power be achieved by having a difference between the thickness or shape of the leading pole tips to those of the trailing pole tips?
• "LaminationsThe induced eddy currents in Ohmic conductors results in Ohmic heating. This is useful in induction furnaces that melt metals, but is undesired in many iron core devices. To reduce this power loss, the cores are often sliced into many thin sheets electrically insulated from each other by thin oxide coatings. The current flow is then confined to lie within a thin sheet and cannot cross over between sheets. "
• "... motor laminations are often annealed after being stamped or cut." [Source ~ BPMMD p.218]
• I put an Ohm meter (logic detector) on the laments of the F&P stator and it detects a connection between all lamenates

• Lamination Thickness:
• Core losses can be reduced by; "Reducing the lamination thickness. Ideally, eddy current losses are directly proportional to the square of the lamination thickness. Therefore, if the lamination thickness is reduced by a factor of two, eddy current losses decrease by a factor of four. [Source ~ BPMMD p.219]
• The thickness of the bought F&P stator is 0.5mm.
• Thickness varies according to frequency of operation, but in machines for 60 Hz (the vast bulk of machines made for industrial use), lamination thickness is typically 0.355mm (0.14").
• The rotorhub will be turning at +/- 700 RPM and the ratio of electrical rpm to mechanical rpm is 24:1. Therefor the electrical frequency will be (700 * 24 / 60) = 280Hz.
• Recommended stator lamination thickness for high power density brushless motors is 0.1mm. [Source ~ PMMT p.365]

• What's new in motor lamination steel technology?

• Metglas
• See [Source ~ PMMT Section 6.12.8]

• [Source ~ PMMT [Source ~ PMMT Section 6.12.9]
• http://www.rcgroups.com/forums/search.php?searchid=25070676&query=cobalt%20steel%20laminations
• Affordability of Power Density

• See section 5.1.4 for the design equations and dimensioning of the laminate [Source ~ HSEM p.5.36]

• Idea for air-cooling of rotor on in-running motor: Make the spider laminations in a conventional manner. When stacking them rotate each group of 2, 3, 4, or > by one stator tooth. This will present a much larger lamination surface area to the air. In addition. the progressive rotation of them will result in the spider arms acting as blades with a pitch to force new air through the rotor. The "pitch' of the spider will be set by the count of laminations in each group. Note that the rotor loading will only be that of transmitting torque to the aero-rotor.

• US 4578853 ~ Method of making a stack of electrical sheet-metal lamellae with aligned winding slots, particularly armatures for dynamo electric machines
• US 6,515,396 ~ Stator flux ring having fastenable pole pieces and method of making same
• US 5,477,096 ~ Laminated core for a motor

• DESIGN ~ Electrotor-SloMo ~ Motor - Radial Flux - Stator - Lamination
• DESIGN: Electrotor-SloMo ~ Motor - Stator - Soft Magnetic Composite (SMC)

• Additional Information: BPMMD, page 33
• Additional Information: PMMT, search gives 42 locations

Introduction Page | SynchroLite Home Page | Electrotor Home Page | UniCopter Home Page | Nemesis Home Page | AeroVantage Home Page: