Permanent-magnet motors

Permanent Magnet Motor. A permanent magnet motor is a direct-current motor in which the field excitation is suppled by permanent magnets. 

The specific power of rare earth permanent magnet motors can exceed 1 kW/kg. The combination of reliable, low-cost, solid-state controllers and brushless permanent magnet motors will find applications in (i) computer accessories like disk drives, printers, x-y plotters, (ii) consumer goods like hand tools, fans, and air-conditioners, (iii) robotics, traction motors, steel mills, lift motors, and (iv) aerospace flight control actuators. 

Pelton wheel, polyurethane, by ESD, 4-in pitch diameter, just right for spinning permanent magnet motors or car alternators at 1,000 to 2,000 rpm for up to t4-inch water jets. Shape is a bit flat to be a true pelton action, but works quite well for the price. Has /2-inch center hole and can be drilled for attachment to a hub. 113... 

WATER COOLING SYSTEM FOR PERMANENT MAGNET MOTOR... 

PERMANENT MAGNET MOTOR—THE SOLUTION FOR MEDIUM POWER... 

The second group comprise the permanent magnet motor, the hybrid motor, and the disc magnet motor. The permanent magnet type offers high dynamic torque at low speed and large step angles. This is a low cost motor used extensively in low inertia applications such as computer peripherals and printers. 

Nonexcited Permanent-Magnet Motors. Permanent-magnet motors have permanent magnets embedded in a squirrel-cage-type rotor (Fig. 5.113). They produce fixed poles that lock into step with the armature field. Because of its relatively high efficiency and power factor, this motor is popular in the fractional- and lower-integral-horsepower range. 

Permanent-magnet motors, available in fractional- and low-integral-horsepower sizes, have several advantages over field-wound types. Excitation power supplies and associated wiring are not required, and reliability is improved. Efficiency and cooling are also improved by ehmination of the power loss associated with an excited field. 

FIGURE 5.121 Schematic and speed vs. torque diagram—dc permanent-magnet motor. 

Permanent Magnet Motor Technology Design and Applications, Jacek F. Gieras and Mitchell Wing... 

Barium carbonate of finely controlled particle size reacts in the soHd state when heated with iron oxide to form barium ferrites. Magnetically aligned barium ferrite [11138-11-7] powder can be pressed and sintered into a hard-core permanent magnet which is used in many types of small motors. Alternatively, ground up magnetic powder can be compounded into plastic strips which are used in a variety of appHances as part of the closure mechanism. 

An elementary motor consists of a rotating electromagnet and a fixed permanent magnet. 

Advise of exciter power characteristics available, or specify manufacturer to provide required exciter (small synchronous motors may use permanent magnets) as direct-connected, belt-driven, or motor-generator set. 

A most recent commercial Nano Indenter (Nano Indenter XP (MTS, 2001)) consists of three major components [66] the indenter head, an optical/atomic force microscope, and x-y-z motorized precision table for positioning and transporting the sample between the optical microscopy and indenter (Fig. 28). The load on the indenter is generated using a voice coil in permanent magnet assembly, attached to the top of the indenter column. The displacement of the indenter is measured using a three plate capacitive displacement sensor. At the bottom of the indenter rod, a three-sided... 

In the schematic the detector coil (hatched boxes) and its associated field lines are shown (dotted) and are seen to be always orthogonal to the permanent magnet field lines (solid). The magnitude of the static field is constant in the horizontal plane (thick black line). A stepper motor and gear-drives for raising the whole assembly relative to the external surface are visible in the photograph. 

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