APPLIED (or INPUT) VOLTAGE (Va) is the DC
voltage measured at the motor terminals.
ARMATURE INERTIA (Ja) is the property of the armature causing it to
resist changes in its rotation speed, expressed in oz-in-sec2(squared).
BACK EMF The voltage generated when a permanent magnet motor is rotated. This voltage is proportional to motor speed and is present regardless of whether the motor winding(s) are energized or de-energized.
Trapezoidal is a four-layer (n-p-n-p) device with an MOS-gated
channel connecting the two n-type regions. In the normal
mode of operation, a positive voltage is applied to the anode
(A) relative to the cathode (K).
Sinusoidal A uniform wave that is generated by a single frequency. A geometric waveform that oscillates (moves up, down or side-to-side) periodically, and is defined by the function y = sin x.
BI-DIRECTIONAL motors have equal performance characteristics in
CW and CCW rotation.
BRUSHLESS MOTOR A DC Brushless Motor uses a permanent magnet external rotor, three phases of driving coils, one or more Hall effect devices to sense the position of the rotor, and the associated drive electronics. The coils are activated, one phase after the other, by the drive electronics as cued by the signals from the Hall effect sensors, they act as three-phase synchronous motors containing their own variable frequency drive electronics
CLOSED LOOP CONTROL A broadly applied term, relating to any system in which the output is measured and compared to the input. The output is then adjusted to reach the desired condition. In motion control, the term typically describes a system utilizing a velocity and/or position transducer to generate correction signals in relation to desired parameters.
CORELESS MOTORS Also known as "ironless" or "basket".
COMMUTATION A term which refers to the action of steering currents or voltages to the proper motor phases so as to produce optimum motor torque. In brush type motors, commutation is done electromechanically via the brushes and commutator. In brushless motors, commutation is done by the switching electronics using rotor position information obtained by Hall sensors, a Tachsyn, or a resolver.
DUTY CYCLE is a ration of operating time to total cycle time, expressed
in percent
.
EFFICIENCY of a motor is the ratio of output power to input power,
and is expressed in percent.
ELECTRICAL TIME CONSTANT (Tm) reflects the time necessary for current
to rise to 63.2% of final value, and may be calculated by La/Ra.
HALL EFFECTS refers to the potential difference (Hall voltage) on opposite sides of a thin sheet of conducting or semiconducting material in the form of a 'Hall bar' or a van der Pauw element through which an electric current is flowing, created by a magnetic field applied perpendicular to the Hall element. The ratio of the voltage created to the amount of current is known as the Hall resistance, and is a characteristic of the material in the element. Dr. Edwin Hall discovered this effect in 1879.
IGBTs (Insulated Gate Bipolar Transistor is a four-layer (n-p-n-p) device with an MOS-gated
channel connecting the two n-type regions. In the normal
mode of operation, a positive voltage is applied to the anode
(A) relative to the cathode (K).
MECHANICAL TIME CONSTANT (Tm) is the time required for the motor to
reach 63.2% of final speed after receiving an input voltage, and is equal
to (Ja x Ra)/(Kt x Ke)
MIL-STD-810F Environmental specifications. Salt, fog, sand, driven rain immersion, humidity,
solar radiation, etc.
MIL-STD-461E Electromagnetic compatibility. Conducted emissions, conducted susceptibility. Radiated emissions,
radiated susceptibility.
MOSFETs (Metal Oxide Silicon Field Effect Transistor a common type of transistor in which charge carriers, such as electrons, flow along channels. The width of the channel, which determines how well the device conducts, is controlled by an electrode called the gate, separated from channel by a thin layer of oxide insulation. The insulation keeps current from flowing between the gate and channel.
NO LOAD SPEED (Snl), expressed in RPM, represents rotational speed
of the motor when no force is applied to the output shaft.
OPEN LOOP A system in which there is no feedback. Motor motion is expected to faithfully follow the input command. Stepping motor systems are an example of open-loop control.
PEAK CURRENT is that amount of amperage which, is equaled or exceeded,
will cause permanent damage to the motor.
PEAK TORQUE (Tpk) represents the momentary level of force the unit
is capable of at 0 RPM, and is equal to (Ktx lpk).
POTENTIAL DIFFERENCE A potential difference between two points gives rise to a "force" called an electromotive force or emf that tends to push electrons or other charge-carriers from one point to the other. A potential difference is generated between the ends of an electrical conductor that moves perpendicular to a magnetic field. Between two points in an electrical circuit the potential difference is equal to the difference in their electrical potentials.
PULSE WIDTH MODULATION is a four-layer (n-p-n-p) device with an MOS-gated
channel connecting the two n-type regions. In the normal
mode of operation, a positive voltage is applied to the anode
(A) relative to the cathode (K).
REGULATION refers to the Speed Regulation Constant and is the slope
of the motor's speed0torque characteristics, expressed in RPM/oz-in.
RESISTANCE (R) is the total motor resistance, equal to Ra + Rb
(See Note 1); where Ra = Armature Winding Resistance, and Rb = Brush Assembly
Resistance.
ROTOR The rotor is made of permanent magnet and can vary from two to eight pole pairs with alternate North (N) and South (S) poles.
RTCA DO-160E Civilian aviation. Electromagnetic & environmental.
STALL CURRENT is the maximum RMS current at 0 RPM; equal to Ts/Kt.
STALL TORQUE (Ts) equals the amount of torque, expressed in oz-in,
the unit is capable of exerting at 0 RPM on a continuous basis.
STATOR The stator of a BLDC motor consists of stacked steel laminations with winding placed in the slots that are axially cut along the inner periphery.
TERMINAL RESISTANCE static line to line resistance @ 25 deg. C.
THREE-PHASE AC SYNCHRONOUS MOTORS As with single-phase motors, if the rotor coils of a three-phase motor are fed a separate field current to create a continuous magnetic field (or if the rotor consists of a permanent magnet), the result is a called a synchronous motor because the rotor will rotate in synchronism with the rotating magnetic field produced by the polyphase electrical supply.
TIR is the Total Indicated Runout of the motor shaft, measured
.5in. from the face, or at end of the shaft if shorter, and represents
the shaft's rotational circularity and straightness.
TORQUE refers to Rated Torque (Tr) and is the maximum continuous motor
output force at rated speed (assuming Vr. and Ir), with armature temperature
equal to its maximum 155 degree C.
TORQUE CONSTANT (Kt) is the relationship
of motor torque and armature current, normally expressed in lb-ft./A. (See
Note 1)
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