Page 7 - Electric Drives and Electromechanical Systems

xii List of principal symbols

L a Armature inductance
L s Induction motor stator inductance
n Gear ratio
n Optimum gear ratio
N Number of teeth on a gear wheel
N L Lead-screw input speed
N p Turns per pole
Number of teeth on belt-drive pulley
N T
p Number of pole pairs in a motor
ppr Pulses per revolution
P Power
Input power
P i
Output power
P o
Armature resistance
R a
s Induction motor slip
R 0 r Referred motor resistance
Stator resistance
R s
Number of teeth on a stepper-motor stack
R T
s Induction motor slip
Dwell time between two moves
t d
t m Time to complete a move
t z Time to reach standstill under regeneration
t o Time to reach zero terminal voltage under regeneration
T Torque
T cm Continuous torque requirement
T e Electrical torque output
T f Friction torque
T i Input torque
T L Load torque
T M Motor torque
T o Output torque
Peak torque
T peak
Torque stiffness
T s
Windage torque
T w
Stall torque
T 0
s
s
v , v , v c s Voltages in a stationary three-axis frame
a
b
Voltages in a rotating two-axis frame
v d , v s
s
v , v s Voltages in a stationary two-axis frame
d q
Brushless-motor terminal voltages
V a , V b , V c
PWM control voltage; Cutting speed
V c
Peak control voltage in a PWM generator
V cpk
Linear speed
V L
Direct current (d.c.) brushed motor terminal voltage
V m
Induction motor induced rotor voltage
V r
Supply voltage
V s
a Acceleration
b Torque angle
D Peak current deviation in a pulse width modulated drive
ε Efficiency