: rated power

: slope of intrinsic mechanical characteristics

: slope of artificial mechanical characteristics

: voltage

: rated voltage

: induced magnetic voltage

: armature electromotive force

: current

: armature current

: induced magnetic current

: rated current

: speed

: angular speed

: rated speed

: ideal no-load speed

: actual no-load speed

: armature resistance

: excited magnetic resistance

: armature series resistance

: magnetic flux

: rated magnetic flux

: magnetic flux divided by rated magnetic flux

: torque

: rated torque

: rated load torque

: load torque

: resistance torque

: no load torque

: electromotive force constant

: number of pole pairs

: total conductors (number of DC armature windings)

: parallel branch pairs (number of DC armature windings)

: torque constant

: input electrical power

: output mechanical power

: no-load power

: copper loss power

: mechanical loss power

: additional loss power

: motor efficiency

[1] Xu-Xiaofen,

*Electric Motor and Drive [M]*, (in Chinese), Beijing, China: Higher Education Press, 2007.

[3] S. J. Chapman,

*Electric Machinery Fundamentals*, 4th ed., New York: McGraw-Hill, 2003.