10 r represents the stator resistance u03c9 i d represents a flux producing current a and i q represents a torque producing current a l d and l q represent direct axis and quadrature axis inductances h respectively u03b3 e represents angular distance u03b3 e 28 rad sec u03c8 m0 represents the magnetic flux wb of the pole pairs of the rotor 22 p n represents the number of permanent magnets of the rotor 22 and t load represents the torque nm exerted against motor 10 by the load self inductance l d and l q may be further represented according to equations 8 and 9 below it should be noted that usually for a surface permanent magnet synchronous motor l d is equal to l q turning to fig2 a dynamic block diagram 30 represents the interior permanent magnet synchronous motor 10 in a synchronous reference frame d q with known values of the three phase voltage waveforms 32 and the relative angular position u03b3 e 34 a coordinate transformation 36 may be performed producing direct axis voltage v d 38 and quadrature axis voltage v q 40 in accordance with equation 5 above a summer 42 adds direct axis voltage v d 38 subtracts direct axis current i d 44 multiplied by stator resistance r 46 and adds voltage e d 48 outputting direct axis change in flux the origin of voltage e d 48 will be discussed further below by multiplying direct axis current i d 44 with direct axis inductance l d 58 direct axis flux u03c8 d 60 is produced direct axis flux u03c8 d 60 may subsequently enter multiplier 62 with stator frequency u03c9 e 64 producing voltage l d l d u03c9 e 66 permanent magnet flux u03c8 m0 68 and stator frequency.