3-Phase BLDC Motor Sensorless Control Using MC56F8013

Motor Related ParametersWhere;T_Cmt[n] : Time for commutation for step n.T_Next[n] (cmt) : Time of the next commutation for step nT_ZCros[n] : Time of the zero crossingfor step nT_zCros0[n] : Time of the previous zero crossing for step nPer_Toff[n+1] : Period of the Toff duration to be applied at step n+1Per_CmtPreset : Preset Commutation Periof fromcommutation tonext commutationif no Zero Crossing was capturedPer_ZCros[n] : Period between last 2 Zero Crossings for step nPer_ZCros0[n] : Previous period between Zero Crossings for step nPer_ZCrosFlt : Estimated period of commutation filtered for step nPer_HlfCmt : Period fromZero Crossing to commutation (half commutation)7.5.3.7 MAX_ZCROSERRMaximum number of commutation period counts with no zero crossing detection, to stop thecommutation.This constant is used to control commutation problems. If no zero crossing is detected forMAX_ZCROSERR commutation cycles, the application switches to the Stop commutation state and triesfor a new alignment, if allowed by the run/stop status.When tuning the software for other motors, this constant can be increased temporarily.7.5.4 General Parameters7.5.4.1 Parameter SummaryThese parameter are generally related witch the motor. They are listed and explained in Table 7-7.Table 7-7. General Parameters SummaryName Description Units Range DefaultFreeMasterLocationSPEED_ROTOR_MAX_RPMMaximum mechanicalrotor speed.RPMDefined bymotor design,no range2000 N/AMOTOR_COMMUTATION_PREVNumber of commutationsper revolution.N/ADefined bymotor design,no range12 N/AOMEGA_MIN_SYSU Minimum speed. Fraction 0–6553 3276 N/ACURR_LIMIT_DESIRED_ADesired current limitationvalue for DC-bus.A 0.1–4.0 4.0Control >Current Limiting7.5.4.2 SPEED_ROTOR_MAX_RPMMaximum mechanical rotor speed.7.5.4.3 MOTOR_COMMUTATION_PREVNumber of commutations per revolution.This value must be set according to the number of motor poles.3-Phase BLDC Motor Sensorless Control using MC56F8013, Rev. 0Freescale Semiconductor 85