KOMPENSIEREN VON EFFIZIENSSCHWANKUNGEN IN MOTOREN

A method for compensating for variations in the operating efficiency of electric motors used in plastic processing machines. The current to the motor is continually monitored during all periods of operation to identify variations in the motor's actual efficiency as it relates to measurable machine performance. Normal operation of the electric motor is monitored to establish baseline current usage for the various periods of the operating cycle under given conditions. With a baseline established, variations in motor efficiency can be detected by monitoring the current during closed loop control of specific parameters and comparing the results to the baseline. Since the parameter is held constant by virtue of the closed loop, a deviation in current from the baseline indicates a change in efficiency. Based on the identified variance, the current to the motor during other (open loop) operations can be adjusted accordingly.