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Entry type: Application example Entry ID: 22078991, Entry date: 09/17/2005

MICROMASTER 440: manually determining the magnetizing current and re-calculating the motor equivalent circuit diagram

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This application only applies to MICROMASTER 4 with Firmware < V4.0



In order to successfully commission a drive system it is important that the rated motor data are correctly downloaded into the drive inverter and a motor identification routine carried-out. The procedure is described in Chapter 3.5 “Commissioning” of the Instruction Manual.

After the “Commissioning” phase has been successfully completed, for most applications the drive can be accelerated up to rated speed. Depending on the motor being used and the mechanical layout it may however be necessary to further optimize the individual controllers.

Especially for SLVC (sensorless closed-loop vector control), the feedback signals for the internal controllers depend on calculated quantities – such as flux actual value and speed actual value – from the motor model.

The value of the magnetizing current has a special influence on the control parameters. This cannot be measured at standstill. This is the reason that it is estimated using the automatic parameterization routine as typical value for a standard SIEMENS motor. Due to the difference between the “real” magnetizing current and the estimated magnetizing current, it is also not possible to precisely determine the values of the magnetizing reactance and rotor resistance.  This can result in difficulties when optimizing the drive - especially for third-party motors,(also refer to ID: 15293059).

The procedure to manually determine the magnetizing current, re-calculate the motor equivalent circuit diagram when the drive is operated with closed-loop vector control are described in the following.


Content of Downloads


Documentation (German) tipps_tricks_004_Ausmessen_des_Magnetisierungsstroms_update_de.pdf ( 102 KB )
Documentation (English) tipps_tricks_004_Measuring_magnetizing_current_update_en.pdf ( 108 KB )





05/2003 first edition

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