Lenze 8400 TopLine - Manual (Page 249)

Lenze · 8400 TopLine · Reference manual · DMS 6.0 EN · 06/2014 · TD05/TD14
249
5 Motor control (MCTRL)
5.9 Servo control (SC)
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General information on temperature behaviour of the asynchronous and synchronous motor
In case of the asynchronous motor, the nameplate data always refer to rated data, i.e. on the rated
load and thus on the rated temperature of the motor. For the 8400 device series, the equivalent
circuit data for stator resistance ( C00084 ) and rotor resistance ( C00082 ) are always given for a cold
asynchronous motor (20 °C) and converted to star connection. In case of a cold motor (20 °C), the
real slip frequency thus corresponds to the calculated setpoint slip. In case of a warm motor, the real
slip frequency is higher. This becomes especially apparent at high torques as an inaccuracy of the
torque over the motor temperature.
In case of the synchronous motor. the field strength generated by the permanent magnet in the
rotor is temperature-dependent. With a rated motor temperature, a rated field strength is
generated. A negative temperature coefficient of -0.11 %/°C means that with a cold motor at the
same setpoint torque a higher output torque is output than with a warm motor.
These errors must be compensated by means of the temperature compensation for asynchronous
and synchronous motors in order to have a constant output torque over the motor temperature
independent of the motor temperature.