908 HEIDENHAIN Technical Manual iTNC 530 HSCI
6.11.9 I
2
t monitoring
General
information
HEIDENHAIN inverter systems feature individual I
2
t monitors, one for each
power module and motor.
Function An I
2
t monitor calculates and supervises the temperature pattern in a thermal
motor or power-stage model during operation, even if temperature
measurement is also provided by the hardware.
The active current, the rated or stall current, (multiplied by MP2302.x for
motors and by MP2304.x for power modules) and a device-specific
temperature model are the basis for calculation. A first-order temperature
module is available for monitoring power modules, first and second-order
modules are available for motors. These models make it possible to
permanently calculate the temperature of the stator winding in the motor or
the semiconductor in the power module.
Temperature models in an example comparison (motor)
The I
2
t monitor responds if this calculated temperature exceeds a certain limit.
Because temperature increase and heat dissipation are uneven when the
motor is stationary or moving slowly, the I²t monitor distinguishes between
standstill and traversing mode.
This limit range is defined in a motor table or power module table The
following entries are important:
F-AC (transition frequency in traversing mode [Hz])
F-DC (transition frequency at standstill [Hz])
0 100 200 300 400 500 600 700 800 900 1
000
0
2020
40
60
80
100
120
140
160
180
200
T [°C]
Motor temperature
Second-order temperature model
First-order temperature model
t [s]
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