Power And Torque Limiting - HEIDENHAIN iTNC 530 Technical Manual

6.8.8 Power and Torque Limiting

February 2002
You can limit the power of your spindle motor to get wider gear ranges. Wide-
range motors are characterized by a larger speed range with higher torque at
low speed.
One solution for bringing about this behavior is to use an oversized motor, and
to limit the maximum power. However, power limiting does not reduce the
high torque to the speed at which power limiting becomes effective. This high
torque (until power limiting takes effect) can be reduced with torque limiting,
in order to keep the mechanics of the machine from becoming overloaded.
With torque limiting you can also limit the torque of the axis motors, in order
to keep the mechanics of the machine from becoming overloaded. Power
limiting for axis motors is not useful.
For axes and spindles, the torque is limited to the value taken from either the
table of power modules or the motor table, whichever is lower.
If a non-HEIDENHAIN inverter or a UE 2xx HEIDENHAIN compact inverter is
used, the maximum torque current , and as a result the maximum torque, is
limited to 70% of the maximum current, since these inverters do not provide
any signal for an excessive dc-link current.
The modular HEIDENHAIN inverter system or the UE 2xxB HEIDENHAIN
compact inverters do provide such a signal (ERR-IZ). As a result, the maximum
torque current is not limited.
This monitoring function must be set for the respective inverter in MP2220.x
bit 2.
The torque can be calculated for any speed:
⋅
P 60
= --------------- -
M
⋅ ⋅
n 2 π
M: Torque [Nm]
P: Power [W]
n: Speed [rpm]
Note
The power and torque limiting can have an effect on the braking of the
spindle in an emergency stop.
7 Enter the maximum power for the spindle in MP2392.x.
7 Enter the maximum torque for the spindle or axis in MP2396.x.
7 For the modular HEIDENHAIN inverter system or the UE 2xxB compact
inverter, activate the monitoring of the ERR-IZ signal with MP2220.x bit 2 = 1.
For non-HEIDENHAIN inverters or the UE 2xx HEIDENHAIN compact
inverter, deactivate the monitoring of the ERR-IZ signal with MP2220.x bit
2 = 0.
The Control Loop 6 – 151