User Manual Instruction Manual

About the Drive 2-9
Leakage Inductance Test
Ixo Voltage Drop (64) is set by the leakage inductance test. This test measures the
inductance characteristics of the motor. A measurement of the motor inductance is
required to determine references for the regulators that control torque. The motor
should not rotate during this test.
Inertia Test
Total Inertia (450) is set by the inertia test. Total Inertia (450) represents the time in
seconds, for the motor coupled to a load to accelerate from zero to base speed at
rated motor torque. During this test, the motor is accelerated to about 2/3 of base
motor speed. This test is performed during the Start-up mode, but can be manually
performed by setting [Inertia Autotune] to “Inertia Tune”. The Total Inertia (450) and
Speed Desired BW (449) automatically determine the Ki Speed Loop (445) and Kp
Speed Loop (447) gains for the speed regulator.
Refer to the description of the Autotune parameter (61) in chapter 11 for more
information about using this feature.
2.3.13 Drive Protection Current Limit
There are six ways that the drive protects itself from overcurrent or overload situations:
• Instantaneous overcurrent trip
• Software Instantaneous trip
• Software current limit
• Heatsink temperature protection
• Overload protection
• Thermal manager
2.3.14 Drive Overload Protection
The drive thermal overload will protect the drive power stage while maintaining
performance as long as the drive temperature and current ratings are not exceeded.
The drive will monitor the temperature of the power module based on a measured
temperature and a thermal model of the IGBT. As the temperature rises, the drive may
lower the PWM frequency to decrease the switching losses in the IGBT. If the
temperature continues to rise, the drive may reduce current limit to try to decrease the
load on the drive. If the drive temperature becomes critical, the drive will generate a
fault.
If the drive is operated in a low ambient condition, the drive may exceed rated levels of
current before the monitored temperature becomes critical. To guard against this
situation, the drive thermal overload also includes an inverse time algorithm. When
this scheme detects operation beyond rated levels, current limit may be reduced or a
fault may be generated.