| The
Motor and Drive Systems Division of General Electric (GEMIS), based
out of Salem, Virginia, is one of the largest manufacturers of
electrical drive systems worldwide. Using VisSim and
VisSim/Real-TimePRO, engineers recently completed prototyping a
Resonance Eliminator Controller (REC) for industrial drive systems
used in metals rolling applications. The goal of the controller,
according to Emil Kuelz and Sandy Gurian, System Engineers for
GEMIS, is to reduce resonance vibrations in the shafts and rolls of
the mechanical system. Kuelz and Gurian modeled the motor and
mechanical system in VisSim, and then incorporated the REC. The REC
computes a motor torque correction signal from shaft torque
measurement, which in turn is applied to the mechanical system at a
specific resonant frequency.
To test the design, Kuelz and Gurian used
two PCs, each running VisSim/Real-TimePRO. One PC contained the
motor and mechanical system simulation; the other, the REC. VisSim's
A-D/D-A real-time interface allowed the two models to exchange
information. This configuration verified that controller performance
would not be degraded by either time delays introduced by the
A-D/D-A conversions or the precision of the 12-bit DAC. "The
simulation results assured us that the REC would function properly
when attached to the actual motor and mechanical system," said
Kuelz.
After verification, Kuelz and Gurian
disconnected the PC with the REC from the PC with the motor and
mechanical system simulation, and reconnected it to the real motor
and mechanical system in GEMIS's in-house laboratory. The first time
the REC was turned ON, it totally eliminated the mechanical system
resonance.
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VisSim model of GE industrial drive system
with Resonance Eliminator Controller. Upper plot shows amount of
correction applied to motor torque. Lower plot shows drive
speed. |
Real-Time I/O cards & data channels can be
configured directly from VisSim via intuitive dialog boxes.
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By developing and testing the REC in
VisSim and VisSim/Real-TimePRO, Kuelz and Gurian focused exclusively
on proving the viability of the design. "The risks of connecting an
unproved design to a large horse power electrical drive and
mechanical system are great," said Kuelz. "If incorrectly designed
and not thoroughly tested, it can cause motor, shaft, and coupling
failure, resulting in a process outage costing millions of dollars."
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