81
4.4.3 Motor Model and Dynamic Load Model Motor Start
The results in this section show simulated induction motor behavior. The dynamic load
model is included in the model. Results are presented using motor manufacturer parameters
with the standard motor model, estimated motor parameters for the standard motor model,
and estimated parameters for the non-linear motor model. The speed, stator current, and
shaft torque is shown for each of the three motors. For clarity, only the phase C stator
current is shown. The remaining two phases behave similar to phase C.
4.4.3.1
10 hp Motor Simulations
Figure 55 shows the speed waveform for a 10 hp motor during a start condition using load
inertia I1. At time t=0, the motor is energized from a standstill. Four curves are shown: a
simulation using the standard motor model with motor manufacturer parameters, a simulation
using the standard motor model with estimated parameters, a simulation using the non-linear
motor model with estimated parameters, and measured data. For all three simulation curves,
the dynamic load model using inertia I1 was used.
The non-linear motor model produces the best agreement with the measured data and the
standard model with the motor manufacturer parameters produces the worst agreement. The
most noticeable characteristic of the standard motor model is that the simulated speed is more
"concave" whereas the measured speed is more "convex". Also, the standard motor model
using the motor manufacturer parameters reaches rated speed much more rapidly than
expected. This is because the motor manufacturer parameters cause the motor to produce
significantly more torque than the estimated parameters. However, the stator current is
unreasonably high, nearly four times the measured value. This can be seen in the current and
torque waveforms shown in Figs 56 and 57 respectively.