ABSTRACT:The simulation package SABER has been employed for model development. The motor is a DC motor. The motor is modeled using the Permanent Magnet Machine available in Saber. This symbol is a permanent magnet DC machine that may act as either a motor or generator depending on how it is connected. The various motor parameters are specified depending on the experimental results obtained.
The fan load is modeled using a "Fan" template with both
viscous damping and windage effects. Its behavior is such that an angular
velocity on the input connection produces two drag torque components one
that is directly proportional to that velocity (viscous damping) and one
that is proportional to the square of the velocity (windage). Here
again the parameters are assigned as per the fan in the experimental setup.
The armature parameters for the motor were obtained using
least squares estimation from standstill time domain step response. The
speed, torque and load constants were obtained by least squares estimation
using steady state measurements of voltage, current and speed; the measurements
encompassed the entire speed range.
In order to create a model of our system in SABER, the
following points were taken into consideration:
The battery is a constant source of DC voltage of magnitude
14V. The battery voltage (Vbat) is modeled by the "Constant Voltage Source"
available in SABER.
The function of the ASIC is primarily to supply a gate drive to the switch. The gate drive is basically a PWM wave of frequency 20kHz and amplitude varying from 0 to battery voltage (Vbat) with a duty cycle variation from 0 to 100% from minimum to maximum speed. This function of the ASIC can therefore be simply modeled using by a voltage source outputting a square wave with adjustable duty cycle and maximum amplitude. Vbat. Thus the gate drive for the MOSFET is modeled by a "Voltage Pulse Source" in SABER.
The switch used is the HDTMOS FET MTP60N06HD manufactured by Motorola. The model for this MOSFET has been used in the simulation circuit.
The block "Discrete Components" is used to describe all
the resistors, capacitors, inductors and diodes shown in the schematic.
Since in our model, we are representing the ASIC by a voltage source, all
the components related to the ASIC need not be modeled.
The motor is a DC motor. The motor is modeled using the
Permanent Magnet Machine available in Saber. This symbol is a permanent
magnet DC machine that may act as either a motor or generator depending
on how it is connected. The various motor parameters are specified depending
on the experimental results obtained.
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