Download Major Modifications

Major Modifications and System
Modeling
• Use a Peltier cooler
• According to the
as an actuator instead
previous design of the
of a power resistor.
temperature board,
the transfer function
of
the
open-loop
• Relocate the ambient
system is
sensor further away
from the aluminum
blocks.
K
G(s) 
e  s d
 bs 1
New Temperature Control Board
System Schematics
Desired Temperature Difference
Plant 1 Temperature Reading
Controller
LM 35 Plant 2 Temperature Sensor
PWM Control Signal
LM 35 Plant 1 Temperature Sensor
Aluminum Block with relatively small thermal mass (Plant 1)
Peltier Cooler (Actuator)
Aluminum Block with relatively large thermal mass (Plant 2)
LM 35 Ambient Temperature Sensor
Plant 2 Temperature Reading
Temperature Difference between Plant 1, Plant 2 or
Ambient (whichever two the user select)
Instantaneous Temperature Difference
Peltier Cooler
• Temperature range: -20oC~85oC
Paralleled Amplifier Configuration
• This configuration is often used when
a single amplifier is incapable of
being operated into a low impedance
load or dissipation per amplifier is to
be reduced without increasing the
load impedance or reducing power
delivered to the load. The output
current is now shared by both
amplifiers - each amplifier supplies
half the load current, and the
dissipation per amplifier is halved.
Output
Technical Obstacles
• The control signal of the Peltier cooler is bidirectional
(-4.5V~4.5V), but the temperature board only provide
voltage from 0~9V. How to convert the voltage signal?
• How to transform the old architecture that is based on
the power resistor to the new one that is based on the
Peltier cooler?
• Overcome the current dissipation problems of
LMC6484IN op amps from the motor control board with
paralleled amplifier configuration.