Model sensor that converts thermal potential difference into electrical potential difference
The Thermocouple block represents a thermocouple using the standard polynomial parameterization defined in the NIST ITS-90 Thermocouple Database . The voltage E across the device in mV is
E(mV) = c0 + c1*t + ... + cn*tn
ci is the ith element of the Coefficients [c0 c1 ... cn] parameter value.
t is the temperature difference in degrees Celsius between the temperature at the thermal port A and the Reference temperature parameter value.
Note: The equation for voltage across the device as a function of temperature difference is defined in mV. The units of the voltage across the actual device is V.
The following equation describes the thermal behavior of the block:
T is the temperature at port A.
Q is the net heat flow into port A.
Kd is the Dissipation factor parameter value.
tc is the Thermal time constant parameter value.
dT/dt is the rate of change of the temperature.
To model the thermocouple in free space:
Connect the thermocouple to the B port of a Simscape™ Convective Heat Transfer block.
Connect the A port of the Convective Heat Transfer block to a Simscape Ideal Temperature Source block whose temperature is set to the ambient temperature.
Set the Area parameter of the Convective Heat Transfer block to an approximate area Anom.
Set the Heat transfer coefficient parameter of the Convective Heat Transfer block to Kd/Anom.
The model is based on the following assumptions:
The high-order polynomials this block uses are very sensitive to the number of significant figures used for computation. Use all available significant figures when specifying the Coefficients [c0 c1 ... cn] parameter.
Coefficients [c0 c1 ... cn] are defined for use over a specified temperature range.
This block does not include the additional exponential term that Type K thermocouples use when parameterized for t > 0.
The vector of coefficients c in the equation
that describes voltage as a function of temperature. The default value
[ 0 0.0054031 1.2593e-05 -2.3248e-08 3.2203e-11 -3.315e-14
2.5574e-17 -1.2507e-20 2.7144e-24 ]. This value specifies
a Type S thermocouple, which is valid in the range -50 to 1064 degrees
Note: You can download parameters for other standard thermocouple types from the NIST database . For information on how to do this, see the Simulink® Approximating Nonlinear Relationships: Type S ThermocoupleApproximating Nonlinear Relationships: Type S Thermocouple example.
The temperature the block subtracts from the temperature at
the thermal port in calculating the voltage across the device. The
default value is
The time it takes the thermocouple temperature to reach 63%
of the final temperature change when a step change in ambient temperature
occurs. The default value is
The thermal power required to raise the thermocouple temperature
by one K. The default value is
The temperature of the thermocouple at the start of the simulation.
The default value is
The block has the following ports:
Thermocouple thermal port
Positive electrical port
Negative electrical port
 NIST ITS-90 Thermocouple Database http://srdata.nist.gov/its90/main