Resistor (Advanced)
Resistor to account for resistance reference error and noise.
Description
The Resistor block represents a linear resistor model with the ability to simulate the following effects:
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Resistor value errors
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Noises during operation
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Thermal dependencies of parameters
You can independently switch the listed options on and off. When all additional options are disabled, the behaviour of the component is identical to the block Resistor.
In its simplest form, the Resistor block models a linear resistor described by the following equation:
,
where:
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- current.
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- voltage.
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- resistance.
Errors
You can add an error to the nominal value specified for the Resistance parameter. Such an error is usually specified in the technical descriptions. The table shows how the unit applies the error and calculates the resistance depending on the selected value of the Tolerance application parameter.
| Tolerance application parameter value | Resistance value |
|---|---|
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Uniform distribution: Normal distribution: |
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In the table:
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- nominal resistance, value of parameter Resistance.
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- error, value of parameter Resistance tolerance (%)/100.
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- value of parameter Number of standard deviations for quoted tolerance.
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and - standard functions for generating random numbers with uniform and normal distribution.
Thermal noise
The resistor block can generate a thermal noise current. If you select the Noise mode checkbox, a discrete variable is added to the defining equations to represent thermal noise:
.
If the interval between calculation steps is , then thermal noise is defined as follows: where:
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- Boltzmann constant, 1.3806504e-23 J/K.
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- temperature.
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- resistance.
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- random number with zero mean and unit standard deviation.
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- two-sided thermal noise power distribution (one-sided equivalent is equal to ).
The unit generates noise according to a normal distribution using a random number generator. You can influence the random number generation by adjusting the Repeatability parameter:
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Not repeatable- the seed of the random generator changes every time you run the model. -
Specify seed- allows you to specify an explicit seed value using the Seed parameter.
Ports
Non-directional
+ - positive
electricity
Electrical port, represents the positive terminal.
- represents the negative terminal
electricity
Electrical port, represents the negative terminal.
H is a heat port
heat
Heat Port.
Dependencies
To use this port, enable the Enable thermal port parameter.
Parameters
Main
Resistance - nominal value of resistance
1 Ohm (by default) | positive | scalar
Nominal resistance value. The resistance value must be greater than zero.
Tolerance (%) - resistance error
5 (By default)
Resistance error specified in the data sheet.
Tolerance application - tolerance application
None - use nominal value (by default) | Random tolerance | Apply maximum tolerance value | Apply minimum tolerance value.
Select how the error is applied during modelling:
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None - use nominal value- Unit does not apply tolerance, uses nominal resistance value. -
Random tolerance- The unit applies a random offset to the resistance value within the error. You can select uniform or normal distribution to calculate the random number using the *Tolerance distribution` parameter. -
Apply maximum tolerance value- the resistance is increased by the specified tolerance value. -
Apply minimum tolerance value- the resistance decreases by the specified tolerance value.
Tolerance distribution - type of tolerance distribution
Uniform (by default) | Gaussian.
Select the distribution type:
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Uniform- uniform distribution. -
Gaussian- normal distribution.
Dependencies
To use this parameter, set the Tolerance application parameter to Random tolerance.
Number of standard deviations for quoted tolerance - used to calculate normally distributed random numbers
4 (By default).
Number of standard deviations for calculating normally distributed random numbers.
Dependencies
To use this parameter, set the Tolerance distribution parameter to Gaussian.
Noise
Enable noise mode - enable noise effect modelling
off (by default) | on
Select the checkbox for noise modelling.
Dependencies
Selecting the Enable noise mode check box opens the related parameters.
Sample time - period of noise values generation
`1e-3 s (By default)
Defines the frequency of random number generation for the noise source. Set this value to reflect the frequencies of interest in your model. Too small an interval between calculation steps will slow down the simulation unnecessarily.
Dependencies
To use this parameter, select the Enable noise mode checkbox.
Repeatability - random number generator control
Not repeatable (By default)` | Specify seed.
To control the random number generator, set this parameter to the following value:
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Not repeatable- the seed of the random generator changes every time you run the model.
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Specify seed- allows you to specify explicit value of seed using Seed parameter.
Dependencies
To use this parameter, select the Enable noise mode checkbox.
Selecting Repeatable or Specify seed opens the related parameters.
Seed - initial value of random number generation
0 (By default)
The initial value must be 0 or a positive integer.
Dependencies
To use this parameter, select the Noise mode checkbox and the Specify seed value for the Repeatability parameter.
Device simulation temperature - device simulation temperature
25 °C (By default).
The value of the temperature at which the resistor will be simulated.
Dependencies
To use this parameter, select the Noise mode checkbox.
Thermal
Enable thermal port - Enable thermal port
` disabled (by default)` | enabled
Whether to enable the thermal port of the unit and simulate the effect of the heat generated and the temperature of the device.
Resistance temperature coefficient - resistance temperature coefficient
`0.00393 1/K (By default).
Coefficient in the equation , which describes resistance as a function of temperature.
By default value for copper.
Dependencies
To use this parameter, enable the Enable thermal port parameter.
Measurement temperature - device simulation temperature
25 °C (By default).
Temperature , for which the nominal resistance is set .
Dependencies
To use this parameter, enable the Enable thermal port parameter.
Thermal mass - the thermal mass associated with the thermal port
100 J/K (by default) | positive number.
The thermal mass associated with the heat port is H. It represents the energy required to raise the temperature of the thermal port by one degree.
Dependencies
To use this parameter, enable the Enable thermal port parameter.