Defining the System Plant

The System or Plant block defines the information about the power supply hardware that needs to be controlled. Because Microchip dsPIC® DSCs are well suited for many different power supply topologies, the DCDT GUI gives you the flexibility to define the plant using any one of these three different methods:

  • Polynomial Transfer Function
  • Pole Zero Transfer Function
  • Import Plant Data
Select-Plant-Entry-Method.PNG

Plant in Polynomial Form

You can enter the transfer function of the System or Plant by expressing this in a Polynomial form, where you define each of the polynomial coefficients.

Polynomial-Plant-Transfer-Function.PNG
Plant-Polynomial-Window.PNG

Plant in Pole Zero Form

The second method to enter the System Plant information is using the frequency domain Real Poles and Real Zeros by entering the frequency location (in Hz). The GUI will compute the system transfer function and use this for all computations.

Pole-Zero-Plant-Transfer-Function.PNG
Plant-Pole-Zero-Window.PNG

Plant Imported From

The third method to define the System Plant is by importing the Gain and Phase information as a data index using a Comma Separated Value (.CSV) file format. This allows you to import the frequency response characteristics from real hardware measurements or data gathered using simulation tools.
The data to be imported must follow formatting guidelines:

  • The file must be saved as Comma Separated Values (.CSV).
  • The first row will not be imported and is assumed to be the column name.
  • The first data column will be the frequency, defined in Hertz (Hz).
  • The second data column will be the Plant Gain magnitude, defined in decibels (dB).
  • The third data column will be the Plant Phase, defined in degrees (°).
  • For good plant resolution it is suggested to have at least 10 data points per frequency decade, there is a maximum plant.
  • The frequency sweep data must be sequential and incrementally organized.
Import-Plant-CSV-Format-Example.PNG

Using the File Browser Menu, locate the data file. Once the data is successfully imported, it will be displayed inside the GUI window, as shown in the Import Plant Window below.

Import-Plant-Window.PNG
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