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Equalis Data Acquisition and Control Systems in action

The Equalis Data Acquisition and Control Systems (DACS) module [1] allows a user to define a mathematical model of a typical control system in the form of a block diagram. From this model you can view critical charts and important characteristics of that system such as step response, Bode, Nyquist Nichols, Pole-Zero, and Singular values plots.

In this example we use our Control and Power Systems module from DACS to analyze a linear model of a permanent magnet DC motor. This motor can be modeled as shown below.

Assuming a constant load, we can consider a DC motor as a SISO sysem, where the applied voltage Va is the input and the motor speed is the output. Using standard mathematical operations (such as summation, gain, integration), let us create a diagram of this SISO system.

The resulting diagram is shown below:

The input Va can be connected to a constant block (this means a constant voltage).

The output w is the speed in rad/s.

Let us use Simulation>Set context to set the following values of constants which appear in the diagram:

J=3.2284E-6; b=3.5077E-6; K=0.0274; R=4; L=2.75E-6;

Now let us analyze the obtained SISO system using the Control and Power Systems module.

For example, let us build a Bode plot. To do this, we open the Linear Analysis palette and place two Operating_Point blocks and one Bode block.

The Operating_Point blocks indicate inputs and outputs of a linear system or subsystem in a diagram.

The only parameter an Operating_Point block is its name (the names of different blocks should be unique).

Let us set the names of two Operating_Point blocks as "begin" and "end" and connect them as displayed follows:

The role of Bode block is to build a bode plot of a SISO system located between two operating points ("begin" and "end").

Let us set its parameters as follows:

When at least one Bode block is present in the diagram and the user clicks Simulation->Start, the system displays a Bode plot. To run a transient simulation the user can (temporally) remove or disable the Bode block.

Now let us start simulation. We will see Bode plot of the transfer function of our system.

Analogously, we can display Nyquist plot and other plots supported by the Control and Power Systems module.


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