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Simulation and Animation of Power Electronics and Electrical Drives

Introduction

The applications notes in this book will guide you through the process of modeling and simulation in Caspoc
Their sole purpose is to guide you on your way exploring the possibilities of the program. You can read them to get a general overview of the possibilities of Caspoc or use them as a reference during your own simulation projects.

Each chapter is written to stand on its own. We recommend you to first read or follow our “Getting Started” guide, to get acquainted with the program.
This will take you about 15-30 minutes, but covers most of the topics. The topics on these chapters are advanced topics, which could be useful during your won modeling and simulation projects.
Also the FAQ list on caspoc.com gives answers to many of your questions.

The very basics

Although explained in the “Getting Started” guide, we will give a brief resume of the basic operations in Caspoc
Both the circuit and the block-diagram are drawn in the same schematic. So your model contains the electric circuit, the control, the electrical load or electrical machine, plus an eventually mechanical system in one workspace.
The difference between the electric circuit and the block-diagram models is indicated by the appearance of the nodes.

Electric circuit
In the electric circuit you can model your power circuit and calculate voltages over components or between nodes and currents through components. The nodes are indicated by round dots.
One node should be assigned to be the reference ground node, which always has a voltage level of 0 volts. Caspoc automatically inserts a ground label, which you can replace afterwards. By clicking the node with the right-mouse button, a dialog box pops up where you can type the label of the node. For a ground reference label type “0” or “ground”. To remove the label, press the [DEL] key.

Block-diagram
In the block-diagram you can model a dynamic system by using blocks which perform an operation on the inputs of the block. For example, an “ADD” block would add the signals at the two inputs and the result is available at the output. Block-diagram blocks are always operating from the inputs to the output and are automatically sorted by Caspoc. The nodes in the block-diagram are indicated by square dots.

Connection between the circuit and the block-diagram
You can measure voltages and currents from the electric circuit using the blocks “VOLTAGE” and “CURRENT” or one of the probes from the library.
Using the controlled voltage source “B” or controlled current source “A” a signal from the block diagram is used a current or voltage in the electric circuit.

Getting output
Use the “Scope” block to display any voltage, current, or block-diagram signal. You can insert a “Scope” in by clicking the first button on the bottom button bar.

Multiple simulations with parameter variations

Suppose we want to make a simulation where we are interested in the dependence of the system on one or more parameters. Instead of changing the parameter and restarting the simulation manually, we use the “Multiple Simulation” option.
In a multiple simulation project, you use the block “Multisim” where the output indicates the number of the simulation.
If wewant the multiple simulation to run 5 times, the output of the block “Multisim” will be equal to 0, 1, 2, .. 5, depending on the number of the simulation. Using the block-daigram, any parameter value can be constructed from the output of the block “Multisim”.
In the dialog box “Multiple Simulation Parameters”, which you open by selecting Simulation/Multiple Simulation Parameters you can specify the number of simulations.
The results from each simulation are stored in the “Scopes”. In the following example, the transient response for various values of the resistor in the circuit is simulated. Create the RLC circuit using the components V=1volt, L=1mH, C=100uF, R=10ohm and one Scope. Place a scope at the output node of the RLC circuit as indicated in the figure below.