**3.2. Simulation parameters and data presentation**

For proper numerical computations Matlab provides various simulation options including the specific numerical method (solver), the allowed tolerance, and mode of computation. Since some numerical methods are more computationally intensive than others, the user may choose a less intensive method for simulations that don't require solving highly nonlinear differential equations, for example. This improves the efficiency of the simulation and accelerates obtaining results. Some trial and error may be necessary to achieve a successful simulation. However, the default simulation options can typically be used for most simulations. If the simulation takes too long to execute or the computed data is incomplete, is at an unacceptable resolution, or has errors, it will be necessary to change simulation parameters. Highly complex simulations may require some time invested in finding the correct solver for the application in order to achieve a good balance between accuracy and computation times. The Configuration Parameters dialog box is found under the Simulation tab in Simulink, Fig. 7. Usually the best choice is to leave these set to "auto" to allow Simulink to determine simulation parameters automatically, based on the model.

148 MATLAB – A Fundamental Tool for Scientific Computing and Engineering Applications – Volume 1


**Table 3.** Common SimPower Power Electronics Models


**Figure 7.** Configuration Parameters Dialog Box

The solvers are categorized into two general types: Fixed step, and Variable step. Fixed step simulations evaluate in user-set time steps that are constant throughout simulation. Variable step solvers dynamically change the simulation step size to optimize simulation time vs. accuracy. Therefore, the goal in choosing the solver is to find the least computationally intensive method that yields the level of accuracy required. Solver types are summarized in Table 4.


**Table 4.** Solver Types

148 MATLAB – A Fundamental Tool for Scientific Computing and Engineering Applications – Volume 1

**Table 3.** Common SimPower Power Electronics Models

**Figure 7.** Configuration Parameters Dialog Box

**A B C**
