Power System Blockset

Simulating with Continuous Integration Algorithms

Choosing the Right Integration Algorithm

Simulink provides a variety of solvers. Most of the variable step solvers will work well with linear circuits. However circuits containing nonlinear models, especially circuits with circuit breakers and power electronics, require stiff solvers.

Fastest simulation speed is usually achieved with ode23tb or ode15s with default parameters:

Solver : ode23tb or ode15s
Relative tolerance = 1e-3
Absolute tolerance = auto
Maximum step size = auto; Initial step size = auto.
Initial step size = auto
Maximum order (for ode15s) = 5

Normally, you can choose auto for the absolute tolerance and the maximum step size. In some occasions you may have to limit the maximum step size and the absolute tolerance. Selecting a too small tolerance can slow down the simulation considerably. The choice of the absolute tolerance depends on the maximum expected magnitudes of the state variables (inductor currents and capacitor voltages). For example, if you work with high power converters where expected voltage and currents are thousands of Volts and Amperes, an absolute tolerance of 1e-1 or even 1.0 should be sufficient. If you are working with low power circuits involving maximum values of 100 V and 10 A, you should use a smaller absolute tolerance like 1e-3 or 1e-2.

Which Integration Method Should Be Used - Continuous or Discrete?

Simulation of Switches and Power Electronic Devices