Recently, I found a decent program called PSCAD. It is a fixed-step nodal analysis based simulator which is mostly meant for high voltage power systems. I developed a number of power converter examples which are being made available to the power community on MotorLab.com. Below is a description and link for each. All examples run in the student version which an be downloaded at
I like PSCAD because it doesn't have some of the limitations that other simulators have. You have to know what you are doing, but PSCAD doesn't give regular convergence problems or connectivity problems when putting components together. One major advantage is that you can create a fairly elaborate simulation in the student version. As you can see in the examples below, the power circuit, modulation, and control all fit in one simulation. This makes PSCAD exceptionally useful for teaching.
This is a standard six-transistor inverter illustrating sine-triangle PWM with third harmonic terms as well as 180 degree VSI. This example also shows PSCAD controls and meters.
This is a three-level diode-clamped inverter with sine-triangle modulation.
A standard six-transistor inverter with an R-L-C output filter between the inverter and load.
A standard inverter controlled with hysteresis current-regulated modulation.
A three-level inverter made by paralleling half bridges with inductors and interleaved switching.
A single-phase nine-level series connected H-bridge inverter.
Active rectifier with constant modulation index and constant phase shift angle.
A brushless dc drive with 180 degree votlage-source inverter operation.
A brushless dc drive supplied from an ideal inverter.
A brushless dc drive with sine-triangle modulation.
An ideal active filter demonstrating control in the synchronous reference frame.
This example illustrates concepts of reference frame theory applied to a 180 degree voltage source inverter.
This example displays a three-phase set of sinusoidal voltages in the synchronous and stationary reference frames.