A non-ideal switch model should simulate a device transition similar to how the real hardware will work. However, the model should not be so complex that the simulation takes forever to complete with questionable numerical stability. We have models that provide meaningful results without simulation stability issues.
Switch losses comprise of switching and conduction losses. The switching and conduction losses are a function of voltage, current, temperature, and gate drive. Performing a detailed switch transition to get the switching losses is sometimes overkill. We have special thermal models for when a detailed switch transition is not required.
Your converter needs to pass electromagnetic interference standards. Before you book time at the local lab, our design tools will let you compare your conducted emission vs the target standard and design a filter so that there are fewer surprises with the hardware.
We recommend the use of ideal switches for most simulations. However, the detail of the actual switch transition can make or break your power converter, literally. You need to observe voltage overshoot, coupling through the miller capacitance, snubber design, switching losses, and interactions with parasitic inductors and capacitors throughout the circuit. A non-ideal switch also has a realistic dv/dt & di/dt during turn on/turn off; this is critical to properly analyze transients in long cables.
We provide several options to model a non-ideal transition with different levels of precision. PSIM has a level 2 switch model which will provide a switch transition that is comparable to a SPICE model. The PSIM level 2 model requires a proper gate drive circuit and a model is available for Si MOSFETs, SiC & GaN FETS, & IGBTs. PSIM also has a level 2 diode which models reverse recovery. In addition, you can link from PSIM to LTspice and use the manufacturers SPICE models directly. The advantage of the PSIM model is it’s convergence and numerical stability.
DSIM has its own non-ideal switch models, which provide astounding accuracy compared to the real hardware but solve in a fraction of the time compared to any other non-ideal switch model on the market.
An important part of any converter will always be efficiency and the main source of losses will be the switches changing state. The two loss types for switches are conduction losses and switching losses. Current, voltage, switching speed, junction temperature, and gate drive are all factors that contribute to the losses. You need to be able to:
Switching losses can be a tough problem for simulation tools to solve. To simulate switching losses properly an accurate non-ideal switch transition is required, which can require a nanosecond or smaller timestep to properly resolve. This very small timestep is not very practical if you want to look at losses for one cycle of the fundamental at 60Hz for a PFC; the simulation would be very long to solve.
PSIM has special thermal models that treat the switch transition as ideal and then compute the losses from a lookup table while considering: voltage across the switch, current through the switch, junction temp, and gate drive circuit. These thermal switches provide excellent correlation with the real world losses with a fraction of the computation requirements of a more realistic switch transition.
For efficiency calculations, the thermal models can provide a good estimate, but using PSIM level 2 models for a realistic device transition will provide better accuracy.
PSIM thermal models: IGBT, MOSFET, Wide bandgap (SiC & GaN) FETs, Diode. Also, inductors and with core and winding losses
PSIM level 2 models: All FETS, IGBT, Diode
Real products need to pass EMI certification. EMI certification has two components: radiated and conducted emissions. We can help you study and mitigate your conducted emissions. Studying conducted EMI requires having the necessary parasitic components for differential and common mode noise and a realistic switch transition.
PSIM level 2 models can provide the realistic switch transitions and parasitic elements can be added to the circuit. However, parasitic capacitors to ground, wire inductance values, and similar parasitic elements are typically very small, these small values can cause difficult and very slow simulations. The strength and robustness of PSIM’s solve engine is put on full display in these simulations as PSIM is able to work through the simulation without numerical or convergence issues.
Make use of our EMI Design Suite to: