MOSFET with Limited di/dt

Purpose

Dynamic MOSFET model with finite current slopes during turn-on and turn-off

Library

Electrical / Power Semiconductors

Description

../../_images/mosfet.svg

In contrast to the ideal MOSFET model that switches instantaneously, this model includes drain current transients during switching. Thanks to the continuous current decay during turn-off, stray inductances may be connected in series with the device.

This MOSFET model is used to simulate overvoltages produced by parasitic inductances and the reverse recovery effect of diodes. Due to simplified voltage and current transient waveforms, the model is not suited for the simulation of switching losses. The dynamic behavior of this MOSFET model is identical with the one of the IGBT with Limited di/dt.

Note

  • Due to the small time-constants introduced by the turn-on and turn-off transients a stiff solver is recommended for this device model.

  • If multiple MOSFETs are connected in series, the off-resistance may not be infinite.

Parameters

Blocking voltage

Maximum voltage \(V_{\mathrm{DSS}}\) in volts \((\mathrm{V})\) that under any conditions should be applied between drain and source.

Continuous drain current

Maximum dc current \(I_{\mathrm{D}}\) in amperes \((\mathrm{A})\) that the MOSFET can conduct.

On-resistance

The resistance \(R_{\mathrm{on}}\) of the conducting device, in ohms \((\Omega)\). The default is 0.

Off-resistance

The resistance \(R_{\mathrm{off}}\) of the blocking device, in ohms \((\Omega)\). The default is 1e6. This parameter may be set to inf unless multiple MOSFETs are connected in series.

Rise time

Time \(t_{\mathrm{r}}\) in seconds \((\mathrm{s})\) between instants when the drain current has risen from 10% to 90% of the continuous drain current \(I_{\mathrm{DS}}\).

Fall time

Time \(t_{\mathrm{f}}\) in seconds \((\mathrm{s})\) between instants when the drain current has dropped from 90% to 10% of its initial value along an extrapolated straight line tangent the maximum rate-of-change of the current.

Stray inductance

Internal inductance \(L_{\mathrm{s}}\) in henries \((\mathrm{H})\) measured between the drain and source terminals.

Initial current

The initial current through the component at simulation start, in amperes \((\mathrm{A})\). The default is 0.

Probe Signals

MOSFET voltage

The voltage measured between drain and source.

MOSFET current

The current through the MOSFET flowing from drain to source.

MOSFET conductivity

Conduction state of the internal switch. The signal outputs \(0\) when the MOSFET is blocking, and \(1\) when it is conducting.