Thyristor

Ideal thyristor: turns on at a fire pulse when forward biased, off when current reverses.

  • Boolean
  • electrical
  • Modelica Standard Library
  • 3 ports
  • 2 parameters
BlockThyristorKindidealThyristorLibrarySemiconductors

Description

An ideal thyristor (SCR). It turns on when fire is true while the anode–cathode voltage is forward, then stays on after fire goes false until its current falls to zero.

Fire is level-sensitive: while fire stays true the thyristor behaves like an ideal diode.

Example

Thyristor and GTO A thyristor that stays on until its current falls to zero, and a GTO that turns off with its gate.

10 V 50 Hz TThyristorLoad Tv TGround T10 V 50 Hz GGTOLoad Gv GGround GFire at 2.5 msFire at 2.5 ms (GTO)
In Gradara, select a Thyristor block and press F1, then choose Open example. It opens as a new model in My models, ready to run.

Also in this example:Voltage sensorGroundResistorAC voltageGTO thyristorBoolean pulse

Ports

Inputs 1

  • gfireBoolean

    Gate command (Boolean). A true value turns the thyristor on if it is forward biased.

Conserving terminals 2

  • Apelectrical

    Anode. Current into p is counted as positive.

  • Knelectrical

    Cathode.

Parameters

  • On resistanceRon0.00001 Ω

    ≥ 0

    On resistance, in ohms: the slope of the conducting branch. 0 or more; the default 10 µΩ is near-ideal.

  • Off conductanceGoff0.00001 S

    ≥ 0

    Off conductance, in siemens: the slope of the blocking branch, so the leakage is Goff · v. 0 or more; the default 10 µS leaks 10 µA per volt.

Equations

Modelica
v = p.v − n.v, i = p.i
Off: i = Goff · v; on: v = Ron · i
off = (s < 0) or (pre(off) and not fire), where s < 0 means v < 0 while off, or i < 0 while on

Implementation

Modelica Standard Library 4.1.0Modelica.Electrical.Analog.Ideal.IdealThyristor
MSL documentation

Assumptions and limitations

  • Knee voltage fixed at 0 V. No holding or latching current, gate current, dv/dt triggering, turn-off time, or reverse recovery.

Tips

  • Short fire pulses are enough to trigger it; delay them from the voltage zero crossing to set the firing angle.

See also

Select a block in Gradara and press F1 to open its page offline.