Description

The back-to-back thyristor model consists of two similar thyristors connected in anti-parallel. This device helps in switching the current in either direction by applying a small current of either polarity between the gate and main terminal.

The model considers various factors like forward bias threshold, forward and reverse break over voltage, blocking current, snubber elements, holding current, on/off resistance. Depending on the user's requirement, there is also an option to select the precision functionality, which allows the user to compensate for errors due to digital implementation of the model during the state switching as a function of time step. The turnoff time Tq is the recovery time between the instant the anode current has decreased to 0 and the instant when the thyristor is capable of withstanding positive voltage without turning on again.

The model also has an option to be controlled from external signals and an option to enter the precision delay D.

Table of Contents

Mask and Parameters

General

Name	Description	Unit	Variable = {Possible Values}
Vmin	Forward voltage drop	V	{[0,1e12]}
Ropen	Open state resistance	Ohm	{(0,1e12]}
Rclose	Closed state resistance	Ohm	{(0,1e12]}
Rsnubber	Snubber resistance	Ohm	{(0,1e12]}
Csnubber	Snubber capacitance	F	{[0,1e12]}
Control type	External Input pins: Schematic control signal; the received integer is converted to a binary string where each digit corresponds to a phase External Input sensors: Target digital inputs

Advanced

Name	Description	Unit	Variable = {Possible Values}
Fail reset	Fail reset		{Enable, Disable}
Precision valve	Enable: Enables recalculation of the state switch command using exact time between steps (as percentage of time step) Disable: does not use precision valve		{Enable, Disable}
Imin	Holding current	A	{[0,1e12]}
Tq	Thyristor turn off time	s	{[0,1e12]}
Fbov	Forward break over voltage	V	{[0,1e12]}
Rbov	Reverse break over voltage	V	{[0,1e12]}

Ports, Inputs, Outputs and Signals Available for Monitoring

Ports

Name	Description
Net_1	Network connection
Net_2	Network connection

Inputs

Name	Description
D	Delay used for precision valves
P	Binary coded firing pulses

Outputs

None

Sensors

Name	Description	Unit
D	Delay used for precision valve, measured from changing point to current time step	s
P	Binary coded firing pulses
FailSig	Fail reset signal
I	Diode current	A
Isw	Switch current	A
Delay	Delay due to forward voltage drop	s
Delay12	Delay in forward Thyristor mode	s
Delay21	Delay in anti parallel Thyristor mode	s
DelayExt12	Delay for external trigger	s
DelayExt21	Delay for external trigger	s
Cmd12	Forward Signal state command
Cmd21	Anti parallel Signal state command
CmdExt12	Signal state external command
CmdExt21	Signal state external command
State12	Forward Thyristor state
State21	Anti-parallel Thyristor state

Note that in the previous table, the suffixes "12" and "21" denote the forward (positive to negative) and anti-parallel (negative to positive) thyristor states respectively. One can identify the positive terminal of the device as the one closest to the input pin. So, in the default (not flipped or rotated) thyristor back-to-back icon, the positive terminal is the top one.

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