GTO
Latched thyristor.
Description
The GTO (Gate Turn-Off Thyristor) block simulates a lockable thyristor. The volt-ampere characteristic of the thyristor is such that the thyristor is open when the gate-cathode voltage exceeds the specified open-loop control voltage. The thyristor is closed if the gate-cathode voltage is below the specified control open voltage or if the load current falls below the specified hold current.
In the open state, the anode-cathode channel behaves like a linear diode with a forward voltage drop and an open state resistance .
In the closed state, the anode-cathode channel behaves like a linear resistor with low conductance in the closed state .
The equations for the anode-cathode current are written as follows:
, if , and one of two conditions is fulfilled: or ,
otherwise ,
where
-
- anode-cathode voltage
-
- forward voltage;
-
- gate voltage;
-
- opening control voltage;
-
- anode-cathode current;
-
- holding current;
-
- latching control voltage;
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- open resistance;
-
- closed state conductivity.
Using the Integral Diode parameters, an internal protection diode can be enabled. A GTO that includes an internal protection diode is also called an asymmetric GTO (A-GTO) or a reverse conductance GTO (RCGTO). The integrated diode protects the semiconductor device by providing a conduction channel for reverse current. An inductive load can create a large reverse voltage spike when the semiconductor device abruptly cuts off the voltage supply to the load.
Set the value of Integral protection diode depending on the purpose.
| Purpose | Value to select | Integral protection diode | |
|---|---|---|---|
Do not enable protection. |
|
Not used |
|
Enable protection. |
Simulation speed priority. |
|
Adds internal unit Diode (Advanced). |
Priority of modelling accuracy - accurate indication of charge dynamics in reverse mode. |
|
Adds internal block Diode (Advanced) with charge dynamics. |
|
Ports
Parameters
Main
Gate-control port - option for specifying the type of gate-control port
Signal control port (by default) | Electrical control port
Option to specify the physical or electrical gate-control port of the switch.
Forward voltage, Vf - forward voltage
0.8 V (by default)
Forward voltage at which the device switches on.
On-state resistance - open-state resistance
`0.01 ohm (by default)
Resistance of the open anode-cathode channel.
Off-state conductance - closed state conductance
1e-6 1/ohm (by default)
Anode-to-cathode conductance in closed state. The value of this parameter must be less than , where is the value of On-state resistance.
Gate trigger voltage, Vgt - control opening voltage
6 V (by default)
Gate-cathode threshold voltage. The device is switched on when the gate-cathode voltage exceeds this value.
Gate turn-off voltage, Vgt_off - latching control voltage
6 V (By default).
Gate-cathode threshold voltage. The device switches off when the gate-cathode voltage is below this value.
Holding current - holding current
`1 A (by default).
Current threshold value. The device remains switched on if the current exceeds this value, even if the gate-cathode voltage falls below the open-loop control voltage.
Integral Diode
Integral protection diode - internal protection diode (suppressor)
None (by default) | Diode with no dynamics | Diode with charge dynamics
Specify whether the unit includes a protection diode (suppressor). By default, `None' is used.
If the internal protection diode is to be enabled, two options are available:
-
Diode with no dynamics. -
`Diode with charge dynamics'.
Forward voltage - forward voltage
0.8 V (by default).
Minimum voltage between anode and cathode of the diode to make the gradient of the diode volt-ampere characteristic equal to 1/ , where is the value of On resistance parameter.
Dependencies
To use this parameter, set Integral protection diode to Diode with no dynamics or Diode with charge dynamics.
On resistance - resistance when directly connected
0.001 ohms (by default).
The diode resistance in the open state when the voltage is higher than the value set by the Forward voltage parameter.
Dependencies
To use this parameter, set Integral protection diode to Diode with no dynamics or Diode with charge dynamics.
Off conductance - closed state conductance
1e-5 1/ohm (by default).
The conductance of the diode when switched back on.
Dependencies
To use this parameter, set Integral protection diode to Diode with no dynamics or Diode with charge dynamics.
Junction capacitance - junction capacitance
5e-8 F (By default).
The value of the capacitance inherent in the depletion zone transition, acting as a dielectric and separating the anode and cathode junctions.
Dependencies
To use this parameter, set Integral protection diode to `Diode with charge dynamics'.
Peak reverse current, iRM - peak reverse current
-235 A (By default).
Peak reverse current measured by an external test circuit. This value must be less than zero. The value by default is -235 A.
Dependencies
To use this parameter, set Integral protection diode to `Diode with charge dynamics'.
Initial forward current when measuring iRM - Initial forward current when measuring iRM
300 A (By default).
Initial forward current (at initial switch-on time) when measuring peak reverse current. This value must be greater than zero.
Dependencies
To use this parameter, set Integral protection diode to `Diode with charge dynamics'.
Rate of change of current when measuring iRM - rate of change of current when measuring iRM
-50 A/µs (By default).
Rate of change of current when measuring peak reverse current. This value must be less than zero.
Dependencies
To use this parameter, set Integral protection diode to `Diode with charge dynamics'.
Reverse recovery time parametrization - type of reverse recovery time definition
| Specify stretch factor (by default) | Specify reverse recovery time directly ` | `Specify reverse recovery charge.
Selecting Specify stretch factor or Specify reverse recovery charge specifies the value used by the unit to calculate the reverse recovery time.
Dependencies
To use this option, set Integral protection diode to `Diode with charge dynamics'.
Reverse recovery time, trr - reverse recovery time
`15 µs (By default)
The amount of time it takes for a diode to switch off when its voltage reverses polarity from forward bias to reverse bias.
The interval between when the current initially crosses zero (when the diode switches off) and when the current drops to less than 10% of the peak current. The value of Reverse recovery time, trr must be greater than the value of Peak reverse current, iRM divided by the value of Rate of change of current when measuring, iRM.
Dependencies
To use this parameter, set the Integral protection diode parameter to `Diode with charge dynamics' and the Reverse recovery time parametrization parameter to `Specify reverse recovery time directly'.
Reverse recovery time stretch factor - reverse recovery time stretch factor
3 (By default).
The value that the block uses to calculate Reverse recovery time, trr. This value must be greater than 1. Specifying the stretch factor is a simpler way of parameterising the reverse recovery time than specifying the reverse recovery charge. The larger the value of the stretch factor, the longer the time required for the reverse recovery current to dissipate.
Dependencies
To use this parameter, set the Integral protection diode parameter to `Diode with charge dynamics' and the Reverse recovery time parametrization parameter to `Specify stretch factor'.
Reverse recovery charge, Qrr - reverse recovery charge
1500 µAs (by default).
The value the unit uses to calculate Reverse recovery time, trrr. Use this parameter if the unit parameters specify the reverse recovery charge value instead of the reverse recovery time value as the type of reverse recovery time definition.
The reverse recovery charge is the total charge that continues to dissipate after the diode is switched off. The value must be less than , where:
-
- value specified for the Peak reverse current, iRM parameter;
-
- the value specified for the parameter Rate of change of current when measuring iRM.
Dependencies
To use this parameter, set the Integral protection diode parameter to `Diode with charge dynamics' and the Reverse recovery time parametrization parameter to `Specify reverse recovery charge'.