Thyristor (Piecewise Linear)

Libraries:
Simscape / Electrical / Semiconductors & Converters

Description

The Thyristor (Piecewise Linear) block models a thyristor. The I-V characteristic for a thyristor is such that the thyristor turns on if the gate-cathode voltage exceeds the specified gate trigger voltage. The device turns off if the load current falls below the specified holding-current value.

To define the I-V characteristic of the thyristor, set the On-state behavior and switching losses parameter to either ```Specify constant values``` or `Tabulate`. The `Tabulate` option is available only if you expose the thermal port of the block.

In the on state, the anode-cathode path behaves like a linear diode with forward-voltage drop, Vf, and on-resistance, Ron. However, if you expose the thermal port of the block and parameterize the device using tabulated I-V data, the tabulated resistance is a function of the temperature and current.

In the off state, the anode-cathode path behaves like a linear resistor with a low off-state conductance, Goff.

The defining Simscape™ equations for the block are:

``` if (v > Vf)&&((G>Vgt)||(i>Ih)) i == (v - Vf*(1-Ron*Goff))/Ron; else i == v*Goff; end ```

where:

• v is the anode-cathode voltage.

• Vf is the forward voltage.

• G is the gate voltage.

• Vgt is the gate trigger voltage.

• i is the anode-cathode current.

• Ih is the holding current.

• Ron is the on-state resistance.

• Goff is the off-state conductance.

Using the Integral Diode tab of the block dialog box, you can include an integral cathode-anode diode. An integral diode protects the semiconductor device by providing a conduction path for reverse current. An inductive load can produce a high reverse-voltage spike when the semiconductor device suddenly switches off the voltage supply to the load.

The table shows you how to set the Integral protection diode parameter based on your goals.

GoalValue to SelectBlock Behavior
Prioritize simulation speed.`Diode with no dynamics`The block includes an integral copy of the Diode block. To parameterize the internal Diode block, use the Protection parameters.
Precisely specify reverse-mode charge dynamics.`Diode with charge dynamics`The block includes an integral copy of the dynamic model of the Diode block. To parameterize the internal Diode block, use the Protection parameters.

Model Gate Port and Thermal Effects

You can choose between physical or electrical ports to control the gate terminal and expose the thermal port to model the heat that switching events and conduction losses generate. To choose the gate-control port, set the Gate-control port parameter to `PS` or `Electrical`. To expose the thermal port, set the Modeling option parameter to ```No thermal port``` or `Show thermal port`.

Thermal Losses

Switching losses are major sources of thermal loss in semiconductors. During each on-off switching transition, the thyristor parasitics store and then dissipate energy.

Switching losses depend on the off-state voltage and the on-state current. When a switching device turns on, the power losses depend on the initial off-state voltage across the device and the final on-state current when the device is in its fully on state.

This block applies switching losses by stepping up the junction temperature with a value equal to the switching loss divided by the total thermal mass at the junction. You must specify the energy dissipated during a single switch-on event. You must also specify the corresponding values of the off-state voltage and on-state current at which you quote the losses. You can parameterize the switch-on loss, depending on the data you have. Use tabulated data if they are available.

• To specify a scalar value for the switch-on loss, set the On-state behavior and switching losses parameter to `Specify constant values`. The Switch-on loss parameter value sets the sizes of the switch-on loss. The block scales the loss by the off-state voltage and the on-state current.

• To specify the switch-on loss as a function of the junction temperature and on-state current, set the On-state behavior and switching losses parameter to `Tabulate`. The Switch-on loss, Eon(Tj,Iak) parameter sets the size of the loss. The block scales the loss by the off-state voltage.

When the current falls below the Holding current parameter value, the device switches off. The Natural commutation rectification loss parameter value defines the switch-off loss. The block does not scale this loss by the off-state voltage or on-state current because it is not possible to know when to measure the starting current or final voltage for the rectification loss.

Reverse recovery loss can be a significant source of thermal loss in diodes. The diode dissipates energy every time it turns off, from its conducting state to the open-circuit state. To model reverse recovery loss:

• Set Modeling option to ```Show thermal port```.

• Set Integral protection diode to ```Diode with no dynamics```.

If you set the Reverse recovery loss model parameter to `Tabulated loss`, the value of the Reverse recovery loss table, Erec(Tj, If) parameter specifies the dissipated energy as a function of the junction temperature and the forward current just before the switching event. The off-state voltage linearly scales the losses relative to the Turn-off voltage when measuring recovery loss, Vrec parameter value. The table uses delayed values for the current and voltage. To use a value in the lookup table that is close to the instantaneous value, set the Filter time constant for voltage and current values parameter to a value that is lower than the fastest switching period.

If you set the Reverse recovery loss model parameter to `Fixed loss`, the value of the Reverse recovery loss parameter specifies the energy dissipated during each turn-off event. If you select the Scale reverse recovery loss with current and voltage parameter, then the block scales this loss value linearly by the on-state current and the off-state voltage. To use scaling values that are close to the instantaneous values, set Filter time constant for voltage and current values to a value that is lower than the fastest switching period.

As an alternative method to model reverse recovery, you can set the Integral protection diode parameter to ```Diode with charge dynamics```. However, this approach requires smaller simulation time steps than using the first approach.

Note

The block does not know the current after a switching event during the simulation, so the block records the on-state current once the current is greater than the holding current for a time longer than the value specified by the Wait time before switch-on current measurement parameter. Similarly, the block records the off-state voltage at the point that the devices switches on. For this reason, the logged simulation data does not report the switching losses to the thermal network until one switching cycle later. To learn how to log and plot simulation data, see the Log and Plot Simulation Data example.

For all ideal switching devices, the logged simulation data reports the thermal losses as `lastTurnOffLoss`, `lastTurnOnLoss`, and `lastReverseRecoveryLoss`. For the Thyristor (Piecewise Linear) block, the `lastTurnOnLoss` is equal to the Natural commutation rectification loss parameter value. These variables include losses as a pulse with an amplitude equal to the energy loss. If you use a script to sum the total losses over a defined simulation period, you must sum the pulse values at each pulse rising edge. Alternatively, you can extract conduction and switching losses from logged data using the `ee_getPowerLossSummary` and `ee_getPowerLossTimeSeries` functions.

You can also access the total accumulated switching losses from the `accumulatedSwitchingLosses` variable in the logged simulation data. This variable sums all switching losses to date, including reverse recovery losses for the diode.

The `power_dissipated` variable in the logged simulation data does not include switching losses because the block models these losses as instantaneous events. The `power_dissipated` variable reports ohmic on-state losses.

If you use tabulated data to model the switching losses or reverse recovery losses, check that the temperature and current are in the range you specify. If you do not define a realistic thermal model, for example, if the junction mass or the conductance from the junction to the case is too small, the temperature can exceed the range you specify, causing the block to extrapolate the losses to nonphysical values.

Variables

To set the priority and initial target values for the block variables before simulation, use the Initial Targets section in the block dialog box or Property Inspector. For more information, see Set Priority and Initial Target for Block Variables.

Use nominal values to specify the expected magnitude of a variable in a model. Using system scaling based on nominal values increases the simulation robustness. Nominal values can come from different sources. One of these sources is the Nominal Values section in the block dialog box or Property Inspector. For more information, see System Scaling by Nominal Values.

Ports

The figure shows the block port names.

Conserving

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Port associated with the gate terminal. You can set the port to either a physical signal or electrical port.

Electrical conserving port associated with the anode terminal.

Electrical conserving port associated with the cathode terminal.

Thermal conserving port.

Dependencies

To enable this port, set Modeling option to `Show thermal port`.

Parameters

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Whether to enable the thermal port.

Main

This table shows how the visibility of Main parameters depends on how you configure the Modeling option and On-state behavior and switching losses parameters. To learn how to read this table, see Parameter Dependencies.

Main Parameter Dependencies

Parameters and Options
Modeling option
```No thermal port``````Show thermal port```
Gate-control portGate-control port
Forward voltage, VfGate trigger voltage, Vgt
On-state resistanceHolding current
Off-state conductanceOn-state behavior and switching losses
```Specify constant values````Tabulate`
Gate trigger voltage, VgtForward voltage, VfOn-state voltage, Vak(Tj,Iak)
Holding currentOn-state resistanceTemperature vector, Tj
Off-state conductanceAnode-cathode current vector, Iak
Off-state conductance

Whether to specify physical or electrical control port for the switch gate.

Parameterization method for on-state behavior and switching losses, specified as one of these values:

• `Specify constant values` — Use scalar values to specify the output current, switch-on loss, and switch-off loss data.

• `Tabulate` — Use vectors to specify the output current and temperature data. Use matrices to specify the switch-on loss and switch-off loss data.

Forward voltage at which the device turns on.

Dependencies

See the Main Parameter Dependencies table.

Anode-cathode resistance when the device is on.

Dependencies

See the Main Parameter Dependencies table.

Anode-cathode conductance when the device is off. The value must be less than 1/R, where R is the value of On-state resistance.

Dependencies

See the Main Parameter Dependencies table.

Gate-cathode voltage threshold. The device turns on when the gate-cathode voltage is above this value.

Dependencies

See the Main Parameter Dependencies table.

Current threshold. The device stays on when the current is above this value, even when the gate-cathode voltage falls below the gate trigger voltage.

Dependencies

See the Main Parameter Dependencies table.

Voltage drop across the device in a triggered conductive state. This parameter is a function of temperature and final on-state output current.

Dependencies

See the Main Parameter Dependencies table.

Temperature values at which you quote the on-state voltage.

Dependencies

See the Main Parameter Dependencies table.

Anode-cathode currents for which the on-state voltage is defined. The first element must be zero. Specify this parameter using a vector quantity.

Dependencies

See the Main Parameter Dependencies table.

Switching Losses

To enable these parameters, set Modeling option to `Show thermal port`.

Energy dissipated during a single switch-on event.

Dependencies

To enable this parameter, set On-state behavior and switching losses to ```Specify constant values```.

Rectification loss applied at the point that the block switches off when the current falls below the Holding current. Specify this parameter using a scalar quantity.

The output voltage of the device during the off state. This is the blocking voltage at which the switch-on loss and switch-off loss data are defined.

Output currents for which the switch-on loss, switch-off loss, and on-state voltage are defined. The first element must be zero. Specify this parameter using a scalar quantity.

Note

This parameter is measured at the point that the gate voltage falls below the Gate trigger voltage, Vgt. The turn-on pulse is longer than the time it takes the current to reach its maximum value.

Dependencies

To enable this parameter, set On-state behavior and switching losses to ```Specify constant values```.

Energy dissipated during a single switch-on event as a function of temperature and final on-state output current.

Dependencies

To enable this parameter, set On-state behavior and switching losses to `Tabulate`.

Temperature values at which you quote the switch-on loss and switch-off loss.

Dependencies

To enable this parameter, set On-state behavior and switching losses to `Tabulate`.

Anode-cathode currents for which the switch-on loss and switch-off-loss are defined. The first element must be zero. Specify this parameter using a vector quantity.

Dependencies

To enable this parameter, set On-state behavior and switching losses to `Tabulate`.

Time to wait before recording the on-state current

Integral Diode

Block integral protection diode.

The diodes you can select are:

• ```Protection diode with no dynamics```

• ```Protection diode with charge dynamics```

Select one of these diode models:

• `Piecewise Linear` — Use a piecewise linear model for the diode, as described in Piecewise Linear Diode. This is the default method.

• `Tabulated I-V curve` — Use tabulated forward bias I-V data plus fixed reverse bias off conductance.

Dependencies

This parameter is visible only when the thermal port is exposed and the Integral protection diode parameter is set to `Protection diode with no dynamics` or `Protection diode with charge dynamics`.

Whether to tabulate the current as a function of temperature and voltage or the voltage as a function of temperature and current.

Dependencies

This parameter is visible only when the thermal port is exposed and the Integral protection diode parameter is set to `Protection diode with no dynamics` or `Protection diode with charge dynamics` and Diode model is set to `Tabulated I-V curve`.

Minimum voltage required across the `+` and `-` block ports for the gradient of the diode I-V characteristic to be 1/Ron, where Ron is the value of On resistance.

Dependencies

To enable this parameter:

• If the thermal port is hidden, set Integral protection diode to ```Diode with no dynamics``` or ```Diode with charge dynamics```.

• If the thermal port is exposed, set Integral protection diode to ```Diode with no dynamics``` or ```Diode with charge dynamics``` and Diode model to `Piecewise linear`.

Rate of change of voltage versus current above the Forward voltage.

Dependencies

To enable this parameter:

• If the thermal port is hidden, set Integral protection diode to ```Diode with no dynamics``` or ```Diode with charge dynamics```.

• If the thermal port is exposed, set Integral protection diode to ```Diode with no dynamics``` or ```Diode with charge dynamics``` and Diode model to `Piecewise linear`.

Forward currents. This parameter must be a vector of at least three nonnegative elements.

Dependencies

To enable this parameter, expose the thermal port and set Diode model to ```Tabulated I-V curve``` and Table type to `Table in If(Tj,Vf) form`.

Vector of junction temperatures. This parameter must be a vector of at least two elements.

Dependencies

To enable this parameter, expose the thermal port and set Diode model to ```Tabulated I-V curve```.

Vector of forward voltages. This parameter must be a vector of at least three nonnegative values.

Dependencies

To enable this parameter, expose the thermal port and set Diode model to ```Tabulated I-V curve``` and Table type to `Table in If(Tj,Vf) form`.

Forward voltages. This parameter must be a vector of at least three nonnegative elements.

Dependencies

To enable this parameter, expose the thermal port and set Diode model to ```Tabulated I-V curve``` and Table type to `Table in Vf(Tj,If) form`.

Vector of forward currents. This parameter must be a vector of at least three nonnegative values.

Dependencies

To enable this parameter, expose the thermal port and set Diode model to ```Tabulated I-V curve``` and Table type to `Table in Vf(Tj,If) form`.

Conductance of the reverse-biased diode.

Dependencies

This parameter is visible only when the Integral protection diode parameter is set to `Diode with no dynamics` or `Diode with charge dynamics`.

Since R2023a

Whether to model fixed or tabulated reverse recovery losses.

Dependencies

To enable this parameter, set the Modeling option parameter to `Show thermal port` and set the Integral protection diode parameter to ```Diode with no dynamics```.

Since R2023a

Dissipated energy in each turn-off event, regardless of the state of the diode before or after the switching event.

Dependencies

To enable this parameter, set the Reverse recovery loss model parameter to `Fixed loss`.

Since R2023b

Option to scale reverse recovery loss with current and voltage.

Dependencies

To enable this parameter:

• Set Modeling option to `Show thermal port`.

• Set Integral protection diode to `Diode with no dynamics`.

• Set Reverse recovery loss model to `Fixed loss`.

Since R2023a

Dissipated energy as a function of the forward current If just before the switching event, and final off-state voltage once the diode is in off state.

Dependencies

To enable this parameter, set the Reverse recovery loss model parameter to `Tabulated loss`.

Since R2023a

Temperature vector used to tabulate reverse recovery loss.

Dependencies

To enable this parameter, set the Reverse recovery loss model parameter to `Tabulated loss`.

Since R2023a

Forward current vector used to tabulate reverse recovery loss.

Dependencies

To enable this parameter, set the Reverse recovery loss model parameter to `Tabulated loss`.

Since R2023b

Forward current through the diode before the reverse recovery event that the block uses to measure recovery loss.

Dependencies

To enable this parameter, set Reverse recovery loss model to `Fixed loss` and select the Scale reverse recovery loss with current and voltage parameter.

Since R2023a

Voltage across the diode after the reverse recovery event used to measure recovery loss.

Dependencies

To enable this parameter, choose from one of these options:

• Set Reverse recovery loss model to `Fixed loss` and select the Scale reverse recovery loss with current and voltage parameter.

• Set the Reverse recovery loss model parameter to `Tabulated loss`.

Since R2023a

Filter time constant for voltage and current values used to calculate reverse recovery loss. Set this parameter to a value that is lower than the fastest switching period.

Dependencies

To enable this parameter, choose from one of these options:

• Set Reverse recovery loss model to `Fixed loss` and select the Scale reverse recovery loss with current and voltage parameter.

• Set the Reverse recovery loss model parameter to `Tabulated loss`.

Diode junction capacitance.

Dependencies

This parameter is visible only when the Integral protection diode parameter is set to `Diode with charge dynamics`.

Peak reverse current measured by an external test circuit. This value must be less than zero. The default value is `-235` `A`.

Dependencies

This parameter is visible only when the Integral protection diode parameter is set to `Diode with charge dynamics`.

Initial forward current when measuring peak reverse current. This value must be greater than zero.

Dependencies

This parameter is visible only when the Integral protection diode parameter is set to `Diode with charge dynamics`.

Rate of change of current when measuring peak reverse current. This value must be less than zero.

Dependencies

This parameter is visible only when the Integral protection diode parameter is set to `Diode with charge dynamics`.

Determines how you specify reverse recovery time in the block. The default value is `Specify reverse recovery time directly`.

If you select `Specify stretch factor` or `Specify reverse recovery charge`, you specify a value that the block uses to derive the reverse recovery time. For more information on these options, see How the Block Calculates TM and Tau.

Dependencies

This parameter is visible only when the Integral protection diode parameter is set to `Diode with charge dynamics`.

Interval between the time when the current initially goes to zero (when the diode turns off) and the time when the current falls to less than 10% of the peak reverse current. The value of the Reverse recovery time, trr parameter must be greater than the value of the Peak reverse current, iRM parameter divided by the value of the Rate of change of current when measuring iRM parameter.

Dependencies

This parameter is visible only when the Integral protection diode parameter is set to `Diode with charge dynamics` and the Reverse recovery time parameterization parameter is set to `Specify reverse recovery time directly`.

Value that the block uses to calculate Reverse recovery time, trr. This value must be greater than `1`. Specifying the stretch factor is an easier way to parameterize the reverse recovery time than specifying the reverse recovery charge. The larger the value of the stretch factor, the longer it takes for the reverse recovery current to dissipate.

Dependencies

This parameter is visible only when the Integral protection diode parameter is set to `Diode with charge dynamics` and the Reverse recovery time parameterization parameter is set to `Specify stretch factor`.

Value that the block uses to calculate Reverse recovery time, trr. Use this parameter if the data sheet for your diode device specifies a value for the reverse recovery charge instead of a value for the reverse recovery time.

The reverse recovery charge is the total charge that continues to dissipate when the diode turns off. The value must be less than $-\frac{{i}^{2}{}_{RM}}{2a},$

where:

• iRM is the value specified for Peak reverse current, iRM.

• a is the value specified for Rate of change of current when measuring iRM.

Dependencies

This parameter is visible only when the Integral protection diode parameter is set to `Diode with charge dynamics` and the Reverse recovery time parameterization parameter is set to `Specify reverse recovery charge`.

Voltage between the diode in steady-state.

Dependencies

This parameter is visible only when the Integral protection diode parameter is set to ```Diode with charge dynamics``` and the Reverse recovery time parameterization parameter is set to `Specify reverse recovery energy`.

Total unintended inductance in the measurement circuit. The block uses this value to calculate Reverse recovery energy, Erec.

Dependencies

This parameter is visible only when the Integral protection diode parameter is set to ```Diode with charge dynamics``` and the Reverse recovery time parameterization parameter is set to `Specify reverse recovery energy`.

Total switching losses due to the diode reverse recovery.

Dependencies

This parameter is visible only when the Integral protection diode parameter is set to ```Diode with charge dynamics``` and the Reverse recovery time parameterization parameter is set to `Specify reverse recovery energy`.

Thermal Port

Use the thermal port to simulate the effects of generated heat and device temperature. For more information on using thermal ports and on the Thermal Port parameters, see Simulating Thermal Effects in Semiconductors.

Version History

Introduced in R2013b

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