Thyristor (Piecewise Linear)

  • Library:
  • 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.

In the on state, the anode-cathode path behaves like a linear diode with forward-voltage drop, Vf, and on-resistance, Ron.

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.Protection diode with no dynamicsThe 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.Protection diode with charge dynamicsThe block includes an integral copy of the dynamic model of the Diode block. To parameterize the internal Diode block, use the Protection parameters.

Modeling Variants

The block provides four modeling variants. To select the desired variant, right-click the block in your model. From the context menu, select Simscape > Block choices, and then one of these variants:

  • PS Control Port — Contains a physical signal port that is associated with the gate terminal. This variant is the default.

  • Electrical Control Port — Contains an electrical conserving port that is associated with the gate terminal.

  • PS Control Port | Thermal Port — Contains a thermal port and a physical signal port that is associated with the gate terminal.

  • Electrical Control Port | Thermal Port — Contains a thermal port and an electrical conserving port that is associated with the gate terminal.

The variants of this block without the thermal port do not simulate heat generation in the device.

The variants with the thermal port allow you to model the heat that switching events and conduction losses generate. For numerical efficiency, the thermal state does not affect the electrical behavior of the block. The thermal port is hidden by default. To enable the thermal port, select a thermal block variant.

Thermal Loss Equations

The figure shows an idealized representation of the output voltage, Vout, and the output current, Iout, of the semiconductor device. The interval shown includes the entire nth switching cycle, during which the block turns off and then on.

Heat Loss Due to a Switch-On Event

When the semiconductor turns on during the nth switching cycle, the amount of thermal energy that the device dissipates increments by a discrete amount. If you select Voltage, current, and temperature for the Thermal loss dependent on parameter, the equation for the incremental change is

Eon(n)=Voff(n)Voff_datafcn(T,Ion(n1)),

where:

  • Eon(n) is the switch-on loss at the nth switch-on event.

  • Voff(n) is the off-state output voltage,Vout, just before the device switches on during the nth switching cycle.

  • Voff_data is the Off-state voltage for losses data parameter value.

  • T is the device temperature.

  • Ion(n-1) is the on-state output current, Iout, just before the device switches off during the cycle that precedes the nth switching cycle.

The function fcn is a 2-D lookup table with linear interpolation and linear extrapolation:

E=tablelookup(Tj_data,Iout_data,Eon_data,T,Ion(n1)),

where:

  • Tj_data is the Temperature vector, Tj parameter value.

  • Iout_data is the Output current vector, Iout parameter value.

  • Eon_data is the Switch-on loss, Eon=fcn(Tj,Iout) parameter value.

If you select Voltage and current for the Thermal loss dependent on parameter, when the semiconductor turns on during the nth switching cycle, the equation that the block uses to calculate the incremental change in the discrete amount of thermal energy that the device dissipates is

Eon(n)=(Voff(n)Voff_data)(Ion(n1)Iout_scalar)(Eon_scalar)

where:

  • Iout_scalar is the Output current, Iout parameter value.

  • Eon_scalar is the Switch-on loss parameter value.

Heat Loss Due to a Switch-Off Event

When the semiconductor turns off during the nth switching cycle, the amount of thermal energy that the device dissipates increments by a discrete amount. If you select Voltage, current, and temperature for the Thermal loss dependent on parameter, the equation for the incremental change is

Eoff(n)=Voff(n)Voff_datafcn(T,Ion(n)),

where:

  • Eoff(n) is the switch-off loss at the nth switch-off event.

  • Voff(n) is the off-state output voltage, Vout, just before the device switches on during the nth switching cycle.

  • Voff_data is the Off-state voltage for losses data parameter value.

  • T is the device temperature.

  • Ion(n) is the on-state output current, Iout, just before the device switches off during the nth switching cycle.

The function fcn is a 2-D lookup table with linear interpolation and linear extrapolation:

E=tablelookup(Tj_data,Iout_data,Eoff_data,T,Ion(n)),

where:

  • Tj_data is the Temperature vector, Tj parameter value.

  • Iout_data is the Output current vector, Iout parameter value.

  • Eoff_data is the Switch-off loss, Eoff=fcn(Tj,Iout) parameter value.

If you select Voltage and current for the Thermal loss dependent on parameter, when the semiconductor turns off during the nth switching cycle, the equation that the block uses to calculate the incremental change in the discrete amount of thermal energy that the device dissipates is

Eoff(n)=(Voff(n)Voff_data)(Ion(n1)Iout_scalar)(Eoff_scalar)

where:

  • Iout_scalar is the Output current, Iout parameter value.

  • Eoff_scalar is the Switch-off loss parameter value.

Heat Loss Due to Electrical Conduction

If you select Voltage, current, and temperature for the Thermal loss dependent on parameter, then, for both the on state and the off state, the heat loss due to electrical conduction is

Econduction=fcn(T,Iout)dt,

where:

  • Econduction is the heat loss due to electrical conduction.

  • T is the device temperature.

  • Iout is the device output current.

The function fcn is a 2-D lookup table:

Qconduction=tablelookup(Tj_data,Iout_data,Iout_data_repmat.*Von_data,T,Iout),

where:

  • Tj_data is the Temperature vector, Tj parameter value.

  • Iout_data is the Output current vector, Iout parameter value.

  • Iout_data_repmat is a matrix that contains length, Tj_data, copies of Iout_data.

  • Von_data is the On-state voltage, Von=fcn(Tj,Iout) parameter value.

If you select Voltage and current for the Thermal loss dependent on parameter, then, for both the on state and the off state, the heat loss due to electrical conduction is

Econduction=(Iout*Von_scalar)dt,

where Von_scalar is the On-state voltage parameter value.

Heat Flow

The block uses the Energy dissipation time constant parameter to filter the amount of heat flow that the block outputs. The filtering allows the block to:

  • Avoid discrete increments for the heat flow output

  • Handle a variable switching frequency

The filtered heat flow is

Q=1τ(i=1nEon(i)+i=1nEoff(i)+EconductionQdt),

where:

  • Q is the heat flow from the component.

  • τ is the Energy dissipation time constant parameter value.

  • n is the number of switching cycles.

  • Eon(i) is the switch-on loss at the ith switch-on event.

  • Eoff(i) is the switch-off loss at the ith switch-off event.

  • Econduction is the heat loss due to electrical conduction.

  • ∫Qdt is the total heat previously dissipated from the component.

Ports

The figure shows the block port names.

Conserving

expand all

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. The thermal port is optional and is hidden by default. To enable this port, select a variant that includes a thermal port.

Parameters

expand all

Main

Forward voltage at which the device turns on.

Anode-cathode resistance when the device is on.

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.

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

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.

Integral Diode

Block integral protection diode. The default value is None.

The diodes you can select are:

  • Protection diode with no dynamics

  • Protection diode with charge dynamics

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

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

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

Dependencies

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

Conductance of the reverse-biased diode.

Dependencies

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

Diode junction capacitance.

Dependencies

This parameter is visible only when the Integral protection diode parameter is set to Protection 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 Protection 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 Protection 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 Protection 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 Protection 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 Protection 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 Protection 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 i2RM2a,

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 Protection diode with charge dynamics and the Reverse recovery time parameterization parameter is set to Specify reverse recovery charge.

For more information on these parameters, see Diode.

Thermal Model

The Thermal Model tab is enabled only when you select a block variant that includes a thermal port.

Select a parameterization method. The option that you select determines which other parameters are enabled. Options are:

  • Voltage and current — Use scalar values to specify the output current, switch-on loss, switch-off loss, and on-state voltage data.

  • Voltage, current, and temperature — Use vectors to specify the output current, switch-on loss, switch-off loss, on-state voltage, and temperature data. This is the default parameterization method.

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.

Time constant used to average the switch-on losses, switch-off losses, and conduction losses. This value is equal to the period of the minimum switching frequency.

Temperature values at which the switch-on loss, switch-off loss, and on-state voltage are specified. Specify this parameter using a vector quantity.

Dependencies

This parameter is visible only when the Thermal loss dependent on parameter is set to Voltage, current, and temperature.

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 vector quantity.

Dependencies

This parameter is visible only when the Thermal loss dependent on parameter is set to Voltage, current, and temperature.

Energy dissipated during a single switch on event. This parameter is defined as a function of temperature and final on-state output current. Specify this parameter using a vector quantity.

Dependencies

This parameter is visible only when the Thermal loss dependent on parameter is set to Voltage, current, and temperature.

Energy dissipated during a single switch-off event. This parameter is defined as a function of temperature and final on-state output current. Specify this parameter using a vector quantity.

Dependencies

This parameter is visible only when the Thermal loss dependent on parameter is set to Voltage, current, and temperature.

Voltage drop across the device while it is in a triggered conductive state. This parameter is defined as a function of temperature and final on-state output current. Specify this parameter using a vector quantity.

Dependencies

This parameter is visible only when the Thermal loss dependent on parameter is set to Voltage, current, and temperature.

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.

Dependencies

This parameter is visible only when the Thermal loss dependent on parameter is set to Voltage and current.

Energy dissipated during a single switch-on event. This parameter is defined as a function of temperature and final on-state output current. Specify this parameter using a scalar quantity.

Dependencies

This parameter is visible only when the Thermal loss dependent on parameter is set to Voltage and current.

Energy dissipated during a single switch-off event. This parameter is defined as a function of temperature and final on-state output current. Specify this parameter using a scalar quantity.

Dependencies

This parameter is visible only when the Thermal loss dependent on parameter is set to Voltage and current.

Voltage drop across the block while it is in a triggered conductive state. This parameter is defined as a function of temperature and final on-state output current. Specify this parameter using a scalar quantity.

Dependencies

This parameter is visible only when the Thermal loss dependent on parameter is set to Voltage and current.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Introduced in R2013b