# Three-Level Converter

Connect three-phase AC network to three-level DC network

Semiconductors

## Description

The Three-Level Converter block models a three-arm converter circuit that connects a three-phase AC network to a three-level DC network.

Each component in the three-arm circuit is the same switching device, which you specify using an option in the Converter block dialog box. The switching devices are in the Semiconductors > Fundamental Components sublibrary.

The figure shows the equivalent circuit for the block using an Ideal Semiconductor block as the switching device.

You control the gate ports of the 12 switching devices via an input to the Three-Level Converter block G port.

1. Use a Twelve-Pulse Gate Multiplexer block to multiplex all 12 gate signals into a single vector.

2. Connect the output of the Twelve-Pulse Gate Multiplexer block to the Three-Level Converter block G port.

You use the Diodes tab of the block dialog box to include an integral protection diode for each switching device. 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 how to set the Integral protection diode parameter based on your goals.

GoalValue to SelectBlock Behavior
Prioritize simulation speed.`Protection diode with no dynamics`The block includes an integral copy of the Diode block. The block dialog box shows parameters relating to the Diode block.
Precisely specify reverse-mode charge dynamics.`Protection diode with charge dynamics`The block includes an integral copy of the Commutation Diode block. The block dialog box shows parameters relating to the Commutation Diode block.

You use the Snubbers tab of the block dialog box to include a snubber circuit for each switching device. Each snubber consists of a resistor and capacitor connected in series. Typically, a snubber circuit protects a switching device against very high voltages produced by an inductive load when the device turns off the voltage supply to the load. Snubber circuits also prevent excessive rates of change of current when a switching device turns on.

## Parameters

### Switching Devices Tab

Switching device

Converter switching device. The default value is ```Ideal Semiconductor Switch```.

The switching devices you can select are:

• `GTO`

• `Ideal Semiconductor Switch`

• `IGBT`

• `MOSFET`

#### GTO Parameters

When you select `GTO`, parameters for the GTO block appear.

#### Ideal Semiconductor Switch Parameters

When you select `Ideal Semiconductor Switch`, parameters for the Ideal Semiconductor Switch block appear.

#### IGBT Parameters

When you select `IGBT`, parameters for the IGBT block appear.

#### MOSFET Parameters

When you select `MOSFET`, parameters for the MOSFET block appear.

### Diodes Tab

Integral protection diode

Integral protection diode for each switching device. Choose between `Diode with no dynamics` and ```Diode with charge dynamics```. The default value is ```Diode with no dynamics```.

#### Parameters for Diode with no dynamics

When you select `Diode with no dynamics`, additional parameters appear.

#### Parameters for Diode with charge dynamics

When you select `Protection diode with charge dynamics`, additional parameters appear.

### Snubbers Tab

Snubber

Snubber for each switching device. The default value is `None`.

Snubber resistance

This parameter is visible only if you set Snubber to ```RC snubber```. The default value is `0.1` `Ohm`.

Snubber capacitance

This parameter is visible only if you set Snubber to ```RC snubber```. The default value is `1e-7` `F`.

## Ports

The block has the following ports:

`G`

Vector input port associated with the gate terminals of the switching devices. Connect this port to a Twelve-Pulse Gate Multiplexer block.

`~`

Expandable three-phase port.

`+`

Electrical conserving port associated with the DC positive terminal.

`0`

Electrical conserving port associated with the DC neutral terminal.

`-`

Electrical conserving port associated with the DC negative terminal.