# Modular Multilevel Converter Leg

Modular multilevel converter leg with series-connected power submodules

**Library:**Simscape / Electrical / Semiconductors & Converters / Converters

## Description

The Modular Multilevel Converter Leg block models a modular multilevel converter leg as a two arms that are implemented with a number of series-connected power submodules.

**Half-Bridge Topology**

**Full-Bridge Topology**

This blocks allows you to select the level of model fidelity by choosing between a detailed model with switching devices or an equivalent model. You can choose from these switching devices are:

GTO — Gate turn-off thyristor. For information about the I-V characteristic of the device, see GTO.

Ideal semiconductor switch — For information about the I-V characteristic of the device, see Ideal Semiconductor Switch.

IGBT — Insulated-gate bipolar transistor. For information about the I-V characteristic of the device, see IGBT (Ideal, Switching).

MOSFET — N-channel metal-oxide-semiconductor field-effect transistor. For information about the I-V characteristic of the device, see MOSFET (Ideal, Switching).

Thyristor — For information about the I-V characteristic of the device, see Thyristor (Piecewise Linear).

Averaged Switch — Semiconductor switch with an anti-parallel diode. The control signal port,

**G**, accepts values in the`[0,1]`

interval. When the value at port**G**is equal to`0`

or`1`

, the averaged switch is either fully opened or fully closed, and it behaves similarly to the Ideal Semiconductor Switch block with an anti-parallel diode. When the value at port**G**is between`0`

and`1`

, the averaged switch is partly opened. You can then average the PWM signal over a specified period. This allows for undersampling of the model or using modulation waveforms instead of PWM signals.

### Piecewise Constant Approximation in Averaged Switch for FPGA Deployment

If you set the **Switching device** parameter to `Averaged switch`

and your model uses a partitioning solver, this block produces nonlinear partitions because the average mode equations include modes, *G _{sat}* that are functions of the input

**G**. To make these equations compatible with hardware description language (HDL) code generation, and therefore FPGA deployment, set the

**Integer for piecewise constant approximation of gate input (0 for disabled)**parameter to a value greater than

`0`

. This block then treats the *G*mode as a piecewise constant integer with a fixed range. This turns the previously nonlinear partitions to linear time varying partitions.

_{sat}An integer value in the range `[0,K]`

, where *K* is the value of the **Integer for piecewise constant approximation of gate input (0 for disabled)**, is now associated with each real value mode in the range `[0,1]`

. The block computes the piecewise constant mode by dividing the original mode by K to normalize it back to the range `[0,1]`

:

$$\begin{array}{l}{u}_{I}=\left(floor\left(u\cdot K\right)\right)\\ \widehat{u}=\frac{{u}_{I}}{K}\end{array}$$

### Variables

To set the priority and initial target values for the block variables prior to 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.

Nominal values provide a way 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 which is the **Nominal
Values** section in the block dialog box or Property Inspector. For more
information, see System Scaling by Nominal Values.

## Ports

### Input

### Output

### Conserving

## Parameters

## References

[1] Saad, Hani, Sebastien
Dennetiere, and Jean Mahseredjian. *“On Modelling of MMC in EMT-Type
Program.”* 2016 IEEE 17th Workshop on Control and Modeling for Power
Electronics (COMPEL), 1–7. Trondheim, Norway: IEEE, 2016.
https://doi.org/10.1109/COMPEL.2016.7556717.

## Extended Capabilities

## Version History

**Introduced in R2020b**

## See Also

Average-Value DC-DC Converter | Bidirectional DC-DC Converter | Buck Converter | Buck-Boost Converter | Converter (Three-Phase) | GTO | IGBT (Ideal, Switching) | MOSFET (Ideal, Switching) | Ideal Semiconductor Switch | PWM Generator | PWM Generator (Three-phase, Two-level) | Three-Level Converter (Three-Phase) | Thyristor (Piecewise Linear) | Boost Converter | PWM Generator (Multilevel) | Modular Multilevel Converter Arm | Modular Multilevel Converter (Three-Phase)