# PWM Generator (Multilevel)

Generate pulse width modulated signal or waveform for modular multilevel converters

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• Simscape / Electrical / Control / Pulse Width Modulation

## Description

The PWM Generator (Multilevel) block implements a pulse width modulation (PWM) generator for modular multilevel converters. The PWM technique controls power transfer from one electrical component to another by quickly switching between full power transfer and no power transfer.

The block calculates gate pulses for a modular, multilevel converter based on the number of power submodules and two converter topologies: half-bridge and full-bridge. You can specify the number of power submodules and the converter topology using the Number of power submodules and Converter topology parameters, respectively.

## Ports

### Input

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Reference signal to calculate the PWM for each power submodule of the multilevel converter, specified as a vector.

### Output

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Pulse width modulation signal for each submodule, returned as a vector.

If you set the Converter topology parameter to `Half-bridge`, the output is a vector specified as:

`$G=\left\{G1_SM1,\text{\hspace{0.17em}}G2_SM1,\text{\hspace{0.17em}}G1_SM2,\text{\hspace{0.17em}}G2_SM2,\text{\hspace{0.17em}}\dots \text{\hspace{0.17em}},\text{\hspace{0.17em}}G1_SMN,\text{\hspace{0.17em}}G2_SMN\right\}.$`

If you set the Converter topology parameter to `Full-bridge`, the output is a vector specified as:

`$G=\left\{G1_SM1,\text{\hspace{0.17em}}G2_SM1,\text{\hspace{0.17em}}G3_SM1,\text{\hspace{0.17em}}G4_SM1,\text{\hspace{0.17em}}G1_SM2,\text{\hspace{0.17em}}G2_SM2,\text{\hspace{0.17em}}G3_SM2,\text{\hspace{0.17em}}G4_SM2,\text{\hspace{0.17em}}\dots \text{\hspace{0.17em}},\text{\hspace{0.17em}}G1_SMN,\text{\hspace{0.17em}}G2_SMN,\text{\hspace{0.17em}}G3_SMN,\text{\hspace{0.17em}}G4_SMN\right\},$`

where Gi_SMj is the reference signal controlling the i-th gate of the j-th power submodule. i ranges from `1` to `2` in a half-bridge topology and from `1` to `4` in a full-bridge topology. j ranges from `1` to N, where N is the number of power submodules specified in the Number of power submodules parameter.

Data Types: `single` | `double`

## Parameters

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Topology of the modular multilevel converter.

Number of power submodules of the modular multilevel converter.

PWM timer period. The Timer period (s) parameter is specified as $\frac{1}{2{f}_{sw}}$, where ${f}_{sw}$ is the switching frequency.

Sample time for the block. For continuous-time simulation, set to zero. For discrete-time simulation, to ensure adequate resolution in the generated signal, specify a positive value that is less than or equal to ```10 * Tper```, where Tper is the Timer period (s).

## Version History

Introduced in R2020b