PWM Generator (Multilevel)

Generate pulses for PWM-controlled modular multilevel converter

Library

Simscape / Electrical / Specialized Power Systems / Power Electronics / Power Electronics Control

Description

The PWM Generator (Multilevel) block generates pulses for a PWM-controlled modular multilevel converter. For a half-bridge converter, carriers are phase-shifted by an angle obtained by dividing 360 degrees by the number of bridges. The number of bridges is a parameter that you specify. For a full-bridge converter, carriers are phase-shifted by an angle obtained by dividing 180 degrees by the number of bridges.

The PWM Generator (Multilevel) block generates one carrier signal for every power module (full-bridge or half-bridge) that is controlled. For example, if you set Bridge type to Full-bridge, and Number of bridges to 10, the block generates 10 carrier signals, each shifted by 18 degrees (180/10) from the other.

Parameters

Bridge Type

Choose whether to control a Half-bridge (default) or a Full-bridge converter.

Number of bridges

Specify the number of bridges (power modules) of the multilevel converter you want to control. The number of bridges must correspond to the number of power modules used in the modular multilevel converter. The default value is 4.

For example, if you want to control a full-bridge MMC converter that contains 22 power modules (the equivalent of 22 full-bridges), set the Bridge type parameter to Full-bridge and the Number of bridges parameter to 22. If you want to control a half-bridge MMC converter that contains 22 power modules (or 22 half-bridges), set Bridge type to Half-bridge and Number of bridges to 22.

Carrier frequency (Hz)

Specify the frequency, in hertz, of the triangular carrier signals. The default value is 540.

Sample time (s)

Specify the sample time of the block. Set to 0 to implement a continuous block. Default is 0.

Show carriers outport

Select this option to show the Cr output port for the carriers’ waveforms. By default, this option is cleared.

Inputs and Outputs

Uref: Vectorized single-phase sinusoidal reference signal used to generate the output pulses. You specify one reference voltage for each bridge of the multilevel converter you want to control. For linear operation of this block, the magnitude of Uref must be between −1 and +1.
P: Vectorized gating signal to control a multilevel converter. When the Bridge type parameter is set to Half-bridge, the block outputs double the Number of bridges pulses. When the Bridge type parameter is set to Full-bridge, the block outputs four times the Number of bridges pulses.
Cr: Carriers’ waveforms. This outport only appears if you enable the Show carriers outport option.

Characteristics

Sample Time	Specified in the Sample Time parameter Continuous if Sample Time = 0
Scalar Expansion	No
Dimensionalized	No

Version History

Introduced in R2016b