The PWM generator generates pulses for carrier-based pulse width modulation (PWM) converters using two-level topology.

Note: This component should be used with the 2-Level Converter (Switching Devices).

Mask and Parameters

Parameter Name	Description	Unit	Variable = {Possible Values}
Description	Use this field to add all kinds of information about the component		Description = {'string'}
PWM carrier frequency	Frequency of the triangular carrier signal	Hz	FrequencyCarrier = { [0, 1e12] }
PWM carrier initial phase	Initial phase of the carrier. A value of 90° means that the triangle carrier initial position is set to midpoint between its minimum and maximum value and the slope is positive.	°	InitialPhase = { [0, 360] }

Inputs, Outputs and Signals Available for Monitoring

Inputs

Name	Description
Vref	Vectorized reference voltage signal containing the phase-ground voltages of the AC side (Va, Vb, Vc).

Outputs

Name	Description
P	Vectorized signal containing six firing pulses to control the converter.

Sensors

Name	Description	Unit
Va	Reference voltage signal from phase A on the AC side.	V
Vb	Reference voltage signal from phase B on the AC side.
Vc	Reference voltage signal from phase C on the AC side.
P1	Signal containing a firing pulse to control Q1 (phase A upper arm of the converter)
P2	Signal containing a firing pulse to control Q2 (phase A lower arm of the converter)
P3	Signal containing a firing pulse to control Q3 (phase B upper arm of the converter)
P4	Signal containing a firing pulse to control Q4 (phase B lower arm of the converter)
P5	Signal containing a firing pulse to control Q5 (phase C upper arm of the converter)
P6	Signal containing a firing pulse to control Q6 (phase C lower arm of the converter)

Additional Information

The reference signal (Vref input), also known as the modulation signal, is compared with a symmetrical triangle carrier. When the reference signal is higher than the carrier, the pulse for the upper switching component is high (1), and that of the lower device is low (0). The carrier frequency (fc) is defined by the frequency of the converter output voltage and by the converter switching ratio, from the following equation:

To control the 2-Level Converter (Switching Devices), the pulse generator generates pulses 1, 3 and 5 for the upper switching components of the first, second and third arms, while pulses 2 , 4 and 6 are generated for the lower switching components of the first, second and third arms.

The figure below describes a technique used to sample the reference signal Vref. The natural sampling technique models the behavior of an analog implementation of a PWM generator. Using this technique allows Vref to be sampled twice at both valley and the peak of the carrier or only once at the valley fo the carrier.

Internal Circuit

Limitations

This component should be used with the 2-Level Converter (Switching Devices).

References

MathWorks, PWM Generator (2-Level) Mathworks.com. https://www.mathworks.com/help/physmod/sps/powersys/ref/pwmgenerator2level.html.

HYPERSIM Documentation

PWM Generator for 2-Level Converter (Switching Devices)