The model PWM Generator is a pulse generator based on the carrier using a two-level topology.

Note: This component should be used with the Full-Bridge 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 method	Type of modulation		PWMmethod = { ['unipolar', 'bipolar'] }
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	Monophasic reference voltage signal.

Outputs

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

Sensors

Name	Description	Unit
Vref	Monophasic reference voltage signal.	V
P1	Signal containing a firing pulse to control Q1.	No unit
P2	Signal containing a firing pulse to control Q2.
P3	Signal containing a firing pulse to control Q3.
P4	Signal containing a firing pulse to control Q4.

Additional Information

The reference signal (input Vref), also known as the modulation signal, is compared with a triangulated symmetric carrier. When the reference signal is higher than the carrier, the pulse of 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 Full-Bridge Converter (Switching Devices), the user can choose between two modulation methods: unipolar or bipolar.

Using unipolar, each arm is controlled independently and a second reference signal is generated internally by phase-shifting the reference signal Vref by 180 degrees.
Using bipolar, the state of the lower switching component of the second arm is the same as that of the upper switching component of the first arm and the state of the upper switching component of the second arm is the same as that of the lower switching component of the first arm.

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 Full-Bridge Converter (Switching Devices).

References

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

PWM Generator for Full-Bridge Converter (Switching Devices)