The PWM average generator is a pulse generator averaged over the time step of the simulation. It uses an interpolation technique to calculate the transition moment within a sample time of the model.

Note: This component should be used with the 3-Level NPC Converter (Switching Function).

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	°	InitialPhase = { [0, 360] }

Inputs, Outputs and Signals Available for Monitoring

Inputs

Name	Description
Vref	Vectorized reference signal containing the phase-ground voltages from the AC side (Va, Vb and Vc). The range of Vref is between -1 and 1.

Outputs

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

Sensors

Name	Description	Unit
Va	Reference signal for voltage from phase A.	V
Vb	Reference signal for voltage from phase B.
Vc	Reference signal for voltage from phase C.
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 upper arm of the converter).
P3	Signal containing a firing pulse to control Q3 (phase A lower arm of the converter).
P4	Signal containing a firing pulse to control Q4 (phase A lower arm of the converter).
P5	Signal containing a firing pulse to control Q5 (phase B upper arm of the converter).
P6	Signal containing a firing pulse to control Q6 (phase B upper arm of the converter).
P7	Signal containing a firing pulse to control Q7 (phase B lower arm of the converter).
P8	Signal containing a firing pulse to control Q8 (phase B lower arm of the converter).
P9	Signal containing a firing pulse to control Q9 (phase C upper arm of the converter).
P10	Signal containing a firing pulse to control Q10 (phase C upper arm of the converter).
P11	Signal containing a firing pulse to control Q11 (phase C lower arm of the converter).
P12	Signal containing a firing pulse to control Q12 (phase C lower arm of the converter).

Additional Information

The interpolation technique of the averaged pulse generator needs to know when a transition from high-to-low or low-to-high occurs within a sample time, allowing this component to provide the timing for these transitions. The use of this type of PWM in addition to the converter modeled using switching function allows simulations with a much larger sample time while keeping high fidelity during the simulation. The figure below shows the operating principle of this model for a carrier frequency (Fc) of 2 kHz and a duty cycle of 0.8. The time step is 50 μs.

The generator emits a pulse value based on a carrier-based modulation technique (natural sampling) and the time step of the simulation. If a transition occurs within a sample time, the generator outputs a pulse value representing the time ratio (a value between 0 and 1) for the ON state over the sample time. For example, in the figure above, the pulse value generated at 0.25 means that the 0 to 1 transition occurred at 0.25 · Ts seconds (it was ON during 25% of the model time step). The offset is represented by the dotted area in brown. For the 1 to 0 transition, the generator provides a value of 0.75, which means that the pulse was active for 75% of the computing time (it entered the OFF state 0.75 · Ts seconds after the previous sample time).

Limitations

This component is to be used with the 3-Level NPC Converter (Switching Function).

To obtain precision, the time step of the simulation must not be more than 1/10th of the period the carrier (1/Fc).

HYPERSIM Documentation

PWM Average Generator for 3-Level Converter (Switching Function)