Introduction

By comparing the inputs of references and carriers, this block generates gating signals, and it also includes advanced features to consider the switching events that happen between intra-time steps for power electronic switches in converters. The output of this block can connect to gating signal input of VSC Configuration Block.

Mask and Parameters

Name	Description
Relational operator	defines the logic operator to apply to the inputs
Mode	defines the comparison modes. The comparison modes include Static mode, TOM mode and Advanced mode

Inputs, Outputs and Signals Available for Monitoring

Inputs

Name	Description	Value
enable	enable the pulse generation	1 for enable and 0 for disable
s	reference signal	range of [-1 1]
car	carrier signal, generated by Carrier Signal Generation Block.	NA

Outputs

Name	Description
y	comparison outputs
!y	complementary of comparison outputs

Description

This block includes three comparison modes:

Static mode	suitable where the sampling frequency is 100 times more than carrier frequency. The output value is either 0 or 1.
TOM mode	suitable where the sampling frequency is between 20 to 100 times of carrier frequency. The output value is between 0 and 1.
ATOM mode	suitable where the sampling frequency is between 4 to 20 times of carrier frequency. The output value is between 0 and 1.

Further, this block has six operators say <,>,<=,>=,=,~=, based on operator selection the gating signal is generated by comparing the reference signal and carrier signal by using the operator selected by user.

Moreover, Time On Mean (TOM) and Advanced TOM (ATOM) will work for all these operators except for = or ~=. The purpose of these TOMs modes is to interpolate the change of event between sample time or model sampling frequency. For example, as shown in Fig. 1, the ratio of sampling frequency (F_samp) to the carrier frequency (F_c) is less than 100; the static mode of operation will not produce appropriate gating signals due to missing samples between the model time-steps, Ts (i.e., as seen in figure due to missing samples static mode will not see the carrier points S_c1 and S_c2, which results in the missing of pulse). In this case, it is recommended to use TOM or ATOM mode based on the above-mentioned range of carrier frequency. Such that these methods with interpolation techniques will approximately identify the pulse generation point as shown in Fig. 1.

Figure 1: Gating Signal During Intra-step event: Expected Actual value, During Static and TOM/ATOM Mode[1]

Note

For TOM mode and ATOM mode, use Carrier Signal Generation Block from the same library to generate the carrier signals.

Limitations

This block is only compatible with fixed step solver in TOM and advanced modes.

References

Li and F. Zhang, "A General Interpolated Model of Voltage Source Converters for Real-time Simulation and HIL Test Applications," 2020 IEEE Energy Conversion Congress and Exposition (ECCE), Detroit, MI, USA, 2020, pp. 6155-6161, doi: 10.1109/ECCE44975.2020.9235715.

MMC User Documentation

PWM Generation Block