How to Use PWM Capture with Differential 5V Gate Signals in RT Box

General
1

I am working with RT Box and I have a question about the PWM Capture block:

  1. I want to use two PWM capture signals that are coming in as 5V differential signals, and feed them to the gate drive. Is there a recommended way to make this work in RT Box?

  2. When I connect additional logic blocks (e.g., Comparator or SR Flip-Flop) after the PWM Capture output, I get errors during simulation/code generation. Is there a specific reason for this limitation, or an alternative way to process the PWM Capture signals with logic?

I would appreciate any guidance or example setup for handling differential PWM signals correctly and for combining PWM Capture with logic blocks inside RT Box.

Thanks in advance!

2

Can you please clarify:

  1. What does the voltage of the coming signals look like? Is it from 0 to 5V (with a complementary signal s’ = 5-s) or from -5 to 5V (with a complementary signal of s’ = -s)? Please show a graphic of what the two signals should like and how that should be resolved into the PWM signal.
  2. Please post a model to share the exact error. There can be datatype conflicts, width errors, and other potential problems.
  3. Are you using a CPU-based or FPGA-based solver (FlexArray / Nanostep)?

A few initial comments:

  1. For FPGA-based solvers you cannot insert logic to modify the incoming signals to the FPGA. You will need external hardware to do this.
  2. For accurate real-time performance the RT Box uses a technique called sub-cycle averaging, where PWM signals are averaged over the RT Box model step returning a value between 0 and 1, providing additional information on when exactly a switching instant occurred within the model step. Resolving the signals from the PWM Capture block into a boolean logic will eliminate the advantages of sub-cycle averaging.