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DMeie.2
Associate III
November 27, 2024
Question

Where can I find HW deadtime setting?

  • November 27, 2024
  • 3 replies
  • 1036 views

We're using a driver that inserts a deadtime by hardware.

It is not clear to me how I have to configure that into the MCWB firmware to get ADC measurement working properly.
I see three deadtime-related settings:
- "minDeadTime" property in the "PhaseVoltageGeneration" feature of the Motor Control Boards Description
- "deadTime" property of the "DrivingHighAndLowSides" HW variant (this reads like this is a fixed deadtime inserted by the PWM timers)
- "SW dead-time" setting in the FOC wizard

I couldn't find a proper documentation for any of those.

What do these values do?
Which of those settings is the correct one for my case?

3 replies

GMA
Technical Moderator
December 16, 2024

Hello @DMeie.2,

Two definitions are present: "minDeadTime" and "deadTime" and come from power board or inverter json files.
Usage depends on the following hardware variant (please refer to our Motor Control Boards Description page:(

  • Driving high and low sides power switches hardware variant.
    In this use case, you are able to drive the High and Low PWM signals and then handled by SW. SW_DEADTIME_NS is used. "minDeadTime" is used as a low-level limit for SW_DEADTIME_NS definition.
  • Driving high sides and one enable hardware variant. 
    In this use case, you are able to drive the High PWM signals with a Enable signal. In this case, Dead Time only depends on HW. HW_DEAD_TIME_NS is used and is defined as "deadTime" value.
If you agree with the answer, please accept it by clicking on 'Accept as solution'.Best regards.GMA
DMeie.2
DMeie.2Author
Associate III
January 8, 2025

@GMA 

We're using variant 1 and drive both high- and lowside.
The driver stage then inserts a configurable deadtime in hardware.

I'd like to account for this inserted deadtime in the ADC current measurement so that it only starts sampling after the external deadtime has elapsed.

Do I have to use those deadtime settings for that? Or do I rather have to use the tNoise/tRise settings for that?
Deadtime is mentioned in the "Current sampling in three-shunt topology using one A/D converter" document, though I'm not sure which one that is supposed to be.

GMA
Technical Moderator
January 9, 2025

Hello @DMeie.2,

If "We're using variant 1 and drive both high- and lowside.", dead time is then managed by software.

 

GMA_0-1736411116337.png

 

If you agree with the answer, please accept it by clicking on 'Accept as solution'.Best regards.GMA