M1 Inverting boost duty cycle

[SteveC]

Is there anything that needs to be done to test and create inverted duty cycle on the M1.

If i test the boost at normal mode it works fine but testing inverted it does nothing so was curious to know if there is anything else that needs setting up.

Boost actuator polarity set to inverting


Also is it possible to do the base feedforward table with an airline and ecu on but engine not started, to get this done before we head to the dyno - but old school but works well as a base

[Stephen Dean]

Hi,

The Boost Inverting Output Resource is for when you have a second solenoid control valve that is working to the same DC but inverted to the Normal output, this is usually used when you have a single pressure source being feed to the top and bottom of the wastegate control valve and you want one side being pressurised and the other bleeding off. When this resource is allocated, the M1 automatically controls the output in that manner.

The Boost Actuator Polarity to to accommodate wiring differences, as a lot of the valves that are used for Boost Control do not have a marked polarity. There is the ability to be able to swap the control direction within the firmware without needing to redo the wiring.

I'm not sure how setting the Feed Forward table in that manner would work. The FF table shows the relationship between Boost Aim/Engine Speed and the duty cycle of the waste gate actuator solenoid to get to that aim.

[SteveC]

Thanks Stephen,

The boost polarity in the help doesn't mention wiring - granted its confusing as i thought it was wiring until i read the help.

Normal : Output Duty Cycle is the requested cycle
Inverting: Output Duty Cycle is the inverse of the requested

So is it wiring or inverse duty ?

[NathanB]

Hi Steve,

In regards to wiring, the boost control output resources are all low side drive, with the exception of the boost servo, which is a full bridge drive.

What this means is that all boost control solenoids are to be wired to their 12V supply, and the output resource will switch them to ground to actuate them. There is no provision in any MoTeC GP package to high side drive (Ie. output resource on one pin and Ground on the other) a boost control output.

[SteveC]

I am not talking about the wiring at all, i am trying to understand the polarity setting vs inversed duty cycle.

[NathanB]

Hi Steve,

When carrying out an output test, the test duty will not take the polarity setting into consideration. If you request 40% duty, the normal output will test at 40% duty, and the inverse output will test at 60%.

I have attached a screen grab of a time graph for the behaviour of the normal and inverting output doing a sim run up to boost with the polarity set to normal and inverting.

As for populating a feed forward table using an air line, it will not be particularly effective, as it ignores engine efficiency, exhaust back pressure , turbo efficiency and many other factors. Correct setup, some sensible starting numbers in the feed forward table and a slightly aggressive integral gain will get the boost to the aim fairly well, and allow you to pause your time graph and quick calibrated your feed forward table numbers.

Perhaps watching the HPA webinar on setting up boost control on M1 is a good place to start:

https://www.hpacademy.com/previous-webi ... -motec-m1/