I have question with no simple answer to be found anywhere
There is an inductive load that is operated by its controller
I need my custom unit to take over the control of the load. No difficulties expected here, I switch it with relay and 10-15 uS after- I can do whatever I want via Mosfet
I also need a load emulator, so that the factory controller does not register a fault
The tricky part- is giving back the control. When my controller senses pulses from factory controller- it has to give back the control asap
That means rapid connection of the inductive load to Mosfet that is already open
So my question is- how bad is the idea? Factory controller should be pretty robust, in terms of flyback protections and stuff, but could something really terrible be happening during the switching caused by, for instance, contact bounce?
So that relay keeps load connected to factory controller by default, and only when energized- reconnect everything to take control
I am open to better solution
Well if you are doing something with the load that is different from what the factory controller is doing with the dummy load and you switch, what do you think will happen?
This way factory controller will be registering an open-circuit condition and stop operation, which is unacceptable
Factory controller should be left untouched, and even if I do that- same thing, load turned on without command- either open circuit, or internal error will be caught
I don't quite catch what you're trying to say
So the factory controller will start controlling the real thing instead of dummy, and my controller will just abort it's thing
It all will happen within 10 us (<1us reaction time, 8us for relay "reaction")
I am not sure I follow
By two mosfets- do you mean one from factory controller, and one from the custom?
Then- again, factory controller will see sudden 0V on the drain, when there was no command for that- and this will be a trigger for an open-circuit fault condition (12v load supply is gone)
Custom controller wants to do dirty things, while the factory one is asleep
If you mean something different- could you please illustrate?
It is monitoring the output (drain) for faults detection
Unit only allows short or open circuit condition for 50us, after that it gets registered, and unit goes to error state, till power is cycled
Correct me, if I am wrong, but won't that make Q2 drive not just an actual load, but also a dummy at all times? That would reduce power going to the load, and also, won't be liked by the controller, cause resistance has to be within spec
I very much appreciate your effort on proposing a better solution, but if there's nothing catastrophically wrong with mine- I would like to stick to it. Factory controller is pretty sophisticated, so trying to dodge all kinds of it's laser alarms is probably not worthing it
And I would really really like to keep it in original state, making my controller only an add-on
I am just not really sure about how all the internal mechanisms work inside of a factory controller, there is no schematic available. D2 could be a problem as well, because of a voltage drop, and therefore- reduced current
So for me it's really easier to let it do it's normal thing, just with a fake load
Around 8 Amps
A 2 ohm solenoid
Very glad to hear, thank you!
I'll definitely give your solution a good think and try, a schottky might have a chance to stay stealthy enough
Arduino RP2040 Connect via Mosfet with help of IR44273LPBF
Another downside of omitting relay- would be, as counterintuitively, as it gets- broken fault detection, hehe
Q1, if blown short, can become a huge problem, that can't be neither detected by any of controllers, nor isolated. That will damage the solenoid, and that would be expensive. Also bit dangerous
It would not be a problem with relay, cause "dirty things" won't last too long, and are pretty occasional themselves
I also have a feeling like it's an overall safer solution
Yes, at this point some context would be useful
It's a car stability control system, and what I am trying to do- is a limited slip differential imitation. It works by applying brakes to the spinning wheel. That transfer some torque to the opposite one. Brake pressure can be directed to respective calliper via system of solenoids.
Normally the unit will sit quiet, just reading speed from abs sensors, and when a wheel spin detected- it hijacks solenoids control via relays and drives them via mosfets.
Operation stops when both wheels speed is close enough, if attempt lasts for too long, or, if factory system is trying to operate the brakes.
If factory system operation is detected- then timeout is set, before my unit is allowed to kick in again.
Some brief comment on the schematic would be extremely appreciated, cause I am, honestly, having hard time reading it, sorry
