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Old 12-07-2016, 11:56 AM   #2911 (permalink)
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ChargE (not yet running) - '92 Mazda MX6 LX
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Ford Prefect - '18 Ford F150 XLT XTR
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Originally Posted by arber333 View Post
Finally someone figured cruise control for this inverter! Which is what V/Hz is yes?
I guess it would work. That's not really why I was wanting it though. The throttle is a torque signal to the controller. So fixing the throttle signal does not *REALLY* work for cruise control. You need a PID around the present speed. The throttle on a gas engine is actually a torque signal as well ... so cruise control should work similar for gas or electric.

Well sort off... I suggest the primary use of V/Hz would be to implement cruise control. You have PID regulation working. You frame it for V/Hz to move found one chosen frequency, fixed by a button switch (on dash) and PID would try to follow this frequency - speed control! Throttle would still be effective upwards from chosen speed, so you could tap the button with throttle and set a higher speed or just tap button with throttle loose and car would deccelerate some. To break the link would require pulse on brake switch line
I think all of this works with the throttle/torque signal as well. No need to switch to the less efficient V/Hz output.

, you have this wired yes?
I have not seen a Brake switch into the controller as yet. It's the lower part of the wig-wag throttle .. so far .. in my testing at least and what I have seen of Paul's Leaf motor cart.

Limp home mode could effect itself automaticaly if encoder signal would be lost. That way you could have some control if sensor was out. It happened to me with my controller. I use optical RPM sensor for arduino (a glorified mouse sensor) and it caught moisture and corrosion. I replaced it with better protected one but it stays a weak link im my car. My 5c...
The switch between a Torque input and a speed input is going to give you a sudden change, I think. If you are cruising at highway speed, going down a small incline for example, you could have your throttle close to 1/3. If the encoder quit, your speed would drop to 1/3 of your maximum speed, which could be a rapid deceleration.

Or you could be accelerating gently from a traffic light, lose the encoder, and now your car wants to keep accelerating to 3/4 speed instead.

I'm kinda worried about the transition. Right now, if you lose the encoder, the motor decelerates rapidly to maybe 1/10 of the speed you were going ... not a perfect solution if you are on a freeway!

If we can come up with a way to do something reasonable and the speed changes gradually then you have time to get to the side of the road, or use your brakes, or let off the throttle. That's sort of what I'm looking for. The car would definitely handle differently in V/Hz than it does in Field Oriented Control. Acceleration and deceleration would be less aggressive and less efficient. But the car should still be drive-able.

I wonder if the throttle input for V/Hz could be interpreted as amps? That is close to a torque setpoint, and there should be no big change when switching from Field Oriented control to V/Hz and back again ....

I need to do some reading ... Google to the rescue!

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