Paul and Sabrina's Cheap 3 Phase Inverter (AC Controller) with Field Oriented Control

[WindyDrew]

A few things.

Originally Posted by thingstodo

Just to make sure I understand - the pin to be used is pulled high and will be grounded to engage the reverse switch. Right?

Correct.

Forward is 'normal' so that a faulty switch does not reverse the car while driving down the interstate at 70 mph.

EVTV has described that the Tesla needs the brake engaged and the speed within a few rpm of 0 before you can change from Park to Drive, Drive to Reverse, Reverse to Park, etc.

Maybe 1 extra input for the brake? It would be tied high, Active low, grounded by the switch.

How about just running the source ground through the brake switch before going to the reverse switch?


Yup - I think so.



One LED lit to show high (normal) and one to show low (reverse)?

I wasn't goingto worry about the led since I'm building a race car and going to simple, but would be easy to implement with another wire.


I have no experience with the code - I will need to look through it eventually. But I'm not much help right now.

Same here

[thingstodo]

Originally Posted by WindyDrew

A few things.

Maybe 1 extra input for the brake? It would be tied high, Active low, grounded by the switch.

How about just running the source ground through the brake switch before going to the reverse switch?

Hmm. I was looking to ignore a reverse signal unless the brake was pressed, speed was about 0, but then have the reverse signal maintained for as long as you wanted to back up.

The wiring through the brake has the reverse signal go away when the brake is released. How do you signal that you want to go forward again? When the brake is pressed again and no reverse signal is there?

In terms of coding, it is preferable to have signals coming from off the MPU that show you what mode you are in. You can keep track in software, but each time you do you need to bullet-proof the conditions for entering and exiting that mode, complete with what could go wrong/fail and get you into that scenario unexpectedly.

If it was my car - I'd use the extra input and make sure the rpm on the car was under a threshold, like maybe 50 rpm. An indication that you are in reverse and not forward would be nice as well.

Are you using regenerative braking? If so, how does the brake signal get tracked now?

[WindyDrew]

Originally Posted by thingstodo

Hmm. I was looking to ignore a reverse signal unless the brake was pressed, speed was about 0, but then have the reverse signal maintained for as long as you wanted to back up.

The wiring through the brake has the reverse signal go away when the brake is released. How do you signal that you want to go forward again? When the brake is pressed again and no reverse signal is there?

In terms of coding, it is preferable to have signals coming from off the MPU that show you what mode you are in. You can keep track in software, but each time you do you need to bullet-proof the conditions for entering and exiting that mode, complete with what could go wrong/fail and get you into that scenario unexpectedly.

If it was my car - I'd use the extra input and make sure the rpm on the car was under a threshold, like maybe 50 rpm. An indication that you are in reverse and not forward would be nice as well.

Are you using regenerative braking? If so, how does the brake signal get tracked now?

My plan required holding the button down for reverse. Once I let off, it would be forward. So having close to 0 rpm would be a good idea. But I also want regen so only restrict forward to 0 rpm. Once it's in drive, I want to use it as a regen pedal when I'm holding the button.

[thingstodo]

Originally Posted by WindyDrew

My plan required holding the button down for reverse. Once I let off, it would be forward. So having close to 0 rpm would be a good idea. But I also want regen so only restrict forward to 0 rpm. Once it's in drive, I want to use it as a regen pedal when I'm holding the button.

EDIT - I hit send before I should have - Paul's code new restricts regen to disengage at 0 rpm for forward. That part is done and working.

So - to review:

button	brake	description
Off	Off 	normal forward controlled by accelerator pedal
Off	On	normal forward but using friction brake pads using hydraulic 
		pressure from how far the brake is pressed
On	On	regen braking as well as friction braking.  I'm not sure how 
		much regen braking when you press the button, or if it 
		increases as you hold the button

Now, we'll add the low rpm - like maybe 50 rpm or something

button	brake	description
Off	Off 	normal forward controlled by accelerator pedal
Off	On	assuming we're stopped below 50 rpm
On	On	assuming we're stopped below 50 rpm, change to reverse.  
		But the throttle works in reverse as long as you don't have 
		the brake pedal to the floor?
Off	On	assuming we're stopped below 50 rpm, after going reverse
Off	Off	back to normal operation in forward

This description assumes no regen braking without pressing the brake pedal and having that switch enable the regen/reverse button on the dash, or steering wheel, or whatever. That is what you meant by

just running the source ground through the brake switch before going to the reverse switch?

I think we're getting close to a description that would be required by anyone who takes on the programming mods ...

[WindyDrew]

Originally Posted by thingstodo

EDIT - I hit send before I should have - Paul's code new restricts regen to disengage at 0 rpm for forward. That part is done and working.

So - to review:

button	brake	description
Off	Off 	normal forward controlled by accelerator pedal
Off	On	normal forward but using friction brake pads using hydraulic 
		pressure from how far the brake is pressed
On	On	regen braking as well as friction braking.  I'm not sure how 
		much regen braking when you press the button, or if it 
		increases as you hold the button

Now, we'll add the low rpm - like maybe 50 rpm or something

button	brake	description
Off	Off 	normal forward controlled by accelerator pedal
Off	On	assuming we're stopped below 50 rpm
On	On	assuming we're stopped below 50 rpm, change to reverse.  
		But the throttle works in reverse as long as you don't have 
		the brake pedal to the floor?
Off	On	assuming we're stopped below 50 rpm, after going reverse
Off	Off	back to normal operation in forward

This description assumes no regen braking without pressing the brake pedal and having that switch enable the regen/reverse button on the dash, or steering wheel, or whatever. That is what you meant by


I think we're getting close to a description that would be required by anyone who takes on the programming mods ...

Not sure that will work after thinking about it. I would like the gas pedal to work as a regen pedal once the reverse button was engaged. I doubt I'll want to hit the brake, gas, and regen button just to start regen braking. Maybe a brake signal before engaging reverse would be best.

[thingstodo]

Originally Posted by WindyDrew

Not sure that will work after thinking about it.

This is the time to change your mind .. before coding!

I would like the gas pedal to work as a regen pedal once the reverse button was engaged.

I'll just rephrase that so I'm sure I understand.

So you are driving on the track, pushing your throttle to go faster. You come to .. say a corner .. and let off the throttle a bit. You press in the reverse button to start regen. The regen starts immediately based on your previous level of acceleration and you are now using regen for braking going into the corner. You press the throttle to get MORE regen. You get around the knee of the corner, back off on the throttle (which you are using as a brake right now) a bit to reduce your regen braking. Now you release the reverse button ... and you go from mild deceleration to mild acceleration. You push the throttle to accelerate out of the corner and down the stretch ...

Did I get that right? I removed the paranoid delays and sequencing stuff to get to more of the driving experience thing that .. I think .. you are looking for.

an I doubt I'll want to hit the brake, gas, and regen button just to start regen braking. Maybe a brake signal before engaging reverse would be best.

So I guess you won't be able to wire the reverse button through the brake switch. That's your call. If you want to make the brake happen before moving into reverse, the brake switch will need to be wired into the controller.

To get the response that you want, changing the throttle code in the AC controller is, I think, the way to go. I'm not sure that is a good idea in the general case, for everyone's car. I'm sure it will work fine on your race car, once you get used to it. You are doing one foot driving with a button on your steering wheel (maybe a lever?) but it may be hard to explain to someone else - push the throttle to brake harder.

If you want some level of paranoia for bad wiring, it may be possible to wire the switch or lever to an analog input. A resistor in series and a resistor in parallel will confirm that the lever is still connected, not just shorted out or open circuit. Like the throttle reading 4.5V at full throttle instead of 5V, the lever could read 4.5V when released. And it could read 0.5V when you are pushing 'reverse' instead of 0V.

That way the controller knows that the lever is disconnected or shorted ... and you can decide if you want to fault the controller and coast to a stop or flash a light of some sort and keep racing without regen.

[WindyDrew]

What about this?

Originally Posted by thingstodo

This is the time to change your mind .. before coding!



I'll just rephrase that so I'm sure I understand.

So you are driving on the track, pushing your throttle to go faster. You come to .. say a corner .. and let off the throttle a bit. You press in the reverse button to start regen. The regen starts immediately based on your previous level of acceleration and you are now using regen for braking going into the corner. You press the throttle to get MORE regen. You get around the knee of the corner, back off on the throttle (which you are using as a brake right now) a bit to reduce your regen braking. Now you release the reverse button ... and you go from mild deceleration to mild acceleration. You push the throttle to accelerate out of the corner and down the stretch ...

Sounds pretty much right, except that I want the full range of the throttle for each direction (I believe that's on my end of the settings) so that I let of the throttle and it will start to coast going into the corner. I hold the reverse/regen button when I'm ready to slow down and push the throttle (now inverted by the button) to start the regen based on how much throttle I give it. As soon as I let off the button, I'd like forward (maybe require the throttle to be 0 first) How does that sound?

Did I get that right? I removed the paranoid delays and sequencing stuff to get to more of the driving experience thing that .. I think .. you are looking for.



So I guess you won't be able to wire the reverse button through the brake switch. That's your call. If you want to make the brake happen before moving into reverse, the brake switch will need to be wired into the controller.

To get the response that you want, changing the throttle code in the AC controller is, I think, the way to go. I'm not sure that is a good idea in the general case, for everyone's car. I'm sure it will work fine on your race car, once you get used to it. You are doing one foot driving with a button on your steering wheel (maybe a lever?) but it may be hard to explain to someone else - push the throttle to brake harder.

If you want some level of paranoia for bad wiring, it may be possible to wire the switch or lever to an analog input. A resistor in series and a resistor in parallel will confirm that the lever is still connected, not just shorted out or open circuit. Like the throttle reading 4.5V at full throttle instead of 5V, the lever could read 4.5V when released. And it could read 0.5V when you are pushing 'reverse' instead of 0V.

That way the controller knows that the lever is disconnected or shorted ... and you can decide if you want to fault the controller and coast to a stop or flash a light of some sort and keep racing without regen.

[thingstodo]

Originally Posted by WindyDrew

Sounds pretty much right, except that I want the full range of the throttle for each direction (I believe that's on my end of the settings) so that I let of the throttle and it will start to coast going into the corner. I hold the reverse/regen button when I'm ready to slow down and push the throttle (now inverted by the button) to start the regen based on how much throttle I give it. As soon as I let off the button, I'd like forward (maybe require the throttle to be 0 first) How does that sound?

I was not thinking that you would release the throttle before beginning regen braking, but you can do that if you like.

What I was describing does have side effects - if the Reverse button wiring were to short out during a race, worst case you would be going full throttle and switch to full regen braking. Enforcing the release of the throttle between throttle and regen braking would make a shorted Reverse button less of a problem ... but it would still be a problem the next time you went to accelerate!

Do you have a preference on the Reverse button connection? I'd prefer an analog input, and a couple of resistors wired into the button to verify that the button is still connected (4.5V) and not open circuit/disconnected (5V), pressed (0.5V) instead of shorted out wiring (0V).

[WindyDrew]

Originally Posted by thingstodo

I was not thinking that you would release the throttle before beginning regen braking, but you can do that if you like.

What I was describing does have side effects - if the Reverse button wiring were to short out during a race, worst case you would be going full throttle and switch to full regen braking. Enforcing the release of the throttle between throttle and regen braking would make a shorted Reverse button less of a problem ... but it would still be a problem the next time you went to accelerate!

Do you have a preference on the Reverse button connection? I'd prefer an analog input, and a couple of resistors wired into the button to verify that the button is still connected (4.5V) and not open circuit/disconnected (5V), pressed (0.5V) instead of shorted out wiring (0V).

I was hoping to use an existing hook up like the led output. I think I would rather run it as forward is high, inverse is pulled low. I figured out a close source for 5v and everything already if that's ok with you.

[thingstodo]

Originally Posted by WindyDrew

I was hoping to use an existing hook up like the led output.

OK - keep it simple - not a problem.

I think I would rather run it as forward is high, inverse is pulled low.

So there is a resistor already to tie the input high? That is convenient.

I figured out a close source for 5v and everything already if that's ok with you.

I'm OK with anything you want to do. I'm just paranoid and am mentioning things that I could see going wrong.

I'll sum up what I think you want in the next message. Do you have Paul's latest software? I want to make sure we are looking at the same thing!