Pmac tuning

[Inwo]

I'm tuning a pmac which I have running smoothly.
ME-3031 S6 Gen4 sevcon. Running in torque mode.
Motor is stable when powered on at zero speed.
With slight throttle F or R accelerates with about 10% torque. Runs away until braked to a stop.
Pushing car in neutral F or R has same effect.
Not intentionally using hill hold or inch modes.

Any ideas?

 

[Inwo]

No fix yet, but it's a neutral braking issue. Set to 10% which explains the torque level.
Torque is supplied in the same rotation as drive when breaking.
Timing problem? Or is there a setting for brake torque positive or negative values?

I need neutral braking, vehicle coasts forever without it.

 

[amberwolf]

Not knowing anything about your system or vehicle system or usage needs, some questions (since I don't know anything about setting up a Sevcon, feel free to ignore me ):

Why is coasting forever bad?

When not actively braking, wouldn't that be more efficient than having it trying to brake whenever you're not accelerating?

 

[Inwo]

Not bad, just not normal. It feels like it's more than coasting.
Raining here so I have not been able to test anything.
Maybe it's different for pmac. What Secon calls neutral braking in induction motor control, is regen when lifting throttle. Down hill I can often see over 50a charging current.

In this pmac dld version, it is also called neutral braking, but it accelerates at the set 10% torque, rather than decel.
I guess what I'm looking for is general motor theory. Can motor being mis-timed allow motor to run correct direction (well), but regen backwards?

tnx

 

[Inwo]

Possible solution.

Put in a known working dcf and I have the same run away. I did not yet change the sw (dld) to known working one.
That seems to point at a dld that controls this function.
Good news I think. Smile
Taking a break from the heat now.