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Old 12-08-2016, 04:41 PM   #2913 (permalink)
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Originally Posted by thingstodo View Post
A summary of what I've read, mixed with a bit of my own experience:
- The amps for an AC motor don't really go much below 25%, even if it is spinning slowly and unloaded, unless you are moving to regenerative braking from motoring.
- So the amps go from 25% to about 115% for the throttle signal, but it depends almost totally on the acceleration/deceleration
- Keeping the amps at 75% the car speeds up slowly (relatively) compared to keeping the amps at 100%. The controller needs to increase the output voltage as the frequency rises to keep the amps at 100%. At some point you run out of voltage and it can no longer maintain 100% current.
- Using Paul's wig-wag style throttle arrangement, and the amps as a setpoint from the throttle, there is a deadband from 25% down to -25% where the motor is not exactly coasting but is not really motoring or regen braking. Perhaps that works OK as a control philosophy?

Switching to using the throttle as a current command when the encoder signal goes away sounds interesting to me. I think Klaus (is that his name?) does a similar thing with the controller that Damien Maguire is using. I think Klaus refers to it as slip control instead of field oriented control. And it uses encoder feeedback .. so maybe I'm off base there?

My my ... I do get long winded!
Well in short, yes i use Johannes inverter in my car, and it is excellent. It uses a sort of V/Hz to spin motor first couple of turns and then switches to slip mode with optical encoder. It uses PI regulator. Even for cruise control it uses PI with time supression. I drive every day. Only one bad thing about it, it is made for ACIM only. I spun my Leaf motor unloaded with it but reverse EMI were so bad my DCDC shorted!

I dont want to use wig-wag throttle since i want to drive a car not a ship or submarine. I really need reverse switch in software.

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