controlling regen

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sparau
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Joined: Fri, 12 Sep 2008, 18:44
Real Name: Shane Parkinson
Location: Sunny Coast

controlling regen

Post by sparau »

i was bit happy to see this posted by AMprentice

21kg 46hp AC motor with 1238 curtis package

It rekindled my hopes of an lightweight sporty electric bike. else 2 in the 205gti could be a possibility - so i am just trying to work out a few AC questions.

1: as far as i understand (lol) the force of the motors running regen *could* be the same as under full load - ie. 21kw or whatever. Does the regen'd energy go back into the controller (current limited to 3c or whatever batteries can manage) or does the energy need to get dumped into an on board charging system so as to not stress out the packs.

2: can you add a pot to the clutch on a car/bike to control the regen? This could require some serious retraining on a bike cause first emergency reaction is to pull the clutch - and you dont need to be locking the rear when you are trying to avoid the driver reading their novel on the freeway...(dont laugh seen it)
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acmotor
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controlling regen

Post by acmotor »

1. correct.

Regen on an AC induction motor is a mirror image of power side of curve. Same peak torque.
regen on a PM AC or BLDC motor is similar although greater at higher revs than lower revs. Motor is running as an alternator.

Some drives (e.g. AC propulsion's, limit regen to 40% of forward power).
One reason is vehicle control, the other is the power and heat issue if the vehicle were to regen down a long steep hill.
Regen returns power to the batteries at the torque and current limits set up in the controller. Regen max voltage is often a preset max for the controller and battery pack voltage may need to be set to match that.

Once the battery pack is full (we all dream of that !) or the charge rate is too high for pack, the controller will reduce regen to stop voltage increasing further. Regen braking effort then reduces unless a braking resistor is available to dump power into.

Overvoltage control without a resistor also works. There is just no regen when the pack is full.

I have tried these variations and would say that regen with brake resistor when batteries are full will replace power assisted brakes on vehicles in the future. Regen that is demanded by the brake pedal under driver control that is. ABS and traction control will be built into this system. Normal vehicle brakes will end up minir items mainly for emergency and parking.

2. correct again.
Some bikes have used clutch lever for regen demand of controller. I would find the re-think OK. Having ridden a number of bikes with various throttle / brake / clutch / gear arrangements you soon learn !
Vectrix uses twist forward of the throttle handgrip for regen.

Another way would be to have loose brake lever / pedal and a pickup on the first part of the travel. Or perhaps a pressure sensor on the hydraulic brakes and apply regen in proportion to light braking.


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sparau
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Posts: 33
Joined: Fri, 12 Sep 2008, 18:44
Real Name: Shane Parkinson
Location: Sunny Coast

controlling regen

Post by sparau »

thx ac

re:2 i did think of the first part of rear brake travel for a bike but thought it could be too hard to get a balance with. As it is often rear brakes on bikes quite hard to judge since you are using a big boot and have anything up to 0% of weight on the tyre.
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