Increase speed and decrease torque. It's possible ?

[Velocyraptor]

Hi
The trike is ok but it will be perfect if I could reduce acceleration and increase the speed without change the wheel diameter ( 280 mm)
It seem the torque is equivalent to amperage and speed is equivalent to voltage.

My voltage is 36V.
I have thinked than if I put a resistor, I could do that because of electrnic law:

 Voltage=Resistance x Amperage

so if max amperage possibility is not use :s (for explaination) it's possible to obtain 48V with (less amperage) ?
And where I could wiring it between the controller and the motor, or between the throttle and the controller withoout damage it.

Resistor = Voltage / Amperage
I repeat the wheel's trike burns always I accelerate because of the too high torque needed for the wheel diameter.
Any idea ?


Greg

[Electrobent]

Damn, I wish I had your problem!

[rolf_w]

... The trike is ok but it will be perfect if I could reduce acceleration and increase the speed without change the wheel diameter ( 280 mm)
It seem the torque is equivalent to amperage and speed is equivalent to voltage.

the first part of your reasoning is correct: torque is proportional to current (for a given diameter) and max rpm is proportional to voltage. But you can't simply trade one for the other...

the max current through the motor at stand still would be very large (the motor windings have only some few 100mOhms) if not for the controller. By chopping the power to the motor windings it limits the max current. This is set by the software in the controller chip - unfortunately you have no access to this setpoint in the BAC controllers.
the max rpm is given by the voltage or by the winding of the motor. If you don't want to increase the voltage you can try to change the windings. The simplest approach is to add a star-delta switch (3x change-over) which will increase max rpm by a factor sqrt(3).

[Bikemad]

I repeat the wheel's trike burns always I accelerate because of the too high torque needed for the wheel diameter.
Any idea ?

Hi Greg,

As you've already said, to go faster you will need more volts. (With 48V you should achieve 20kmh instead of 15kmh)

To reduce the acceleration, you will need to decrease the available current.

My suggestion would be to use a 48Volt battery with some form of current limiting device (i.e. Cycle Analyst), but only if the speed controller can cope with 48V.

Does anyone know if the 36 Volt Regenerative controller can be run at 48V without damaging it?

I'm considering making a very simple restrictor unit for the Magic Pie, which could simply be plugged in-line with the throttle wires and be adjusted to restrict the maximum available power for legal reasons, but as this is still on paper at the moment, so I don't know how it's going to affect the acceleration, until I can actually try it out.

Here's the revised circuit diagram if anyone is interested:



The other power reduction option I'm considering using with the Magic Pie is this dual voltage setup:



Unfortunately, this circuit diagram is as far as I've got, as I have lots more important things still waiting to be done!

Alan
 

[Velocyraptor]

Hi

Thanks you !
I will try it soon, now I know it's possible.

Byye

[Leslie]

Yes I have used a single schottkey diode as one way of limiting the throttle by .5v or a resistor.  I think 12 ohm will give you a good enough drop without choking out the current.