freewheel/regen mode switch

[Mordaz]

Any ideas on how to implement such function with a regen controller?

[myelectricbike]

Switching supply power to the controller on and off is the only way I know. The new, new regenerative controller is expected to allow  user specification of freewheel width at both ends and in the middle but not a random or arbitrary point of freewheel, so again a supply power switch is needed.

[mustangman]

 When can we expect the new regen controller to be available (36V Or 48V) and how we can tell the difference from the old and the new versions?

[Mordaz]

I have just received the regen controller but have not tried it yet.  How can I tell the new, new model from the old version? 

With the regular controller I can pedal along with the motor and get faster.  But the regen function is really great when going downhill.  That's why I think a freewheel/regen mode switch would come in handy.

[mustangman]

 That is exactly what I am looking for !! Here in SJ valley there aren't very many hills but plenty of silly drivers who don't stop at stop signs so the regen/brake will come in very handy. Oh, mordaz, was that 48V or 36v??

[myelectricbike]

Sorry guys, I hate to report that I have not received either the 30 kits, the wheel chair sample or the new, new regen controller yet. I can report that today I have received six samples of Allegro's new Three Phase Power MOSFET Controller which I will hopefully be testing over the next few weeks.

...not suitable for hub motor regenerative commutation, sorry.

[mustangman]

 What battery chemistries does the allegro controller support? SLA LiPo, LiFeP04, Nimh. ?? 

[myelectricbike]

Since it is programmable I would say all chemistries are capable of support by the OEM but let me check further and see if Allegro or one of its OEM's specifically state or do this. Adaptation to battery chemistries is definitely not a built-in function of the commutation chip.

Also, it appears that the BRAKE function of both Allegro commutation chips does not support regeneration.

[cadstarsucks]

Since it is programmable I would say all chemistries are capable of support by the OEM but let me check further and see if Allegro or one of its OEM's specifically state or do this. Adaptation to battery chemistries is definitely not a built-in function of the commutation chip.

Also, it appears that the BRAKE function of both Allegro commutation chips does not support regeneration.

A 3PH bridge into a boost converter would effect regen braking.

Dan

[myelectricbike]

As I understand it when the BRAKE function is not selected and no power is applied the MOSFETS are open and simply allow the motor to spindown whereas when the BRAKE function is selected all MOSFETs are shorted. Thus you have freewheel from the chip when the BRAKE input is not active. Although you can insert diodes across the MOSFET pins and create a 3ph bridge rectifier when the BRAKE function is active there is no provision on the chip for PWM to control the level of regen, so that the instant you release the throttle and switch to regen you get 100% regen instead of a throttled amount. This is why the current Golden regen controllers use a microcontroller and software for everything instead of a commutation chip. I'm looking for a commutation chip that has PWM braking, and hence PWM regen built-in.

[cadstarsucks]

As I understand it when the BRAKE function is not selected and no power is applied the MOSFETS are open and simply allow the motor to spindown whereas when the BRAKE function is selected all MOSFETs are shorted. Thus you have freewheel from the chip when the BRAKE input is not active. Although you can insert diodes across the MOSFET pins and create a 3ph bridge rectifier when the BRAKE function is active there is no provision on the chip for PWM to control the level of regen, so that the instant you release the throttle and switch to regen you get 100% regen instead of a throttled amount. This is why the current Golden regen controllers use a microcontroller and software for everything instead of a commutation chip. I'm looking for a commutation chip that has PWM braking, and hence PWM regen built-in.

There is no way for a controller to do regen braking with the same FETs it uses to drive the motor since the motor voltage is less than the supply rail.  It takes a second 3PH bridge switching into a boost topology in order to effect regen.
Dan

[myelectricbike]

And indeed the Golden regen controller uses 12 MOSFETs instead of 6, but there must be a commutation chip somewhere that offers the same regen capability in hardware versus using software and a microcontroller chip.

[Mordaz]

mustangman, I got the 36V controller.

I was wondering, wouldn't a diode do the trick?  (battery+ to anode; cathode to controller+; mode switch in parallel with the diode).  I know a regular diode would pose a significant power loss, so I was thinking of a 'zero-volt diode' implementation with a power mosfet. 

[mustangman]

  mordaz, I was looking for the 48volt regen (version 3) that might get more speed and better regen braking than the 36volt version. Otherwise, I bought an extra battery to run my lighting with.(LOL) When RAGE had a sales, I got 4 18Ah SLA for 24.05 each including shipping(no sales tax) with the thought of upgrading to 48 volt for more speed since I live in California(30MPH limit!!). I will have to wait for MEB to finish up any testing and post results before I can make a decision. Email me if you have any questions.

[myelectricbike]

Instead of building your own MOSFET switch you can buy a 12 to 24 volt coil solid state 30 amp relay like power companies use in home energy management systems to switch water heaters on and off.