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  #11  
Old 11-09-2011, 06:16 AM
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dougingraham dougingraham is offline
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Default Re: Regenerative braking with an industrial vfd

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Originally Posted by smoothflow View Post
The last option is to use a high frequency inverter circuit i.e. mosfets / scr switches, high frequency transformer and then bridge rectifier to convert 96 V DC to 600 V DC. Then use a similar circuit in reverse for regen. Is it possible? Because here in India I can get high frequency inverter circuits for about 100-150 USD.
You mentioned 10A at 600V which even at 100% efficiency is 6000 watts (8hp). So you need a step up converter that can do 6kw for motor drive. This is 62.5A on the 96V side. That is not a lot of power in the EV world but it is a pretty good amount of power for a portable switching supply. This is the kind of thing you need for a battery charger so if you can get stuff that handles 6kw power levels for 100 to 150 dollars you should be packaging it up and selling it as battery chargers. Chargers with that kind of power level sell for $2000 and up and would be a really decent profit margin.

At the power levels you are hinting at this must be for a motor cycle. It just isn't enough power to operate a car at reasonable speeds. You have a 96 battery. A device to boost that battery voltage to 600V at 6000w power levels. A 6000w motor controller which can do the motor drive and produce the power during regen. You need a device that can take the regen energy during braking and step it down and put it back into the battery. And if you want to be able to charge when out driving around there will need to be a device that can charge the battery when plugged into an AC outlet. Some of these components could be designed to do a couple of the functions in one device. The step down converter could be configured as the battery charger. That is what it does when it is regenning anyway. But to combine the boost converter and buck converter in the same device along with the charger is a whole huge project all by itself and not something you can just buy off the shelf. And it is going to be pretty bulky to place on a motorcycle even if combined into one black box. Three separate devices will be even worse.

Can it be done? Sure. Is it practical? Not in my opinion. The extra cost, complexity, weight and space considerations all work against it.
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  #12  
Old 11-09-2011, 09:39 AM
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frodus frodus is offline
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Default Re: Regenerative braking with an industrial vfd

Quote:
Originally Posted by smoothflow View Post
The last option is to use a high frequency inverter circuit i.e. mosfets / scr switches, high frequency transformer and then bridge rectifier to convert 96 V DC to 600 V DC. Then use a similar circuit in reverse for regen. Is it possible? Because here in India I can get high frequency inverter circuits for about 100-150 USD.
That's a type of boost converter, but a lossy one because you have to first convert DC to AC, go through a transformer, then rectifier then to the VFD.

A DC boost converter that boosts DC would be easier, and no huge transformer (but a huge inductor). The problem is, with any converter of any decent power, it's large and heavy.


I'm sure he wants a motorcycle that can put out over 10kw and isn't 600lbs.




I think he should ditch the 600V inverter idea and just use a normal motor and controller. 96-600V isn't practical whether he does that or 600V battery pack, it's going to be dangerous to work on.
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Last edited by frodus; 11-09-2011 at 09:41 AM.
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dc-dc converter, electric motorcycle., industrial vfd, regenerative braking

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