[ausev] DC or AC motors - which make the best generators?

[Ian Ward]

Gil,

Regen is more important to some than others. My truck loses a lot of energy
to weight and aero drag, so I find it quite useful in getting back at least
a little of the energy I would otherwise use in braking. Those who drive in
hilly areas or deal with the typical patterns of stop-and-go traffic should
see the most benefit.

- ian

On Tue, Jun 3, 2008 at 10:01 AM, m. edmund howse <bytedawg at bytetamer.com>
wrote:

>  Gil,
>
> Actually, every brushed DC motor has regen capabilities. Essentially all
> that is needed is a relay
> to switch the input to the motor off and then the output of the motor which
> is now a generator to the charging ckt.
>
> marv
>
> Gil Dawson wrote:
>
> Here's my impression:
>
> Choosing a design with AC vs DC generators is very similar to the
> design choice of Alternator vs Generator in an ICE car.  An
> alternator's AC output is rectified with diodes to drive the charging
> buss.
>
> The reason DC motors don't show up with regen very often might be
> because the controller for a DC motor is relatively simple, and so
> appeals to the individual car builder.  The controller for an AC
> motor, howevr, is relatively sophisticated yet permits more precise
> control of the car's handling.  AC controllers, therefore, would
> appeal more to designers in a competitive market who can recover
> their engineering costs over thousands of units sold.
>
> You could theoretically add regen features to the design of a DC
> Controler, but then the controler would cost more, pricing it out of
> the homebrew market.  Adding regen capability to an AC controller
> would presumably add a smaller proportion to the cost, yet produce a
> feature that is known to the public and can be used in marketing the
> car.
>
> Regen isn't worth a whole lot, anyway.  Individuals can build a fine
> car without it.
>
> It's interesting how this division between AC and DC favoring
> distinct design goals echoes the arguments between Tesla and Edison
> between AC and DC for electrical distribution standards.  Edison
> favored DC, which would have led to an industry of many independent
> local power plants each with its own distribution system.  Tesla
> favored AC, which led to an integrated transmission system, and power
> plants could be located practically anyplace.  Edison wanted
> customers for his products.  Tesla wanted to light up the world.
>
> --Gil
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