Re: Regenerative Braking?
- From: Mike Swift <tomswift@xxxxxxxxxx>
- Date: Thu, 09 Mar 2006 21:58:01 -0800
In article <1141842105.410326.270820@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
"BobG" <bobgardner@xxxxxxx> wrote:
This sounds like snake oil. Lets say the battery bank is 48V. We're
driving along at 40mph, maybe humping 35V into the motor.... now take
foot off the gas... motor is outputting about 30V lets say.... to get
this back into the battery, you need to hump it up above 48V right? And
to load down the motor to apply braking, you would need a low impedance
load to hook across the motor that would absorb that 30V.... maybe a
bank of boostcaps, but then you need a separate dc to dc converter to
get it out of the boostcap bank and back into the batteries?
One method of supplying regenerative breaking on a PM motor is after the
drive transistors are off to short the armature with a transistor for a
short period of time (microseconds) current will rise in the rotor
because of the back emf and inductance of the rotor. When the shorting
transistor is turned off the energy stored in the inductance of the
motor causes the motors rotor voltage to rise until it exceeds the
battery voltage, and current passes through a diode around the
controllers power transistors. In this way a motor with a back emf of
30 volts can charge a battery of 48 volts
--
Mike Swift
Two things only the people anxiously desire?bread and circuses.
Decimus Junius Juvenalls
.
- References:
- Regenerative Braking?
- From: John Schutkeker
- Re: Regenerative Braking?
- From: Steve Spence
- Re: Regenerative Braking?
- From: BobG
- Regenerative Braking?
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