Regenerative breaking on MMM

[BrianG]

Originally Posted by auto2

...or use virbration to charge the batterys. i saw a flashlight you had to shake to build up a charge. the shocks could do that.

Enter Bose (yes, the same Bose that does audio): http://auto.howstuffworks.com/car-suspension9.htm

The flashlight you shake is basically a piston-like motor. Instead of the rotor turning, it goes up and down. Either way, it induces a voltage in a coil, just not nearly as well as a rotary motor.

[rabosi]

Originally Posted by BrianG

Enter Bose (yes, the same Bose that does audio): http://auto.howstuffworks.com/car-suspension9.htm.....

If it works as advertised that will be awesome. nice find.

[TexasSP]

Well damn is that is slicker than dog snot.

I wonder did Dr. Bose have a heavy hand in this himself or was this designed by other Bose engineers? The guy is a genius for sure!

[HighKalibre]

I work on large mine size diesel-electric wheel loaders. The engine drives a large generator which supplies power to 4 wheel motors. These have a very complex control system too them. These use resistive braking instead of regenerative braking, same idea the energy is just used differently. wasted as heat through a bank of resistors instead of "topping" up the batteries.

We also have electric trolley buses that run off overhead lines. when they brake or travel down hill the motors turn into generators and pump electricity back into the grid.

Lemme get to my point. The way I know regenerative braking to work. You can't power the motor to move the vehicle at the same time as you're making it generate power. if that makes any sense.

With the wheel loader for example. you step on the throttle and power is supplied to the motors to move the vehicle. The moment the operator takes his foot off the throttle. Power is no longer being supplied and all 4 motors turn into generators, pushing power through the resistor bank and slowing the loader down.

If you were to use the drag brake as you suggest. When the batteries fall below ~80%, the drag brake engages and tops the batteries up.

The batteries being at 80% and then applying a 20% added load to the motor might slow the vehicle down to the point where the drag brake is doing nothing for the vehicle. Voltage gives you speed, as your motor slows it'll draw more amps from the battery. Further draining it, the cycle continues until your battery is dead. Sorry if its overly exaggerated

Have you thought about coupling a small 12v or even 24v alternator to the motor to keep the batteries topped up. To me this would seem like a smaller overall load then the drag brake. In this way you could still use the motor to generate power when traveling down hills or during braking applications. coupling the alternator to the motor (depending on the size of motor you are going to use) may or may not grossly affect the rotating mass of the motor.

In which case an idea just came to mind. An electo magnetic clutch (EMC to simplify) to activate/deactivate the alternator drive. Once you're up to speed the EMC could activate and the alternator would top your battery up as needed.

Or also if you wanted to try and collect the wasted heat energy from the exhaust or cylinder head. What about a thermocouple/thermopile to generate power? mind you it may be more involved than you would like

Ignore me if this makes no sense

[Pdelcast]

Originally Posted by johnrobholmes

Using a MMM on the generator side would be a horrible idea IMO, the efficiency is not there for generator use.

Now why would you say that? The efficiency is pretty good actually, it's just not optimized for generation.... but neither is a 3 phase bridge rectifier either. Above about 35% braking the motor starts dissipating a bit of power as the phase currents get really high -- and that causes a loss of efficiency.

The main difference is that a bridge won't ever BOOST the voltage for the battery -- if the battery voltage is lower than the motor EMF voltage, the bridge won't do a thing. An active boost brake (like on the Monster) will boost the voltage higher to charge the battery.

Patrick

[auto2]

ok so my putting mechanical brakes on my buggy is causing a LOSS in run time cause the motor is not charging up the battery during braking? very interesting

Awesome info!

I figured this was a good way to go because this is how a lot of hybrids work, they use brushless motors as generators when the ICE is performing optimally. I don't imagine that this is something that would be the primary focus of CC since you aren't in the market of making hybrids, but I doubt the technology is that much different.

So, this set up is so easy. It's all very trivially simple.

For cyclists, there are "Flip-Flop" hubs that have a fixed gear on one side (like a track bike) and a coaster gear on the other (like a BMX bike.) Off of the fixed gear, I'd attach the motor so that, so long as the vehicle is moving, the shaft of the motor is moving. If the motor is under power, the vehicle goes. When the motor isn't under power, it spins idle OR can generate power.

On the coaster side, the diesel engine. Simple engine, clutch set up allows the engine to idle at a stop, and the engine continues to idle until the wheel is spinning at the engine's optimal speed. Then engages.

When the engine is engaged, the motor idles or charges.

One speed, two power plants, existing bike parts, and a very simple bit of logic.

Originally Posted by Pdelcast

Now why would you say that? The efficiency is pretty good actually, it's just not optimized for generation.... but neither is a 3 phase bridge rectifier either. Above about 35% braking the motor starts dissipating a bit of power as the phase currents get really high -- and that causes a loss of efficiency.

The main difference is that a bridge won't ever BOOST the voltage for the battery -- if the battery voltage is lower than the motor EMF voltage, the bridge won't do a thing. An active boost brake (like on the Monster) will boost the voltage higher to charge the battery.

Patrick