parts of a regenerative braking system

Hi!

I'm planning to modify my motorcycle to turn it into a hybrid bike (an experiment).

I'm thinking of adding an electric motor mounted on the swing arm which would then drive the chain and the rear wheel.

Most of the electric vehicles I've read about use brushless motors. Should it be an AC or a DC motor?

How do I control the motor speed? Do I use some kind of variable resistor? a potentiometer? (whatever that is)

Most, important, how do I turn the motor into regenerative brakes? Can anyone explain what's going on in the car electronics when the motors turns into regenerative brakes/generators?

In a simple circuit, batteries would be connected to the motor and this motor is usually powered by the battery... but when regenerative brakes are used, the battery is still connected to the motor but this time, it is the motor which powers and recharges the batteries.

Can anyone tell me WHAT makes regenerative braking happen?

I already asked a few people and they say that generators/alternator have diodes to make electricity just flow out and not in.

So is it possible to incorporate regenerative brakes with just the use of some diodes?

If for example an electric car were running and then, at an instant, diodes were installed in the circuit between the battery and the motor, then would the motor turn into a generator and charge the batteries?

Would there be a need for an inverter or a rectifier?

Reply to
lethaldriver
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Just curious--what kind of bike?

A very interesting project, indeed. Might want to just kluge a kit from an electic car, which would have all this built in.

BUT, I think you're a little behind an 8-ball, practicality-wise. Keep in mind that these motors, in an electric car, are dual purpose: alternately generating mechanical power to drive the car and then electric power to brake the car. In your application, it would be *robbing* mechanical power (to a small extent), and then only generating electric power for braking. As well as being cumbersome, etc.

If you really wanted to experiment with regenerative power, take this concept and build a dynamometer for your bike! Same stuff, much more elegant application, imo.

Might could use a treadmill motor, but not sure.

Not the way real dynamometers work, from what I saw on the history channel or someplace, but just as valid. Real dynamometers physically measure a torque or force or sumpn.

Reply to
Proctologically Violated©®

Look for info here:

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Reply to
CraigFL

That depends on how complex a control system you are able to build. AC motors are more efficient, but particularly for variable speed, regenerative braking, and DC supply installations, much more complex.

Only for the simplest DC motor

That's basically a variable resistor, but usually rated for small signal applications. Neither are terribly efficient solutions for power control. Pulse Width Modulation is better.

With a DC motor, it involves increasing the motor field current which increases the motor's internal e.m.f. Once this exceeds the battery voltage, power starts flowing from the motor back into the battery. The motor becomes a generator.

For an AC motor with a variable speed control, this involves advancing the AC phase and/or frequency to increase motor power or retarding it to cause the motor to generate.

Any motor (AC or DC) will become a generator when driven above its no load speed by an external mechanical power input. When operating at a constant speed (driving along), the trick is to modify the input to the motor (field current, phase and frequency) to cause this no load speed to drop below your current cruising speed.

Alternators do.

Nope.

For an AC motor, yes. But its a lot more complex than a simple inverter.

Reply to
Paul Hovnanian P.E.

Why then would it be robbing power? I don't get it.

My plan is to use around four 12volt batteries connected in series to make a total of 48volts. and when the batteries run out of power then the engine's stator or alternator can recharge these batteries. Also, I have the option to charge the batteries at home.

I guess it would be nice if the batteries have gauges to monitor their condition (volt meter, ammeter, etc)

perhaps, you can recommend any company that sells brushless motors and regenerative brakes upgrades?

Reply to
lethaldriver

What would I need to do to advance the AC phase and frequency (whatever that means)???

Home come I read in some post that the only difference between a motor and a generator is the direction of the current/power flow?

Thank you for the explanation but

is there any other simpler explanation on how to turn the AC or DC motor into a generator? What should be done or added?

Reply to
lethaldriver

You'll need something like an inverter whose phase and frequency can be controlled based on numerous sensors and inputs.

That's the result. The way you get one to reverse its power flow is rather involved.

Not really. Its a rather involved problem in power and control systems. You'll need to study up on the basics of electrical devices, motors, electromagnetics, etc.

Reply to
Paul Hovnanian P.E.

Where can I get such an inverter?

Any specific manufacturers?

I've been reading a lot on motors, generators, inverter, rectifier and other electrical related stuff but all I get are information on how regenerative brakes work.

but what I really need to know is what is needed to make such a thing work.

Okay then, I will try to research more on controlling field current, phase and frequency.

I thought I was getting closer to knowing the secret to regenerative braking but then I was wrong and it seems to be a long way until I complete it.

Reply to
lethaldriver

Remember the old bike safety-lite friction driven by the bicycle wheel? That seemed to me to be regenerative braking. Man, when that goddamm bulb was lit, you could really feel the drag! Disconnect the bulb (stop the current flow), and pedaling was really easier. Neat little generator.

Mebbe I was just weak as shit, as well. :)

Reply to
Proctologically Violated©®

actually I also did consider something like that.

but instead of a dynamo, I'm using a car alternator which would be connected to the rear wheel by a pulley by a loose belt, and when I want regenerative brakes to work then I would tighten the belt with a tensioner. or the alternator belt could always be tight enough but the alternator wiring connection to the battery could be cut so that it won't be charging the battery when not needed.

BUT I still think the motor-generator is a superior design since it's compact and lighter and turning the regenerative brakes is simpler (assuming that everything needed is in place)

snipped-for-privacy@hovnanian.com...

Reply to
lethaldriver

Indeed the electronic controls are the real high-tech part of hybrids. Do NOT use a variable resistor to control speed. Most of the hybrid systems I know of use a very complex electronic control system. The DC from the batteries is "chopped" into a hybrid signal, either AC (most common) or a pulsating DC.

On braking the voltage from the motor is stepped up in a special voltage converter , then rectified to DC and fed to the battery.

If you are not good in high power electronic control systems this part of the conversion will be something you need to farm out to an EE who is.

The control system is basically a computer that takes into account the vehicle speed, acceleration or brake commands, battery charge level, and such, then computes how to modify the battery or motor generator voltages, and drives high power electronic voltage conversion electronics.

Reply to
Don Stauffer in Minnesota

I'm not familiar with any systems sized for bicycles or motorcycles. The people that play around with this sort of thing on autos might be able to give you some advice.

Try Googling "hybrid hacking"

Reply to
Paul Hovnanian P.E.

can you help me complete the list for components needed in an electric vehicle

  1. brushless motor
  2. motor speed controller
  3. batteries
  4. throttle control

what else? Can one build a very basic electric vehicle with only these components?

Reply to
lethaldriver

I really do plan to ask for the help of an electrical engineer although I haven't found one who's good with motors/generators.

about the control system, I think that it doesn't have to be very complicated since regenerative braking systems can be found on electric bikes.

i still need an answer to the question: What makes motors different from generators/alternators? What parts make them different from each other?

Is it possible to do it the other way around? What should be done to an alternator to convert it into a motor?

Reply to
lethaldriver

Ask the motor/generator thing on rec.crafts.metalworking.

These guys know a lot about motors/controls, 3 ph converters, pumps, the whole nine.

Tell'em I sent you. :)

Reply to
Proctologically Violated©®

It's a different world.

The question is whether you care about efficiency and battery life. If you don't care about efficiency, you just use a DC brush-type motor for power... you apply PWM to it and adjust the pulse width for speed control, then you reverse it and use the battery as a load with the same PWM device.

Eventually this wrecks the battery since the battery wants to see a constant voltage and isn't happy as a random current sink, but it's the way a lot of those devices work.

A DC brush type permanent magnet motor is the same thing as a DC generator. But, there are plenty of other kinds of motors out there, and brushless motors and induction motors are totally different things and cannot easily be used in reverse.

A DC universal motor has a field coil in place of the permanent magnet, and if it is supplied with DC, the motor can be used as a generator.

If you look inside a typical hybrid golf cart, you will see a DC permanent magnet motor in most cases, which is used in reverse as a generator to charge the battery once the gasoline engine picks up at higher speeds.

The Audel's Small Motor Repair Handbook has an introduction to the various kinds of motors.

--scott

Reply to
Scott Dorsey

That's a good outline for a basic system. Unfortunately, you aren't going to be able to walk into a parts shop with this list and walk out with anything useful.

Reply to
Paul Hovnanian P.E.

hmmmm.... I think that using deep-cycle lead-acid batteries would be best for my applications. these batteries are used in golf carts and other electric utility vehicles and they are more tolerant to discharging.

Reply to
lethaldriver

Any electric motor will act as a generator, and vis versa. It depends on the rpm of the motor and the voltage feeding it or loading it.If something mechanical turns a motor faster than the applied voltage is trying to drive it, it will generate its own voltage/current and feed it back to the supply. But you need to step up the voltage to get it to charge properly. That voltage conversion is the high-tech part of the electronics.

Reply to
Don Stauffer in Minnesota

No, not at all. For example, an induction motor relies on the current in the field coil to induce an opposing voltage in the armature. If there is no current to the field coil, there is no opposing voltage in the armature. You can spin it all you want and there will be no voltage on the leads.

Now, any PM motor will act as a generator, and most universal motors can be easily rewired turn them into generators by providing external power for the field coil.

--scott

Reply to
Scott Dorsey

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