efficiency of regenerative braking?

What is a super cap?

-- Rich

You know how much current it takes to accelerate a train to just=20 one rpm, clueless f*****ad?

Do you know what a stepper motor is, shit-for-brains?

Are you an engineer, stupid f*ck?

It would depend. Do Brit trains spin on their long axis, or end-over-end?

Have you ever used google ?

Graham

The last numbers I saw from Toyota claimed the regenerative braking system on the Prius was capable of a 30% recovery rate.

A life cycle assessment by CNW Marketing/Research [20] does however show that the Prius uses more energy than the average car, and also more energy than several larger cars such as the Hummer H3. Toyota's own life cycle assessment also shows that the amount of energy required to manufacture a Prius is higher than that of a similar gasoline powered vehicle.

It is a motor where the armature can be rotated in small increments or steps. Really doesn't have much to do with what we are talking about.

In answer to Bret's question, yes, the efficiency is over a fairly wide range. It goes down under heavy loads at low rpm because high currents are needed to produce high torque, and resistance losses are proportional to the square of the current. That is why it is best to use a transmission even though an electric motor can work without one.

I kinda thought I covered that with, "Using capacitors eliminates the battery losses, but they mean added complexity, cost and weight."

| > Do you know what a stepper motor is, shit-for-brains? |=20 | It is a motor where the armature can be rotated in small increments or | steps. Really doesn't have much to do with what we are talking about.

Stepper motors I've used can stop on a dime. Try loading the National grid with one by reversing it.=20 This is really very simple, all you do is try to drive in reverse. I've hooked up an ordinary 3-phase squirrel cage motor to an old Rolls Royce engine out of a scrapped Vanden Plas, connected=20 the supply and started the engine. Bingo, the supply meter ran=20 backward. Fuel was natural gas, heat was used to warm the workshop,=20 a water jacket around the exhaust pipe.=20

=20 | In answer to Bret's question, yes, the efficiency is over a fairly = wide | range. It goes down under heavy loads at low rpm because high = currents | are needed to produce high torque,=20

In either direction.

| and resistance losses are | proportional to the square of the current. That is why it is best to | use a transmission even though an electric motor can work without one.

Nothing wrong with gearing, I agree. You need that to accelerate rapidly, so it will for deceleration too. Cahill is not an engineer, he's an idiot troll pumping out one-liner questions to be antagonistic and argumentative.=20 If you have one train approaching a station and another stationary, couple them electrically without external supply then the approaching train will slow as the stationary train accelerates, simply energy = transfer. Dynamic braking I've used on AC electric motors by shorting out the windings. They stop as fast as they start.

By definition, braking takes places over a wide range of rpms.

But generators and alternators ain't so efficient over a wide range of rpms.

What's the solution?

Bret Cahill

Same as your car. Use the handbrake, idiot.

Clearly the added factors are worth it.

The also help supply power for acceleration too AIUI.

Graham

Aren't they ?

To work with what you've got and make the best of it.

Graham

Stepper motors are normally used to position things, like the slide on a machine tool. A single revolution may be broken down into 3600 steps. The motor can be made to stop at any of the positions and resist being pushed from that position. When used to turn a screw that can translate into positioning to .00001 inches. With most drive motors they don't worry so much about the position as the rpm.

Yes, and when stopped they use energy to hold a position. So you are best off to use a friction brake to hold a position once stopped. They don't wear out that way anyway.

Yes, but the energy is wasted as heat that way. Better than wearing out brake pads but not as good as feeding power back in to the grid and turning the meter backwards.

You'll need friction braking in addition to dynamic braking for rapid braking anyway.

Hence it can also be used to bring a vehicle to a stop.

Graham

No, it is not clear. It all depends on the intended use of the vehicle. For a battery powered electric car intended for use mostly on uncongested highways with few hills the added efficiency of the capacitors may not amount to enough to cover their added weight, to say nothing about the added cost due to the more complex system.

Yes, it would be kind of pointless to charge the capcitors up and then not use them to get the car back up to speed wouldn't it.

No-one I know is going to buy a car that won't go up hills and isn't suitable for busy roads.

You're being disingenuous.

The caps are better than batteries at handling large currents overall.

Graham

| > | > Do you know what a stepper motor is, shit-for-brains? | > | | > | It is a motor where the armature can be rotated in small = increments or | > | steps. Really doesn't have much to do with what we are talking = about. | >

| > Stepper motors I've used can stop on a dime. Try loading the = National | > grid with one by reversing it. | > This is really very simple, all you do is try to drive in reverse. | > I've hooked up an ordinary 3-phase squirrel cage motor to an | > old Rolls Royce engine out of a scrapped Vanden Plas, connected | > the supply and started the engine. Bingo, the supply meter ran | > backward. Fuel was natural gas, heat was used to warm the workshop, | > a water jacket around the exhaust pipe. |=20 | Stepper motors are normally used to position things, like the slide on | a machine tool. A single revolution may be broken down into 3600 | steps. The motor can be made to stop at any of the positions and | resist being pushed from that position. When used to turn a screw = that | can translate into positioning to .00001 inches. With most drive | motors they don't worry so much about the position as the rpm.

You mean like this:

| >

| > | In answer to Bret's question, yes, the efficiency is over a fairly = wide | > | range. It goes down under heavy loads at low rpm because high = currents | > | are needed to produce high torque, | >

| > In either direction. |=20 | Yes, and when stopped they use energy to hold a position. So you are | best off to use a friction brake to hold a position once stopped. = They | don't wear out that way anyway.

No problem using a friction brake. |=20 | >

| > | and resistance losses are | > | proportional to the square of the current. That is why it is best = to | > | use a transmission even though an electric motor can work without = one. | >

| > Nothing wrong with gearing, I agree. You need that to accelerate | > rapidly, so it will for deceleration too. Cahill is not an = engineer, | > he's an idiot troll pumping out one-liner questions to be = antagonistic | > and argumentative. | > If you have one train approaching a station and another stationary, | > couple them electrically without external supply then the = approaching | > train will slow as the stationary train accelerates, simply energy = transfer. | > Dynamic braking I've used on AC electric motors by shorting out the | > windings. They stop as fast as they start. |=20 | Yes, but the energy is wasted as heat that way. Better than wearing | out brake pads but not as good as feeding power back in to the grid = and | turning the meter backwards.

Exactly. Just not practical for the application I was working on. What = IS practical is starting and stopping trains, and what is even more = practical is a computer controlled subway system, and what is even more practical than that is a country-wide rail system under computer control with each car individually powered, delivering merchandise directly from port to = city overnight without trucks on roads. The rail infrastructure is there and=20 under-used because it runs on Victorian rules.