The 10 Most Important Inventions of Nikola Tesla... Known (my add)

originally posted by: Cauliflower
a reply to: mbkennel

Tesla was a media "voice" and the Tesla announcement style was very loose and esoteric so that it could be (mis)interpreted easily.

Sure. If claiming to have built a "death ray" which could "bring down 10,000 planes" counts as "esoteric".

And if people "misinterpret" "having a death ray" as "having a death ray" instead of the truth which was "not having a death ray".

a reply to: tanka418

What are you talking about? Induction motors are very efficient. Over 90% efficient.

I guess you don't know what you're talking about. Sad!

originally posted by: C0bzz
a reply to: tanka418

What are you talking about? Induction motors are very efficient. Over 90% efficient.

I guess you don't know what you're talking about. Sad!

Sorry man...I guess an Electrical Engineer wouldn't actually know.

Course then again, I wasn't referring to just the motor...but rather the over all system. I could tell y'all a story about how they don't use real AC, but, y'all wouldn't believe an Electrical Engineer...we don't know.

The reality is that it takes energy to operate inverters...the devices that convert DC into AC, and that the control circuitry also is far from 100%.Oh, by the way...it is unlikely that the induction motors are quite 90%...though I might buy up to 85%.

Then there is the rest of the drive train...I mean really? Gears?!!???

A DC system would work much better and achieve better efficiency ratings...(4 smaller DC motors and no gears).

a reply to: tanka418

Sorry man...I guess an Electrical Engineer wouldn't actually know.

I highly doubt you are an electrical engineer, even if you were then all you're telling me is you have very little experience with power electronics, electric vehicles, or electric motors.

Course then again, I wasn't referring to just the motor...but rather the over all system. I could tell y'all a story about how they don't use real AC, but, y'all wouldn't believe an Electrical Engineer...we don't know.

An induction motor requires AC to operate. Therefore, how are they not using "real" AC?

The reality is that it takes energy to operate inverters...the devices that convert DC into AC, and that the control circuitry also is far from 100%

AC motor controllers are typically over 95% efficient. Besides, to operate a brushed DC machines will also require a method of torque control as well, most likely this will be a DC-DC converter, which will have similar efficiency characteristics to an AC controller. Actually a DC-DC converter with synchronous switching is effectively a single phase-leg of a three-phase inverter, so your argument is nonsense.

Note that BL"DC" machines need a 3-ph inverter.

Oh, by the way...it is unlikely that the induction motors are quite 90%...though I might buy up to 85%.

Real figure is likely up to 90-95%.

hen there is the rest of the drive train...I mean really? Gears?!!???

Tesla doesn't have gears. It has a fixed gear.

A DC system would work much better and achieve better efficiency ratings...(4 smaller DC motors and no gears).

DC Motors are old technology and are largely inferior to AC motors, they require brushes to operate. They are prone to wear. The current state-of-the-art is typically BLDC, PMSM, or Induction. Those three technologies need 3-ph inverters to operate. That's why all commercial electric cars, and most new locomotives all use some form of AC technology.

Also having 4 motors would mean you need four separate motor controllers located around the vehicle. So that's four times the complexity. If you have one motor driving each wheel individually, you then require complex algorithms to implement torque vectoring in order to have a drivable vehicle. Also need CV joint on the front wheels. So in all your idea is a horrible one.

originally posted by: C0bzz
a reply to: tanka418

What are you talking about? Induction motors are very efficient. Over 90% efficient.

I guess you don't know what you're talking about. Sad!

I dont like calling people out but Tesla vehicles are highly inefficient one reason is converting DC to AC you lose alot of potential energy. Now im to lazy to look up the efficiency of tesla motors but id bet not over 60 or 70 percent max. Being lazy ill tell you how to find out heres the equation just plug in the numbers.

Efficiency is defined as the ratio of the output to that of input,

Efficiency = input / output but its a three phase induction motor so we also need rotor output/ rotor input but we also need to know gross mechanical power developed / rotor input. And finally power generated at shaft / electrical input to the motor. Calculate these three turn them into percentages than average them. Id be shocked if you get 60 percent.

a reply to: C0bzz

DC Motors are old technology and are largely inferior to AC motors, they require brushes to operate.

Not no more. Brushless motors are pretty damned cool.
www.teslamotors.com...

a reply to: dragonridr

Nonsense.

tritium.com.au...

Here's another:
www.brusa.eu...

97% Efficiency.

Even if you consider battery charging, battery discharge, resistive losses, motor controller losses, and motor losses, you're unlikely going to get under 80% for any EV.

a reply to: Phage

I don't know why BLDC motors are called "DC" motors. In reality the back-EMF is trapezoidal rather than sinusoidal or flat "DC" so they still need a three-phase inverter to operate. Also you can actually drive a BLDC motor with a sinusoidal drive although torque ripple will be present and it might be a bit louder.

a reply to: C0bzz
Maybe because they use a DC power source?
Maybe because they aren't induction motors?

In reality the back-EMF is trapezoidal rather than sinusoidal or flat "DC" so they still need a three-phase inverter to operate.

So, by that definition a standard DC motor is also an AC motor since the brushes act as inverters?

originally posted by: C0bzz
a reply to: dragonridr

Nonsense.

tritium.com.au...

Here's another:
www.brusa.eu...

97% Efficiency.

Even if you consider battery charging, battery discharge, resistive losses, motor controller losses, and motor losses, you're unlikely going to get under 80% for any EV.

Sorry that cruise efficiency unfortunately most driving doesnt occur in cruise. i told you how to find out do the math. ill bet your surprised.

a reply to: dragonridr

So, by that definition a standard DC motor is also an AC motor since the brushes act as inverters?

The brushes are part of the motor though. In BLDC motors for electric vehicles the inverter typically isn't integrated into the motor itself. You have you go build or buy on separately. Generally inverters support both BLDC and PMSM since they are so similar, the main difference is the resolver/encoder needs to be different.

a reply to: C0bzz

I know, but the "back-EMF" is the same.
And they are not induction motors.

a reply to: dragonridr

It doesn't matter if they're not induction motors. PMSM motors aren't induction motors either.

a reply to: C0bzz

Tesla Motors uses induction motors.

a reply to: Phage

I am aware - I posted that on the previous page.

a reply to: C0bzz

I am aware - I saw that you did.

You also said DC motors have brushes. They did. Now they don't.

originally posted by: C0bzz
I highly doubt you are an electrical engineer, even if you were then all you're telling me is you have very little experience with power electronics, electric vehicles, or electric motors.

Wow...Busted I guess; while I do have a Master's in Electrical Engineering...I do not, nor have I ever designed circuitry for cars. I've been mostly a computer and software type. However, that does not change any of the Laws used in Electronics, nor does it invalidate my education or experience.

In short; current flow is current flow...just ask Ohm and Kirchhoff...

An induction motor requires AC to operate. Therefore, how are they not using "real" AC?

Yes indeed an induction system required AC or its equivalent.

By the way..."sliced" (pulsed) DC is electronically the same as AC. That's how Tesla Motors does it without using inverters. Which by the way are typically rather inefficient.

AC motor controllers are typically over 95% efficient.

No! Quite simply; just NO. You have issues with thermodynamics, resistive and reactive losses (in the form of heat). All in all; any electrical system is quite lucky if it gets better than 70% efficiency.

Besides, to operate a brushed DC machines will also require a method of torque control as well, most likely this will be a DC-DC converter, which will have similar efficiency characteristics to an AC controller. Actually a DC-DC converter with synchronous switching is effectively a single phase-leg of a three-phase inverter, so your argument is nonsense.

Torque control = current control. It is not difficult to control the torque of an electrical motor; just control the current flowing through it (control it's magnetic fields). That can be done by controlling the voltage applied...however, the control elements are not simple and loose vast amounts of energy due to heat.

Note that BL"DC" machines need a 3-ph inverter.

BLDC motor = Brushless DC motor. No need of inverters, switching systems (except for torque control)...apply current and go...

Tesla doesn't have gears. It has a fixed gear.

Oh? The last I heard Tesla cars had two forward and one reverse gear...AND, since they use AC induction motors; they require gears for reverse...AC motors only turn one direction.

DC Motors are old technology and are largely inferior to AC motors, they require brushes to operate. They are prone to wear. The current state-of-the-art is typically BLDC, PMSM, or Induction. Those three technologies need 3-ph inverters to operate. That's why all commercial electric cars, and most new locomotives all use some form of AC technology.

DC motors are not older technology than AC motors; they're motors...same level of tech. DC motors no longer require brushes, haven't for decades...They are no more prone to wear than any other mechanical system.

Your BLDC (brushless DC) and PMSM (permanent magnet synchronous motor) do not use AC per se. The BLDC uses only DC, though it may be pulsed for torque and rpm control, The PMSM requires pulsed DC for operation. There is a flavor of PMSM we used to call a "stepper motor"...it too required only DC, but would move a specific number of degrees of rotation when a pulse was applied. You have motors like this in your computer.

Also having 4 motors would mean you need four separate motor controllers located around the vehicle. So that's four times the complexity. If you have one motor driving each wheel individually, you then require complex algorithms to implement torque vectoring in order to have a drivable vehicle. Also need CV joint on the front wheels. So in all your idea is a horrible one.

Yes sir...4 motors require 4 controllers...though of lesser power capability. Four controllers also gives me the ability to control what each tire is doing...so I never "have" to loose traction, I can control the speed of each tire in a tur, making that turn easier to "take" and at the same time I can improve performance of the overall car's handling...making it a safer car.

Yes...absolutely the car will require more computer control...that only makes the overall system more efficient, better performing, safer...this list continues for a while...

You have many misconceptions about electric autos, and their technology. You would do well to actually listen and or do some serious research...after you complete the first two semesters of an Electrical Engineering course (DC circuits, AC circuits).

a reply to: tanka418

However, that does not change any of the Laws used in Electronics, nor does it invalidate my education or experience.

Your main problem is that you think the laws of physics used in electronic design support your contentions. Just like one plus one does not equal three, simply stating Kirchhoff laws and ohms law does not magically support your arguments. You have to use them to construct an argument. So I ask, how do they support your argument? So far, it's almost as if you're pretending to be someone who actually knows something, the word for that is sciolist.

Yes indeed an induction system required AC or its equivalent.

Then why were you saying that Tesla does not "use real AC"? Also what do you mean by an "equivalent" to AC? There is AC. And there is DC. It's that simple. If you take the frequency spectra of any waveform, then the y-value when x equals 0 is the DC component. Everything else can be considered AC. This is the same for transients as well.

By the way..."sliced" (pulsed) DC is electronically the same as AC.

The terminology you use is extremely confusing. I've never heard a real electrical engineer use terminology like this. Are you referring to PWM? Systems using PWM can output DC or AC depending on the converter topology and control method. Inverters are typically a 3-phase H-bridge, with switches (typically IGBTs or MOSFETs) utilizing PWM. That's how they work.

That's how Tesla Motors does it without using inverters.

Induction Motors require AC to operate. Since the battery in an EV is DC, they need something to convert DC to AC. That device is called an Inverter. Yes, Inverters use PWM. Are you confusing alternator with inverter?

No! Quite simply; just NO. You have issues with thermodynamics, resistive and reactive losses (in the form of heat). All in all; any electrical system is quite lucky if it gets better than 70% efficiency.

I could explain the physics of why an inverter is so efficient, but I can't be bothered. Instead I will direct you to look at inverter product pages, already posted (with datasheets included), that show inverter efficiency. Over 90% in practically all conditions, over 95% efficient in most conditions. And for the record, electrical systems that handle large amounts of power have to be very efficient. If they're not efficient they get destroyed.

Torque control = current control. It is not difficult to control the torque of an electrical motor; just control the current flowing through it (control it's magnetic fields). That can be done by controlling the voltage applied...however, the control elements are not simple and loose vast amounts of energy due to heat.

This isn't relevant.

BLDC motor = Brushless DC motor. No need of inverters, switching systems (except for torque control)...apply current and go...

This is nonsense.

The Brushes in a brushed DC motor provide commutation mechanically. A BLDC motor stands for Brushless DC Motor. That means commutation is required via electronics. Since torque control is necessary, the voltage applied to the BLDC motor needs to be variable. That means an inverter is required. Actually many BLDC motors have waveforms that more closely resemble a sine wave, rather than a square wave. All of these reasons are why I dispute the notion that BLDC motors need simple DC current. They don't.

Oh? The last I heard Tesla cars had two forward and one reverse gear...AND, since they use AC induction motors; they require gears for reverse...AC motors only turn one direction.

Do you know how an Induction machine works? A rotating magnetic field is created, typically via three-phase AC power. Change the direction of the rotating magnetic field and the direction of the motor will change. This can be accomplished by a 4 quadrant inverter. Which is what Tesla uses. I have already linked two 4Q motor controllers.

Tesla does not need gears.

Your BLDC (brushless DC) and PMSM (permanent magnet synchronous motor) do not use AC per se. The BLDC uses only DC, though it may be pulsed for torque and rpm control, The PMSM requires pulsed DC for operation. There is a flavor of PMSM we used to call a "stepper motor"...it too required only DC, but would move a specific number of degrees of rotation when a pulse was applied. You have motors like this in your computer.

Please do not ever refer to an inverter output as being "pulsed DC". It's AC created via PWM and the topology of the inverter itself. This can be justified by looking at the frequency spectra of such an inverter. PMSM needs AC. Therefore it needs an inverter if powered from a battery or you want precise speed and/or torque control.

Yes sir...4 motors require 4 controllers...though of lesser power capability. Four controllers also gives me the ability to control what each tire is doing...so I never "have" to loose traction, I can control the speed of each tire in a tur, making that turn easier to "take" and at the same time I can improve performance of the overall car's handling...making it a safer car.

Yes...absolutely the car will require more computer control...that only makes the overall system more efficient, better performing, safer...this list continues for a while...

Yes, I am aware of the advantages of torque vectoring. Putting a motor on each wheel makes the car more complex, more expensive, heavier, and less efficient. The fact that it can improve handling doesn't mean it's a great idea in every application. Also Tesla already uses torque vectoring via individual control of the brakes (not as good as an electric motor but it's still something).

You have many misconceptions about electric autos

I design electric vehicles.

and their technology

You have no idea power electronics, motor control, or electric vehicles. As I have shown.

You would do well to actually listen and or do some serious research

You would do well to stop pretending to be an engineer when you clearly have no idea what you're talking about. And if you are an engineer maybe learn where you lack knowledge so that you can listen. Also speaking of research, I can gladly provide research papers on effectively everything I mentioned above.

a reply to: dragonridr

Sorry that cruise efficiency unfortunately most driving doesnt occur in cruise.

I already provided resources which show the efficiency of motor controllers / inverters. Please read the information provided, in particular datasheets, then get back to me. If you still disagree I can gladly tell you the physics of why they are so efficient.

Overall efficiency depends on many things for an EV, like the power station, transmission lines, charging, discharge, motor controller, motor, and mechanical drivetrain. Then you might get a figure under 50%. But we were talking about the motor controller here. By itself that part is going to be around 95% efficient.

a reply to: C0bzz

You have no idea power electronics, motor control, or electric vehicles. As I have shown.

Actually; all that you have shown is that you have no understanding of electricity, what so ever!

Did you know that it is possible to have: 1 + 1 = 3? There is actually a mathematical "proof" that it is true. Of course, it is only "Math humor", but it does exist...and it is valid.

Magnetic induction is created when a conductor moves relative to magnetic lines of force.

I could explain the physics of why an inverter is so efficient, but I can't be bothered.

Oh, oh...I wanted to hear "why" inverters are so efficient...

But you can't be bothered...so; I'll just ask...what happens to all the heat? Where did it come from, and "why". Have you ever seen the heat sinks in EV car?

As we have all said: BLDC = brushless DC motor...is there some part of DC you didn't get?

Do you know how an Induction machine works? A rotating magnetic field is created, typically via three-phase AC power. Change the direction of the rotating magnetic field and the direction of the motor will change. This can be accomplished by a 4 quadrant inverter. Which is what Tesla uses. I have already linked two 4Q motor controllers.

AC motors typically have only one direction of rotation, depending on how they are "wound". This is because AC involves the reversal of current flow typically for 50% of the duty cycle. IF we were to wind a motor so that we could use a controller to reverse the direction of the magnetic field movement; then we would no longer have an "AC induction" motor, we would have something else.

PWM?!!??? Do you even know what that is? Seriously, do you?

Inverters are typically a 3-phase H-bridge, with switches (typically IGBTs or MOSFETs) utilizing PWM. That's how they work.

You should go an look up an "H-bridge"...its not quite what you think. And, using a bipolar transistor in a case like this? Well, let me just say; I must have been doing software too long...I would NEVER use a bipolar transistor in an application like this. The use of field effect technology seems a better choice.

Also Tesla already uses torque vectoring via individual control of the brakes (not as good as an electric motor but it's still something).

Wow! Really!?? Ya know I was thinking about getting a Tesla Roadster, but, IF they are controlling individual wheels with the breaks...I don't want one...the breaking system will be unreliable, and over used. It will experience excessive wear to breaking components. Probably break fade after only a little use...

You accuse me of "not knowing" yet with every post you demonstrate that you really have no idea what is being discussed here. Your knowledge and understanding of electricity, it use, and operation is less than a typical high school kid. You would do very well to at least read a child's book on basic electricity; to attempt to gain a fundamental understanding of AC and DC current.