---> The Ideal Motor Solution?

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This was an article taken from Tesla Motors:

http://www.teslamotors.com/blog4/?p=45

Brushless or Induction?

Back in the 1990s all of the electric vehicles except one were powered by DC brushless drives. Today, all the hybrids are powered by DC brushless drives, with no exceptions. The only notable uses of induction drives have been the General Motors EV-1; the AC Propulsion vehicles, including the tzero; and the Tesla Roadster.

Both DC brushless and induction drives use motors having similar stators. Both drives use 3-phase modulating inverters. The only differences are the rotors and the inverter controls. And with digital controllers, the only control differences are with control code. (DC brushless drives require an absolute position sensor, while induction drives require only a speed sensor; these differences are relatively small.)

One of the main differences is that much less rotor heat is generated with the DC brushless drive. Rotor cooling is easier and peak point efficiency is generally higher for this drive. The DC brushless drive can also operate at unity power factor, whereas the best power factor for the induction drive is about 85 percent. This means that the peak point energy efficiency for a DC brushless drive will typically be a few percentage points higher than for an induction drive.

In an ideal brushless drive, the strength of the magnetic field produced by the permanent magnets would be adjustable. When maximum torque is required, especially at low speeds, the magnetic field strength (B) should be maximum – so that inverter and motor currents are maintained at their lowest possible values. This minimizes the I² R (current² resistance) losses and thereby optimizes efficiency. Likewise, when torque levels are low, the B field should be reduced such that eddy and hysteresis losses due to B are also reduced. Ideally, B should be adjusted such that the sum of the eddy, hysteresis, and I² losses is minimized. Unfortunately, there is no easy way of changing B with permanent magnets.

In contrast, induction machines have no magnets and B fields are “adjustable,â€￾ since B is proportionate to V/f (voltage to frequency). This means that at light loads the inverter can reduce voltage such that magnetic losses are reduced and efficiency is maximized. Thus, the induction machine when operated with a smart inverter has an advantage over a DC brushless machine – magnetic and conduction losses can be traded such that efficiency is optimized. This advantage becomes increasingly important as performance is increased. With DC brushless, as machine size grows, the magnetic losses increase proportionately and part load efficiency drops. With induction, as machine size grows, losses do not necessarily grow. Thus, induction drives may be the favored approach where high-performance is desired; peak efficiency will be a little less than with DC brushless, but average efficiency may actually be better.

(the article continues so you might want to follow the link and read it)

 

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I'm very much interested in the Induction motor, but it seems that it also shares the same kinds of problems in that it's best performance comes in a certain set of circumstances. The peak efficiency still seems to be found in the DC brushless motor (at it's peak efficiency rpm only!!!) so it definitely makes me value the possibility of gears as still "in the running" for the best possible solution. The DC Brushless motor has the best peak efficiency (90%), the Induction motor smooths out the efficiency across a larger rpm spread, but never equals the same peak values and the introduction of gearing spreads the peak efficiency out across the speeds desired, but adds mechanical complexity and lowers the overall efficiency.

There is no easy answer, but... I'd like to see an Induction motor solution for the power range we are working with.

How about an Induction motor that is a hub motor?

(normally they are either DC Brushed or DC Brushless motors)

If the efficiency could be spread out across the entire rpm range so that you could climb hills at 80% efficiency and also hit your top speed at 80% efficiency then the extra few percentage points of efficiency that the DC Brushless solution provides at it's best rpms might seem insignificant. The killer on all the fixed geared bikes is the terrible low rpm performance and the Induction motor smooths out that problem...

 

[cadstarsucks]

I'm very much If the efficiency could be spread out across the entire rpm range so that you could climb hills at 80% efficiency and also hit your top speed at 80% efficiency then the extra few percentage points of efficiency that the DC Brushless solution provides at it's best rpms might seem insignificant. The killer on all the fixed geared bikes is the terrible low rpm performance and the Induction motor smooths out that problem...

The situation is the same in a brushless. You can still cut back on the drive voltage and the frequency to voltage to current relationship still holds. You can still elevate the drive voltage with frequency to increase output power. You can get a very slow motor at normal conditions and drive it faster.

Anyone have a 12V 30RPM 200W brushless? We can get 300PRM at 2000W!

Dan

 

[dirty_d]

no, there is a difference you cant control the stator field in a brush less motor, in an induction motor you can like it said in the article. i read this a few months ago i thought it was pretty interesting.

 

[cadstarsucks]

no, there is a difference you cant control the stator field in a brush less motor, in an induction motor you can like it said in the article. i read this a few months ago i thought it was pretty interesting.

True, you can not control the stator field, but you can still drive the motor at higher frequencies than the nameplate claims and gain the same advantages of increased rail voltage.

Driving a brushless as an AC motor is more efficient than an induction motor since you are not using some of your power to create the stator field.

Dan

 

[dirty_d]

that actually wouldn't work with the brushless motor, you need to keep the frequency correct for the current rpms changing the frequency for the same motor speed would just screw it all up, the reason it works in an induction motor is that the changing waveform is creating the magnetic field in the stator, in the brushless its just a static magnetic field from the permanent magnets.

Driving a brushless as an AC motor is more efficient than an induction motor since you are not using some of your power to create the stator field.

that is only the case for the peak efficiency point which is a very narrow region for a permanent magnet motor at any given voltage. the induction motor has a lower peak efficiency but it is spread over a much larger rpm range. so basically with a permanent magnet motor you need to use gears and change voltage to keep the motor rpm in the high efficiency zone, for an induction motor you change the voltage and change the frequency to do the same. and since gears introduce friction and mechanical complexity with induction you get an overall higher efficiency.[/quote]

 

[safe]

The Induction motor does require energy to be used to create the magnetic field, but you only create a field of the size that is needed for the rpm you are at. The DC Brushed and Brushless motors both use a permanent magnet and so that means you have a linear BackEmf that corresponds to the backwards "pressure" of the permanent magnets and that increases with rpms. When you take out the permanent magnets it means that there's no more BackEmf, well, no more than you need, for the Induction motor.

The real question in my mind is whether an Induction motor with it's slightly lower inherent efficiency compared to the DC Brushless motor is going to equal or outperform a DC Brushless with gears added on top. The gears add an extra 20% more power (see "The Gearing Advantage" thread) over the status quo for the DC Brushless motor, but the Induction motor doesn't require gears to get there, so one has to wonder what the efficiency of the gears are... how much do you lose in mechanical losses? Does that cancel out the 20%? Does it reduce it to 10%?

So in the end the question becomes:

Is the DC Brushless + Gears greater than or less than an Induction motor alone?

It might also be good to know the "heat profile" of an Induction motor to see how they compare. If the heat generation is worse then you can mostly rule it out, but if it's better that's another big plus.

 

[xyster]

The gears add an extra 20% more power (see "The Gearing Advantage" thread) over the status quo for the DC Brushless motor,

Not true. Gears do not increase power. In terms of power, gearing down increases torque by the same amount doing so decreases RPMs. Power = Torque X RPMs.

 

[dirty_d]

well if you had a CVT that was 95% efficient then the brushless would win but CVTs are pretty inefficient i think since they all rely on friction and high pressure.

 

[dirty_d]

Not true. Gears do not increase power. In terms of power, gearing down increases torque by the same amount doing so decreases RPMs. Power = Torque X RPMs.

well no they dont take the power form the motor and increase it they just allow the motor to run at a rpm that would put out more power than if it was at another ratio at any given speed, take this as an example, you have a motor geared at 20:1 by the time the bike is up to probably 12 mph the motor is near no load and cant go any faster since the power put out by the motor at that speed equals the power required to go that speed, now you decrease the ratio to 10:1 the motor is brought down to a lower rpm where more power is available again and the bike continues to accelerate until the power from put out by the motor equals the power required to go whatever speed it is when you reach your top speed.

 

[Beagle123]

Not true. Gears do not increase power. In terms of power, gearing down increases torque by the same amount doing so decreases RPMs. Power = Torque X RPMs.

I hate to "pile-on" xter, but I agree with dirty on this one.

The equation is:

Power out of motor = torque X RPM

Howver,

Power out of motor = Power into motor X Efficiency

And pover(in) is the number you care about.

So,

Power(in) X Eff = torque X rpms

The critical factor is that motors tend to operate at maximum efficiency at around 3000 rpms (varies). But when you operate them at much lower rpms the efficiency goes WAY down.

So suppose you were to ride your bike up a hill twice--once in 1st gear @ 3000 rpms, and the second time in 4th gear at 1000 rpms. Also imagine that your batteries/controller are capable of putting-out 500 watts continuous.

In this situation, when the bike is in first gear (3000 rpms) the efficiency is around 80%. In 4th gear its perhaps 50%


1st gear:
500w X 0.8% = 400 watts to wheels

4th gear:

500w X 0.5 = 250 watts to wheels

So you're getting less power out of the motor at lower rpms.

So how is this situation apply to "real life?"

The bike in 1st gear will happily buzz up the hill with a reasonable current draw. But the bike in 4th gear will only have 250 watts going to the wheels so it will <b>slow down</b> a bit. But then the rpms will go down to 950 which causes the efficiency to go down to 48%. So now the motor is generating less overall power to the wheels:

500w X 0.48 = 240 watts

Now, with less power available, the rpms go down, the efficiency goes down etc. It can snowball to the point where the bike refuses to climb the hill. And beleive me, my bike refuses to climb certain hills.

I know your bike is very powerful, but on my bike you realize that there is a threshold, when your bike starts to slow down, the amps go "through the roof" trying to keep-up because the efficiency is dropping. A really underpowerd bike will have two states: "happily buzzing along" and "spiraling downward".

If your power=torqueXrps were true, underpowered bikes wouldn't ever stop on hills. They would just climb slowly.

One of my goals on my new bike is to try to keep the rpms at the max efficiency point in all situations because I want to avoid losing power in the low rpm zones.

Another thing I've observed is that if I get a "running start" on one hill, I can continue up it at 22mph, however, if I tried to accelerate from a standing start, I couldn't hit 20mph. I beleive its becase I can't cross over into the high-efficiency zone of the motor.


But what do I know? I'm going to go bend the parts for my frame with a hammer (the way a monkey would do). I'm not kidding.

 

[cadstarsucks]

Not true. Gears do not increase power. In terms of power, gearing down increases torque by the same amount doing so decreases RPMs. Power = Torque X RPMs.

I hate to "pile-on" xter, but I agree with dirty on this one.

The equation is:

Power out of motor = torque X RPM

Howver,

Power out of motor = Power into motor X Efficiency

And pover(in) is the number you care about.

So,

Power(in) X Eff = torque X rpms

The critical factor is that motors tend to operate at maximum efficiency at around 3000 rpms (varies). But when you operate them at much lower rpms the efficiency goes WAY down.

You are both right and wrong. That is true of normal motors. Hub motors are designed for 300RPM max (multiple poles), of course they are also rated for street legal use

In an oversimplified way xyster was right...he was just neglecting the efficiency. But I think he was looking at the wheel and not at the motor...gearing down the motor does increase torque at the wheel while the motor itself is spinning faster. There might be a misunderstanding, I think you are looking at the motor while he is looking at the wheel.

Dan

 

[xyster]

Not true. Gears do not increase power. In terms of power, gearing down increases torque by the same amount doing so decreases RPMs. Power = Torque X RPMs.

I hate to "pile-on" xter, but I agree with dirty on this one.

The equation is:

Power out of motor = torque X RPM

Howver,

Power out of motor = Power into motor X Efficiency

And pover(in) is the number you care about.

So,

Power(in) X Eff = torque X rpms

The critical factor is that motors tend to operate at maximum efficiency at around 3000 rpms (varies). But when you operate them at much lower rpms the efficiency goes WAY down. ...

"WAY down" is the part we disagree about.

snip snip paste paste from another thread:

Basically, the throttle keeps the motor in its sweet spot efficiency wise. Take a look at the two graphs below for your 406, with a 20 amp controller like you have, but an 80 volt battery pack like I have. At full throttle, top speed is about 54mph and motor efficiency at that point is about 88%. At half throttle, speed is about 27mph, and efficiency at that point is about 82%. The ideal geared system would get you that 6% difference. But geared systems aren't ideal of course, and the extra frictional losses cut into that 6% benefit. Also, consider that the bulk of your efficiency loss is due to wind resistance, plus losses from rolling resistance, controller and other electrical losses. The 6% idealized gain is really a much, much smaller fraction of total efficiency -- it's late and I'll leave the math to someone else if they want -- but suffice it to say that going a fraction of a MPH slower, or pedaling a tiny bit more, will probably buy you more additional range than will the difficult switch from direct hubmotor drive to indirect stokemonkey-like hubmotor drive.

 

[fechter]

There's probably a reason the EV-1, Tesla, and T-zero use induction motors. Those guys are smart. The Tesla has a 2 speed transmission since it can only go 120mph in first gear.

As with many aspects of EV design, there are trade-offs.

To compare a multi-speed geared motor to a single speed motor, you need to know the efficiency of the gearing. Multi-speed gear setups are more expensive to make and require more maintenance than a single speed. Remember Murphy's law too.

With single speed, direct drive there are NO gearing losses.

Induction motors tend to be more efficient in larger sizes. I'm not exactly sure why this is. I've never seen a bike sized induction motor that's over 70%, but I've seen huge industrial induction motors approach 98% eff.

It seems like it should be possible to make an induction hub motor, with the rotor on the outside. Since the diameter of the gap is large, it might behave like the more efficient larger motors. A standard Xlyte motor is pretty close already. Just the rotor part would need to be made differently. With careful rotor design, efficiency could be optimized.

There aren't any bike-sized induction motor controllers available that I've seen. The closest thing would be a Curtis or Sevcon, and they're very expensive. In theory, the power stage would be the same as a regular brushless controller, so just the control logic would be different. Therefore, it should be possible to produce an induction controller for around the same price.

 

[safe]

Not true. Gears do not increase power.

Actually gearing a bike down DOES increase power. Refer to "The Gearing Advantage" thread for the full story. The reason it increases power is that when you gear a bike down for a particular loading situation the rpms rise and so it effectively shifts the powerband from out of the poor power situation and into the strongest peak power.

Essentially gears "correct the error" of a powerband because they shift the peak power around.

The fact remains... gearing produces roughly a 20% ACTUAL power increase across the range of speeds that a bike can go. You are not required to use all the power all the time, but you might as well because it's high efficiency power anyway.

Xyster... you really need to comprehend gears... one day... one day...

(or you need to spend some time riding an actual geared bike so you can get that "ah ha " moment of discovery)

 

[safe]

Basically, the throttle keeps the motor in its sweet spot efficiency wise.

This is true, however you've effectively sidestepped the question. The question was about raw POWER and the fact is that when it comes to the power coming out the rear wheel you get a 20% advantage with gears. (approximately... obviously there are many variables) You can indeed get a little better efficiency with your "throttle twiddling" technique, but it's never as good as gears because gears are ALWAYS running at peak power and peak efficiency. You can never beat multiple gears with a one speed.

However, we are diverging from the real issue which is:

"Assuming a DC Brushless motor AND Gears is it possible that an Induction motor could equal or exceed this configuration?"

It's pretty much a "given" that any fixed motor setup is going to be worse than a geared setup.

 

[xyster]

(or you need to spend some time riding an actual geared bike so you can get that "ah ha " moment of discovery)

I do ride a geared bike. As a puny, peaky-powerband ~150-watt human, I have to use them to pedal effectively. The motor suffers no such limitation. You should try a properly-powered hubmotor some time so you can get that "ah ha I've been operating under yet another idealized delusion all these years" moment of discovery.

Where's the 20% efficiency to be gained (where are you getting this extra 20% power you claim if not from efficiency gain)? Between 1/2 throttle and full throttle on a less-efficient 406, I see only 6% (82% versus 88%). As Fechter rightly notes, there's added frictional losses in a motor driving through the gears that eats into this 6%. Maybe there's 20% to be gained on those toy-sized lilliputian motors you like to use.

And that 6% pertains only to the motor's efficiency, and doesn't address the big kahuna: wind resistance.

 

[safe]

Induction motors tend to be more efficient in larger sizes. I'm not exactly sure why this is. I've never seen a bike sized induction motor that's over 70%, but I've seen huge industrial induction motors approach 98% eff.

It seems like it should be possible to make an induction hub motor, with the rotor on the outside. Since the diameter of the gap is large, it might behave like the more efficient larger motors. A standard Xlyte motor is pretty close already. Just the rotor part would need to be made differently. With careful rotor design, efficiency could be optimized.

There aren't any bike-sized induction motor controllers available that I've seen. The closest thing would be a Curtis or Sevcon, and they're very expensive. In theory, the power stage would be the same as a regular brushless controller, so just the control logic would be different. Therefore, it should be possible to produce an induction controller for around the same price.

70% would be very poor compared to small DC Brushed and Brushless motors. I guess my technical question becomes "why" are the smaller Induction motors showing such low efficiency numbers and the bigger ones showing such good (98%) numbers?

It does seem that at this point I'd have to rate the solutions in order from worst to best as:

1. DC Brushed Fixed Hub Motor. (78% peak eff, 100% relative power)
2. DC Brushed Geared Single Speed Motor (82% peak eff, 100% relative power)
3. DC Brushless Fixed Hub Motor (88% peak eff, 100% relative power)
4. DC Brushed Multispeed Gearing (75% peak eff, 120% relative power)
5. DC Brushless Multispeed Gearing (83% peak eff, 120% relative power)
6. Induction Motor? (unsure where it really belongs)

 

[safe]

Maybe there's 20% to be gained on those toy-sized lilliputian motors you like to use.

The law says 750 watts, so if you are talking about the "real world" of design that's the area you need to pay attention to.

What you've done is created a machine that has lot's of power and you just run it at 1/4 of what it could theoretically do. The future is not going to allow large motors... not legally... so for what we are going to have to be focused on (getting the most out of small motors) this is what needs to be done. The Induction motor might be a great way to achieve a near perfect 750 watts across the entire powerband and at high efficiency.

The Etek or PMG 132 are the most efficient and powerful things around... and also clearly something that is going to place any bike using it into the motorcycle class.

A really aerodynamic bike like the "White Hawk" could go 69.1 mph using only 750 watts of power:

http://www.kreuzotter.de/english/espeed.htm

...if it's possible to get close to 50 mph with a more practical bike then the 750 watts might be all anyone ever needs.

 

[xyster]

Maybe there's 20% to be gained on those toy-sized lilliputian motors you like to use.

The law says 750 watts, so if you are talking about the "real world" of design that's the area you need to pay attention to.

What you've done is created a machine that has lot's of power and you just run it at 1/4 of what it could theoretically do. The future is not going to allow large motors... not legally...

I certainly didn't create the 750-watt rated motor I use. And the law is 3000 watts where you live. Small EV-sized electric motors won't be outlawed because lawmakers wouldn't have their golf carts, industry their forklifts, etc etc. That's a silly fear.

 

[cadstarsucks]

1. DC Brushed Fixed Hub Motor. (78% peak eff, 100% relative power)
2. DC Brushed Geared Single Speed Motor (82% peak eff, 100% relative power)
3. DC Brushless Fixed Hub Motor (88% peak eff, 100% relative power)
4. DC Brushed Multispeed Gearing (75% peak eff, 120% relative power)
5. DC Brushless Multispeed Gearing (83% peak eff, 120% relative power)
6. Induction Motor? (unsure where it really belongs)
[/b][/color][/size]

DC brushless wheel 98% eff

Dan

 

[fechter]

Here's a fairly detailed analysis of induction motor behavior:

http://www.reliance.com/prodserv/motgen/b7097_2.htm

 

[safe]

Efficiency and Losses

Returning to the AC motor equivalent circuit of Figure 2b, we can identify three of the five basic component losses which exist in AC induction motors. The losses dissipated in the resistance of the stator and rotor windings, plus the core loss (eddy current and hysteresis losses in lamination steel) are modeled in the equivalent circuit. A fourth component loss is the friction and windage of the rotor, fan, bearings, etc. Finally, there is the "leftover’ category of stray load losses. These are losses which are a compilation of various less easily modeled losses, but are often a significant loss in highly efficient machines. The stray load losses include eddy current losses in the conductors, core losses due to flux distortion with load, etc.

Since the friction and windage and core losses are essentially independent of load, while the other losses vary as the square of load (current), the efficiency of an AC induction motor falls off precipitously at light loads

This is what makes the Induction motor so attractive. Unlike the DC Brushed or Brushless motor where high load translates into poor efficiency the Inductance motors efficiency is highest at it's highest load.

It's an "upside down" motor!!!

All the time we think about the DC Brushed and Brushless motors we are thinking in terms of:

"How can I get the best efficiency when all the power is someplace else?"

...and that's where things like gears come into view as a way to CORRECT the error of the DC Brushed and Brushless motor that doesn't really do what we want it to do. (also MCL is a corrective technique)

The Inductance motor is very interesting... 8)

 

[safe]

DC brushless wheel 98% eff

Oh yeah... all day long... :wink:

You have to be careful of exaggerated manufacturers claims of their products, the typical DC Brushless motor is only a few percentage points better than the Brushed variety in most cases. Also, there are even cases of Brushless motors that show worsening efficiency as the voltage is increased. (which is disappointing)

The typical Brushed motor is around 80% at peak in ideal conditions and the typical Brushless motor is around 88% at peak in ideal conditions. But one must stress "ideal" and what does that mean? What aren't they telling you about their product?

We are talking about electric bike motors right? Industrial motors that weigh a ton can have much better efficiency sometimes, but what's out there on the market for us tends to run in the 80% - 88% range.

 

[safe]

TIMELINE OF THE SECOND INDUSTRIAL REVOLUTION - THE INVENTIONS AND DISCOVERIES

1851 - Isaac Singer invented the modern sewing machine

1851 - Léon Foucault invented the Foucault pendulum a device demonstrating the effect of the Earth's rotation

1855 - Henry Bessemer presented the process (Bessemer process) for the mass-production of steel from molten pig iron

1858 - August Kekulé founded the theory of chemical structure

1859 - Charles Darwin presented the theory of natural selection

1859 - Gaston Planté invented electric battery

1859 - Edwin Drake first drilled oil in the United States

1860 - Louis Pasteur and Robert Koch presented important discoveries from bacteriology

1860 - Etienne Lenoir invented the internal combustion engine

1861 - Johann Philipp Reis constructed one of the first working telephones

1861 - James Clerk Maxwell created the first color photography

1863 - William Bullock invented the rotary printing press

1864 - Siemens-Martin process was introduced in steel production

1865 - Gregor Mendel discovered the inheritance law

1865 - Nicholas-Joseph Cugnot constructed the Steam Tractor

1866 - Ernst Werner von Siemens invented dynamo

1866 - Robert Whitehead invented torpedo

1867 - Christopher Sholes invented typewriter

1867 - Joseph Lister, 1st Baron Lister introduced sterile surgery

1867 - Alfred Nobel discovered dynamite

1867 - Siegfried Markus invented the ignition device

1868 - Pierre Janssen discovered helium

1868 - John Wesley Hyatt invented celluloid

1869 - Dmitri Mendeleev created the periodic table

1876 - Alexander Graham Bell and Antonio Meucci separately invented telephone

1876 - Nikolaus Otto invented the internal-combustion engine

1877 - Thomas Alva Edison invented the phonograph

1879 - Thomas Alva Edison invented the long lasting light bulb

1880 - Frederic Eugene Ives invented the half-tone letterpress

1881 - the first electric passenger train started to drive in Berlin

1881 - Robert Koch discovered the tuberculosis bacillus

1883 - Gottlieb Daimler invented the modern petrol engine

1883 - Hiram Stevens Maxim invented the automatic machine gun

1884 - Charles Algernon Parsons invented the steam turbine

1884 - Ottmar Mergenthaler invented the Linotype machine

1885 - Comte de Chardonnay developed first artificial silk

1885 - James Starley invented chain-driven bicycle

1885 - Louis Paster created the first vaccine for rabies

1885 - Karl Benz invented the gasoline-powered automobile

1885 - Gottlieb Daimler invented the gasoline-powered two-wheeler considered the first motorcycle

1885 - first operation of Vermiform appendix was performed

1885 - aseptic technique was first used during operation

1886 - Heinrich Hertz demonstrated the existence of electromagnetic radiation

1887 - Emile Berliner invented the disc record gramophone

1887 - Paul Héroult invented the electric steel furnace

1887 - Nikola Tesla invented induction motor

1888 - John Boyd Dunlop developed the first practical pneumatic tyre

1889 - Mikhail Dolivo-Dobrovolsky transmitted electric power at the distance

1890 - Sigmund Freud began with the psychoanalysis

1891 - Nikola Tesla invented the magnifying transmitter

1891-96 Otto Lilienthal made first repeated successful gliding flights

1892 - Emil von Behring developed an antitoxin for diphtheria

1893 - Carl von Linde liquefied air

1894 - the bacterium of plague was discovered

1895 - X-rays (or Röntgen rays) were discovered by Wilhelm Röntgen

1895 - the Bayer company of Germany discovered aspirin

1895 - the Lumiere brothers, Auguste and Louis, held the first screening of projected motion pictures

1896 - Rudulf Diesel invented the diesel engine

1897 - J. J. Thomson discovered electron

1898 - Radium was discovered by Maria Curie and her husband Pierre

1899 - Valdemar Poulsen developed a magnetic wire recorder

1899 - Frederick G. Creed invented teleprinter

1900 - first Zeppelin was made by German Count Ferdinand von Zeppelin

1901 - Guglielmo Marconi invented wireless telegraph

1903 - the Wright brothers, Orville and Wilbur, built the first fixed-wing aircraft