Resonance in motors

[mbrownn]

sorry guys, just spent a few days at the beach so havent been on line

kenny_PPM, I cant find the post you tried to link to

wrtner yes I always put the resistance in my modeling but with AC and pulsed DC the iron losses seem to be bigger than the resistance ones in the real world.

[kenny_PPM]

sorry guys, just spent a few days at the beach so havent been on line

kenny_PPM, I cant find the post you tried to link to

wrtner yes I always put the resistance in my modeling but with AC and pulsed DC the iron losses seem to be bigger than the resistance ones in the real world.

Posted by Kyoat at overunity.com reply#39
Induction motors and capacitors lowers amps "consumption"


My plan:
Take a 15 hp single phase Induction motor and install capacitance to reach the "sweet spot" which should be about an 80% reduction in amps in.
we will call this our C-motor.

Then connect this motor to an industrial "quality" generator of lets say 10Kw. We will call this our Gen.

[nueview]

yes Ken
we tried this on a smaller scale with a 5hp induction motor and a 1kw gen set. i have mentioned it in this thread before.
the problem seemed to be the squirrel cage rotor is a hole one throws power into but you get nothing back from it.
the gap that needed to be closed was about 28% for self running.

let me try to explain to drive the rotor takes almost no amps at idle no load condition but add an amp load and it costs 1.28 amp for the rotor.
Martin

[kenny_PPM]

yes Ken
we tried this on a smaller scale with a 5hp induction motor and a 1kw gen set. i have mentioned it in this thread before.
the problem seemed to be the squirrel cage rotor is a hole one throws power into but you get nothing back from it.
the gap that needed to be closed was about 28% for self running.

let me try to explain to drive the rotor takes almost no amps at idle no load condition but add an amp load and it costs 1.28 amp for the rotor.
Martin

So then motor selection and design is one the most important thing.
In your research, what type of AC motor did you see the biggest advantage with, biggest drop in amps consumed?
Shaded pole, split-phase, perm-split?

thanks

[nueview]

Hi Ken
As of right now i have several different motors we are looking at in our local group they range from regular induction motors to automotive alternators to a small bench top HP permanent magnet three phase motor.

it seems to have the best construction so far and two of the three phases can be used to generate at the same time.

i also want to go down the flynn paralell path as it is seeming likely it is a good contender as well.

induction motors were called rotary transformers by tesla the term has some relivance.
Martin

[kenny_PPM]

Hi Ken
As of right now i have several different motors we are looking at in our local group they range from regular induction motors to automotive alternators to a small bench top HP permanent magnet three phase motor.

it seems to have the best construction so far and two of the three phases can be used to generate at the same time.

i also want to go down the flynn paralell path as it is seeming likely it is a good contender as well.

induction motors were called rotary transformers by tesla the term has some relivance.
Martin

You and I are on the same thought process.
I have thought about Flynn's and Thane Heins also.
And Hildebrandts magnetic 'valve'.
All of which are a bit different than each other but share the same outcome.
That is moving/switching flux with the best efficiency.

What is so appealing about Thane Heins is that he had a solid state transformer. I have built motors and generators by hand in my research over the years and one can clearly see the advantage of a solid state device vs. one that is constantly rotating and will need maintenance.

I can pass this on to you, if you're hand winding coils using Flynn's approach, I have replicated the basic test as you probably did the same. And found out that you can get the same effect at the exact same flux level with less power input by using bifilar coils. They use less energy in to get the same flux out. I have done this myself with multiple coils and verified with my gaussmeter that this is indeed fact. Whether a bifilar air coil by itself or wrapped around a core, they use less power in to get the same amperes.
I believe it was around the inverse square root of 2, power in for same output flux.
.707

Good luck

[nueview]

sorry for the poor picture it is of a design in the works and going through many mods right now but can give you a starting idea.
the circuit needs to transform when it begins running to get the best results.

RDTPPMtest1.png picture by geshbeddin - Photobucket

Martin

[nueview]

i have been thinking allot about the romero muller motor of lately and some thing seems to keep eating at me about how it was all relpicated.
Martin

[mbrownn]

I will reply without looking at your links as my 1.5Gbps connection is running at 1kbps at the moment, Thanks sky

The problem with induction motors and resonant circuits is two fold

The first problem is it is a 4 pole or two pole motor giving roughly 1500 or 3000 rpm at 50 Hz. By the time we get up to a resonant frequency that would be high enough to have the effects we are looking for we would be in many tens of KHz requiring impossible RPMs.

The second problem is that the squirrel cage makes the motor work like a a transformer, draining energy from the resonant circuit during changing loads and draining energy because the secondary winding is shorted.

Power factor correction helps with the amp draw at unloaded speeds but the effect is significantly lower under loaded conditions.

A universal motor is more like a bucking coil which has the effect of increasing Henries, allowing more energy to be stored and discharged from the coils, I believe this would increase under load but could be wrong. This is only the case when the motor is run on AC or pulsed DC. As no energy is shorted all the current can oscillate in and out of the capacitor until it dissipates through losses. Losses are typically 65% which is much higher than an induction motor at low frequencies but once the frequency reaches a point where the current drop time is closer to the rise time the efficiency improves as in PWM. At say 10 to 20 KHz, efficiencies of above 80% are often quoted. This gives us our first clue about what we have to do.

What we are looking for is a situation where the current fall time is slower than the current rise time

[nueview]

there are three phase permanent magnet generators that fit the required design specs you have just implied due to the many poles and magnet orientation for low cogging.
useing two phases for power output and one for the drive circuit AC or Pulsed DC should work.
the voltage difference should be enough to run charging and still drive the unit with resonance the speed is the main problem so the number of poles needs to be fairly high say 24 poles or the like.
Martin

[mbrownn]

If using AC with an induction type motor it is the number of poles that set the speed for a given frequency.

For example divide the frequency by the number of poles and multiply by 60 seconds to get RPM 60/2x60=1800RPM

Now if the resonant frequency of the coil in that motor is 20kHz the result would be 20,000/2x60= 600,000RPM. Now when you calculate the power required to get that motor up to that speed you see that the motor could never handle that level of power. That is the first problem with induction motors.

Universal motors don't have that problem.

This represents a universal motor running on AC in a resonant circuit. Note how we have to power it with pulsed DC. It does show overunity but in reality because of iron losses and BEMF it wont be.

Circuit Simulator Applet

If we have the right motor working in the right conditions, overunity is possible but you cannot do it using the motor in the way it was designed to be run. More on this when I have test results.

[nueview]

ok what mbrown is saying is true for some applications but not for all.
as the number of poles increase the volume of wire for the fields increases as well driving the resonant characteristics of the coil to lower frequency and the torque rating will be going up as the number of poles increases and then there is the pole length to consider as well.
a pole having 3 inches of field strength being say 1/4 inch wide has more torque developed than a field length of only 1 inch wide. yet the amount of wire in the longer field will be almost double the shorter field length.
Martin

[mbrownn]

Sorry for the long delay in my reply but my internet connection is currently running at a few hundred bits per second, Thanks Sky cable!!!.

I hear what you are saying and Tesla did build motors like you have suggested but I don't know of anyone that produces these motors today.

For an AC induction motor to run at 3000RPM on 10kHz it would need 200 poles. If that motor was 1 Hp these poles would have to be very small to keep the motor a reasonable size making its manufacture very difficult. Notice that Tesla's high frequency motors were very large in diameter, he considered it better to change the frequency rather than pursue this method for the induction motor.

High frequency does give a better solution in many ways but this does introduce other problems, iron losses being one of them. Maybe this is why he said something like placing iron in a motor is a waste of energy. The iron does however lower the frequency of the coil so we have a trade off.

Getting back to how motors work, the magnetism in a motor comes from the number of ampere turns so it makes sense to have a high number of turns if your current is low but this introduces resistance which is just a loss, again we have a compromise. We could use bigger wire but this makes motors bigger and more expensive and also introduces limits on speed and power. Modern motors are a good compromise if you are not concerned with "real" efficiency

[mbrownn]

The cable guy was just here, he pinged everything and got 100% data loss needless to stay my connection is still almost dead. I got better connection with a VIC 20 and a modem that you had to place a telephone receiver on top, showing my age now

Getting back to the motors; When we oscillate a motor in an LC circuit we only have to top up losses which are resistance and iron losses. the magnetism does not consume energy. Now it makes sense that motive power in a motor is not consumed energy but is a byproduct of passing current through a coil of wire. In normal motors this current is shorted out on the source but if we captivate it in an LC circuit we only need to top up the losses.

As I said before, induction motors are not practical for this process because of their speed requirement on high frequency and the transformer requirement to power the squirrel cage where the current is just shorted.

A universal motor however; can do this as the speed is not related to frequency and the transformer losses are only the eddy currents. Iron losses should be similar to induction motors but for some reason they are less efficient. This loss cannot be accounted for by the friction of the brushes. If you have any ideas as to why this is the case, I am all ears.

My thoughts are it is because of the changing inductance's in the rotor, caused by the commutation, fighting against each other as the motor spins. A non interconnecting star wound rotor would not have this problem. A partial solution would be to have a much higher frequency of oscillation than the frequency of switching on the commutator. This is easily done by limiting the speed of the motor which is also a requirement to limit BEMF.

BEMF will limit the resonant circuit by opposing the current in the oscillation. Because of this we well have proportionally less power in the oscillation and effectively a loss that we have to top up. To make the circuit as efficient as possible we have to limit BEMF. The only way to do this is to limit the speed

The simplest way to do this is to use our motor to power an AC generator that is phase linked to the grid. A universal motor will usually spin at 10,000 to 20,000 RPM when unloaded, generating maximum BEMF which is just below the forward EMF. If our generator is limited to 1500 RPM by the grid we will generate less than 1/6 or 1/12 of the BEMF in our motor. This is a requirement so as not to limit the resonant circuit power.

As a motor usually drops speed under load, the BEMF falls in direct proportion to the load and current rises as a result causing the motor to adjust its power to the load. As our conditions of running the motor in low speed but current limited by the frequency our motor will not raise current in direct proportion to the load therefore any increase in load above what our limited current can supply will result is a stall. Because of this we will require a load that is fixed or reduces with speed. An AC generator that is linked to the grid will do exactly that, making the motor control simple.

[nueview]

@MBrown
i agree with what you are saying but there was allot left out from what you were saying as well and it is down those avenues i want to go looking.
i remember when electric r/c planes were considered impossible but some unique things were figured out about how to keep the power up and get the size down using larger wire for the windings.
this reduced the reverse voltage which allowed for higher torque motors and higher speeds. so there are tradeoffs that energy can perform that have not yet been tried.
yes there is a trade off with magnetics and resonance and i believe this is why the greater part of the power can be generated by recycling.
as for the core being iron the rules of induction change when iron is saturated.
two magnetic fields 90* out of phase are like two gears and they expend almost no energy between them just as resistance real or virtual as reactance all play a part so the number of poles and amount of wire do not have to be as great as you might think.
also the drive coils will have to reconfigure with the circuit i thank you for your opinions and they are all valid points but i need to keep going the way i am planning if just to find out.
Martin