Lots of words up here.
I guess I'm the only one surprised to see higher torque density in induction machines vs pmsm?
I looked at your comparison sheet and don't understand it. E.g. I see columns for Nm and Volume [m3] and torque density [Nm/m3]. But the torque density column does not equal...
I did run a quick, crude test on a motor we had mounted on the dyno. Frankly, I could not make sense of the results at the time and shelved it. Maybe I can revisit it with a better approach.
What I did is spin the (smallish ~11kW) motor up to 3000rpm with a load of about 7Nm, held it there and...
I don't think the inductance of the machine truncates the high frequency current ripples from the pwm switching. If you stick an accelerometer on a motor, you will see vibrations centered around the pwm frequency, fanning out at odd harmonics of the electrical commutation frequency. These are...
I have to disagree about the skin effect being due to multiple turns or braids, but it is fundamentally due to magnetic induction in single wire strands and creation of Eddy currents therein.
Op I think this is a very interesting question. I can say that we ignore pwm frequencies when thinking...
Are you asking about the 381.5A?
The general approach with induction machines is a locked rotor test, wherein you ramp up the voltage at some frequency (e.g. 25% of rated frequency) until the current reaches the rated current.
Maybe there are standards for this, but I'm not familiar with anything.
Seems like the type of application where you need to do some engineering based on material strengths and loads. There's going to be different required thicknesses depending on whether you're making it out of soft aluminum...
Lots of good information above.
We design and manufacture electric machines at my place of work. In my experience, it's not uncommon to see up to 10-15C differences between thermal devices on our test motors that we dyno. We mostly use thermocouples, but have at least 1 RTD installed in every...
electrical steel is usually produced in thin laminations. What i can see on Carpenter, is that hiperco comes in .35mm and .15mm thickness. these are stacked into cores and welded or stitched together. we've turned down cores of silicon steel on a lathe here. you have to take light passes so it...
Search around for Hiperco 50 or Supermendur. This material was invented in the 50's. Permendur has been around since the 30's, so I'm not entirely sure what you mean by materials that did not exist until a few years ago. I would think that anyone who designs electric motors would be aware of...
Op is asking about soft magnetic materials, ie electrical steel. Permanent magnets are hard magnets. Though it's not clear op understands this distinction, as ferromagnetic material can be either soft or hard - and silicon steel is already soft.
I will reiterate again, you need to look at BH...
Electromagnets are made of coils of wires. Magnetic field strength is proportional to both current and number of turns in series. 100 amps through one turn produces the same field strength as 1 amp through 100 turns - so it's not enough information to ask only about the current. The induced flux...
I'm only familiar with these tests in regards to ac motors.. The primary difference (other than the magnitude) is the electric stress distribution across the groundwall between ac and dc tests. The ac hipot yields an electric stress distribution more similar to that found during normal...
Electromagnetic torque is produced at the interface between field and armature fluxes or, considering that at least the armature is an electromagnet, as the product of electrical and magnetic loading. Torque estimates from geometry can be made, proportional to D2L, as an estimation of the airgap...
Flattered you remember me Pete.
I used to spend a lot more time analyzing motors, but have been too bogged down in pm motor design to do that for a while now.
Cogging arises from the non-uniform permeance the rotor poles see as they rotate relative to the stator. The permeance in the magnetic...
I'm surprised you would see diverging information on reducing cogging.
fractional slot/poles, small slot openings, larger airgap, skewing stator/rotor, profiling magnets or magnetization, and dummy slots can all be used to mitigate cogging... slotless stator and airgap winding is the best...
Oh, I see. you are interested in finding overall sound power, not necessarily extrapolating existing data to 63Hz.
You could of course sum what data you have. You can just put the 16kHz dB value in the 63Hz octave spot. They should be interchangeable; I'd try swapping a couple to make sure this...
You are talking about measured data? I would think not.
Roughly speaking, you might have a loud, sharp single-tone at 63Hz or you might have a situation where the system is high-passed at 100Hz and there's virtually no lower frequency noise.
There is this "salary wizard" tool from salary.com:
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You can update the job title and location... For some reason, I've been unable to find this tool on their website outside of this (and similar) direct links...
>I am trying to figure out why you went for the harmonic resonator in your presentation. I have never seen that type of device fitted to any rotating electrical machine. Why not just balance the motor and generator rotors?
There are excitations in electric motors that can't be balanced away. If...
