source would be a typical 2-3KW 3600rpm gas generator - appliances - TV and DVD player - maybe a small fridge
looking at one blog, the raw cost of the inductors involved exceeded the cost of the generator
generator already purchased.
Are there any practical filter schemes (which do some real good) to go between the generator and load?
looking at one blog, the raw cost of the inductors involved exceeded the cost of the generator
generator already purchased.
Are there any practical filter schemes (which do some real good) to go between the generator and load?
Just check if the alternator is really giving noisy output.
Try earthing it.
Try an old tube light magnetic ballast if you are at 110 volts, the 220 one are designed to drop the voltage to 110...
0.1 uF, 400v, and a 2.2 k resistor across live and neutral work as noise filter.
In fact most EMI filters should work, about $10...
Try earthing it.
Try an old tube light magnetic ballast if you are at 110 volts, the 220 one are designed to drop the voltage to 110...
0.1 uF, 400v, and a 2.2 k resistor across live and neutral work as noise filter.
In fact most EMI filters should work, about $10...
Depends on what you mean by "typical". My generator starts generating based on residual magnetism in the rotor, somehow ultimately regulating to 220VAC, center tapped - when spun at 3600 RPM. A different more famous brand model I once had actually PWM'd the rotor current with an electronic regulator.
These different designs make me wonder where the noise is coming from in the first place? One would think the sine wave would be pretty pure, unless the commutator slip rings are delivering inherently noisy current to the rotor winding, which in turn... I suppose capacitively decoupling the downstream side of that arrangement would be quite a challenge.
Do you have any speaker inductors with the big fat square copper windings? Any film or large oil caps of appropriate voltage rating? An engineering colleague used to tell me how he'd control the speed of home fan motors using series capacitors and claim that no power was expended. He also said you could connect a capacitor directly across the AC line, to lower it's impedance. Not just any capacitor, but the right capacitor, type and value.
Perhaps you have an adequate solution right from your own junkbox. Fire up LTSpice, look at the steady state currents for different values. I think I've had 0.1 or 1.0, 400V film directly across the AC line 24/7 with no issue. Maybe you have some oil filled caps - I wonder what they can take for dissipation before the cans start to bulge?
These different designs make me wonder where the noise is coming from in the first place? One would think the sine wave would be pretty pure, unless the commutator slip rings are delivering inherently noisy current to the rotor winding, which in turn... I suppose capacitively decoupling the downstream side of that arrangement would be quite a challenge.
Do you have any speaker inductors with the big fat square copper windings? Any film or large oil caps of appropriate voltage rating? An engineering colleague used to tell me how he'd control the speed of home fan motors using series capacitors and claim that no power was expended. He also said you could connect a capacitor directly across the AC line, to lower it's impedance. Not just any capacitor, but the right capacitor, type and value.
Perhaps you have an adequate solution right from your own junkbox. Fire up LTSpice, look at the steady state currents for different values. I think I've had 0.1 or 1.0, 400V film directly across the AC line 24/7 with no issue. Maybe you have some oil filled caps - I wonder what they can take for dissipation before the cans start to bulge?
Power factor improvement capacitors are available here, should use as 30% kVAR of load kVA.
So a small capacitor should work as well.
0.1 to 1 uF / 400 V in series with load limiting resistor should work too.
Series capacitors are now the latest in fan speed regulators, the tapped transformers evolved to series resistors, then triacs, finally series capacitors.
Brushless DC fan motors are a different game though.
The other industrial solution in my Japanese molding machine was a 1:1 transformer, 750vA, for the control circuit, it has primary tappings for different voltages, 200-220-240, and 210 for the secondary, it works as a filter , all the noise is trapped there.
I use a 275/20 MOV permanently across mains as a filter at home and work.
Your mileage may vary...
So a small capacitor should work as well.
0.1 to 1 uF / 400 V in series with load limiting resistor should work too.
Series capacitors are now the latest in fan speed regulators, the tapped transformers evolved to series resistors, then triacs, finally series capacitors.
Brushless DC fan motors are a different game though.
The other industrial solution in my Japanese molding machine was a 1:1 transformer, 750vA, for the control circuit, it has primary tappings for different voltages, 200-220-240, and 210 for the secondary, it works as a filter , all the noise is trapped there.
I use a 275/20 MOV permanently across mains as a filter at home and work.
Your mileage may vary...
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Granted, there are a number of different types of generators being manufactured today.
Some have commutator/slip ring field (really old school).
Some have SCR-controlled field.
Some have PWM-controlled field.
Some are self-excited, most are PMG.
Some are actually inverter output (could be sine or stepped sine).
At its most basic, you rotate a DC magnetic field through a stationary winding, which produces a voltage in the winding (armature). What part of this physics produces noise, such that you need filtering?
If you don't know exactly what topology/construction your generator is, thinking you need filtering (or anyone on this forum recommending a filtering solution) is futile.
The largest shortcoming of the generator will be speed/frequency regulation, which of course no amount of filtering will address.
Some have commutator/slip ring field (really old school).
Some have SCR-controlled field.
Some have PWM-controlled field.
Some are self-excited, most are PMG.
Some are actually inverter output (could be sine or stepped sine).
At its most basic, you rotate a DC magnetic field through a stationary winding, which produces a voltage in the winding (armature). What part of this physics produces noise, such that you need filtering?
If you don't know exactly what topology/construction your generator is, thinking you need filtering (or anyone on this forum recommending a filtering solution) is futile.
The largest shortcoming of the generator will be speed/frequency regulation, which of course no amount of filtering will address.
That one only has 120V??
Mine is 115/230V and does not seem to give trouble. Computers, router, TV all work normally; of course TV audio is interferred-with by exhaust note. Mine may be a little bigger than yours. I sized to carry a well-pump.
A basic alternator does not naturally make a Sine wave, but comes close enough for government work. (Literally: I had a gig with the local government Parks program.) Size/economy lead to a slightly flat top, you have to design for a near-sine. The sine is better miles down the road.
If you want to figure: 120V 30A is 4 Ohms, like a speaker. 60Hz is bass. A passive L-C crossover for say 100Hz with much less than 0.4 Ohms ESR is a BIG filter.
See attached. 9mH and 280uFd. At 120Vrms and 30 Amps. Interestingly I do find a 10mH air-core but it would not last long at 15 Amps (the wire would take it stretched-out but not wound up like this). And the DCR id MUCH too high.
Jantzen Audio 10mH 15 AWG Air Core Inductor Crossover Coil
A 270uFd cap needs >168V rating so we could series a couple of these:
500uF 100V Electrolytic Non-Polarized Crossover Capacitor
I'm sure the "100V" is a "speech/music" rating, not steady power; this really wants to be a trashcan size film cap.
Mine is 115/230V and does not seem to give trouble. Computers, router, TV all work normally; of course TV audio is interferred-with by exhaust note. Mine may be a little bigger than yours. I sized to carry a well-pump.
A basic alternator does not naturally make a Sine wave, but comes close enough for government work. (Literally: I had a gig with the local government Parks program.) Size/economy lead to a slightly flat top, you have to design for a near-sine. The sine is better miles down the road.
If you want to figure: 120V 30A is 4 Ohms, like a speaker. 60Hz is bass. A passive L-C crossover for say 100Hz with much less than 0.4 Ohms ESR is a BIG filter.
See attached. 9mH and 280uFd. At 120Vrms and 30 Amps. Interestingly I do find a 10mH air-core but it would not last long at 15 Amps (the wire would take it stretched-out but not wound up like this). And the DCR id MUCH too high.
Jantzen Audio 10mH 15 AWG Air Core Inductor Crossover Coil
A 270uFd cap needs >168V rating so we could series a couple of these:
500uF 100V Electrolytic Non-Polarized Crossover Capacitor
I'm sure the "100V" is a "speech/music" rating, not steady power; this really wants to be a trashcan size film cap.
Attachments
The "AVR" part of the diagram suggests "auto voltage regulator" and on Westinghouse models that feature "AVR", they also claim sine wave output. So where is the noise coming from, if it's making an electronically regulated sine wave already?
I wonder what the stepper motor does? - I assume throttle. Gone are the days when the cooling fan would blow against a vane and, balanced against a spring, would maintain 3600 RPM. My old, old yet functional POS doesnt have a VFT meter...
Interesting how "Control Module" connects to Eng Switch, Oil sensor and spark coil - but also to the output voltage. I wonder if it gets its timing from the AC waveform? No points are shown about the ignition coil.
I wonder what the stepper motor does? - I assume throttle. Gone are the days when the cooling fan would blow against a vane and, balanced against a spring, would maintain 3600 RPM. My old, old yet functional POS doesnt have a VFT meter...
Interesting how "Control Module" connects to Eng Switch, Oil sensor and spark coil - but also to the output voltage. I wonder if it gets its timing from the AC waveform? No points are shown about the ignition coil.
I think you should try it first.
The alternator scheme is like that of a car, should be normal in use if properly earthed and connected.
If your amp has SMPS, and this has PWM then you may have issues.
Go for a solar or wind system to charge batteries, and use those to power a car system....no noise then.
The alternator scheme is like that of a car, should be normal in use if properly earthed and connected.
If your amp has SMPS, and this has PWM then you may have issues.
Go for a solar or wind system to charge batteries, and use those to power a car system....no noise then.
Harmonics and noise in 60 Hz AC systems are NOT synonymous. This generator output will likely have fewer harmonics than your utility feed. Most generators will have less than 2% THD, although their specs typically state 5% since the mfg cannot know what type of loads you connect.
There is no way you will install LC filtering to successfully remove harmonics. The only thing you will accomplish is self-exciting the stator with the huge capacitance you install, and the AVR will lose control as the voltage rises above nominal. Futility, as I noted earlier. I offer to PM you $1000 if you successfully 'clean up' the supposed dirty sine wave.
This also confirms you have no noise, as the unit is a PMG with DC field. Zero noise. Thread will end up going nowhere.
There is no way you will install LC filtering to successfully remove harmonics. The only thing you will accomplish is self-exciting the stator with the huge capacitance you install, and the AVR will lose control as the voltage rises above nominal. Futility, as I noted earlier. I offer to PM you $1000 if you successfully 'clean up' the supposed dirty sine wave.
This also confirms you have no noise, as the unit is a PMG with DC field. Zero noise. Thread will end up going nowhere.
thanks all - - The manufacturer says its clean enough:
"Champion portable generators will output an industry standard total harmonic distortion (THD) rating of about 12%-20% depending on load applied. They will produce a sine wave, not a modified or square wave. This is perfectly acceptable for running common commodities found in your home such as TVs, computers, your appliances, etc."
btw, there is this paper which seems interesting:
https://ijournals.in/wp-content/uploads/2017/07/6.41203-Imran.compressed.pdf
"Champion portable generators will output an industry standard total harmonic distortion (THD) rating of about 12%-20% depending on load applied. They will produce a sine wave, not a modified or square wave. This is perfectly acceptable for running common commodities found in your home such as TVs, computers, your appliances, etc."
btw, there is this paper which seems interesting:
https://ijournals.in/wp-content/uploads/2017/07/6.41203-Imran.compressed.pdf
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There is a field and an excitation winding, so the moving part / armature sees current through slip rings, which is varied to control the voltage in the main (fixed) winding.
Should not be noisy until the slip rings see a lot of wear.
You really should have checked out the circuit and the unit before posting, and if you ordered it, maybe the order can be cancelled, maybe not.
Please remember that in auto applications, a 12V battery has to be charged between 14.2 and 14.8 volts, and the voltage and current can both be varied by the controller.
Many chip makers make the regulator ICs for these applications.
And similar chips / controllers are common in 110/220/440 volts alternators.
So you got what is a fairly simple and reliable machine.
Enjoy.
Should not be noisy until the slip rings see a lot of wear.
You really should have checked out the circuit and the unit before posting, and if you ordered it, maybe the order can be cancelled, maybe not.
Please remember that in auto applications, a 12V battery has to be charged between 14.2 and 14.8 volts, and the voltage and current can both be varied by the controller.
Many chip makers make the regulator ICs for these applications.
And similar chips / controllers are common in 110/220/440 volts alternators.
So you got what is a fairly simple and reliable machine.
Enjoy.