What type of circuit can convert single phase electric power into three phase electric power? Can the circuit diagram be posted in this thread?
single phase motor, pulley going to three phase generator
you would need a circuit with capacitors to make up the energy that doesn't exist at the single phases frequencies.
Are you wanting to do much more than demonstrate the 3 sinusoids on a CRO, or operate a tiny 3ø model motor?What type of circuit can convert single phase electric power into three phase electric power? Can the circuit diagram be posted in this thread?
An oscillator can be designed (using R's, C's and transistors or op-amps) to provide the three low-power sinewaves with correct phase differences. These in turn control high power amplifiers.And what keeps the three currents out of phase?
I assumed you'd be wanting 3ø sinusoids. If it is good enough to have 3 rough stepwise approximations, then you can use a switching arrangement and this is more efficient. But it is rare that a 3 phase application will accept squarewaves, the most efficient of all to generate.Is there some kind of electronic timing mechanism that delays currents so that when the first phase is on, the other two phases are off and the same applies to the other two phases?
Can the diagram for this type of design be posted so that the exact parts and their location in the circuitry can be identified?
Sure it can, provided it is already in the public domain.Can the diagram for this type of design be posted so that the exact parts and their location in the circuitry can be identified?
That is not a 1-phase to 3-phase converter, not in the usual meaning of the term. What you are referring to is a dodgy arrangement that allows a small 3∅ motor to run on a single phase supply.Here is a diagram of the 1-phase to 3-phase converter:
Because they are generating only 2 phases, not 3. It's a rough and ready compromise, but it works because motors can run off 2 phases, though at reduced power.The website posting the article about 1-phase to 3-phase conversion stated that a capacitor is used to cause a phase shift for the 3rd phase to be out of phase. But why did it not mention the use of a capacitor to cause the 2nd phase to be out of phase?
So are you interested in operating a 3∅ motor off a single phase?
No, just interested in figuring out how to do it. Is it possible to combine 2, 2-phase converters and suddenly end up with a 3-phase converter?
Are these the correct schematics for such converters?
It represents in principle a method to convert from 3ϕ to single phase: you rectify the 3ϕ and use that DC to power an inverter. But I would need to examine his "transformer" arrangement very closely (at a low testing voltage) before anything else, as it is unusual. You might consider using an AC→DC→AC inverter like this if your need was for a single phase frequency that was different from that of the mains 3ϕ, or if it were essential that you must load all 3 phases equally (this could be a power authority condition). Otherwise, why not just connect your single phase motor (or its associated transformer) between any two of the phases from your 3ϕ supply?Additionally is this diagram for 3-phase to 1-phase conversion correct:
The 3 power phases can be connected to inductors which will be placed in proximity to a larger inductor that is the same size as the sum of the volume of the 3 smaller inductors. The power will then be transferred through electromagnetic radiation and the inductors will thus serve as a transformer with all the energy being fed to one inductor. Because of the overlap of currents coming from the 3-phase power supply, the output inductor can be connected to a rectifier which will then be connected to an inverter to produce a 1-phase output.
This is a thought experiment, is it? You want to take one of the phases from 3ɸ and mess with its angle? Sure you can do that. Simply adding a capacitor to the phase from the mains won't do it, but if you use a transformer-inductor and capacitor as illustrated in earlier schemes, you could change the angle. It probably wouldn't have any practical use, as far as I can see -- I presume 120° is the all round optimum for rotating machinery.Would it also be possible to use two capacitors to change the phase angle of the two other phase terminals where C2>C1 so that the third phase terminal will be out of phase to a greater degree than the second terminal?
This is a thought experiment, is it? You want to take one of the phases from 3ɸ and mess with its angle? Sure you can do that. Simply adding a capacitor to the phase from the mains won't do it, but if you use a transformer-inductor and capacitor as illustrated in earlier schemes, you could change the angle. It probably wouldn't have any practical use, as far as I can see -- I presume 120° is the all round optimum for rotating machinery.
No, the intention was to use the device to convert 1-phase to 3-phase current. The supply would be split into 3 sets of terminals, 1 with no capacitor and the other 2 with capacitors of different ratings to give each one a different phase angle.
Do not forget that virtually all three phase machines - PM, induction motors and VRM have their torque dependent on the current.
For example, if a PM machine has sinusoidal windings, you need to excite those windings with current that is exactly in the phase with the back EMF. Since the stator winding inductance is constant and your capacitors values are constant, the intended phase shift would work for one frequency only.
Why don't you buy a flux drive and hook it up to a full-bridge rectifier to get 1ph->DC->3ph ac variable speed?
But each of the two capacitors will have differing values, is that not enough to produce three phase angles?
First, if the two capacitors are connected to a DC link (which is a voltage source) then they are slaved to it. Voltage on them would not have any phase shift. There would need to be an inductive element between the voltage source and these capacitors to produce phase shift.
Also, the phase shift would appear only at a certain frequency - so you would need to pull current at a certain frequency to have the two cap voltages phase shifted 120d to each other.
At zero frequency the caps would resonate with their phase inductors. Provided non-zero resistance, it's a second order damped system. When the initial ringing dies out, both caps will have the same DC voltage as the source.
A capacitor in series with the mains is a dodgy arrangement that allows a motor to see a phase with a leading angle, but that won't be anywhere near 120° as far as I can see, though I'm no expert. It relies on a characteristic of the motor winding. If you use a different motor, you'll need a different capacitor or performance will suffer even more.No, the intention was to use the device to convert 1-phase to 3-phase current. The supply would be split into 3 sets of terminals, 1 with no capacitor and the other 2 with capacitors of different ratings to give each one a different phase angle.
If the mains see the capacitors in parallel with the load then those capacitors can do nothing more than PF correction. The 1ɸ mains has to see them in series with something to achieve a phase lead.The capacitors of the design are in parallel to the load.