# two phase from single phase

Discussion in 'Electronic Basics' started by Jon Slaughter, Mar 29, 2007.

1. ### Jon SlaughterGuest

Is it possible to create two phase(or more) from single phase using passive
components(definitely not any motors) and maybe transistors(or
semi-conductors)? The design would need to handle large currents and
voltages so one can't directly use an summing op amp or anything like that.

Thanks,
Jon

2. ### Homer J SimpsonGuest

Two phase in what sense? 90 or 180 degrees apart?

You can run three phase motors from single phase with various devices.

3. ### Greg NeillGuest

Center tapped transformer for two phases, 180 degrees.

4. ### ian fieldGuest

There are plenty of 2-phase motors around, these use a large capacitor to
drive one of the windings (which is obviously inductive). So it is clearly
possible to do with only passive components.

5. ### Jon SlaughterGuest

What I mean by two phase is 90 degree's apart(probably should have said
that). Also, it does not have to be exact but just approximate(it can depend
on the load but not to a great extentent).

6. ### Homer J SimpsonGuest

Doable but not for a variable load IIRC.

7. ### Paul E. SchoenGuest

The following circuit will generate 3 phase 144 VAC at 915 Watts output,
from 122 VAC single phase, at 946 watts input. This is for nearly ideal
components, and a balanced load. R4 in the circuit must be adjusted to the

The voltage across R4 will always be 90 degrees to the input voltage, but
will vary according to load. If R1-R2-R3 are changed to 1k each, the output
voltage across R4 will reach 1.7 kV, and the input current will be 48 amps.
Obviously this will only occur if adequately rated components are used, but
the phase angle is still 90 degrees to the input. You can adjust the
resistances to get various outputs.

I have built a circuit similar to this and it will run a 208/240 VAC three
phase motor. I used three powerstats and two 120/240 autotransformers.

It is critical to adjust the inductance and capacitance so they have equal
reactance at 60 Hz. They form a resonant circuit which must be damped by
the resistance; otherwise the input current will increase along with the
output voltage to dangerous levels. I was surprised a couple of times when
I noticed rather juicy arcs before the input circuit breaker tripped.

HTH,

Paul

==========================================================
Version 4
SHEET 1 880 680
WIRE 112 128 -144 128
WIRE 416 128 112 128
WIRE 608 128 416 128
WIRE 112 160 112 128
WIRE 416 160 416 128
WIRE -144 208 -144 128
WIRE 608 208 608 128
WIRE 112 256 112 240
WIRE 112 256 48 256
WIRE 416 256 416 224
WIRE 496 256 416 256
WIRE 112 288 112 256
WIRE 224 288 112 288
WIRE 416 288 416 256
WIRE 416 288 304 288
WIRE 608 336 608 288
WIRE 608 336 272 336
WIRE -144 368 -144 288
WIRE 0 368 -144 368
WIRE 272 368 272 336
WIRE 272 368 0 368
WIRE 112 416 112 288
WIRE 160 416 112 416
WIRE 272 416 272 368
WIRE 272 416 240 416
WIRE 304 416 272 416
WIRE 416 416 416 288
WIRE 416 416 384 416
WIRE 608 416 608 336
WIRE 0 432 0 368
WIRE 112 480 112 416
WIRE 224 480 112 480
WIRE 416 480 416 416
WIRE 416 480 304 480
WIRE 112 560 112 480
WIRE 144 560 112 560
WIRE 256 560 224 560
WIRE 304 560 256 560
WIRE 416 560 416 480
WIRE 416 560 384 560
WIRE 256 608 256 560
WIRE 496 608 256 608
WIRE 608 608 608 496
WIRE 608 608 496 608
FLAG 0 432 0
FLAG 48 256 PH-A
FLAG 496 256 PH-C
FLAG 496 608 PH-B
SYMBOL voltage -144 192 R0
WINDOW 3 -121 130 Left 0
WINDOW 123 0 0 Left 0
WINDOW 39 -121 158 Left 0
SYMATTR InstName V1
SYMATTR Value SINE(0 180 60 0 0 0 60)
SYMATTR SpiceLine Rser=.1
SYMBOL ind 96 144 R0
SYMATTR InstName L3
SYMATTR Value 100m
SYMBOL cap 400 160 R0
SYMATTR InstName C1
SYMATTR Value 73µ
SYMBOL res 128 576 R270
WINDOW 0 32 56 VTop 0
WINDOW 3 0 56 VBottom 0
SYMATTR InstName R1
SYMATTR Value 68
SYMBOL res 400 544 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName R2
SYMATTR Value 68
SYMBOL res 320 464 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName R3
SYMATTR Value 68
SYMBOL ind2 256 400 R90
WINDOW 0 5 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName L4
SYMATTR Value 2
SYMATTR Type ind
SYMBOL ind2 400 400 R90
WINDOW 0 5 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName L5
SYMATTR Value 2
SYMATTR Type ind
SYMBOL ind2 592 192 R0
SYMATTR InstName L1
SYMATTR Value 2
SYMATTR Type ind
SYMBOL ind2 592 400 R0
SYMATTR InstName L2
SYMATTR Value 2
SYMATTR Type ind
SYMBOL res 320 272 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName R4
SYMATTR Value 3k
TEXT -160 392 Left 0 !.tran 500m startup
TEXT -160 448 Left 0 !K2 L4 L5 1
TEXT 464 368 Left 0 !K1 L1 L2 1

8. ### Paul E. SchoenGuest

Here is a simpler circuit that produces 208 VAC three phase at over 2 kW
into three 65 ohm loads. The A-C voltage is at 90 degrees to the input. It
uses a 3:1 autotransformer (which could be made from a 120:240 transformer.

Without any transformer, 122 VAC input makes about 71 VAC 3 phase.

The resistors may be varied to obtain various voltages and phase shifts.

Paul

====================================================================
Version 4
SHEET 1 880 680
WIRE 416 32 256 32
WIRE 608 32 416 32
WIRE 560 96 -144 96
WIRE 608 160 608 32
WIRE 160 176 112 176
WIRE 256 176 256 32
WIRE 256 176 240 176
WIRE 288 176 256 176
WIRE 416 176 368 176
WIRE -144 208 -144 96
WIRE 112 256 112 176
WIRE 112 256 48 256
WIRE 416 256 416 176
WIRE 496 256 416 256
WIRE 560 336 560 96
WIRE 608 336 608 240
WIRE 608 336 560 336
WIRE -144 368 -144 288
WIRE 0 368 -144 368
WIRE 112 384 112 256
WIRE 224 384 112 384
WIRE 416 384 416 256
WIRE 416 384 304 384
WIRE 608 416 608 336
WIRE 0 432 0 368
WIRE 112 496 112 384
WIRE 416 512 416 384
WIRE -144 608 -144 368
WIRE 112 608 112 576
WIRE 112 608 -144 608
WIRE 416 608 416 576
WIRE 416 608 112 608
WIRE 608 608 608 496
WIRE 608 608 416 608
FLAG 0 432 0
FLAG 48 256 PH-A
FLAG 496 256 PH-C
FLAG 416 32 PH-B
SYMBOL voltage -144 192 R0
WINDOW 3 -121 130 Left 0
WINDOW 123 0 0 Left 0
WINDOW 39 -121 158 Left 0
SYMATTR InstName V1
SYMATTR Value SINE(0 180 60 0 0 0 60)
SYMATTR SpiceLine Rser=.1
SYMBOL ind 96 480 R0
SYMATTR InstName L3
SYMATTR Value 100m
SYMBOL cap 400 512 R0
SYMATTR InstName C1
SYMATTR Value 70µ
SYMBOL res 144 192 R270
WINDOW 0 32 56 VTop 0
WINDOW 3 0 56 VBottom 0
SYMATTR InstName R1
SYMATTR Value 65
SYMBOL res 384 160 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName R2
SYMATTR Value 65
SYMBOL ind2 592 144 R0
SYMATTR InstName L1
SYMATTR Value 8
SYMATTR Type ind
SYMBOL ind2 592 400 R0
SYMATTR InstName L2
SYMATTR Value 2
SYMATTR Type ind
SYMBOL res 320 368 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName R3
SYMATTR Value 65
TEXT -160 392 Left 0 !.tran 500m startup
TEXT 464 368 Left 0 !K1 L1 L2 1

9. ### Paul E. SchoenGuest

An even more efficient circuit puts the loads across the inductor and
capacitor. It requires an additional autotransformer, but the output
voltage phase to phase is greater than the input voltage. 120 VAC input
produces about 140 VAC 3 phase, so 200 to 220 VAC will produce 208 to 240
VAC three phase output.

The schematic follows:

Paul

==============================================================================

Version 4
SHEET 1 880 680
WIRE 256 32 -144 32
WIRE 416 32 256 32
WIRE 144 112 112 112
WIRE 256 112 256 32
WIRE 256 112 224 112
WIRE 288 112 256 112
WIRE 416 112 368 112
WIRE -144 208 -144 32
WIRE 112 256 112 112
WIRE 112 256 48 256
WIRE 416 256 416 112
WIRE 496 256 416 256
WIRE -144 368 -144 288
WIRE 0 368 -144 368
WIRE 112 384 112 256
WIRE 224 384 112 384
WIRE 416 384 416 256
WIRE 416 384 304 384
WIRE 0 432 0 368
WIRE 112 464 112 384
WIRE 144 464 112 464
WIRE 256 464 224 464
WIRE 288 464 256 464
WIRE 416 464 416 384
WIRE 416 464 368 464
WIRE 112 496 112 464
WIRE 416 512 416 464
WIRE -144 608 -144 368
WIRE 112 608 112 576
WIRE 112 608 -144 608
WIRE 256 608 256 464
WIRE 256 608 112 608
WIRE 288 608 256 608
WIRE 416 608 416 576
WIRE 416 608 288 608
FLAG 0 432 0
FLAG 48 256 PH-A
FLAG 496 256 PH-C
FLAG 288 608 PH-B
SYMBOL voltage -144 192 R0
WINDOW 3 -121 130 Left 0
WINDOW 123 0 0 Left 0
WINDOW 39 -121 158 Left 0
SYMATTR Value SINE(0 180 60 0 0 0 60)
SYMATTR SpiceLine Rser=.1
SYMATTR InstName V1
SYMBOL ind 96 480 R0
SYMATTR InstName L3
SYMATTR Value 100m
SYMBOL cap 400 512 R0
SYMATTR InstName C1
SYMATTR Value 70µ
SYMBOL res 128 480 R270
WINDOW 0 32 56 VTop 0
WINDOW 3 0 56 VBottom 0
SYMATTR InstName R1
SYMATTR Value 69
SYMBOL res 384 448 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName R2
SYMATTR Value 69
SYMBOL res 320 368 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName R3
SYMATTR Value 69
SYMBOL ind2 128 128 R270
WINDOW 0 32 56 VTop 0
WINDOW 3 5 56 VBottom 0
SYMATTR InstName L1
SYMATTR Value 2
SYMATTR Type ind
SYMBOL ind2 272 128 R270
WINDOW 0 32 56 VTop 0
WINDOW 3 5 56 VBottom 0
SYMATTR InstName L2
SYMATTR Value 2
SYMATTR Type ind
TEXT -160 392 Left 0 !.tran 500m startup
TEXT 440 112 Left 0 !K1 L1 L2 1
TEXT -96 536 Left 0 ;X(L3) = 37.7 ohms
TEXT 456 544 Left 0 ;X(C) = 37.7 ohms