Phase voltage and Line-Line voltage relation

[PhysicsTest]

Homework Statement:

Find the phase voltage and Line-Line voltage relation

Relevant Equations:

Kirchhoff voltage and current laws

The below is the diagram i want to find the phase and line-line voltage relation

I am finding difficulty in identifying the loop and applying the KVL.
One attempt is
U_{VA} - U_R - U_L -U_O - U_L - U_R = U_VB
U_{VA} - 2(U_R+U_L) = U_VB -> eq1

Is my attempt correct? i am not confident please help.

 

[osilmag]

UVA and UVB should actually be equal if this is a schematic of a wye transformer. They should both be 120V. The line to line voltage would be UAB.

 

[DaveE]

Probably a 3Φ motor drive or inverter, since there are ideal DC sources in there. But it could be a rectifier, I guess. Much depends on the switches. Normally KVL would only be applied for a specific switch state since the network changes when switches change.

What is this circuit supposed to do? How are the switches controlled?

 

[PhysicsTest]

Yes it is inverter

SAt	SBt	SCt	U_VA	U_VB	U_VC	U_AB	U_BC	U_CA	Ua	Ub	Uc
1	0	0	udcbus/2	-udcbus/2	-udcbus/2	udcbus	0	-udcbus
0	1	0	-udcbus/2	udcbus/2	-udcbus/2	-udcbus	udcbus	0
0	0	1	-udcbus/2	-udcbus/2	udcbus/2	0	-udcbus	udcbus
1	1	0	udcbus/2	udcbus/2	-udcbus/2	0	udcbus	-udcbus
1	0	1	udcbus/2	-udcbus/2	udcbus/2	udcbus	-udcbus	0
0	1	1	-udcbus/2	udcbus/2	udcbus/2	-udcbus	0	udcbus

I want to calculate the voltages Ua, Ub, Uc
For the 1st case if i consider
1 0 0 the circuit will be as below

If i write KVL
a. 1 0 0
VDCBus/2 + Ua -Ub + VDCBus/2 = 0;
Ua - Ub + VDCBus=0 -> 1

b. 0 1 0
VDCBus/2 + Ub -Ua + VDCBus/2=0
-Ua + Ub + VDCBus = 0 -> 2

c. 0 0 1
VDCBus/2 + Uc - Ub + VDCBus/2 = 0 -> 3

Very confusing am i in correct direction? The document is user guide page 51.