Engineering Phase voltage and Line-Line voltage relation

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SUMMARY

The discussion focuses on the relationship between phase voltage and line-to-line voltage in a wye transformer configuration, specifically in the context of a three-phase inverter circuit. The user attempts to apply Kirchhoff's Voltage Law (KVL) to derive equations for the voltages Ua, Ub, and Uc, while expressing uncertainty about their approach. It is established that the phase voltages U_VA and U_VB should both equal 120V, and the line-to-line voltage U_AB is derived from these phase voltages. The circuit's behavior is influenced by the switching states of the inverter.

PREREQUISITES
  • Understanding of three-phase electrical systems
  • Familiarity with Kirchhoff's Voltage Law (KVL)
  • Knowledge of inverter operation and control
  • Basic concepts of voltage relationships in wye and delta configurations
NEXT STEPS
  • Study the principles of three-phase power systems
  • Learn about the operation of three-phase inverters
  • Explore detailed applications of Kirchhoff's Voltage Law in circuit analysis
  • Investigate the voltage relationships in wye and delta transformer configurations
USEFUL FOR

Electrical engineers, students studying power systems, and professionals involved in inverter design and analysis will benefit from this discussion.

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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
1676305359954.png

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.
 
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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.
 
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?
 
Yes it is inverter
SAtSBtSCtU_VAU_VBU_VCU_ABU_BCU_CAUaUbUc
100udcbus/2-udcbus/2-udcbus/2udcbus0-udcbus
010-udcbus/2udcbus/2-udcbus/2-udcbusudcbus0
001-udcbus/2-udcbus/2udcbus/20-udcbusudcbus
110udcbus/2udcbus/2-udcbus/20udcbus-udcbus
101udcbus/2-udcbus/2udcbus/2udcbus-udcbus0
011-udcbus/2udcbus/2udcbus/2-udcbus0udcbus
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
1676390674623.png


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.
 

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