Single phase bridge inverter

Single phase bridge inverter

The function of inverter is convert DC to AC voltage.

  • Two types of single phase bridge inverter
  1. single phase half bridge inverter
  2. single phase full bridge inverter

Single phase half bridge inverter

 

Circuit Description :-
  •  Two Thyristor S1 and S2 are used along with two feedback diode D1 and D2 respectively.
  • Resistive load is connect between point A and B, as shown in fig:-
  • Supply voltage is divided intp 2 parts, here two DC voltage source are used V/2 and V/2.
  • Fig of the single phase half bridge inverter is given below:
 Single phase half bridge inverter
Fig : Single phase half bridge inverter

Working:

Mode 1 (0 to T/2):-

  • During this mode switch S1 is ON and switch S2 is OFF From period 0 to T/2.
  • Current flowing path during this mode is V/2-S1-B-R(Load resistor)-A-V/2.
  • Hence the voltage across the load is positive V/2
 Single phase half bridge inverter
Fig: conducting mode 1

Mode 2 (T/2 to T):-

  • During this mode switch S1 is OFF and switch S2 is ON From period T/2 to T.
  • Current flowing path during this mode is V/2-A-R(Load resistor)-B-S2-V/2.
  • Hence the voltage across the load is negative V/2.
 Single phase half bridge inverter
Fig: conducting mode 2

 

  1. Load is resistive hence it does not store any charge therefore feedback diode D1 and D2 are not effective here.
  2. The main drawback of half bridge inverter is that two DC voltage source are require. By using full bridge inverter we can overcome that drawback.
Waveform of output voltage thyristor current with resistive load are shown in fig
waveform single phase half bridge inverter
fig: waveform single phase half bridge inverter

 

Single phase Full bridge inverter

Circuit Description :-
  • Four thyristor are used in full bridge inverter. Thyristor S1 and S2 are used along with two feedback diode D1 and D2 and thyristor S3 and S4 are used along with another two feedback diode D3 and D4 respectively.
  • Fesistive load is connect between point A and B,as shown in fig:-
  • DC voltage source is applied to circuit.
  • Fig of the single phase full bridge inverter is given below:
single phase full bridge inverte
Fig: single phase full bridge inverter

Mode 1 (0 to T/2):-

  • During this mode switch S1 and switch S2 are ON and switch S3 and switch S4 are  OFF From period 0 to T/2.
  • Current flowing path during this mode is Vdc – S1- P -R(load reistor) – Q – S2 – Vdc.
  • Voltage across the load resistor is   positive Vdc
single phase full bridge inverte
fig; conducting mode 1

Mode 2 (T/2 to T):-

  • During this mode switch S3 and switch S4 are ON and switch S1 and switch S2 are OFF From period T/2 to T.
  • Current flowing path during this mode is Vdc – S3 – Q – R(load reistor) – P – S4 – Vdc.
  • Voltage across the load resistor is negative Vdc.
single phase full bridge inverte
fig : conducting mode 2
  1. Load is resistive hence it does not store any charge. therefore, feedback diode D1, D2, D3 and D4 are not effective here.
WAVEFORM OF OUTPUT VOLTAGE THYRISTOR CURRENT WITH RESISTIVE LOAD ARE SHOWN IN FIG:
waveform single phase full bridge inverter
fig: waveform single phase full bridge inverter

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