Battery Charger with Full Bridge:

 

Equivalent DC Circuit:

 

 

Peak Charging Voltage: Vpeak= 12 V + (5 W )(15 A) = 87 V

 

Secondary Transformer Voltage: Vpeak/Ö 2= 61.5 V

 

Battery Current Waveform:

 

 

 

 

 

From MatLab Simulation:

Rms of Battery Current:

 

From MatLab Simulation:

 

Dissipated Power (on charging resistance): Ploss = R(Io,rms)2 = 5x102.01 = 510.1 W

 

Average Charging Power:

 

From Matlab Simulation:

 

 

Stored Power: 611.7 – 510.1 = 101.7 W

 

Average dc Voltage: Vo = 12 +RIo = 55 V DC

 

DC Power: PDC = VI= 473 VA DC

 

Primary Current rms: IP = (61.5/120)Io,rms = 5.13 A

 

Transformer Rating: ST = VPI P= 615.6 VA

 

TUF:

 

TUF = PDC/ST= 473 VA DC/615.6 VA = 0.768 (76.8 %)