SLAA602A June 2013 – August 2017 AMC1100 , SM72295 , TMS320F2802-Q1 , TMS320F28027 , TMS320F28027-Q1 , TMS320F28027F , TMS320F28027F-Q1 , TPS54202 , TPS54231
In the mains mode, when the input AC is present and is within valid range, the relay between Input AC and the inverter output is closed and the input AC directly goes to the output load. The same AC is fed to transformer, and the H-bridge consisting of MOSFETs or IGBTs are driven through microcontroller to charge the battery. A bridge less rectification principle is used to charge the battery where basically both the high-side FET is switched off and both lower side FETs to ground in the H Bridge are switched at the same time with the duty Cycle proportional to the Battery Charge current.
Whenever the lower FETs are turned ON at the same time, that is, there is a generation of boosted voltage across the leakage inductance of the primary inductance connected to H Bridge by the Ldi/dt effect and this energy stored in the Leakage Inductance flow through the body diode of the high-side MOSFETs (Each high-side MOSFETs body diode conducts on AC half cycle) and charge the Battery. Hence the charging current is proportional to the duty cycle of the PWM switching on lower side FETs.