How do you use a common H bridge - FET Switchs for both inverter and battery charger application in a Sinewave offline UPS using PIC16F72 Micro controller?

Answer 1

In a sine wave inverter, during inverter operation the four switches of the H bridge are switched using sine wave PWM signals normally generated using a µ-controller or an analog circuit. One upper and the opposite lower switch is switched in sequence with necessary delay between the two. This will continue for one half cycle and the other two switch pairs are switched during the next half cycle to make a full sine wave output. During Mains mode, the same transformer used to inverter and boost voltage to line voltage in inverter mode is connected to the mains power using a relay. A bridge less rectification principle is used to charge the battery by boosting the voltage produced in the transformer primary using the inductance of the winding,by switching the lower MOSFET banks.. The lower MOSFET switches are switched and upper switches kept turned OFF, The body diodes of the upper MOSFETS will act as rectifiers . The pulse width of the switching pulses of the lower bank is proportional to the output current , voltage. By varying the pulse width variable currents can be obtained. The current is sampled and fed back to the control circuit to limit and obtain variable power levels. PF correction can also be obtained during charging using PF correction control circuit in the charging mode.