Full bridge power conversion circuit

A full-bridge converter circuit can be formed by replacing the two electrolytic capacitors in the half-bridge converter circuit with two other high back-voltage power transistors and matching them with appropriate drive circuits, as shown in the figure. VTl, VT2, VT3, and VT4 form four bridge arms. High frequency transformer T is connected between them. VTl, VT4 and VT2, VT3 on the opposite arm are excited by the drive circuit and turned on alternately, converting the DC input voltage into a high-frequency square wave AC voltage. Its working process is the same as that of push-pull power conversion circuit. In this way, when the high-frequency transformer is working, the voltage obtained by its primary coil is the power supply voltage. It is twice the output voltage of the half-bridge circuit, and the withstand voltage of each transistor is still the power supply voltage, doubling the output power. If the current reaches the level of the half-bridge circuit, that is, if the current is doubled, the output power can be increased by 4 times. The main disadvantage of the full-bridge circuit is that it requires four sets of transistor base drive circuits that are insulated from each other, which increases the cost and complexity of the control drive circuit.