Dual forward converter schematic diagram

When a larger output power is required, a dual forward converter circuit with voltage superposition is generally adopted, as shown in the figure. Circuit features: (1) Two forward converter circuits are connected in parallel, T1 and T2 are driven in anti-phase 180o, the power is doubled, the output frequency is doubled, and the ripple and dynamic response are improved; (2) S1 and S2 are connected in series (S3 and S4 are connected in series), and the withstand voltage of the switch tube is halved; (3) The feedback coil is cancelled, V1, V2, VpV4 are all energy feeding paths, which reduces the requirements for the manufacturing process of the transformer; (4) It has a dead zone limitation characteristic, and the two parts of the circuit do not have a common conduction problem, and the reliability is high. Characteristic analysis: Forward: When turned on, the input feeds power to the load, and when turned off, L supplies power to the load. Withstand voltage: Single tube forward, the maximum voltage of the switch tube is 2Uin. Double tube forward: The maximum voltage of the switch tube is Uin. Transformer: The transformer utilization rate is not high (only the first quadrant of the hysteresis loop is used), and a feed coil must be added in the process. Application: Since the dual-tube forward parallel circuit has high output power, doubled output square wave frequency, easy filtering, and half the voltage resistance of the switch tube (approximately the input voltage Ui), it is widely used in high-power conversion circuits and is considered to be one of the main circuits with high reliability and uncomplicated manufacturing.