Design Of Synchronous Control For A Dual-Output Forward Converter

Cross-regulation has a great impact on performance of multi-output forward converter. When the cross-regulation is poor, the slave output voltage accuracy is very low. In order to improve cross-regulation, many control methods are proposed currently. Such as: optimization of transformer design, but its effect is not significant; weighted voltage control method, the master output voltage accuracy is reduced in this method, the error is redistributed between master and slave output, but it is not eliminated; a DC / DC or linear regulator output is added in slave output; this method improves the accuracy of the slave output, but greater power loss and power costs are brought.The master and slave output are fixed in traditional multi-output forward converter, the master and slave output are not exchanged. The causes of dual-output forward converter cross regulation is analyzed in this paper. For this problem, a synchronization control model for a dual-output is proposed in this paper, and soft and hardware are completed. The master and slave output can be judged through this proposed control strategy. That is when the master output is controlled with PID, the slave output is also controlled with a voltage closed-loop control. So the cross regulation of dual-output forward converter is improved.Base on the theoretical analysis, it is tested that this control strategy is right by using simulation of MATLAB / Simulink software. In order to validate the theory and simulation, a dual output forward DC-DC converter is made by using a digital controller STM32F103RBT6. Its input voltage DC 24 ~ 48 V, the two outputs are 5V/3A and 15V/1A power. It is tested that the synchronous control strategy has significantly improved on cross-regulation of dual output power supply.