Constant voltage/current with slowly rising control for high power DC-DC converter based on FPGA digital control

Abstract

In this paper, a hill-climbing method is adopted to control the output of full bridge circuit to achieve desired constant voltage/current output. A novel technology also is presented to control the rising time of the DC converter output. The hardware implementation of this digital control is based on the Field Programmable Gate Array (FPGA) digital chip. The proposed hill-climbing control algorithm can automatically adjust the Pulse Width Modulation (PWM) control parameter to handle the DC converter output approaching desired one. High frequency power supply with DC switching circuit has been paying more attention to its small size, light weight, and small electromagnetic interference. Digital control has many different control modes than continuous circuit one, and digital control can be updated at any control mode, unlike continuous circuit design cannot be changed once it is completed. That is, the merit of digital control is flexible and programmable which is why the FPGA digital control used in this paper to control the DC switching circuit. We obtain the FPGA execution code by establishing its corresponding Matlab/Simulink simulation model. After meeting simulation test, the Matlab/Simulink model can be directly transformed into Hardware Description Language (HDL) code. This greatly saving the time of writing HDL code which often is a barrier to the electrical engineer. Finally, a high power, 7.2 KW, DC-DC converter experiment is presented to confirm the feasibility of the proposed control method and design procedure.