Switching power supply is the source of energy for many electrical equipment Its stability and reliability are the guarantee of the normal operation of the electrical equipment Currently,analog control methods are commonly used to design switching power supply.With the development of digital control chips,the advantages of digital control methods for switching power supply are constantly emerging.Many advanced control algorithms that are difficult to implement in analog control methods can be applied to the control of switching power supply by digital control methods,which greatly enrich the control methods of switching power supply.Power fault management,real-time diagnostics,and monitoring of operational status are easier to implement in digital power supplies.In this paper,DSP was used as the digital control chip,and the digital control unit of the power supply was designed with the phase-shifted full-bridge converter been the controlled object It is convincing that digital control mode can be used to control the switching power supply.In order to control the phase-shifted full-bridge converter,this paper first introduced the working principle of the phase-shifted full-bridge converter and the requirements for the digital control unit,laying the foundation for the design and implementation of the digital control unit Subsequently,the MOSFET drive circuit,the power supply circuit of each chip in the power supply,and the feedback circuit were designed.The power supply circuit takes power from the auxiliary winding of the transformer.At the moment of power-on,the auxiliary winding cannot supply power.Therefore,the start-up circuit were designed in this paper.When these circuits have been designed,the controlled object can work and provide a verification platform for the digital control unit.In order to inplement the digital control unit,the hardware were first designed,including digital ground and analog ground isolation circuit,reset circuit,clock circuit and JTAG interface circuit Then the PID algorithm was introduced.Finally,the output of the control waveform,the A/D conversion of the output voltage,and the digital PID algorithm are realized by programming the DSP.At the end of this paper,the test of the power supply shows that the digital control unit can complete the control task of the phase-shifted full-bridge converter. |