The Design Of 28V DC-SSPC Based CPLD

The Solid-State Power Controller (SSPC) is used to receive the input logic control cmmand, and turn on or turn off the power to the load according to the load current. if the circuit breaks down as a result of overload, the SSPC would trip according to the characteristic of inverse-delay, the time of delay and the overload-current have a relation of index. The SSPC's trip time depends on the current level, from several seconds to hundreds of microseconds. Even there is a strong current in the load circuit when short circuit, the SSPC would trip in tens of microseconds. Simultaneously, the SSPC feeds back state to the upper controller through status lines.This paper introduces a design of the 28 V DC-SSPC using complex programmable logic device (CPLD).a detailed description of the whole system is presented. The SSPC is composed of control and logic device, solid-state switch device and current-sense device. The control and logic device receives the control command from the upper controller, and orders the switch device connect or disconnect, Simultaneously, offers the upper controller the status and trip signal according to the state of SSPC and the information from the current-sense device. The current-sense device tests the load current, and sends the trip signal to the control and logic device if happened overloads. The solid state switch device uses power MOSFET as soft switch, so, the spark doesn't appear when the circuit turn on or turn off. In the design of programmable logic units, the logic control function of SSPC is accomplished by Very-high-peed-IC Hardware Description Language (VHDL) programmed on CPLD.The basic function of SSPC is accomplished in experiment cooperation. At the last of the paper, the performance characteristic of the SSPC has been presented; the experimental result shows that, it has so many advantages as high integration and speed, strong ability of anti-jamming, high reliability etc. Several SSPC have been integrated in a circuit board and each can works independently. So the power density of the whole system can be improved. There is sizeable value in practical project.