2008 Volume 34 Pages 159-166
This paper presents new types of digitally emulated current mode control soft switching DC-DC converters using FPGA. The proposed system can use A/D converter with few MSPS conversion rate. The A/D converter fetches only one or few points of the real reactor curent during “off-state” of main switch. Using the degitalized reactor current, both the vallery point and the reactor current during “on-state” of main switch in the next switching cycle are emulated by FPGA. Comparing the emulated current with the reference current, the coincident point of them is found out, and the main switch, which is turned on at the bigining of the switching cycle, is turned off at the same point. These porcedures are repeated in every cycle.
The implemented prototype is the soft switching DC-DC boost converter with such ratings as input voltage of dc60V, output voltage of dc200V, output current of dc2A and switching frequency of 100kHz. The applied control system is newly proposed “Fixed one point detection of reactor curent” using FPGA of Spartan 3 type XC3S400-4 and two types of AID converters.
It is demonstrated that the prototype is stably implemented without sub-harmonic oscillation by the aid of the digital slope-compensation. The output characteristics are also included the step response from 10% to full load condition with satisfactory results.
