Development of a 1.5kW digital controlled DC-DC converter for Mild Hybrids

This paper presents a development of a 1.5kW digital controlled DC-DC converter for Mild Hybrids. DC-DC converters for Mild Hybrids must support not only power control but also communications such as controller area network (CAN) and RS232. In this paper, a 1.5kW digital controlled DC-DC converter for Mild Hybrids is developed with a single MCU for both of power control and communications. The MCU used in this development is dsPIC33FJ128MC802 with a fixed control period of 20μs and outputs 100kHz switching frequency to the DC-DC converter developed. In this DC-DC converter, the range of input voltage is 16 to 30V and that of output voltage is 11 to 15V. The maximum load current at the nominal output voltage of 14V is 110A. In order to obtain a stable feedback loop, a PI compensation is designed by using MATLAB SISOTOOL. In this PI design, delays due to analog-to-digital conversion and PWM signal generation are considered and anti-windup strategy for suppression of lager overshoot voltage at the output is also employed. Through the experiment of the developed DC-DC converter, it is confirmed that the converter normally operated for the specified line and load conditions. And it is obtained that the line and load regulation are lower than 0.45% and 0.5% respectively, and the maximum efficiency is 95% at nominal line and half load.