Symmetrical power supply for 42 v automotive applications

The Positive Channel Two Input Two Output (PCTITO) converter is a third order MIMO DC-to-DC unidirectional and non-isolated switching converter that is de- rived from the non-inverting buck-boost converter. Negative and Dual Channel TITO converters are also presented. In steady state one of the PCTITO outputs is positive while the other is negative. Although the outputs could be regulated to provide dif- ferent absolute values, an interesting application of the new converters is to provide symmetrical outputs (i.e., 15 V) to supply balanced loads. Since the absolute value of the outputs could be greater or smaller than the input voltage, the PCTITO con- verter will be suitable for present 14 V (from 9 to 16 V) or for future 42 V (from 30 to 50 V) automotive voltage distribution buses. To regulate the outputs, two in- phase equal-switching frequency PWM-based multivariable control loops have been designed. The closed-loop system must provide low audiosusceptibility and good line and load regulation at both outputs. In addition, the common mode voltage between the two outputs that could appear in unbalanced load operation has to be minimized. With these general guidelines, several control parameter adjustments have been con- sidered, validated using an averaged model of the system, and tested by simulation.