42-V/3-V Watkins-Johnson converter for automotive use

In this paper, the Watkins-Johnson (WJ) converter was found to best step down the future automotive 42-V power network to 3 V or lower for the supply of microcontrollers and semiconductors. The particularity of the WJ converter is that it only employs a tapped-inductor and three other components. The use of a tapped-inductor is well-known and gives an extra-degree of freedom by the insertion of the winding ratio of the tapped-inductor into the transfer function of the WJ converter. It also permits the duty cycle to be adjusted to a value at which the efficiency of the converter is improved. The converter can be slightly modified and used as a multiple output converter while employing few components, diminishing the weight, size, cost, and complexity of a system. Practical test results for the single-output WJ converter are presented.