Ripple-Free Boost-Mode Power Supply Using Photonic Power Conversion

Photonic power converters (PPCs) are a class of photovoltaic devices designed for efficient conversion of monochromatic (laser or LED) light to electricity. These devices are composed of multiple p-n junction diodes arranged in a tandem configuration and connected in series. They have reached high energy conversion efficiencies (70%) and areal power densities of 100 W/cm(2). When these devices are illuminated with a high-efficiency diode laser, they can provide isolated dc-dc conversion from the laser voltage (< 2.3 V) to the open-circuit voltage of the PPC (1.2 to 23 V) with low capacitance and low conducted electromagnetic interference (EMI) compared to conventional switching power converters. The voltage conversion ratio is controlled by varying the number of p-n junctions in the PPC from 1 to 20 in demonstrated designs. In this paper, we demonstrate the use of photonic power conversion within two new applications. First, the laser/PPC unit is applied as a linear photonic boost converter, producing a regulated 12 V output stepped-up from a 3.3 V input to the control board. Output ripple is negligible as compared with a switching boost converter of similar size. Efficiency of this linear, regulated dc-dc conversion system was 12.7%, compared with a 77.6% reference switch-mode converter. Power density was 0.18 W/cm(3), compared with 1.5 W/cm(3) for the reference. Relative to switch-mode power conversion, the photonic technology has lower efficiency and lower power density, but superior isolation and rejection of ripple and EMI. Both technologies are highly scalable. For the second application, the same unit is applied to power a 650-V SiC MOSFET gate driver requiring high galvanic isolation, demonstrating a 20 dB reduction in conducted-current EMI from the power circuit into the low-voltage control systems.