Ultrafast Optically Controlled Power Switch: A General Design and Demonstration With 3.3 kV SiC MOSFET

Optically controlled high-voltage power devices are desirable for grid and renewable energy applications. This work proposes a hybrid device consisting of a high-voltage, high-power transistor, and two low-voltage, low-power photodiodes (PDs) to achieve the optically controlled power switching. This hybrid device is driven by complementary optical signals, which are applied to two PDs to charge and discharge the capacitances of the power device in the turn-OFF and turn-ON transients. This design can fast switch unipolar devices with an ultralow optical power, as only the driver signals are optically modulated but the device current is not photogenerated. We experimentally demonstrate this design using two InGaAs PDs to switch a 3.3 kV SiC MOSFET, the highest-voltage industrial unipolar device available. Under an optical power of 21.7 mW applied on each PD, 1500 V/3 A hard-switching is demonstrated with a rise time and fall time of 152 and 215 ns, respectively. This represents the highest switching voltage, fastest switching speed, and highest ratio between the power capacity and optical power reported in optically controlled unipolar power switches. The switching dynamics are also modeled to project the frequency scalability of this hybrid device. In addition to achieving a record performance, this general device design is also applicable to the future development of integrated optics for power electronics.