Hybrid CCM-DCM Operation of High Gain Quadratic Extended-Duty-Ratio Boost Converter with Low Device Stress

This paper proposes a hybrid continuous-discontinuous mode (CCM-DCM) operation of non-isolated quadratic extended-duty-ratio (Q-EDR) boost converter for low power, high gain applications. The input inductors are operated in continuous conduction mode (CCM) while the EDR stage inductors are operated in discontinuous conduction mode (DCM) to attain the benefits of both CCM and DCM operation. The low input current ripple due to interleaving and low voltage stress of the EDR stage switches are retained. With the proposed hybrid mode of operation, the inductance value of EDR stage inductor reduces significantly. A further reduction in switch voltage is achieved during turn-on transition in the proposed operation, leading to significant reduction in turn-on switching losses. This enables converter operation at higher switching frequency, thus, reducing the size of EDR inductors by 45% in this case. The proposed concept is verified experimentally by a 2-phase Q-EDR hardware prototype operating at 30 V-40 V to 400 V output, easily achieving a gain above 12 at duty close to 0.54. The converter is able to achieve a peak efficiency of 95.5% at 300 W, 135 kHz switching frequency with all silicon switches.