This paper introduces a novel discontinuous pulse width modulation (DPWM) method to minimize the dc-link ripple current in back-to-back converters. DPWM is used in power converters to curtail the stress on the switching devices, therefore, extending the lifespan. However, as the conventional DPWM is used in a back-to-back topology, the ripple current of the dc-link severely increases during the regions when the power switches are clamped to the dc-bus. Furthermore, the dc-link ripple current reaches the amplitude value when the power switches of both converters are clamped to different dc-link buses.
As a result, the life-span of the dc-link capacitor decreases as it endures more stress. To surmount this issue, the reference voltages should be obtained considering the intervals with the increased ripple current of the dc-link. It is achieved by adjusting the zero-sequence component to match the clamping states of both inverters. The efficacy and performance of the proposed method are demonstrated via the PSIM simulation and the experimental results.
