Voltage Injection Based MPDPC Technique for Individual Phase Loss Reduction in Active Front-End Rectifier

Active front-end (AFE) rectifiers are a well-known solution in industries due to bidirectional power flow, sinusoidal line currents, and dc-link voltage adjustment. Typically, in three-phase AFE rectifiers, the power is distributed evenly among the phase legs, aiming for a natural balancing of aging over time. However, uneven thermal stress caused by different switching frequencies or design of cooling system and prior replacement of failure power switches might create an unavoidable aging mismatch between phase legs of AFE rectifier. In this article, a per-phase model predictive direct power control with offset voltage injection is proposed. The proposed method notably reduces power loss of the weakest phase to improve the lifespan of circuit and reduce maintenance costs. The power components of the AFE rectifier are regulated utilizing predicted rectifier voltages, which are changed by adding proper zero-sequence signal to decrease losses in the most aging leg. The minimum power loss of the weakest leg involves avoiding changing the corresponding switching state for two-thirds of the source period. Simulations and experiments are conducted to validate the developed technique.