A Carrier-Based Modulation Strategy for Modular Isolated Matrix Rectifiers

An isolated matrix rectifier is promising as it can provide galvanic isolation and maintain high power density due to the high-frequency link when compared with dc link in voltage source converter based solutions. To increase power rating or extend the output dc voltage range, this article proposes the input-parallel–output-parallel (IPOP) and input-parallel–output-series (IPOS) modular structures. These modular structures can achieve favorable features such as modularity and scalability without circulating current issues. To facilitate the operation of an IPOS- or IPOP-connected isolated matrix rectifier, this article proposes a carrier-based modulation strategy. Compared to space vector modulation methods, the proposed carrier-based modulation strategy is preferable due to the low complexity even under a high number of modules. The proposed modulation method can well compensate for the duty cycle loss to reduce current harmonics. Compared to conventional modulation methods, the narrow pulse is reduced to achieve high current quality even at a low modulation index. Moreover, the common-mode voltage is reduced by 50%. Simulation and experimental results are provided to validate the feasibility and performance of the proposed carrier-based modulation method.