Diode open-circuit fault research on the parallel-connected 24-pulse rectifier with DC-side passive harmonic reduction circuit

Multipulse rectifiers (MPRs) with dc side passive harmonic reduction circuits often have lower input current total harmonic distortion (THD) values and power losses, that fulfill power requirements for many industrial occasions. In addition to normal operation properties, fault tolerance is another aspect closely related to overall performance of MPRs. This article takes a common parallel-connected 24-pulse rectifier as an example, researches its operation characteristics and fault tolerance under diode open-circuit fault conditions. Operation modes under single or double diodes open-circuit fault in the main circuit, as well as diode open-circuit fault in the dc side harmonic reduction circuit are discussed in details. It can be determined that load voltage is the characteristic parameter that directly reflects the fault information. Related simulation and experimental verifications are performed, all results are consistence with theoretical waveforms. This article provides useful guidance for fault handling and clarifies factors related to the reliability of MPRs, which are helpful for novel MPRs design.