Browsing by Keyword "multilevel converter"
Now showing 1 - 3 of 3
Results Per Page
Sort Options
Item Enhancing Inductive Operation of Low-Capacitance Cascaded H-Bridge StatComs Using Optimal Third-Harmonic Circulating Current(2021-09) Rodriguez, Ezequiel; Leyva, Ramon; Liu, Qingxiang; Townsend, Christopher; Farivar, Glen; Ceballos, Salvador; Pou, Josep; POWER ELECTRONICS AND SYSTEM EQUIPMENTThe cascaded H-bridge (CHB) low-capacitance static compensator (LC-StatCom) has a limited operating range in the inductive region compared to a conventional StatCom due to the inherent large oscillations on the capacitor voltages. This limitation constitutes a great drawback of CHB LC-StatComs. This article presents an effective hardware-free solution to overcome this drawback. The proposed solution is based on the injection of an optimal third-harmonic circulating current to suitably shape the capacitor voltages aiming at avoiding overmodulation. Considering all the effects of the third-harmonic circulating current, the article proposes a reference design that guarantees a prescribed safe operating voltage limit, thus increasing the operational range of the LC-StatCom. The proposed approach takes into account the inherent induced oscillation on the capacitor voltages. This approach has been verified by simulation and experimentally with a laboratory prototype, corroborating the excellent performance that agrees with the theoretical analysis.Item Fault-tolerant neutral-point-clamped converter solutions based on including a fourth resonant leg(2011-06) Ceballos, Salvador; Pou, Josep; Zaragoza, Jordi; Robles, Eider; Villate, José Luis; Martín, José Luis; POWER ELECTRONICS AND SYSTEM EQUIPMENT; RENOVABLES OFFSHORE; GENERALThis paper presents a new three-level topology based on the neutral-point (NP)-clamped converter. An additional leg is added to the basic topology. The main purpose of this leg is to provide the converter with fault-tolerant capabilities. In addition, during normal operation mode, the fourth leg can be used to balance the NP voltage. In this way, the low-frequency voltage oscillations that appear in the NP under some operating conditions are cancelled out effectively. As a result, the modulation strategy of the three main legs of the converter does not have to take care of the voltage balance and can focus on other aspects such as, for instance, minimizing the switching losses of the converter. However, the inclusion of the fourth leg produces some additional losses. A resonant topology is proposed to minimize the switching losses of this leg. Three different fault-tolerant solutions based on the fourth-leg topology are presented. A comparison of these topologies showing their respective advantages and drawbacks is made. Experimental results are presented to show the viability of this approach.Item Performance evaluation of fault-tolerant neutral-point-clamped converters(2010-08) Ceballos, Salvador; Pou, Josep; Robles, Eider; Zaragoza, Jordi; Martin, Jos Lus; POWER ELECTRONICS AND SYSTEM EQUIPMENT; RENOVABLES OFFSHOREThis paper presents a study of the fault tolerance capacity of a neutral-point-clamped converter. Different faults in power semiconductors are considered, and the available postfault states of the converter are shown. In regard of the operation limits, two possible solutions are presented. In these solutions, adding a reduced number of additional components, the behavior of the converter when a switch fails improves considerably. Furthermore, an analysis of the neutral-point voltage balancing conditions after a fault and reconfiguration of the system is also evaluated. Experimental results that prove the correct operation of the proposed topologies are shown.