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Three-level active neutral-point-clamped (NPC) (3L-ANPC) voltage-source converters (3L-ANPC-VSCs) enable additional switch states and commutations compared to the three-level NPC voltage-source converters (3L-NPC-VSCs). They are used to overcome one important disadvantage of the 3L-NPC-VSC, the unequal semiconductor loss distribution. With an accurate switching model (obtained directly from the measurements), it is possible to improve the junction temperature distribution among the power devices, increasing the 3L-ANPC-VSC output power and/or increasing the frequency and/or decreasing the derating of the converter. This paper presents the characterization of a 4.5-kV–5.5-kA integrated gate-commutated thyristor (IGCT) within a 3L-ANPC phase leg. A quantitative analysis of the switching losses using 5SHY55L4500 IGCTs and D1961SH45T press-pack diodes for a current range from 1 to 4.5 kA and junction temperatures between 25 ^\circ \C and 125 ^\circ \C is presented. The 3L-ANPC phase leg performs 32 different commutations. Each commutation exhibits different switching losses, as a result of the different commutation paths and their stray inductances. This switching energy range is presented and quantified. Finally, a simplified switching loss model considering the maximal switching losses in terms of the commutation current and the junction temperature is presented. [ABSTRACT FROM AUTHOR]

Three-level active neutral-point-clamped (NPC) (ANPC) (3L-ANPC) voltage-source converters (3L-ANPC VSCs) offer three additional switch states and an increase of commutations by a factor of four, compared to the three-level NPC voltage-source converter. This paper presents, for the first time, a detailed analysis of all 3L-ANPC VSC commutations using high-power 5SHY55L4500 integrated gate-commutated thyristors. Starting with a description of the switching states and commutations, a new 3-kV 5-kA medium-voltage 3L-ANPC testbench is described. To verify the function of all commutations, this paper derives suitable switching sequences and analyzes the commutations and switching transients in detail for dc-link voltages of 2.13–2.43 kV and load currents of 3.95–4.36 kA. The experimental investigations show that, although the ANPC commutations substantially differ from NPC commutations, the ANPC commutations do not present critical operating conditions for the power semiconductors or the converters. Thus, all 32 ANPC commutations can be applied in a new medium-voltage converter realization. [ABSTRACT FROM PUBLISHER]

This paper introduces a new iterative design procedure of L and LCL filters for low-voltage active-front-end PWM two-level voltage source converters. The analytical expression of the converter harmonic voltages by Bessel functions is applied to design the filter parameters for defined maximum grid current harmonics. Different filter designs are derived for various resonance frequencies and inductance split factors of LCL filter. The minimum amount of stored energy of passive components is used to select a final filter design. A voltage-oriented control scheme, including active damping, is applied in the (400 V and 50 kVA) experimental setup. Both simulation and experimental investigations are presented to verify the accuracy of the filter design procedure. Finally, the steady state and transient performance of the active front end with different LCL filters are depicted. [ABSTRACT FROM AUTHOR]

This paper compares the expense of power semiconductors and passive components of a (2.3 kV, 2.4 MVA) two-level, three-level neutral-point-clamped, three-level flying-capacitor, four-level flying-capacitor, and five-level series- connected H-bridge voltage source converter on the basis of the state-of-the-art 6.5-, 3.3-, 2.5-, and 1.7-kV insulated gate bipolar transistors for industrial medium-voltage drives. The power semiconductor losses, the loss distribution, the installed switch power, the design of flying capacitors, and the components of an LC sine filter for retrofit applications are considered. [ABSTRACT FROM AUTHOR]

This paper presents a technology review of voltage-source-converter topologies for industrial medium-voltage drives. In this highly active area, different converter topologies and circuits have found their application in the market. This paper covers the high-power voltage-source inverter and the most used multilevel-inverter topologies, including the neutral-point- clamped, cascaded H-bridge, and flying-capacitor converters. This paper presents the operating principle of each topology and a review of the most relevant modulation methods, focused mainly on those used by industry. In addition, the latest advances and future trends of the technology are discussed. It is concluded that the topology and modulation-method selection are closely related to each particular application, leaving a space on the market for all the different solutions, depending on their unique features and limitations like power or voltage level, dynamic performance, reliability, costs, and other technical specifications. [ABSTRACT FROM AUTHOR]

The low-frequency line transformer in todays ac rail vehicles suffers from poor efficiency and a substantial weight. Future traction drives may operate directly from the mains without this transformer. A feasible concept for a transformerless drive system consists of series connected medium voltage converters applying modern high-voltage insulated gate bipolar transistors (HV-IGBTs). In a first design step, the switching characteristics and losses of 6.5-ky IGBTs are compared to 3.3-kV and 4.5-kV IGBTs which are already commercially used in traction applications. Based on the considered HIV-IGBTs, the properties of multilevel converters are analyzed and their applicability to the transformerless system is evaluated. The paper focusses on a loss analysis of the converters. Reliability aspects and harmonic spectra are briefly discussed. Taking these design aspects into account, the three-level neutral point clamped converter turns out to be a reasonable solution to realize line and motor converter modules in a transformerless traction system. [ABSTRACT FROM AUTHOR]