Extended multilevel converters: an attempt to reduce the number of independent DC voltage sources in cascaded multilevel converters

Abstract

The cascaded multilevel converters are the most favorable topologies of multilevel converters. However, they have the main disadvantage of using multiple independent dc voltage sources. This study proposes new cascaded multilevel converter topologies in which the number of independent dc voltage sources is reduced. In the proposed topologies, for a specific number of voltage levels, the number of dc voltage sources is halved. Beside the number of dc voltage sources, in one of the proposed topologies the number of switches is also reduced in comparison with that of the conventional cascaded multilevel converter. A new modified pulse-width modulation method is presented to control the proposed topologies. Also, a method for compensating non-ideality of the dc voltage sources is presented. Simulation results using PSCAD software as well as experimental results from a laboratory-scale prototype are presented to verify the proposed multilevel converters.

Nine Level H Bridge Grid Connected Inverter Operated Photovoltaic Module Using Matlab

“…The pair of switches (S1, S2) and (S3, S4) with proper switching states as listed in Table 1 gives the output voltage levels -V/2, -3V/2, +V/2 and +3V/2. ↑ -Charge ↓ -Discharge To enable natural balancing of capacitors and reduce one source, two capacitors and one DC source are employed (14) the proposed MHB module is investigated through an inductive load as shown in Figure 2. The voltage balance between two capacitors is assured by a charge balance control method (15).…”

A Cascaded Modular Multilevel Inverter Topology Using Novel Series Basic Units with a Reduced Number of Power Electronic Elements

“…6. Suggested CMMLI topologies in (a) Ref [12] (b) Ref [14] (c) Ref [20] (d) Ref [21]& [25] (e) Ref [22] (f) Ref [24] (g) First Top of Ref [26] (h) Second Top of Ref [26].…”

“…In the symmetric comparison, the proposed topology based on the first recommended algorithm is compared with the MLVSIs proposed in [12], [14], [20]- [22], [25] and the two suggested structures in [26] in terms of the number of required power switches or gate drivers, the total value of the blocked voltage, the maximum number of current path components and the number of required dc link voltages for the specific number of output voltage levels ( N 25 level  ) that can be generated by all of the structures. These comparisons are summarized by Table II which can corroborate the salient advantages of the proposed topology compared to the existing structures in terms of most of the key parameters.…”

“…In this case, although the variety of isolated dc voltage sources is high, the number of generated output voltage levels is a lot more than the symmetric structures which attempts to achieve a better power quality through a lower value of the THD and a reduced number of power electronic elements [22]- [26]. Nevertheless, using an additional full H-bridge unit in the new developed MLVSIs usually leads to an increase in the number of power switches and in the maximum number of current path components which can enhance the total conduction loss and degrade the overall efficiency thereby.…”

Compound-Type Hybrid Energy Storage System and Its Mode Control Strategy for Electric Vehicles

“…However, these studies fail to reduce the times of energy converted [17], [20]- [24]. Multi-output DC-DC converter topologies have also been generated on the basis of multiple or cascaded converter configurations [25], [26]. Considering the cost and the efficiency, these configurations may be not suitable for the application of HESS in EVs.…”