Recent Advances and Industrial Applications of Multilevel Converters
Citations
332 citations
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Cites background from "Recent Advances and Industrial Appl..."
...This is the base of this new family of converters, usually named multilevel converters [13], [14]....
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328 citations
Cites background or methods from "Recent Advances and Industrial Appl..."
...However, there are marked differences between these two PSC schemes, and it is imperative to reveal them: (It is supposed that MMC and CHB have the same number (2 N ) of full-bridge SMs within one phase....
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...However, since CHB does not have the dc terminal and therefore has no circulating current, the traditional PSC scheme to CHB only needs to take consideration of the output voltage harmonics, where the carriers are distributed equally among all the 2N SMs, with a phase shift of π/2N [30]....
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...For the case of the CHB, a large number of isolated dc sources are required when transferring active power, which have to be fed from phase-shifting isolation transformers and multiphase rectifiers, which are very expensive and bulky [29]....
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...(46) D. Comparison Between the Proposed PSC for Full-Bridge MMC and Traditional PSC for CHB At first sight, the proposed PSC scheme for full-bridge MMC are quite similar with the traditional PSC scheme for CHB, as they are both dealing with the full-bridge SM and both capable of increasing the equivalent switching frequency....
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...Particularly, it must be pointed out that the PD-PWM is not very preferred for MMC, as it causes an uneven power distribution among the different SMs [29]....
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298 citations
Cites background from "Recent Advances and Industrial Appl..."
...should be mentioned that the voltage balancing and the unequal share of losses between switching devices in NPC converters can be solved by neutral clamping switches [91]....
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293 citations
Cites background from "Recent Advances and Industrial Appl..."
...Moreover, the high number of levels enables a significant reduction in the device’s average switching frequency without compromising the power quality [3]....
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References
6,472 citations
"Recent Advances and Industrial Appl..." refers background in this paper
...of electronic power conversion for high power applications [1]–[10]....
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"Recent Advances and Industrial Appl..." refers background in this paper
...Classic multilevel converter topologies (only one phase shown): a) Three-level Neutral Point Clamped (NPC) featuring IGCTs, b) Three-level Flying Capacitor (FC) featuring MV-IGBTs and c) Five-level Cascaded HBridge (CHB) featuring LV-IGBTs. followed by a review of recent advances in multilevel…...
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2,296 citations
"Recent Advances and Industrial Appl..." refers background in this paper
...This enables a variable speed range of ± 30% above and below synchronous speed [265], which is sufficient to cover...
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2,254 citations
"Recent Advances and Industrial Appl..." refers background in this paper
...are an important alternative that competes with PWM-CSI in classic applications: compressors, pumps, fans, rolling mills and conveyors to name a few [2], [3], [5]–[9]....
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Related Papers (5)
Frequently Asked Questions (21)
Q2. What contributions have the authors mentioned in the paper "Recent advances and industrial applications of multilevel converters" ?
However, this is still a technology under development, and many new contributions and new commercial topologies have been reported in the last few years. The aim of this paper is to group and review these recent contributions, in order to establish the current state of the art and trends of the technology, to provide readers a comprehensive and insightful review of where multilevel converter technology stands and is heading. The paper first presents a brief overview of the well established multilevel converters, strongly oriented to their current state in industrial applications, to then center the discussion on the new converters that have made their way to industry. Also new promising topologies are discussed. A great part of the paper is devoted to show nontraditional applications powered by multilevel converters, and how multilevel converters are becoming an enabling technology in many industrial sectors. Finally, some future trends and challenges in the further development of this technology are discussed, to motivate future contributions that address open problems and explore new possibilities.
Q3. What future works have the authors mentioned in the paper "Recent advances and industrial applications of multilevel converters" ?
The main reason is to improve efficiency, to extend the device limits, and to have a practically feasible cooling system. However, an assessment comparing the classic and newer multilevel converter topologies in relation to witching and conduction losses is something still pending and is a challenge for further research that can provide valuable insight on the newer topologies. Reliability is also a key ingredient in the future development of multilevel converters. Nonetheless, the possibility to actually use this strength relies on the ability ( accuracy and speed ) to detect and diagnose a fault, so the fault tolerant reconfiguration of the converter can be performed before damage generated by the fault takes place.
Q4. What is the main advantage of the multilevel current source?
Instead of avoiding series connection of devices to reach higher voltage operation while improving voltage waveform quality with a voltage source multilevel converters, the multilevel current source avoids parallel connection of devices and reaches higher output currents while improving current waveform quality.
Q5. What are the main issues that are important to multilevel converters?
Apart from the development of modulation methods and the extension of control methods for multilevel converters, some operation specific issues like capacitor voltage control, common-mode voltage reduction/elimination and fault detection, diagnose and tolerant operation of multilevel converters are equally important.
Q6. What is the main drawback of the phase-shifting transformer?
Although the phase-shifting transformer is needed to enable the series connection of matrix converter cells to reach medium voltage and high power operation, and also improves the input/output power quality, it adds volume and weight affecting negatively one of the features of classic matrix converters.
Q7. What is the future of multilevel converters?
In the future, high voltage SiC power semiconductors could allow extending the applicability of multilevel converters to higher voltage applications, especially for those related to electrical utilities.
Q8. What is the way to avoid the gearbox?
If multipole generators are considered, the gearbox can be avoided by achieving electromechanically the speed conversion between the low speed rotor shaft (around 15 rpm) to the grid frequency (usually 50 or 60 Hz).
Q9. What is the main purpose of multilevel converters?
Multilevel converters can be used to interconnect the photovoltaic strings in a more intelligent way to reach higher voltages closer or even of same value of the point of common coupling.
Q10. How many dcs are needed to produce the same air-gap flux?
In order to produce the same air-gap flux in the machine, the voltage amplitude required for the motor is divided in the two total dc voltages of the converters at both sides of the stator, in two equal or unequal parts (depending on the dc ratio used).
Q11. Why do diode clamped converters have not found industrial acceptance?
they have not found industrial acceptance because the series connection of diodes are necessary to block the increased voltage produced by the series connection of the capacitors above and below the node where the output phase has been clamped.
Q12. Why is the power quality of multiphase machines very welcome?
The power quality in particular is very welcome because of EMI/EMC issues, which imposestrong requirements in the automotive industry.
Q13. What is the important parameter that is strongly related to the modulation stage?
As stressed throughout the paper, one of the most important parameters that is strongly related to the modulation stage is the average device switching frequency.
Q14. What is the key challenge for the development of multilevel converter technology?
Since multilevel converters have better performance and power quality than these two topologies, it is the availability, reliability, efficiency, size and costs the key challenges for the development of multilevel converter technology to make it more competitive against these topologies for these applications.
Q15. What is the main advantage of the use of predictive control in the field of multilevel converters?
In effect, the use of predictive control avoids the need of modulators and linear controllers to generate, for example, controlled currents to the load.
Q16. How many converters are needed to handle the full power of state of the art turbines?
To reach the power levels of state of the art turbines, several converters in parallel are needed to handle the full power, since the current rating is generally high considering the output voltage of the conversion systems is usually around 690 V.
Q17. How much of variable speed can improve efficiency at different load and operating conditions?
it has been shown that even a small % of variable speed operation above and below synchronous speed can improve efficiency at different load and operating conditions.
Q18. What is the main reason why the newer topologies discussed in this paper are able?
This is why many of the newer topologies discussed in this paper are able to generate more voltage levels (5L-HNPC, modular multilevel converter, cascaded matric converter, etc.).
Q19. How can the converter be used for three-phase drives?
It can also be used for three-phase drives with open end stator windings, by connecting two of the converter phases to each winding of the motor.
Q20. What is the need to include between the propulsion converter and the ship switchboard?
As these systems become more complex there is need to include passive or active filters or other FACTS, between the propulsion converter and the ship switchboard to compensate and support the power system.
Q21. What is the main reason why some works propose additional control mechanisms?
Therefore some works propose additional control mechanisms also based on switching state redundancies, to improve the dynamic performance of the voltage balance.