A Medium-Voltage Motor Drive With a Modular Multilevel PWM Inverter
TL;DR: In this article, the authors describe the control and operating performance of a modular multilevel PWM inverter for a transformerless medium-voltage motor drive, where the inverter is prominent in the modular arm structure consisting of a cascaded stack of multiple bidirectional choppercells.
Abstract: This paper describes the control and operating performance of a modular multilevel PWM inverter for a transformerless medium-voltage motor drive. The inverter is prominent in the modular arm structure consisting of a cascaded stack of multiple bidirectional chopper-cells. The dominant ac-voltage fluctuation with the same frequency as the motor (inverter) frequency occurs across the dc capacitor of each chopper-cell. The magnitude of the voltage fluctuation is inversely proportional to the motor frequency. This paper achieves theoretical analysis on the voltage fluctuation, leading to system design. A downscaled model rated at 400 V and 15 kW is designed and built up to confirm the validity and effectiveness of the nine-level (17-level in line-to-line) PWM inverter for a medium-voltage motor drive.
Citations
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TL;DR: A general overview of the basics of operation of the MMC along with its control challenges are discussed, and a review of state-of-the-art control strategies and trends is presented as mentioned in this paper.
Abstract: The modular multilevel converter (MMC) has been a subject of increasing importance for medium/high-power energy conversion systems. Over the past few years, significant research has been done to address the technical challenges associated with the operation and control of the MMC. In this paper, a general overview of the basics of operation of the MMC along with its control challenges are discussed, and a review of state-of-the-art control strategies and trends is presented. Finally, the applications of the MMC and their challenges are highlighted.
1,765 citations
Cites methods from "A Medium-Voltage Motor Drive With a..."
...The application of the MMC in quadrature torque motor drives has been investigated in [106] and [107]....
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TL;DR: In this paper, the modular multilevel cascade converter (MMCC) family based on cascade connection of multiple bidirectional chopper cells or single-phase full-bridge cells is classified from circuit configuration.
Abstract: This paper discusses the modular multilevel cascade converter (MMCC) family based on cascade connection of multiple bidirectional chopper cells or single-phase full-bridge cells. The MMCC family is classified from circuit configuration as follows: the single-star bridge cells (SSBC); the single-delta bridge cells (SDBC); the double-star chopper cells (DSCC); and the double-star bridge cells (DSBC). The term MMCC corresponds to a family name in a person while, for example, the term SSBC corresponds to a given name. Therefore, the term “MMCC-SSBC” can identify the circuit configuration without any confusion. Among the four MMCC family members, the SSBC and DSCC are more practical in cost, performance, and market than the others although a distinct difference exists in application between the SSBC and DSCC. This paper presents application examples of the SSBC to a battery energy storage system (BESS), the SDBC to a static synchronous compensator (STATCOM) for negative-sequence reactive-power control, and the DSCC to a motor drive for fans and blowers, along with their experimental results.
1,018 citations
Cites background or result from "A Medium-Voltage Motor Drive With a..."
...This is a significant difference in experimental system configuration between this present paper and the previous paper [ 23 ]....
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...In [22] and [ 23 ], a detailed explanation of the averaging and balancing control methods including their control block diagrams is given....
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...Fig. 12(a) shows the circuit configuration of the DSCC for a motor drive [22], [ 23 ]....
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TL;DR: It is shown that the sum capacitor voltage in each arm often can be considered instead of the individual capacitor voltages, thereby significantly reducing the complexity of the system model.
Abstract: Theory for the dynamics of modular multilevel converters is developed in this paper. It is shown that the sum capacitor voltage in each arm often can be considered instead of the individual capacitor voltages, thereby significantly reducing the complexity of the system model. Two selections of the so-called insertion indices, which both compensate for the sum-capacitor-voltage ripples, are considered. The dynamic systems which respectively result from these selections are analyzed. An effective dc-bus model, which takes into account the contribution from the submodule capacitors, is obtained. Finally, explicit formulas for the stationary sum-capacitor-voltage ripples are derived.
580 citations
TL;DR: In this paper, the authors investigated how the arm currents and capacitor voltages interact when the submodules are connected and bypassed in a sinusoidal manner, and derived the analytical expression for the arm current.
Abstract: The fundamental frequency component in the arm currents of a modular multilevel converter is a necessity for the operation of the converter, as is the connection and bypassing of the submodules. Inevitably, this will cause alternating components in the capacitor voltages. This paper investigates how the arm currents and capacitor voltages interact when the submodules are connected and bypassed in a sinusoidal manner. Equations that describe the circulating current that is caused by the variations in the total inserted voltage are derived. Resonant frequencies are identified and the resonant behaviour is verified by experimental results. It is also found that the effective values of the arm resistance and submodule capacitances can be extracted from the measurements by least square fitting of the analytical expressions to the measured values. Finally, the analytical expression for the arm currents is verified by experimental results.
511 citations
01 Nov 2010
TL;DR: In this article, an operating mode for low phase current frequencies which enables MMLCs to magnetize and start induction machines with quadratic torque loads is presented and the achievable torque-speed characteristic is derived.
Abstract: Modular Multilevel Converters (MMLC) based on series connected half-bridges achieve high phase voltages, need little or no filters and feature redundancy and modularity. In contrast to the similar series connected H-bridge converters an expensive and lossy transformer is not necessary. The capacitors buffer power fluctuations at fundamental and second harmonic frequency, therefore the capacitor voltage ripple magnitude increases with decreasing phase current frequencies and will become infinite at zero phase current frequency. This is a problem in variable speed drive applications where phase current frequencies from starting from zero are needed. An operating mode for low phase current frequencies which enables MMLCs to magnetize and start induction machines with quadratic torque loads is presented and the achievable torque-speed characteristic is derived. It is also shown that rotor flux optimization also reduces the capacitor voltage ripple at low torque. The method has successfully been tested in an experimental converter.
416 citations
Cites background from "A Medium-Voltage Motor Drive With a..."
...However the capacitor voltage ripple and the peak capacitor voltage of MMLC PEBBs are inversely proportional to the phase frequency and thus they cannot provide very low frequency or DC phase currents without additional measures [1], [4]....
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...Experiments with MMLC induction motor drives have already been conducted at frequencies above half nominal [2], [4]....
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References
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TL;DR: In this paper, a new instantaneous reactive power compensator comprising switching devices is proposed, which requires practically no energy storage components, and is based on the instantaneous value concept for arbitrary voltage and current waveforms.
Abstract: The conventional reactive power in single-phase or three- phase circuits has been defined on the basis of the average value concept for sinusoidal voltage and current waveforms in steady states. The instantaneous reactive power in three-phase circuits is defined on the basis of the instantaneous value concept for arbitrary voltage and current waveforms, including transient states. A new instantaneous reactive power compensator comprising switching devices is proposed which requires practically no energy storage components.
3,331 citations
"A Medium-Voltage Motor Drive With a..." refers background in this paper
...3, p and q represent the instantaneous active and reactive power on the ac side of the inverter [15], [16], and pd is the dc-side instantaneous active power defined as:...
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Book•
01 Jan 2007
TL;DR: The p-q theory in three-phase, four-wire Shunt Active Filters as discussed by the authors has been applied to power flow control in power electronics equipment and has been shown to be useful in many applications.
Abstract: Preface. 1. Introduction. 1.1. Concepts and Evolution of Electric Power Theory. 1.2. Applications of the p-q Theory to Power Electronics Equipment. 1.3. Harmonic Voltages in Power Systems. 1.4. Identified and Unidentified Harmonic-Producing Loads. 1.5. Harmonic Current and Voltage Sources. 1.6. Basic Principles of Harmonic Compensation. 1.7. Basic Principles of Power Flow Control. References. 2. Electric Power Definitions: Background. 2.1. Power Definitions Under Sinusoidal Conditions. 2.2. Voltage and Current Phasors and the Complex Impedance. 2.3. Complex Power and Power Factor. 2.4. Concepts of Power Under Non-Sinusoidal Conditions -Conventional Approaches. 2.5. Electric Power in Three-Phase Systems. 2.6. Summary. References. 3 The Instantaneous Power Theory. 3.1. Basis of the p-q Theory. 3.2. The p-q Theory in Three-Phase, Three-Wire Systems. 3.3. The p-q Theory in Three-Phase, Four-Wire Systems. 3.4. Instantaneous abc Theory. 3.5. Comparisons between the p-q Theory and the abc Theory. 3.6. Summary. References. 4 Shunt Active Filters. 4.1. General Description of Shunt Active Filters. 4.2. Three-Phase, Three-Wire Shunt Active Filters. 4.3. Three-Phase, Four-Wire Shunt Active Filters. 4.4. Shunt Selective Harmonic Compensation. 4.5. Summary. References. 5 Hybrid and Series Active Filters. 5.1. Basic Series Active Filter. 5.2. Combined Series Active Filter and Shunt Passive Filter. 5.3. Series Active Filter Integrated with a Double-Series Diode Rectifier. 5.4. Comparisons Between Hybrid and Pure Active Filters. 5.5. Conclusions. References. 6 Combined Series and Shunt Power Conditioners. 6.1. The Unified Power Flow Controller (UPFC). 6.2. The Unified Power Quality Conditioner (UPQC). 6.3. The Universal Active Power Line Conditioner (UPLC). 6.4. Summary. References. Index.
2,038 citations
"A Medium-Voltage Motor Drive With a..." refers background in this paper
...3, p and q represent the instantaneous active and reactive power on the ac side of the inverter [15], [16], and pd is the dc-side instantaneous active power defined as:...
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Book•
01 Jan 2006
TL;DR: In this article, the authors present a model for high-power switchings with SCR rectifiers and demonstrate how to use SCR Rectifiers to control high power switchings.
Abstract: Preface. Part One Introduction. 1. Introduction. 1.1 Introduction. 1.2 Technical Requirements and Challenges. 1.3 Converter Configurations. 1.4 MV Industrial Drives. 1.5 Summary. References. Appendix. 2. High-Power Semiconductor Devices. 2.1 Introduction. 2.2 High-Power Switching Devices. 2.3 Operation of Series-Connected Devices. 2.4 Summary. References. Part Two Multipulse Diode and SCR Rectifiers. 3. Multipulse Diode Rectifiers. 3.1 Introduction. 3.2 Six-Pulse Diode Rectifier. 3.3 Series-Type Multipulse Diode Rectifiers. 3.4 Separate-Type Multipulse Diode Rectifiers. 3.5 Summary.(c) References. 4. Multipulse SCR Rectifiers. 4.1 Introduction. 4.2 Six-Pulse SCR Rectifier. 4.3 12-Pulse SCR Rectifier. 4.4 18- and 24-Pulse SCR Rectifiers. 4.5 Summary. References. 5. Phase-Shifting Transformers. 5.1 Introduction. 5.2 Y/Z Phase-Shifting Transformers. 5.3 /Z Transformers. 5.4 Harmonic Current Cancellation. 5.5 Summary. Part Three Multilevel Voltage Source Converters. 6. Two-Level Voltage Source Inverter. 6.1 Introduction. 6.2 Sinusoidal PWM. 6.3 Space Vector Modulation. 6.4 Summary. References. 7. Cascaded H-Bridge Multilevel Inverters. 7.1 Introduction. 7.2 H-Bridge Inverter. 7.3 Multilevel Inverter Topologies. 7.4 Carrier Based PWM Schemes. 7.5 Staircase Modulation. 7.6 Summary. References. 8. Diode-Clamped Multilevel Inverters. 8.1 Introduction. 8.2 Three-Level Inverter. 8.3 Space Vector Modulation. 8.4 Neutral-Point Voltage Control. 8.5 Other Space Vector Modulation Algorithms. 8.6 High-Level Diode-Clamped Inverters. 8.7 Summary. References. Appendix. 9. Other Multilevel Voltage Source Inverters. 9.1 Introduction. 9.2 NPC/H-Bridge Inverter. 9.3 Multilevel Flying-Capacitor Inverters. 9.4 Summary. References. Part Four PWM Current Source Converters. 10. PWM Current Source Inverters. 10.1 Introduction. 10.2 PWM Current Source Inverter. 10.3 Space Vector Modulation. 10.4 Parallel Current Source Inverters. 10.5 Load-Commutated Inverter (LCI). 10.6 Summary. References. Appendix. 11. PWM Current Source Rectifiers. 11.1 Introduction. 11.2 Single-Bridge Current Source Rectifier. 11.3 Dual-Bridge Current Source Rectifier. 11.4 Power Factor Control . 11.5 Active Damping Control. 11.6 Summary. References. Appendix. Part Five High-Power AC Drives. 12. Voltage Source Inverter-Fed Drives. 12.1 Introduction. 12.2 Two-Level VBSI-Based MV Drives. 12.3 Neutral-Point Clamped (NPC) Inverter-Fed Drives. 12.4 Multilevel Cascaded H-Bridge (CHB) Inverter-Fed Drives. 12.5 NPC/H-Bridge Inverter-Fed Drives. 12.6 Summary. References. 13. Current Source Inverter-Fed Drives. 13.1 Introduction. 13.2 CSI Drives with PWM Rectifiers. 13.3 Transformerless CSI Drive for Standard AC Motors. 13.4 CSI Drive with Multipulse SCR Rectifier. 13.5 LCI Drives for Synchronous Motors. 13.6 Summary. References. 14. Advanced Drive Control Schemes. 14.1 Introduction. 14.2 Reference Frame Transformation. 14.3 Induction Motor Dynamic Models. 14.4 Principle of Field-Oriented Control (FOC). 14.5 Direct Field-Oriented Control. 14.6 Indirect Field-Oriented Control. 14.7 FOC for CSI-Fed Drives. 14.8 Direct Torque Control. 14.9 Summary. References. Abbreviations. Appendix Projects for Graduate-Level Courses. P. 1 Introduction. P. 2 Sample Project. P. 3 Answers to Sample Project. Index. About the Author.
1,870 citations
"A Medium-Voltage Motor Drive With a..." refers background in this paper
...Attention has been paid to medium-voltage adjustable-speed motor drives for energy savings of fans, blowers, compressors and pumps [10], [11]....
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TL;DR: In this article, two types of pulsewidth-modulated modular multilevel converters (PWM-MMCs) with focus on their circuit configurations and voltage balancing control are investigated.
Abstract: A modular multilevel converter (MMC) is one of the next-generation multilevel converters intended for high- or medium-voltage power conversion without transformers. The MMC is based on cascade connection of multiple bidirectional chopper-cells per leg, thus requiring voltage-balancing control of the multiple floating DC capacitors. However, no paper has made an explicit discussion on voltage-balancing control with theoretical and experimental verifications. This paper deals with two types of pulsewidth-modulated modular multilevel converters (PWM- MMCs) with focus on their circuit configurations and voltage-balancing control. Combination of averaging and balancing controls enables the PWM-MMCs to achieve voltage balancing without any external circuit. The viability of the PWM-MMCs, as well as the effectiveness of the voltage-balancing control, is confirmed by simulation and experiment.
1,506 citations
"A Medium-Voltage Motor Drive With a..." refers background or methods in this paper
...1(a), iP u and iN u are the positive and negative arm currents, iu is the motor current, and iZu is the circulating current along the u-phase dc loop [9]....
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...The authors of this paper have proposed the following balancing controls in [9]: 1) the control using the polarity of the arm current, 2) the control using the arm current, and 3) the control using the motor current....
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...Reference [9] has made a detailed explanation of the averaging and balancing controls, including their control block diagrams....
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...The authors of this paper have proposed a stable voltage control that combines averaging and balancing controls [9]....
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05 Dec 2005
TL;DR: This paper deals with general pure active filters for power conditioning, and specific hybridactive filters for harmonic filtering of three-phase diode rectifiers.
Abstract: Unlike traditional passive harmonic filters, modern active harmonic filters have the following multiple functions: harmonic filtering, damping,isolation and termination, reactive-power control for power factor correction and voltage regulation, load balancing, voltage-flicker reduction, and/or their combinations. Significant cost reductions in both power semiconductor devices and signal processing devices have inspired manufactures to put active filters on the market. This paper deals with general pure active filters for power conditioning, and specific hybrid active filters for harmonic filtering of three-phase diode rectifiers.
954 citations
"A Medium-Voltage Motor Drive With a..." refers background in this paper
...2-kV IGBTs into the motor drive [18], [19]....
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