EPE Association: EPE 2005 - Topic 05-3a - DS: Converter control sets and modulation strategies

EPE 2005 - Topic 05-3a - DS: Converter control sets and modulation strategies
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2005 - Conference > EPE 2005 - Topic 05: MODULATION STRATEGIES AND SPECIFIC CONTROL METHODS FOR STATIC CONVERTERS > EPE 2005 - Topic 05-3a - DS: Converter control sets and modulation strategies

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   A NOVEL TECHNIQUE FOR CONTROL OF CASCADED MULTILEVEL INVERTER FOR PHOTOVOLTAIC POWER SUPPLIES
By NAIK Raghuram; YARAGATTI Udaykumar [View]
[Download]

Abstract: Multilevel voltage source inverters offer several advantages compared to their conventional counterparts. By synthesizing the AC output terminal voltage from several levels of voltages, staircase wave forms can produced, which approach the sinusoidal wave form with low harmonic distortion, thus reducing filter requirements. The need of several sources on the DC side of the converter makes multilevel technology attractive for photovoltaic applications. The basic modulation techniques enable harmonic elimination by predetermination of the switching angles. This is determined according to a previously calculated and stored pulse width modulated waveform. It has the advantage of operating at fundamental frequency switching. However, this technique is seriously limited as the number of levels increases because of the increased complexity and the reduced accuracy of the non-linear solutions. This paper proposes a novel Multilevel PWM technique (phase-shifted sinusoidal PWM) to over come all these limitations while maintaining switching at fundamental frequency, found better THD. Simulation results are presented in the paper.

   A Simple, Digital Current Control Design for Grid-connected Inverters
By GHRIBI Mohsen; KOJABADI Hossein; GADOURA Idris [View]
[Download]

Abstract: In this paper, a robust predictive current control strategy has been proposed and studied. The predictive current control offers the potential for achieving more precise current control with minimum distortion and harmonic noise. However, the traditional predictive current controller has a poor performance under component parameter variations, and is less robust to filters inductance mismatch. Both simulation and experimental results show that the proposed method is more robust to parameter mismatch than traditional one.

   Analysis of standard and non-standard control modes for modular converters with synchronous modulation
By OLESHCHUK Valentin; BOJOI Radu; ERMURATSKI Vasili; PROFUMO Francesco; TENCONI Alberto [View]
[Download]

Abstract: The paper describes operation of cascaded (modular) converters with synchronous pulsewidth modulation (PWM), mainly for control regimes different from conventional Volts/Hertz control. Modular multilevel converter consists from three standard three-phase inverter modules along with an 0.33 p.u. output transformer. The proposed PWM method provides synchronisation of the voltage waveforms of each module and of the composed voltage at the output of the converter. The line-to-line output voltage of modular converter (with two, three or four levels in dependence of modulation index) has quarter-wave symmetry during the whole control range for both linear and non-linear control modes and regimes. Basic versions of continuous and discontinuous schemes of synchronous PWM, based on vector approach for determination of the pulse patterns, have been analysed and compared by simulations of the systems with low switching frequencies, which are used normally in high power systems.

   Analytical Evaluation of the Total Harmonic Current in Three Phase Voltage and Current Source Converters
By FUCHS Friedrich Wilhelm; BIERHOFF Michael [View]
[Download]

Abstract: To facilitate the design of ac side filters, this work gives analytical expressions for the root mean squarevalue of the total harmonic phase currents in voltage and current source converters depending on themodulation schemes and passive filter components. Novel equations were found for the calculation oftotal harmonic phase currents regarding the CSC with LC filter. The results are verified by appropriatemeasurements for selected PWM schemes and are valid for most common applications.

   Comparison of low frequency hysteresis current control power inverters with accurate selection of applied vectors – two and three level comparators
By PIRES Armando; MARTINS JoãO [View]
[Download]

Abstract: Two feedback current controllers for three phase pulse width modulated power inverters with accurate selection of applied voltage vectors are compared. The voltage vectors applied to the load are accurately selected, due to the use of two three level comparators or four two level comparators. Simulation and experimental results are presented to support the comparison between both strategies.

   Control of front-end converter with shunt active filter using adaptive gain
By PHUNG Ngoc Lan; PUNZET Alfred; MUELLER Volkmar; LUU Hong Viet [View]
[Download]

Abstract: In this paper, a new control scheme for front-end PWM converter extended with shunt active filter is proposed. By controlling independently active and reactive power flows a front-end converter can act as conventional converter and shunt active filter in parallel. Thereby, a conventional front-end converter can be extended functionally with active filter without any hardware added. In addition, in order to handle the case of power rating exceeded, an adaptive gain control is proposed to control the power flow required by a conventional PWM converter and an active filter. In this work, the proposed control schemes are investigated on the front-end voltage source converter and verified by simulation and experiment.

   Control of Zero-Sequence Current in Parallel Connected Voltage Source PWM Rectifiers Using Converter-Flux-Based Control
By NIEMELAe Markku; POeLLAeNEN Riku; PYRHOeNEN Juha; TARKIAINEN Antti [View]
[Download]

Abstract: A new zero vector selection strategy for the Converter Flux based Control (CFC) of voltage source PWM rectifiers is introduced. With this strategy the circulating current in paralleled rectifiers is effec-tively suppressed and independent operations of the individual converter units are achieved. In addi-tion to normal line filter, no additional passive components such as transformers or current sharing reactors are required to parallel the converters. Simulation and experimental results validate the devel-oped model and the proposed zero vector selection scheme.

   Current Controller with Low Total Harmonic Distortion
By ORTEGA Carlos; ARIAS Antoni; ALDABAS Emiliano; ROMERAL Luis [View]
[Download]

Abstract: A new digital current controller with active-null state modulation for Voltage Source Inverter systems (VSI) is presented. The major advantages of the proposed current controller system are: minimisation of the Total Harmonic Distortion (THD) of the output current waveform and maximisation of the time of application of the voltage vectors.

   DESIGN OF A PREDICTIVE CURRENT CONTROLLER FOR A SEPARATED STARTER-GENERATOR APPLICATION
By HOBRAICHE Julien; VILAIN Jea; BERNARD FrançOi [View]
[Download]

Abstract: This paper proposes a predictive current controller to control the phase currents of a separated starter-generator (SSG) on the whole speed range. A comparison with hysteretic current controller and regulation in d-q axis is done to highlight the spectral benefits of predictive controller at high speed.

   High Dynamic Control a PWM Rectifier under Unbalanced Voltage Supply with Deadbeat Current Controllers
By LUU Hong Viet; VOLKMAR Mueller; PHUNG Ngoc Lan [View]
[Download]

Abstract: In this paper, a control scheme of a three phase PWM boost rectifier using two parallel current deadbeat controllers will be proposed. An unbalanced three-phase system will produce the second order oscillation of the main frequency in DC link voltage. Two separated positive and negative sequence synchronous reference frames will be applied [4][5]. By using a notch filter to delete the second order harmonic on each frame, the remaining current components appear as dc parts, which will be then processed by the inner control loop. Since the deadbeat digital controller has been proved itself a good solution with fast response, full digitalization, especially for applications based on Microcontroller or DSP, the inner current controllers are here implemented by deadbeat technique instead of conventional PI controllers [6]. Simulation results with Matlab/Simulink/Plecs are also presented to demonstrate the control scheme.

   Multi-Resonant State Feedback Current Control Structure with Pole Placement Approach
By ETXEBERRI; REYERO RauL; GUIRAUD JoTL; GUILLAUD Xavier; LOPEZ DE HEREDIA Amaia; GAZTAÑAGA Haizea; BACHA Seddik [View]
[Download]

Abstract: Most of the studies carried out as far as now concerning multi-resonant current control applications consider a classical structure, consisting in the direct addition of single resonant controllers in a series or shunt configuration. In addition they do not take into account explicitly the digital implementation related delay effects on their tuning approaches, which can be critical at active filter applications. In this paper the conventional state feedback structure has been rearranged and adapted to a new configuration which is better fitted for multi-resonant current control purposes. In addition the effects of the digital implementation related delay effects have been explicitly taken into account in the tuning process in order to avoid stability and performance degradation effects. The rearranged state feedback configuration has been experimentally tested at an active filter application confirming the good performances observed in the preliminary theoretical studies.

   Network Friendly Low-Switching Frequency High-Power Three-Level PWM Rectifier
By HOLTZ Joachim; RODRIGUEZ Jose; NEWMAN Patricio; LIENDO Alvaro; PONTT Jorge [View]
[Download]

Abstract: High-power converters for regenerative drives and distributed generation need a network-friendly operation with low switching frequency for high reliability and performance. This paper presents a multipulse connection of two three-level NPC PWM rectifiers with the selective harmonics elimination technique (SHE) and a novel optimal method for minimal current distortion.

   Optimized Selection of Switching Algorithm in Space Vector Modulated Three-level Clamped Converters
By MADANI Nima; RADAN Ahmad [View]
[Download]

Abstract: The Neural Point Clamped (NPC) converter has found a wide range of application in MV, high power drives. Minimization of losses and regulation of Neutral Point Voltage (NPV) of this converter are the objects aimed in this paper. The converter losses and variations of NPV are measured from the simulation results for possible switching patterns of Space Vector Modulation (SVM). IGBTs with linear fall and tail current model are selected as power switches of converter. Through a comparative study among the converter losses and variations of NPV resulted from the all-possible switching sequences of three level SVM, it is shown that a unique switching algorithm cannot minimize both the switching losses and variations of NPV. Therefore the paper proposes a sub-optimized switching algorithm resulting in very satisfactory conditions for the converter from the viewpoint of losses and of variations of NPV. Using this switching algorithm, the converter losses and variations of NPV reach either to their minimum or to a value near their minimum.

   PWM Control of Direct Frequency Converter in AC Electric Drive System
By SHREINER Rudolf; KRIVOVYAZ Vladimir; KALYGIN Andrey [View]
[Download]

Abstract: The paper is dedicated to the problem of direct frequency converter (DFC) control in AC electric drive system. The general two-step control strategy based on the coordinate PWM is presented. The developed DFC control system provides converter output voltages and input currents parameters equal to their reference values. The control system synthesis, taking into account a distorting influence of real power switches commutation process on the DFC commutation function, is conducted. The results of experimental study of operating modes of induction motor drive, fed by the two-stage DFC, are presented.

   Simple direct capacitor voltage balancing of a flying capacitor converter
By CLOS Gerhard; SCHINDELE Lothar; GAeRTNER Stefan; FRANKE Tobias [View]
[Download]

Abstract: This paper proposes a new charge control method for voltage balancing of flying capacitor multilevel conver-ters. Only the signs of the deviations from the nominal capacitor voltages and the sign of the output current are needed to choose proper switching states for charging or discharging the capacitors.

   Sinusoidal Waveform Compensator for Optimum Digital Control of Three-Phase PWM inverter
By KATO Toshiji; KURODA Shinsaku; INOUE Kaoru [View]
[Download]

Abstract: Optimal digital control method for a three-phase PWM inverter is proposed. It is based on the single-phase control method which has already reported. It utilizes the internal model principle to eliminate steady-state errors and to improve responses. Its principle is very simple that two phases are controlled as if they were independent and the other is controlled with the negative sum value of the two as long as the filter inductor and capacitor values are the same. It has a big advantage that there is no problem for unbalanced loads. It is validated for its performances through linear unbalanced and nonlinear loads theoretically by a simulator Saber and experimentally with a DSP-based digital control system.

   THE PWM CURRENT SOURCE INVERTER WITH IGBT TRANSISTORS
By KRZEMINSKI Zbigniew; WLAS Miroslaw; GLAB Marcin [View]
[Download]

Abstract: A control system for the induction motor fed by a PWM CSI based on a multiscalar model is presented in the paper. The current source inverter topology and principle of PWM modulation are taken into account. The vector model of the induction motor fed by CSI with output capacitors of inverter is presented in the paper. Complete equations of three multiscalar models of the induction motor are presented. The first multiscalar model is based on the stator current and rotor flux vectors. The second model is based on the stator current and stator flux vectors. The third model is based on the stator current and main flux vectors. Properties of the new control systems are compared and results of simulations are presented.

   Three-phase Sigma-Delta Modulation using zero-sequence components
By MERTENS Axel; GANESAN Vijay [View]
[Download]

Abstract: This paper presents new analytic results on the performance of Sigma-Delta Modulated (SDM) three-phase voltage source inverters, in terms of harmonic distortion of output current, conduction and switching losses of the inverter devices, and rms current of the dc link capacitor. The results are compared with the same magnitudes for PWM. For easier analysis and better visualization, a three-dimensional representation of the three-phase output voltages is chosen which also gives another view to space-vector transformation. This makes it possible to visualize the potential for optimizing SDM with respect to inverter component ratings. A zero-sequence component of the three modulator input signals is taken into account and is used to improve SDM with respect to the said performance criteria.

   Verification of Frequency Converter With Small Dc-link Capacitor
By PYRHÖNEN Olli; SAREN Hannu; RAUMA Kimmo; LAAKKONEN Ossi [View]
[Download]

Abstract: Traditionally, large dc-link capacitors have been used in voltage source inverters. By using MPPF-type capacitor the line current harmonic content is improved and the unreliable electrolytic capacitor can be omitted. In this paper, the dynamic behavior of an inverter with small dc-link capacitor has been studied by simulations and laboratory tests. A new modulating principle, named Differential Space Vector Pulse Width Modulation (DSVPWM), can deal with heavily fluctuating dc-link voltage and produce correct voltage vector with high accuracy. The performance of the DSVPWM has been verified with simulations.

EPE 2005 - Topic 05-3a - DS: Converter control sets and modulation strategies
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2005 - Conference > EPE 2005 - Topic 05: MODULATION STRATEGIES AND SPECIFIC CONTROL METHODS FOR STATIC CONVERTERS > EPE 2005 - Topic 05-3a - DS: Converter control sets and modulation strategies
	[return to parent folder]

	A NOVEL TECHNIQUE FOR CONTROL OF CASCADED MULTILEVEL INVERTER FOR PHOTOVOLTAIC POWER SUPPLIES By NAIK Raghuram; YARAGATTI Udaykumar	[View] [Download]
Abstract: Multilevel voltage source inverters offer several advantages compared to their conventional counterparts. By synthesizing the AC output terminal voltage from several levels of voltages, staircase wave forms can produced, which approach the sinusoidal wave form with low harmonic distortion, thus reducing filter requirements. The need of several sources on the DC side of the converter makes multilevel technology attractive for photovoltaic applications. The basic modulation techniques enable harmonic elimination by predetermination of the switching angles. This is determined according to a previously calculated and stored pulse width modulated waveform. It has the advantage of operating at fundamental frequency switching. However, this technique is seriously limited as the number of levels increases because of the increased complexity and the reduced accuracy of the non-linear solutions. This paper proposes a novel Multilevel PWM technique (phase-shifted sinusoidal PWM) to over come all these limitations while maintaining switching at fundamental frequency, found better THD. Simulation results are presented in the paper.

	A Simple, Digital Current Control Design for Grid-connected Inverters By GHRIBI Mohsen; KOJABADI Hossein; GADOURA Idris	[View] [Download]
Abstract: In this paper, a robust predictive current control strategy has been proposed and studied. The predictive current control offers the potential for achieving more precise current control with minimum distortion and harmonic noise. However, the traditional predictive current controller has a poor performance under component parameter variations, and is less robust to filters inductance mismatch. Both simulation and experimental results show that the proposed method is more robust to parameter mismatch than traditional one.

	Analysis of standard and non-standard control modes for modular converters with synchronous modulation By OLESHCHUK Valentin; BOJOI Radu; ERMURATSKI Vasili; PROFUMO Francesco; TENCONI Alberto	[View] [Download]
Abstract: The paper describes operation of cascaded (modular) converters with synchronous pulsewidth modulation (PWM), mainly for control regimes different from conventional Volts/Hertz control. Modular multilevel converter consists from three standard three-phase inverter modules along with an 0.33 p.u. output transformer. The proposed PWM method provides synchronisation of the voltage waveforms of each module and of the composed voltage at the output of the converter. The line-to-line output voltage of modular converter (with two, three or four levels in dependence of modulation index) has quarter-wave symmetry during the whole control range for both linear and non-linear control modes and regimes. Basic versions of continuous and discontinuous schemes of synchronous PWM, based on vector approach for determination of the pulse patterns, have been analysed and compared by simulations of the systems with low switching frequencies, which are used normally in high power systems.

	Analytical Evaluation of the Total Harmonic Current in Three Phase Voltage and Current Source Converters By FUCHS Friedrich Wilhelm; BIERHOFF Michael	[View] [Download]
Abstract: To facilitate the design of ac side filters, this work gives analytical expressions for the root mean squarevalue of the total harmonic phase currents in voltage and current source converters depending on themodulation schemes and passive filter components. Novel equations were found for the calculation oftotal harmonic phase currents regarding the CSC with LC filter. The results are verified by appropriatemeasurements for selected PWM schemes and are valid for most common applications.

	Comparison of low frequency hysteresis current control power inverters with accurate selection of applied vectors – two and three level comparators By PIRES Armando; MARTINS JoãO	[View] [Download]
Abstract: Two feedback current controllers for three phase pulse width modulated power inverters with accurate selection of applied voltage vectors are compared. The voltage vectors applied to the load are accurately selected, due to the use of two three level comparators or four two level comparators. Simulation and experimental results are presented to support the comparison between both strategies.

	Control of front-end converter with shunt active filter using adaptive gain By PHUNG Ngoc Lan; PUNZET Alfred; MUELLER Volkmar; LUU Hong Viet	[View] [Download]
Abstract: In this paper, a new control scheme for front-end PWM converter extended with shunt active filter is proposed. By controlling independently active and reactive power flows a front-end converter can act as conventional converter and shunt active filter in parallel. Thereby, a conventional front-end converter can be extended functionally with active filter without any hardware added. In addition, in order to handle the case of power rating exceeded, an adaptive gain control is proposed to control the power flow required by a conventional PWM converter and an active filter. In this work, the proposed control schemes are investigated on the front-end voltage source converter and verified by simulation and experiment.

	Control of Zero-Sequence Current in Parallel Connected Voltage Source PWM Rectifiers Using Converter-Flux-Based Control By NIEMELAe Markku; POeLLAeNEN Riku; PYRHOeNEN Juha; TARKIAINEN Antti	[View] [Download]
Abstract: A new zero vector selection strategy for the Converter Flux based Control (CFC) of voltage source PWM rectifiers is introduced. With this strategy the circulating current in paralleled rectifiers is effec-tively suppressed and independent operations of the individual converter units are achieved. In addi-tion to normal line filter, no additional passive components such as transformers or current sharing reactors are required to parallel the converters. Simulation and experimental results validate the devel-oped model and the proposed zero vector selection scheme.

	Current Controller with Low Total Harmonic Distortion By ORTEGA Carlos; ARIAS Antoni; ALDABAS Emiliano; ROMERAL Luis	[View] [Download]
Abstract: A new digital current controller with active-null state modulation for Voltage Source Inverter systems (VSI) is presented. The major advantages of the proposed current controller system are: minimisation of the Total Harmonic Distortion (THD) of the output current waveform and maximisation of the time of application of the voltage vectors.

	DESIGN OF A PREDICTIVE CURRENT CONTROLLER FOR A SEPARATED STARTER-GENERATOR APPLICATION By HOBRAICHE Julien; VILAIN Jea; BERNARD FrançOi	[View] [Download]
Abstract: This paper proposes a predictive current controller to control the phase currents of a separated starter-generator (SSG) on the whole speed range. A comparison with hysteretic current controller and regulation in d-q axis is done to highlight the spectral benefits of predictive controller at high speed.

	High Dynamic Control a PWM Rectifier under Unbalanced Voltage Supply with Deadbeat Current Controllers By LUU Hong Viet; VOLKMAR Mueller; PHUNG Ngoc Lan	[View] [Download]
Abstract: In this paper, a control scheme of a three phase PWM boost rectifier using two parallel current deadbeat controllers will be proposed. An unbalanced three-phase system will produce the second order oscillation of the main frequency in DC link voltage. Two separated positive and negative sequence synchronous reference frames will be applied [4][5]. By using a notch filter to delete the second order harmonic on each frame, the remaining current components appear as dc parts, which will be then processed by the inner control loop. Since the deadbeat digital controller has been proved itself a good solution with fast response, full digitalization, especially for applications based on Microcontroller or DSP, the inner current controllers are here implemented by deadbeat technique instead of conventional PI controllers [6]. Simulation results with Matlab/Simulink/Plecs are also presented to demonstrate the control scheme.

	Multi-Resonant State Feedback Current Control Structure with Pole Placement Approach By ETXEBERRI; REYERO RauL; GUIRAUD JoTL; GUILLAUD Xavier; LOPEZ DE HEREDIA Amaia; GAZTAÑAGA Haizea; BACHA Seddik	[View] [Download]
Abstract: Most of the studies carried out as far as now concerning multi-resonant current control applications consider a classical structure, consisting in the direct addition of single resonant controllers in a series or shunt configuration. In addition they do not take into account explicitly the digital implementation related delay effects on their tuning approaches, which can be critical at active filter applications. In this paper the conventional state feedback structure has been rearranged and adapted to a new configuration which is better fitted for multi-resonant current control purposes. In addition the effects of the digital implementation related delay effects have been explicitly taken into account in the tuning process in order to avoid stability and performance degradation effects. The rearranged state feedback configuration has been experimentally tested at an active filter application confirming the good performances observed in the preliminary theoretical studies.

	Network Friendly Low-Switching Frequency High-Power Three-Level PWM Rectifier By HOLTZ Joachim; RODRIGUEZ Jose; NEWMAN Patricio; LIENDO Alvaro; PONTT Jorge	[View] [Download]
Abstract: High-power converters for regenerative drives and distributed generation need a network-friendly operation with low switching frequency for high reliability and performance. This paper presents a multipulse connection of two three-level NPC PWM rectifiers with the selective harmonics elimination technique (SHE) and a novel optimal method for minimal current distortion.

	Optimized Selection of Switching Algorithm in Space Vector Modulated Three-level Clamped Converters By MADANI Nima; RADAN Ahmad	[View] [Download]
Abstract: The Neural Point Clamped (NPC) converter has found a wide range of application in MV, high power drives. Minimization of losses and regulation of Neutral Point Voltage (NPV) of this converter are the objects aimed in this paper. The converter losses and variations of NPV are measured from the simulation results for possible switching patterns of Space Vector Modulation (SVM). IGBTs with linear fall and tail current model are selected as power switches of converter. Through a comparative study among the converter losses and variations of NPV resulted from the all-possible switching sequences of three level SVM, it is shown that a unique switching algorithm cannot minimize both the switching losses and variations of NPV. Therefore the paper proposes a sub-optimized switching algorithm resulting in very satisfactory conditions for the converter from the viewpoint of losses and of variations of NPV. Using this switching algorithm, the converter losses and variations of NPV reach either to their minimum or to a value near their minimum.

	PWM Control of Direct Frequency Converter in AC Electric Drive System By SHREINER Rudolf; KRIVOVYAZ Vladimir; KALYGIN Andrey	[View] [Download]
Abstract: The paper is dedicated to the problem of direct frequency converter (DFC) control in AC electric drive system. The general two-step control strategy based on the coordinate PWM is presented. The developed DFC control system provides converter output voltages and input currents parameters equal to their reference values. The control system synthesis, taking into account a distorting influence of real power switches commutation process on the DFC commutation function, is conducted. The results of experimental study of operating modes of induction motor drive, fed by the two-stage DFC, are presented.

	Simple direct capacitor voltage balancing of a flying capacitor converter By CLOS Gerhard; SCHINDELE Lothar; GAeRTNER Stefan; FRANKE Tobias	[View] [Download]
Abstract: This paper proposes a new charge control method for voltage balancing of flying capacitor multilevel conver-ters. Only the signs of the deviations from the nominal capacitor voltages and the sign of the output current are needed to choose proper switching states for charging or discharging the capacitors.

	Sinusoidal Waveform Compensator for Optimum Digital Control of Three-Phase PWM inverter By KATO Toshiji; KURODA Shinsaku; INOUE Kaoru	[View] [Download]
Abstract: Optimal digital control method for a three-phase PWM inverter is proposed. It is based on the single-phase control method which has already reported. It utilizes the internal model principle to eliminate steady-state errors and to improve responses. Its principle is very simple that two phases are controlled as if they were independent and the other is controlled with the negative sum value of the two as long as the filter inductor and capacitor values are the same. It has a big advantage that there is no problem for unbalanced loads. It is validated for its performances through linear unbalanced and nonlinear loads theoretically by a simulator Saber and experimentally with a DSP-based digital control system.

	THE PWM CURRENT SOURCE INVERTER WITH IGBT TRANSISTORS By KRZEMINSKI Zbigniew; WLAS Miroslaw; GLAB Marcin	[View] [Download]
Abstract: A control system for the induction motor fed by a PWM CSI based on a multiscalar model is presented in the paper. The current source inverter topology and principle of PWM modulation are taken into account. The vector model of the induction motor fed by CSI with output capacitors of inverter is presented in the paper. Complete equations of three multiscalar models of the induction motor are presented. The first multiscalar model is based on the stator current and rotor flux vectors. The second model is based on the stator current and stator flux vectors. The third model is based on the stator current and main flux vectors. Properties of the new control systems are compared and results of simulations are presented.

	Three-phase Sigma-Delta Modulation using zero-sequence components By MERTENS Axel; GANESAN Vijay	[View] [Download]
Abstract: This paper presents new analytic results on the performance of Sigma-Delta Modulated (SDM) three-phase voltage source inverters, in terms of harmonic distortion of output current, conduction and switching losses of the inverter devices, and rms current of the dc link capacitor. The results are compared with the same magnitudes for PWM. For easier analysis and better visualization, a three-dimensional representation of the three-phase output voltages is chosen which also gives another view to space-vector transformation. This makes it possible to visualize the potential for optimizing SDM with respect to inverter component ratings. A zero-sequence component of the three modulator input signals is taken into account and is used to improve SDM with respect to the said performance criteria.

	Verification of Frequency Converter With Small Dc-link Capacitor By PYRHÖNEN Olli; SAREN Hannu; RAUMA Kimmo; LAAKKONEN Ossi	[View] [Download]
Abstract: Traditionally, large dc-link capacitors have been used in voltage source inverters. By using MPPF-type capacitor the line current harmonic content is improved and the unreliable electrolytic capacitor can be omitted. In this paper, the dynamic behavior of an inverter with small dc-link capacitor has been studied by simulations and laboratory tests. A new modulating principle, named Differential Space Vector Pulse Width Modulation (DSVPWM), can deal with heavily fluctuating dc-link voltage and produce correct voltage vector with high accuracy. The performance of the DSVPWM has been verified with simulations.