EPE Association: EPE 1999 - Topic 04b: Modulation Strategies

EPE 1999 - Topic 04b: Modulation Strategies
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1999 - Conference > EPE 1999 - Topic 04: CONTROL > EPE 1999 - Topic 04b: Modulation Strategies

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   Analysis of the Current Ripple in Induction Motor Drives Controlled by SVM Technique
By D. Casadei; G. Serri; A. Tani; L. Zarri [View]
[Download]

Abstract: A method that allows the determination of the current ripple of induction motor drives controlled by space vector modulation is analysed in this paper. Two modulation techniques have been considered and the corresponding analytical expressions of the peak value of the current ripple as a function of the modulation index have been determined. Numerical and experimental tests have been carried out confirming the validity of the theoretical analysis.

   Analysis of the General Harmonic Families Elimination Problem
By Paolo Bolognesi; G. Carrara; D. Casini; L. Taponecco [View]
[Download]

Abstract: In the ambit of the steady state control techniques for inverters, despite its conceptual validity the harmonic elimination concept is scarcely employed due to the difficulties involved in the actual determination of the solution for the classic methods applying it. In fact, for these methods the solution can be obtained only in approximated way, and separately per each case considered, by mean of iterative numerical algorithms requiring a not negligible computational effort. The application of the same base concept to the zeroing of entire harmonic families, rather than single components, allows instead to conceptually overcome the above problems: in fact, despite the greater complexity of this formulation, it results theoretically possible to translate the problem into a suitable system of simple linear algebraic homogeneous equations, that can be so easily exactly solved at least in ideal terms. This paper presents the theoretical treatment of the general harmonic families elimination problem by mean of structural properties, including application considerations and a numerical example.

   Analysis of Two-Phase PWM Technique In Inverter AC Drives
By S. Halasz; A. Zaharov [View]
[Download]

Abstract: This paper deals with that kind of two-phase PWMs which inquires the lowest motor harmonic losses. The different modulation strategies are investigated and two different PWM schemes are suggested. The accurate and the approached analytical equations of motor voltage harmonics of two modulation schemes are given and it is shown that these equations provide a good precision of calculations. It is shown that both PWM schemes produce the same values of harmonic losses, torque ripples and speed oscillations but with different harmonic content. For the same inverter commutation frequency these two-phase PWMs produce lower motor harmonic losses than the three-phase ones in the high fundamental voltage region but the torque and speed ripples of two-phase PWMs are higher than for three-space vector modulation almost in the whole control region.

   Estimation of the Most Favorable Switching Variants for a Direct Frequency Conversion
By L. Rutmanis; J. Stabulnieks; L. Ribickis [View]
[Download]

Abstract: The paper presents a method by means of which the purposefulness of 729 variously summed possible switching variants of two input voltage levels of all the three phases are evaluated in each time interval. Choosing integral equality of the difference of input voltages and the converter output reference voltage on both sides of the reference voltage as the basis of evaluation for each switching variant, we obtain, as a result, a limited number of switching variants of input voltages that suit best of all the formation of the output voltage within the given interval. The results obtained may be used further to compile control programmes of direct frequency converters.

   Modeling and Comparison of Two Modified Vector Modulation Schemes with Feed-Forward for the Quasi-Single Stage Three-Phase Zero-Voltage Zero-Current Switched...
By C. Cuadros; S. Chandrasekaran; K. Wang; D. Boroyevich; F. C. Lee [View]
[Download]

Abstract: A Large signal average model for the Quasi-Single Stage (QSS) Three-Phase Zero-Voltage Zero-Current (ZVZCS) Buck rectifier operated with two variations of Space Vector Modulation (SVM) is developed. The model reveals strong non-linear relations between applied and effective duty-cycles, near the 60° sector boundaries, which lead to high input current distortion and output voltage ripple inadmissible in telecommunications applications. PLL and look-up table based SVM, and analog filter inductor current and output voltage compensators are implemented to provide both minimum number of sampled variables (maximum sampling frequency and loop bandwith) and easy introduction of duty-cycle feed-forward compensation (equalization) through power series approximation. Results from a 6 kW prototype validate both the large signal model and duty-cycle compensation scheme.

   New Synthesis Method for PWM Control Strategies
By C. Bogus; S. Birca-Galateanu [View]
[Download]

Abstract: A new synthesis method for PWM control strategies is proposed for a bridge with any number of columns. the method is simple; reasoning is done in "one" dimension, rather than "two" with the space vector method SVM. Best strategies are easily recognised. Some control strategies are described using the proposed method; among them a minimum-loss PWM strategy.

   Novel PWM Strategy for Single-phase Inverters
By S.R. Bowes; S. grewal [View]
[Download]

Abstract: A novel Pulse-Width Modulation (PWM) strategy is presented which closely approximates the harmonic performance of the off-line harmonic minimized PWM technique for single-phase PWM inverters. The proposed on-line PWM technique digitally reproduces the characteristics of Hysteresis Band Modulation with the switching frequency directly controlled by adapting the width of the Hysteresis Band. The software implementation is achieved using the conventional equations for Regular-Sampled PWM combined with a Pulse-Position Modulation (PPM) function characteristic of Hysteresis Band Modulation

   Properties of the AC/DC/AC-PWM Converter Current Control Loop Minimizing the Transistors Switching Frequency
By A. Sikorski; T. Citko [View]
[Download]

Abstract: The control system of the AC/DC/AC transistors converter useful for the electric drive with the AC motor application is presented in this paper. The converter is characterized by the common for both converters quasi-resonant circuit enabling the transistor switching with zero voltage. the minimization of both converters transistors switching frequency is the main task of the proposed control system. The laboratory model investigation basing on the presented in the paper oscillograms are discussed.

   Randomness and Random PWM
By K.K. Sung; S. Sathiakumar; S.Y. R. Hui; Y. Shrivastava [View]
[Download]

Abstract: The concept of a new pulse-width modulation (RPWM) scheme and weighted RPWM (WRPWM) scheme has been explored and put to test. Both schemes have been developed based on the very idea that harmonic energy at distinct frequencies can be spread out by randomizing the switching pattern. The formulation and analysis of RPWM / WRPWM schemes depends on the notion of randomness. However in practice we only use so called "pseudo-random" sequences generated by computers and/or circuits for implementation of these schemes. In this paper we discuss the effect of such pseudo-random sequences on the performance of RPWM / WRPWM schemes.

   Sliding Mode Controls for a Two-cell Chopper
By D. Pinon; M. Fadel; T. Meynard [View]
[Download]

Abstract: In this paper, the authors present three different sliding mode controls for a two-cell chopper. First, the synthesis of the control is treated. By the study of the limit cycle, the authors have developed a new control in steady state that imposes a phase shift of ð between the control signals of the switches. They also present a sliding mode control at fixed frequency.

   Space Vector Modulation Technique with Reduced Switching Losses
By F. Zare; G. Ledwich [View]
[Download]

Abstract: An optimum space vector modulation technique for a three-phase voltage source inverter based on a minimum-loss strategy is described in this paper. This new method has six switching transactions per cycle less than the minimum-loss strategy due to a zero vector which does not alternate between each sector. Matlab simulations are carried out for calculation of timing values of each pulse and generation of pulse pattern for constant switching losses. Finally, the harmonic spectrum and weighted total harmonic distortion for these strategies are compared and results show up to 7% weighted total harmonic distortion improvement over previous minimum-loss strategy.

   Three-Phase AC/DC/AC Converter with Random Pulse Position PWM
By B.-R. Lin; H.-H. Lu [View]
[Download]

Abstract: A three-phase ac/dc/ac converter using the d-q axis concept and hysteresis current control strategy to improve power quality in the input side and using a random pulse-width modulation (RPWM) approach in the output side to reduce annoyed tonal noise or mechanical vibration is proposed in this paper. The control scheme based on the synchronous reference frame for three-phase rectifier is adopted to achieve a high power factor and low harmonic currents. To reduce the mechanical vibration from ac machine drive, stochastic asynchronous PWM scheme with random lagging or leading edge modulation is adopted. The frequency distribution of harmonics is spreading in a wide frequency range. Simulation and experimental results are presented to verify the characteristics of unity power factor at the input side and the absence of annoyed tonal noise in the motor drive.

EPE 1999 - Topic 04b: Modulation Strategies
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1999 - Conference > EPE 1999 - Topic 04: CONTROL > EPE 1999 - Topic 04b: Modulation Strategies
	[return to parent folder]

	Analysis of the Current Ripple in Induction Motor Drives Controlled by SVM Technique By D. Casadei; G. Serri; A. Tani; L. Zarri	[View] [Download]
Abstract: A method that allows the determination of the current ripple of induction motor drives controlled by space vector modulation is analysed in this paper. Two modulation techniques have been considered and the corresponding analytical expressions of the peak value of the current ripple as a function of the modulation index have been determined. Numerical and experimental tests have been carried out confirming the validity of the theoretical analysis.

	Analysis of the General Harmonic Families Elimination Problem By Paolo Bolognesi; G. Carrara; D. Casini; L. Taponecco	[View] [Download]
Abstract: In the ambit of the steady state control techniques for inverters, despite its conceptual validity the harmonic elimination concept is scarcely employed due to the difficulties involved in the actual determination of the solution for the classic methods applying it. In fact, for these methods the solution can be obtained only in approximated way, and separately per each case considered, by mean of iterative numerical algorithms requiring a not negligible computational effort. The application of the same base concept to the zeroing of entire harmonic families, rather than single components, allows instead to conceptually overcome the above problems: in fact, despite the greater complexity of this formulation, it results theoretically possible to translate the problem into a suitable system of simple linear algebraic homogeneous equations, that can be so easily exactly solved at least in ideal terms. This paper presents the theoretical treatment of the general harmonic families elimination problem by mean of structural properties, including application considerations and a numerical example.

	Analysis of Two-Phase PWM Technique In Inverter AC Drives By S. Halasz; A. Zaharov	[View] [Download]
Abstract: This paper deals with that kind of two-phase PWMs which inquires the lowest motor harmonic losses. The different modulation strategies are investigated and two different PWM schemes are suggested. The accurate and the approached analytical equations of motor voltage harmonics of two modulation schemes are given and it is shown that these equations provide a good precision of calculations. It is shown that both PWM schemes produce the same values of harmonic losses, torque ripples and speed oscillations but with different harmonic content. For the same inverter commutation frequency these two-phase PWMs produce lower motor harmonic losses than the three-phase ones in the high fundamental voltage region but the torque and speed ripples of two-phase PWMs are higher than for three-space vector modulation almost in the whole control region.

	Estimation of the Most Favorable Switching Variants for a Direct Frequency Conversion By L. Rutmanis; J. Stabulnieks; L. Ribickis	[View] [Download]
Abstract: The paper presents a method by means of which the purposefulness of 729 variously summed possible switching variants of two input voltage levels of all the three phases are evaluated in each time interval. Choosing integral equality of the difference of input voltages and the converter output reference voltage on both sides of the reference voltage as the basis of evaluation for each switching variant, we obtain, as a result, a limited number of switching variants of input voltages that suit best of all the formation of the output voltage within the given interval. The results obtained may be used further to compile control programmes of direct frequency converters.

	Modeling and Comparison of Two Modified Vector Modulation Schemes with Feed-Forward for the Quasi-Single Stage Three-Phase Zero-Voltage Zero-Current Switched... By C. Cuadros; S. Chandrasekaran; K. Wang; D. Boroyevich; F. C. Lee	[View] [Download]
Abstract: A Large signal average model for the Quasi-Single Stage (QSS) Three-Phase Zero-Voltage Zero-Current (ZVZCS) Buck rectifier operated with two variations of Space Vector Modulation (SVM) is developed. The model reveals strong non-linear relations between applied and effective duty-cycles, near the 60° sector boundaries, which lead to high input current distortion and output voltage ripple inadmissible in telecommunications applications. PLL and look-up table based SVM, and analog filter inductor current and output voltage compensators are implemented to provide both minimum number of sampled variables (maximum sampling frequency and loop bandwith) and easy introduction of duty-cycle feed-forward compensation (equalization) through power series approximation. Results from a 6 kW prototype validate both the large signal model and duty-cycle compensation scheme.

	New Synthesis Method for PWM Control Strategies By C. Bogus; S. Birca-Galateanu	[View] [Download]
Abstract: A new synthesis method for PWM control strategies is proposed for a bridge with any number of columns. the method is simple; reasoning is done in "one" dimension, rather than "two" with the space vector method SVM. Best strategies are easily recognised. Some control strategies are described using the proposed method; among them a minimum-loss PWM strategy.

	Novel PWM Strategy for Single-phase Inverters By S.R. Bowes; S. grewal	[View] [Download]
Abstract: A novel Pulse-Width Modulation (PWM) strategy is presented which closely approximates the harmonic performance of the off-line harmonic minimized PWM technique for single-phase PWM inverters. The proposed on-line PWM technique digitally reproduces the characteristics of Hysteresis Band Modulation with the switching frequency directly controlled by adapting the width of the Hysteresis Band. The software implementation is achieved using the conventional equations for Regular-Sampled PWM combined with a Pulse-Position Modulation (PPM) function characteristic of Hysteresis Band Modulation

	Properties of the AC/DC/AC-PWM Converter Current Control Loop Minimizing the Transistors Switching Frequency By A. Sikorski; T. Citko	[View] [Download]
Abstract: The control system of the AC/DC/AC transistors converter useful for the electric drive with the AC motor application is presented in this paper. The converter is characterized by the common for both converters quasi-resonant circuit enabling the transistor switching with zero voltage. the minimization of both converters transistors switching frequency is the main task of the proposed control system. The laboratory model investigation basing on the presented in the paper oscillograms are discussed.

	Randomness and Random PWM By K.K. Sung; S. Sathiakumar; S.Y. R. Hui; Y. Shrivastava	[View] [Download]
Abstract: The concept of a new pulse-width modulation (RPWM) scheme and weighted RPWM (WRPWM) scheme has been explored and put to test. Both schemes have been developed based on the very idea that harmonic energy at distinct frequencies can be spread out by randomizing the switching pattern. The formulation and analysis of RPWM / WRPWM schemes depends on the notion of randomness. However in practice we only use so called "pseudo-random" sequences generated by computers and/or circuits for implementation of these schemes. In this paper we discuss the effect of such pseudo-random sequences on the performance of RPWM / WRPWM schemes.

	Sliding Mode Controls for a Two-cell Chopper By D. Pinon; M. Fadel; T. Meynard	[View] [Download]
Abstract: In this paper, the authors present three different sliding mode controls for a two-cell chopper. First, the synthesis of the control is treated. By the study of the limit cycle, the authors have developed a new control in steady state that imposes a phase shift of ð between the control signals of the switches. They also present a sliding mode control at fixed frequency.

	Space Vector Modulation Technique with Reduced Switching Losses By F. Zare; G. Ledwich	[View] [Download]
Abstract: An optimum space vector modulation technique for a three-phase voltage source inverter based on a minimum-loss strategy is described in this paper. This new method has six switching transactions per cycle less than the minimum-loss strategy due to a zero vector which does not alternate between each sector. Matlab simulations are carried out for calculation of timing values of each pulse and generation of pulse pattern for constant switching losses. Finally, the harmonic spectrum and weighted total harmonic distortion for these strategies are compared and results show up to 7% weighted total harmonic distortion improvement over previous minimum-loss strategy.

	Three-Phase AC/DC/AC Converter with Random Pulse Position PWM By B.-R. Lin; H.-H. Lu	[View] [Download]
Abstract: A three-phase ac/dc/ac converter using the d-q axis concept and hysteresis current control strategy to improve power quality in the input side and using a random pulse-width modulation (RPWM) approach in the output side to reduce annoyed tonal noise or mechanical vibration is proposed in this paper. The control scheme based on the synchronous reference frame for three-phase rectifier is adopted to achieve a high power factor and low harmonic currents. To reduce the mechanical vibration from ac machine drive, stochastic asynchronous PWM scheme with random lagging or leading edge modulation is adopted. The frequency distribution of harmonics is spreading in a wide frequency range. Simulation and experimental results are presented to verify the characteristics of unity power factor at the input side and the absence of annoyed tonal noise in the motor drive.