EPE Association: EPE 2005 - Topic 05-1 - LS: Converter control sets and modulation strategies

EPE 2005 - Topic 05-1 - LS: 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 05-1 - LS: Converter control sets and modulation strategies

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   Algorithm for the virtual vectors modulation in three-level inverters with a voltage-balance control loop
By POU Josep; BUSQUET; SALA Vicenç; BOROYEVICH Dushan; RODRIGUEZ Pedro [View]
[Download]

Abstract: The modulation strategy based on virtual vectors can remove the low-frequency voltage oscillation that appears in the neutral point of the three-level inverter. However, this strategy has no natural voltage balancing. This work presents a novel space-vector modulation algorithm that includes voltage-balancing control and therefore can remove any possible imbalance. Since the algorithm takes advantage of symmetry in the space-vector diagram, it can be processed quickly in a digital-signal processor. The proposed method is verified by simulation and experiment.

   Evaluation of Stationary Frame and Fixed Switching Frequency Digital Current Control Techniques for Power Active Filters
By ROYE Daniel; ETXEBERRI; GAZTAÑAGA Haizea; REYERO Raul; GUIRAUD JoTL; BACHA Seddik; LOPEZ DE HEREDIA Amaia [View]
[Download]

Abstract: In this paper two stationary frame digital current control techniques, the RST and the Multi-Resonant controller, are analysed and experimentally tested in an active filter application. The RST controller has been tuned in order to obtain a deadbeat response. The method used to tune the Multi-Resonant controller is based on a frequency response approach that guarantees the stability and robustness of the system. It is well-known that the performance of deadbeat controllers is constrained to the accuracy of the plant model as well as the accuracy of the reference and disturbance predictions. The accuracy of the Multi-Resonant controller is guaranteed as long as the system is stable and the harmonics of the reference and the disturbance coincide with the resonance frequencies of the controller. Theoretically the main advantages of the deadbeat controller are its simplicity and its dynamics. However, in a complex application such as the active filtering the intrinsic delay of the controller is unacceptable and therefore it is necessary to use reference (and eventually disturbance) prediction techniques. The use of these techniques can have a non-negligible effect on the characteristics of the system and can be detrimental for both the dynamics and the simplicity of the system. In this paper two different prediction techniques have been implemented: periodicity and resonant. It is shown that the steady-state performances in both cases are satisfactory and similar to those obtained with the Multi-Resonant controller. Nevertheless, the first of the prediction techniques deteriorates significantly the dynamic performance of the system while the second one increases considerably its complexity, showing that the Multi-Resonant controller is better adapted for this kind of applications than the studied deadbeat controller.

   Space vector modulation schemes for a five-phase voltage source inverter
By IQBAL Atif; LEVI Emil [View]
[Download]

Abstract: Application of power electronics in electric drives enables utilisation of AC machines with a phase number higher than three. Such multiphase motor drives are nowadays considered for various applications. Multiphase drives are invariably supplied from multiphase voltage source inverters (VSIs) and adequate methods for VSI pulse width modulation (PWM) are therefore required. This paper analyses different space vector PWM (SVPWM) schemes for a five-phase VSI, which can be used for five-phase motor drives. A detailed model of a five-phase VSI is presented first in terms of space vectors. Next, the existing technique of utilising only large space vectors is elaborated. It is shown that this SVPWM method leads to generation of high amounts of low-order output voltage harmonics. Finally, a novel SVPWM method is introduced, which enables operation with pure sinusoidal output voltages up to a certain reference voltage value, which is smaller than the maximum achievable with the given DC link voltage. To enable full utilisation of the DC bus voltage, this SVPWM scheme is complemented with another one, which unavoidably does lead to generation of some low order harmonics. These harmonics are however of significantly lower values than when only large vectors are used. A detailed performance evaluation of the existing and newly developed schemes is done and it is presented in terms of quality of the output voltage waveforms. Simulation results are included throughout the paper to illustrate and verify the theoretical considerations.

EPE 2005 - Topic 05-1 - LS: 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 05-1 - LS: Converter control sets and modulation strategies
	[return to parent folder]

	Algorithm for the virtual vectors modulation in three-level inverters with a voltage-balance control loop By POU Josep; BUSQUET; SALA Vicenç; BOROYEVICH Dushan; RODRIGUEZ Pedro	[View] [Download]
Abstract: The modulation strategy based on virtual vectors can remove the low-frequency voltage oscillation that appears in the neutral point of the three-level inverter. However, this strategy has no natural voltage balancing. This work presents a novel space-vector modulation algorithm that includes voltage-balancing control and therefore can remove any possible imbalance. Since the algorithm takes advantage of symmetry in the space-vector diagram, it can be processed quickly in a digital-signal processor. The proposed method is verified by simulation and experiment.

	Evaluation of Stationary Frame and Fixed Switching Frequency Digital Current Control Techniques for Power Active Filters By ROYE Daniel; ETXEBERRI; GAZTAÑAGA Haizea; REYERO Raul; GUIRAUD JoTL; BACHA Seddik; LOPEZ DE HEREDIA Amaia	[View] [Download]
Abstract: In this paper two stationary frame digital current control techniques, the RST and the Multi-Resonant controller, are analysed and experimentally tested in an active filter application. The RST controller has been tuned in order to obtain a deadbeat response. The method used to tune the Multi-Resonant controller is based on a frequency response approach that guarantees the stability and robustness of the system. It is well-known that the performance of deadbeat controllers is constrained to the accuracy of the plant model as well as the accuracy of the reference and disturbance predictions. The accuracy of the Multi-Resonant controller is guaranteed as long as the system is stable and the harmonics of the reference and the disturbance coincide with the resonance frequencies of the controller. Theoretically the main advantages of the deadbeat controller are its simplicity and its dynamics. However, in a complex application such as the active filtering the intrinsic delay of the controller is unacceptable and therefore it is necessary to use reference (and eventually disturbance) prediction techniques. The use of these techniques can have a non-negligible effect on the characteristics of the system and can be detrimental for both the dynamics and the simplicity of the system. In this paper two different prediction techniques have been implemented: periodicity and resonant. It is shown that the steady-state performances in both cases are satisfactory and similar to those obtained with the Multi-Resonant controller. Nevertheless, the first of the prediction techniques deteriorates significantly the dynamic performance of the system while the second one increases considerably its complexity, showing that the Multi-Resonant controller is better adapted for this kind of applications than the studied deadbeat controller.

	Space vector modulation schemes for a five-phase voltage source inverter By IQBAL Atif; LEVI Emil	[View] [Download]
Abstract: Application of power electronics in electric drives enables utilisation of AC machines with a phase number higher than three. Such multiphase motor drives are nowadays considered for various applications. Multiphase drives are invariably supplied from multiphase voltage source inverters (VSIs) and adequate methods for VSI pulse width modulation (PWM) are therefore required. This paper analyses different space vector PWM (SVPWM) schemes for a five-phase VSI, which can be used for five-phase motor drives. A detailed model of a five-phase VSI is presented first in terms of space vectors. Next, the existing technique of utilising only large space vectors is elaborated. It is shown that this SVPWM method leads to generation of high amounts of low-order output voltage harmonics. Finally, a novel SVPWM method is introduced, which enables operation with pure sinusoidal output voltages up to a certain reference voltage value, which is smaller than the maximum achievable with the given DC link voltage. To enable full utilisation of the DC bus voltage, this SVPWM scheme is complemented with another one, which unavoidably does lead to generation of some low order harmonics. These harmonics are however of significantly lower values than when only large vectors are used. A detailed performance evaluation of the existing and newly developed schemes is done and it is presented in terms of quality of the output voltage waveforms. Simulation results are included throughout the paper to illustrate and verify the theoretical considerations.