Direct control strategy for a four-level three-phase flying-capacitor inverter

A direct predictive control strategy is proposed for a three-phase four-level flying-capacitor (FC) inverter in this paper. The balancing of the FC voltages, a challenge in applications with small capacitors and low switching frequencies, is done without any modulation, simply using tables calculated offline. These allow the realization of fast-dynamics output currents with reduced dv/dt in the output voltages and reduced switching frequencies. Moreover, no interharmonics are created when operating at low switching frequencies and with reference currents containing multiple harmonic components, which is a key feature for active power filters. Simulations and experimental results are presented to demonstrate the excellent performance of the direct control strategy in comparison with a conventional pulsewidth-modulation control technique, mostly for operation at low switching frequencies

A predictive control with flying capacitor balancing of a multicell active power filter

Unlike traditional inverters, multicell inverters have the following advantages: lower switching frequency, high number of output levels, and less voltage constraints on the insulated-gate bipolar transistors. Significant performances are provided with this structure which is constituted with flying capacitors. This paper deals with a predictive and direct control applied to the multicell inverter for an original application of this converter: a three-phase active filter. To take advantage of the capabilities of the multicell converter in terms of redundant control states, a voltage control method of flying capacitor is added, based on the use of a switching table. Flying capacitor voltages are kept on a fixed interval, and precise voltage sensors are not necessary. The association of predictive control and voltage balancing increases considerably the bandwidth of the active filter

Między epokami

This review is a short presentation and an analysis of the book България – страна на розите, published in 2018. The book consists of three parts – a phototypical copy of the first Polish edition of the collective book from 1938, a translation of this edition into Bulgarian language with biographies of the authors of the texts and several studies, dedicated to Metodi Konstantinov (the 1938’s edition editor), to Polish-Bulgarian political and cultural relations in the late 1930s and their local repercussions in Poznań and last but not least – to the language of the first edition and its translation and re-translation. The aim of the publication – to remind the first edition of the book, to make it accessible for Bulgarian readers and to restore the memory about its authors and editors – is thoroughly fulfilled. Moreover, an additional advantage of the book is that it makes its readers more aware of the difference in Bulgarians’ self-representational practices before and after the Second World War.This review is a short presentation and an analysis of the book България – страна на розите, published in 2018. The book consists of three parts – a phototypical copy of the first Polish edition of the collective book from 1938, a translation of this edition into Bulgarian language with biographies of the authors of the texts and several studies, dedicated to Metodi Konstantinov (the 1938’s edition editor), to Polish-Bulgarian political and cultural relations in the late 1930s and their local repercussions in Poznań and last but not least – to the language of the first edition and its translation and re-translation. The aim of the publication – to remind the first edition of the book, to make it accessible for Bulgarian readers and to restore the memory about its authors and editors – is thoroughly fulfilled. Moreover, an additional advantage of the book is that it makes its readers more aware of the difference in Bulgarians’ self-representational practices before and after the Second World War

Mono inverter dual parallel PMSM - Structure and Control strategy

This paper presents a dual parallel connected PMSM fed by a single power inverter. Both motors have to respect the synchronism even if they have different load torque. The rotor position of the two motors that is to say the load applied on each motor are consequently permanently compared. The motor with the highest load is set as the master one and is auto-piloted. The other one which has the same applied voltage has the same electric pulsation and so the same speed rotation. The change of the master choice is done whereas the load applied on the machine is changing so that oscillations appear during this change. The steady state is however rapidly attained and the synchronism stays always observed

Motion control of elastic joint based on kalman optimization with evolutionary algorithm

Actual industrial ambition is to remove a maximum of sensor to improve reliability and cost. Performances are then decreasing a lot, specially for a system with variable parameters and direct drives. Moreover, a two-mass system representing numerous class of industrial problem can become unstable. Keeping stability, a simple controller and observer tuning approach and a lower time consuming are main goals of this study. A previous calculated state feedback is used as base for two Kalman filters with special a noise matrix. An evolutionary algorithm optimizes observer's degrees of freedom to keep stability all over the stiffness variation. The results show that the stability and performances are kept on an experimental test bench

Mono inverter multi-parallel permanent magnet synchronous motor:structure and control strategy

This study presents a new and original Mono inverter multi-parallel permanent magnet synchronous motor (PMSM) system. To obtain the stability of such a system, each of the motor synchronisms should always be respected regardless of their load torque. In this case, only one motor, called ‘master motor’, will be self-piloted. If the chosen master motor is the one with the highest applied load torque, synchronism is respected for each of the motors. To find this machine, a solution that compares the rotor positions is thus developed. Experimental results are given for a system with two PMSM plugged in parallel. The proposed solution can, however, be applied to systems whatever the motor numbers; therefore additional simulations are provided for a four-PMSM system

O emisiji buke iz izmjeničnih pogona upravljanih pulsno-širinskom modulacijom

The paper presents and analyses the experimental acoustic noise of AC motors controlled by drives using different PWM techniques. After a discussion upon PWM methods concerning noise reduction, measure based comparisons are interpreted. Five criteria are taken into account: motor type, motor power, rotor speed, switching frequency and PWM method.U radu se izlaže eksperimentalna analiza buke emitirane iz izmjeničnih pogona upravljanih različitim postupcima pulsno-širinske modulacije (PWM). Nakon izlaganja utjecaja izbora PWM postupka na stupanj redukcije buke, uspoređeni su i interpretirani mjerni rezultati. Uzeto je u obzir pet kriterija: tip motora, snaga motora, brzina vrtnje, sklopna frekvencija i tip PWM postupka

Generalized inverses applied to Pulse Width Modulation for static conversion: a first study

This paper points out the generic matrix approach to design Pulse Width Modulation strategies of three-phase Voltage Source Inverters. This well-known problem has infinitely many solutions, and many modulation methods already exist. This mathematical approach deserves to be explored by its rigor and mustidentify known but also new solution

O emisiji buke iz izmjeničnih pogona upravljanih pulsno-širinskom modulacijom

The paper presents and analyses the experimental acoustic noise of AC motors controlled by drives using different PWM techniques. After a discussion upon PWM methods concerning noise reduction, measure based comparisons are interpreted. Five criteria are taken into account: motor type, motor power, rotor speed, switching frequency and PWM method.U radu se izlaže eksperimentalna analiza buke emitirane iz izmjeničnih pogona upravljanih različitim postupcima pulsno-širinske modulacije (PWM). Nakon izlaganja utjecaja izbora PWM postupka na stupanj redukcije buke, uspoređeni su i interpretirani mjerni rezultati. Uzeto je u obzir pet kriterija: tip motora, snaga motora, brzina vrtnje, sklopna frekvencija i tip PWM postupka

Molecular detection and maternal transmission of a bacterial symbiont Asaia species in field-caught Anopheles mosquitoes from Cameroon

Background Malaria control relies mainlyon insecticide-based tools. However, the effectiveness of these tools is threatened by widespread insecticide resistance in malaria vectors, highlighting the need for alternative control approaches. The endosymbiont Asaia has emerged as a promising candidate for paratransgenic control of malaria, but its biology and genetics still need to be further analyzed across Africa. Here, we investigated the prevalence of Asaia and its maternal transmission in the natural population of Anopheles mosquitoes in Cameroon. Methods Indoor-resting adult mosquitoes belonging to four species (An. coluzzii, An. arabiensis, An. funestus and An. gambiae) were collected from eight localities across Cameroon from July 2016 to February 2020. PCR was performed on the Asaia-specific 16S ribosomal RNA gene, and samples positive by PCR for Asaia were confirmed by Sanger sequencing and phylogenetic analysis. The vertical transmission of Asaia was investigated by screening F1 mosquitoes belonging to F0 Asaia-positive females. Results A total of 895 mosquitoes were screened. We found 43% (384) Asaia infection prevalence in four mosquito species. Phylogenetic analysis revealed that Asaia from Cameroon clustered together with the strains of Asaia isolated from other parts of the world. In addition, seven nucleotide sequence variants were found with low genetic diversity (π = 0.00241) and nucleotide sequence variant diversity (Hd = 0.481). Asaia was vertically transmitted with high frequency (range from 42.5 to 100%). Conclusions This study provides field-based evidence of the presence of Asaia in Anopheles mosquitoes in Cameroon for exploitation as a symbiont in the control of malaria in sub-Saharan Africa