Dinamička analiza SEPIC pretvarača

In this paper a dynamic analysis of the nonisolated and isolated dc-dc SEPIC (Single Ended Primary Inductance Converter) based on the substitution of the switches (transistor and diode) by PWM averaged switch model equivalent circuit is presented. The SEPIC converter is used when the wide range of input voltages is required. Besides the switches the SEPIC converter circuit consists of two inductors and two capacitors. Due to this, its dynamic model is of the fourth order differential equations system. The duty cycle and transformer turn ratio have great impact on the converter dynamics. The system parameters design guidelines are given to assure that the dynamic system has well separated resonance frequencies. The derived dynamic model was verified by simulation toolbox SimPowerSystems.U radu je prikazana dinamička analiza SEPIC pretvarača (engl. Single Ended Primary Inductance Converter) bez galvanskog odvajanja i s galvanskim odvajanjem. U analizi se sklopke (tranzistori i diode) nadomještaju ekvivalentnim modelom s usrednjavanjem zasnovanim na širinsko-impulsnoj modulaciji. SEPIC pretvarači omogućuju veliki raspon ulaznog napona pretvarača. Sam pretvarač može raditi kao silazni i uzlazni dc-dc pretvarač. Strukturu pretvarača osim poluvodičkih komponenata čine i dvije zavojnice i dva kondenzatora, što omogućuje njegovo modeliranje diferencijalnom jednadžbom četvrtoga reda. Na dinamiku pretvarača značajan utjecaj imaju i vrijeme vođenja i transformatorski prijenosni. U članku su dane preporuke za projektiranje SEPIC pretvarača kojima se postiže dovoljno veliko razdvajanje rezonantnih frekvencija koje se pojavljuju u frekvencijskoj karakteristici pretvarača. Razvijeni je model pretvarača provjeren simulacijama pomoću programskog alata SimPowerSystems programa MATLAB

Korekcija faktora faznog pomaka trofaznog trorazinskog uzlaznog ispravljača zasnovanog na PWM-u

Pulse width modulation (PWM) strategy for a matrix structured three-phase three-level AC to DC boost rectifier is developed. Such approach has been used on purpose to control the input displacement power factor close to unity. The connection between matrix switching function and PWM requirement very well describes all restrictions that occur in the modulation algorithm. This modulation algorithm enables the input displacement factor correction without an input current sensor. The only necessary control variable is the measured displacement angle between input voltage and input current.U radu je razvijen PWM algoritam za upravljanje matrično-strukturiranim trofaznim trorazinskim ispravljačem. Takav način upravljanja uzet je radi mogućnosti korekcije faktora pomaka (cos fi) na jediničnu vrijednost. Veza između prekidačkih funkcija i zahtjeva na impulsno-širinski modulator jasno opisuje sva ograničenja modulacijskog algoritma. Razvijeni modulacijski algoritam omogućuje korekciju faktora pomaka bez mjerenja ulazne struje pretvarača. Za potrebe te korekcije dovoljno je samo mjerenje faznog kuta između napona i struje na ulazu ispravljača

Silazni DC-DC pretvarač bez izlaznog kondenzatora

Low-power switched-mode power supply converters are used in applications where size and efficiency are critical. The buck converter size can be reduced by elimination of the bulky filter capacitor. The filtering function of this capacitor can be replaced by an output current ripple compensation circuit. The compensating circuit is applied, based on inductor current measurement and linear amplifier. The proposed compensating algorithm is investigated theoretically by simulation, and verified experimentally.DC-DC pretvarači malih snaga se koriste u uredjajima gdje su važni dimenzije i učinkovitost. Dimenzije pretvarača se mogu smanjiti sa izostavljanjem filtarskog kondenzatora. Umjesto sa kondenzatorom se funkcija gladjenja izlaznog napona može izvesti sa kompenzacijom valovitosti struje zavojnice. Za kompenzaciju valovitosti struje je potrebno mjeriti trenutnu vrijednost struje induktora koja se preko obrade u linearnom pojačalu dodaje u protifazi struji zavojnice. Predloženi kompenzacijski postupak je istraživan teoretski te verificirani simulacijski i eksperimentalno

A Survey on the State-of-the-Art and Future Trends of Multilevel Inverters in BEVs

All electric vehicles are the only way to decarbonize transport quickly and substantially. Although multilevel inverters have already been used in some transportation modes, they are rarely used in road transportation, especially in light-duty passenger BEVs. With the transition to a high 800-V DC link to extend the driving range and enable extreme fast charging, the possibility of using multilevel inverters in commercial light-duty passenger BEVs becomes feasible. Higher efficiency, higher power density, better waveform quality, lower switching frequency, the possibility of using low-rated switches, and inherent fault tolerance are known advantages of multilevel inverters that make them an efficient option for replacing 2-level inverters in high DC link passenger BEVs. This paper discusses high DC link voltage benefits in light-duty passenger BEVs, presents the state-of-the-art of different conventional multilevel inverter topologies used in BEVs, and compares them with conventional 2-level inverters from different aspects and limitations. Based on commercial upper-class passengers’ BEV data and a review of multilevel inverters on the market, future trends and possible research areas are identified

Energetska elektronika

Pričujoče gradivo vsebuje navodila za laboratorijske vaje pri predmetu Energetska elektronika za študente prvega letnika magistrskega študijskega programa Elektrotehnika, smer Avtomatika in robotika ter smer Močnostna elektrotehnika in študente prvega letnika magistrskega študijskega programa Mehatronika. V navodilih je predstavljeno pet laboratorijskih vaj, ki obravnavajo usmerniška vezja s korekcijo faktorja moči, trifazna šestkoračna razsmerniška vezja, sinusno pulznoširinsko modulacijo v enofaznih razsmernikih z dvoin tri-nivojskim izhodom s poudarkom na harmonski analizi vhodnih oz. izhodnih signalov vezij. Vse vaje vsebujejo gradnjo simulacijskega modela vezij in potrditev simulacijskih rezultatov z meritvami na eksperimentalnem modelu

An Improved SPWM-Based Control with Over-Modulation Strategy of the Third Harmonic Elimination for a Single-Phase Inverter

In single-phase inverter systems (grid-connected, Uninterrupted Power Supply systems or motor drives), the high quality Total Harmonic Distortion (THD) factor must always be considered, along with the utilization rate of the DC link. In cases when the supplying DC voltage is reduced, the output voltage can still be assured constant in a limited range by using over-modulation. Unfortunately, this operation incurs fundamental frequency related higher order harmonics’ force (especially the third is dominant) into the inverter output voltage, which is a huge drawback in almost all applications. This paper provides a comprehensive spectrum analysis of three-level output voltage in a single-phase inverter working in over-modulation regime. The output voltage is generated by triangular Sinusoidal Pulse-Width Modulation (SPWM) and, based on the analytical results of a frequency spectrum evaluation, the opposite third harmonic component in the modulator unit forces this component in the output voltage close to zero. Other remaining higher harmonics can be attenuated more easily by using a smaller filter. Although the voltage gain of the fundamental harmonic component is lower at higher over-modulation, such a solution assures lower THD in the wide inverter’s working range. The proposed SPWM procedure was validated experimentally