ESTE ARTÍCULO PROPONE UNA TOPOLOGÍA DE CONVERTIDOR DE POTENCIA CC-DC BASADA EN UN CONVERTIDOR FLYBACK (FC) MODIFICADO. EL OBJETIVO DE LA TOPOLOGÍA PROPUESTA ES AUMENTAR LA GANANCIA DE TENSIÓN CONECTANDO LAS ENTRADAS DE N FCS AISLADAS EN PARALELO Y LAS N INDUCTANCIAS SECUNDARIAS EN SERIE. ESTE ESQUEMA REDUCE LA CORRIENTE EN CADA CONMUTADOR Y REDUCE LAS PÉRDIDAS ASOCIADAS. UN SOLO DIODO Y UNA CAPACITANCIA DE SALIDA COMPLETAN EL CIRCUITO CONVERTIDOR DE POTENCIA. SE USA UN CONTROLADOR PROPORCIONAL + INTEGRAL (PI) PARA CONTROLAR LA TENSIÓN DE SALIDA CON EL CONVERTIDOR FUNCIONANDO EN MODO DE CORRIENTE DISCONTINUA. EL CONVERTIDOR PROPUESTO PUEDE MANEJAR MÁS POTENCIA QUE EL FC ESTÁNDAR CON UN BAJO NÚMERO DE DISPOSITIVOS DE POTENCIA ACTIVA. EL SISTEMA ES MODELADO USANDO LA PLATAFORMA PSIM Y LOS RESULTADOS EXPERIMENTALES SE PRESENTAN CONSIDERANDO UN PROTOTIPO DE 1KW

A MULTILEVEL MODULAR DC?DC POWER CONVERSION TOPOLOGY BASED ON CASCADED H-BRIDGE CONVERTERS IN A DOUBLE II CONFIGURATION IS PRESENTED. THE TOPOLOGY IS INTENDED TO INTERCONNECT LARGE POWER DC NETWORKS. A TWO LEVEL CONTROL HIERARCHY IS USED TO REGULATE THE DC VOLTAGE OF EACH H-BRIDGE MODULE. AT THE TOP LEVEL, DC AND CIRCULATING AC CURRENTS ARE USED TO CONTROL THE TOTAL ENERGY CONVERTER IN ALL BRANCHES (BOTH PARALLELS AND SERIES) OF EACH II ARRANGE. AT BOTTOM LEVEL, THE VOLTAGE BALANCE OF A CONVERTER BRANCH, WHICH COMPRISES N H-BRIDGE MODULES, IS CARRIED OUT BY BALANCING (N-1) CAPACITOR VOLTAGE DEVIATIONS, WITH RESPECT TO THE AVERAGE CAPACITOR VOLTAGE. THE ENTIRE TOPOLOGY AND CONTROL STRATEGIES ARE SIMULATED IN A PSIM ENVIRONMENT. SIMULATION RESULTS WITH THREE H-BRIDGE CONVERTERS PER BRANCH ARE SHOWN AND PRELIMINARY EXPERIMENTAL RESULTS WITH A LOW POWER PROTOTYPE ARE ALSO INCLUDED.

IN THIS PAPER, A CONTROL STRATEGY INTENDED TO ELIMINATE ANY DC VOLTAGE OFFSET CAUSED BY A COMMON-MODE AND ZERO SEQUENCE VOLTAGE REDUCTION MODULATION, FROM THE MACHINE TERMINALS, IS PRESENTED. IN ORDER TO ACHIEVE THAT GOAL, A PI RESONANT CONTROLLER IS PROPOSED TO CONTROL THE MACHINE CURRENTS. SIMULATION AND EXPERIMENTAL RESULTS ARE PRESENTED AND DISCUSSED.

AN OPEN-END WINDING INDUCTION MOTOR FED BY A TWO-OUTPUT STAGES INDIRECT MATRIX CONVERTER (IMC) IS PRESENTED. THE CAPABILITY OF THE IMC INPUT STAGE TO PRODUCE DIFFERENT DC VOLTAGE LEVELS IS EXPLOITED. THE IMC OUTPUT STAGES COMMUTATES AT REDUCED DC VOLTAGE WHEN THE OUTPUT VOLTAGE REQUIREMENT IS LOW. FURTHERMORE, THE MODULATION STRATEGY FOR THE OUTPUT INVERTERS AIMS TO REDUCE THE COMMON-MODE VOLTAGE AND COMPENSATE THE ZERO SEQUENCE CURRENTS IN THE LOAD. TO ENSURE A GOOD TRACKING OF THE MACHINE CURRENTS, A RESONANT CONTROLLER (RC) IS USED. SIMULATION RESULTS SHOWING THE PERFORMANCE OF THE CONTROL SCHEME AND THE REDUCTION OF COMMON-MODE VOLTAGE ARE PRESENTED USING A PSIM/MATLAB SIMULATION PLATFORM.

THIS PAPER PRESENTS A CONTROL STRATEGY FOR A GRID CONNECTED PHOTOVOLTAIC (PV) SYSTEM AIMING TO REGULATE THE ACTIVE AND REACTIVE POWER INJECTED TO THE ELECTRIC SYSTEM DURING ASYMMETRICAL VOLTAGE FAULTS. THE ACTIVE POWER REFERENCE IS OBTAINED FROM A MAXIMUM POWER POINT TRACKING (MPPT) ALGORITHM. THE PROPOSED CONTROL STRATEGY GENERATES THE REQUIRED REFERENCE CURRENTS TO BE IMPOSED BY THE GRID-TIED INVERTER FROM THE DESIRED ACTIVE AND REACTIVE POWER AND THE MEASURED SUPPLY VOLTAGE. THE SCHEME IS VALIDATED FOR A SINGLE STAGE PV SYSTEM WHERE THE INVERTER CURRENTS ARE REGULATED VIA PREDICTIVE CONTROL. RESULTS SHOWING THE PERFORMANCE OF THE STRATEGY ARE PRESENTED DURING UNBALANCED VOLTAGE SAGS AND SWELLS.

THIS WORK PROPOSES A MULTICELL TOPOLOGY BASED ON CURRENT-SOURCE CELLS IN ORDER TO INHERIT THE ADVANTAGES OF CURRENT-SOURCE TOPOLOGIES SUCH AS REDUCED LOAD DV/DT VOLTAGE AND NATURAL BIDIRECTIONAL POWER FLOW AND TO ADOPT A SIMILAR BEHAVIOR OF THE MULTICELL TOPOLOGY BASED ON A VOLTAGE SOURCE CONVERTER SUCH AS VOLTAGE CONTROLLED BEHAVIOR WHERE N C CELLS ARE CONNECTED IN SERIES TO FEED ONE LOAD PHASE. IN ORDER TO CHECK THE TECHNICAL FEASIBILITY AND PERFORMANCE OF THE PROPOSED TOPOLOGY, A MATHEMATICAL MODEL IS INTRODUCED AND STUDIED AND KEY DESIGN GUIDELINES OF PASSIVE COMPONENTS ARE DEFINED. THE ANALYSIS SHOWS THE POSSIBILITY OF USING COMPONENTS WITH A LOWER VOLTAGE RATING THAN THAT OF THE CLASSIC MULTILEVEL CURRENT SOURCE TOPOLOGIES AND ALLOWS THE USE OF LOW SWITCHING FREQUENCIES IN BOTH RECTIFIER AND INVERTER STAGES WHILE AT THE SAME TIME OBTAINING A HIGH-QUALITY WAVEFORM IN BOTH LOAD VOLTAGE AND CONVERTER INPUT CURRENTS. A CASE OF EXAMPLE IS USED TO CORROBORATE THE THEORETICAL ANALYSIS AND THE COMPONENT DESIGN METHODOLOGY, AS WELL AS THE PERFORMANCE OF THE TOPOLOGY USING A LOW-POWER PROTOTYPE.

A STRATEGY FOR AN INDIRECT MATRIX CONVERTER WITH TWO OUTPUTS TO SUPPLY ENERGY TO A VECTOR CONTROLLED OPEN-END WINDING INDUCTION MACHINE IS PRESENTED. THE MODULATION SCHEMES FOR THE INPUT AND TWO OUTPUT STAGES AIM TO REDUCE THE VIRTUAL DC LINK VOLTAGE FOR LOW SPEED OPERATION AND ELIMINATE THE ZERO SEQUENCE VOLTAGE IN THE LOAD.

POWER ELECTRONIC CONVERTERS ARE NOWADAYS THE MOST SUITABLE SOLUTION TO PROVIDE A VARIABLE VOLTAGE/CURRENT IN INDUSTRY. THE MOST COMMONLY USED POWER CONVERTER IS THE THREE-PHASE TWO-LEVEL VOLTAGE SOURCE INVERTER WHICH TRANSFORMS A DIRECT-CURRENT INPUT VOLTAGE INTO ALTERNATING-CURRENT OUTPUT VOLTAGE WITH ADJUSTABLE MAGNITUDE AND FREQUENCY. POWER INVERTERS ARE USED TO SUPPLY THREE-PHASE LOADS WHICH ARE TYPICALLY CONNECTED IN WYE OR DELTA CONFIGURATIONS. HOWEVER, IN PREVIOUS YEARS, A TYPE OF CONNECTION CONSISTING ON LEAVING BOTH TERMINAL ENDS OF THE LOAD OPENED HAS BEEN STUDIED AS AN ALTERNATIVE TO STANDARD WYE OR DELTA CONNECTION. TO SUPPLY LOADS WITH THIS TYPE OF CONNECTION, TWO POWER INVERTERS (ONE AT EACH TERMINAL END OF THE LOAD) ARE REQUIRED IN A CIRCUIT TOPOLOGY CALLED DUAL-INVERTER. IN THIS CHAPTER, A GENERAL STUDY OF THE DUAL-INVERTER TOPOLOGY IS PRESENTED. THE ADVANTAGES AND ISSUES OF SUCH CONVERTER ARE STUDIED AND DIFFERENT MODULATION STRATEGIES ARE SHOWN AND DISCUSSED. MOREOVER, MULTILEVEL DUAL-INVERTER CONVERTERS ARE PRESENTED AS AN EXTENSION TO THE BASIC TWO-LEVEL IDEA. FOR EVALUATION PURPOSES, SIMULATIONS RESULTS ARE PRESENTED.

IN THIS PAPER AN INDIRECT MATRIX CONVERTER (IMC) TOPOLOGY SUITABLE FOR CONTROLLING AN OPEN-END WINDING INDUCTION MACHINE IS PRESENTED. THE IMC IS A DIRECT POWER CONVERTER HAVING NO BULKY ENERGY STORAGE ELEMENTS WITH AN INPUT OR CURRENT RECTIFYING STAGE AND A VOLTAGE SOURCE INVERTER AS AN OUTPUT STAGE. TO PROVIDE ENERGY TO AN OPEN-END WINDING INDUCTION MACHINE TWO OUTPUT STAGES ARE NEEDED. THEN, IT IS POSSIBLE TO OBTAIN A VOLTAGE ACROSS ANY PHASE OF THE LOAD UP TO 1.5 TIMES THE INPUT PHASE VOLTAGE WITHOUT OVER MODULATION. TWO PULSE WIDTH MODULATION STRATEGIES ARE PRESENTED: THE FIRST ONE IS BASED ON SPACE VECTOR MODULATION THAT SUPPRESSES THE ZERO SEQUENCE VOLTAGE IN THE LOAD WHEREAS THE SECOND ONE IS A CARRIER-BASED MODULATION WHICH GENERATES LOWER DISTORTED INPUT CONVERTER CURRENTS. RESULTS ARE PRESENTED AND DISCUSSED.

AC DRIVES BASED ON CURRENT-SOURCE CONVERTERS (CSC) PRESENT AN INTERESTING ALTERNATIVE FOR MEDIUM VOLTAGE MOTORS, BECAUSE OF HIGH QUALITY OF BOTH AC INPUT CURRENTS AND LOAD VOLTAGE WAVEFORMS. THIS KIND OF POWER CONVERTERS ALLOWS AVOIDING WAVE REFLECTION PROBLEMS THAT ARE TYPICAL OF VOLTAGE-SOURCE INVERTERS. HOWEVER, THE USE CSC IN ACTIVE POWER FILTERS IS LIMITED BY POWER LOSSES CAUSED BY THE DC CURRENT. IN THIS WORK WE STUDY THE USE OF MULTILEVEL CURRENT-SOURCE CONVERTER BASED STATCOM, USING MINIMUM DC CURRENT LEVEL IN EACH CONVERTER. FOR THE ABOVE, THE STATCOM CURRENT LEVEL REQUIRED TO COMPENSATE BOTH LOAD REACTIVE POWER AND STATCOM LOSSES IS COMPUTED, USING THE HIGHEST MODULATION INDEX POSSIBLE. MATHEMATICAL ANALYSIS CORROBORATED BY PSIM SIMULATIONS, SHOWS THAT IT IS POSSIBLE TO REDUCE POWER LOSSES IN THE OVERALL EQUIPMENT, BY INCREASING THE NUMBER OF CONVERTERS IN THE STATCOM.

OPEN-END WINDING INDUCTION MACHINES FED FROM TWO STANDARD TWO-LEVEL VOLTAGE SOURCE INVERTERS (VSI) PROVIDE AN ATTRACTIVE ARRANGEMENT FOR AC DRIVES. AN ALTERNATIVE APPROACH IS TO USE A DUAL OUTPUT INDIRECT MATRIX CONVERTER (IMC). IT IS WELL KNOWN THAT IMC PROVIDES FULLY BIDIRECTIONAL POWER FLOW OPERATION, WITH SMALL INPUT SIZE FILTER REQUIREMENTS. WHILST A STANDARD IMC CONSISTS OF AN AC?DC MATRIX CONVERTER INPUT STAGE FOLLOWED BY A SINGLE VSI OUTPUT STAGE, IT IS POSSIBLE TO REPLICATE THE VSI TO PRODUCE MULTIPLE OUTPUTS. IN THIS CHAPTER, AN OPEN-END WINDING INDUCTION MACHINE FED BY AN IMC WITH TWO OUTPUT STAGES IS PRESENTED. DIFFERENT MODULATION STRATEGIES FOR THE POWER CONVERTER ARE ANALYZED AND DISCUSSED.

THIS PAPER PRESENTS A PREDICTIVE CURRENT CONTROL STRATEGY FOR ACTIVE FRONT END (AFE) RECTIFIER SUPPLYING ACTIVE AND REACTIVE POWER TO THE ELECTRIC SYSTEM DURING UNSYMMETRICAL VOLTAGE FAULT CONDITIONS WITHOUT THE USE OF A PHASE LOCKED LOOP (PLL) OR FREQUENCY LOCKED LOOP (FLL). FOR A GIVEN ACTIVE AND REACTIVE POWER AND SUPPLY VOLTAGE, THE STRATEGY GENERATES THE REQUIRED REFERENCE CURRENTS. A PREDICTIVE CURRENT CONTROL STRATEGY IS USED TO IMPOSE THOSE CURRENTS BY THE AFE RECTIFIER. IT IS SHOWN THAT THE AMOUNT OF ACTIVE AND REACTIVE POWER THAT CAN BE INJECTED INTO THE GRID WILL DEPEND ON VOLTAGE UNBALANCED LEVEL. SIMULATIONS AND EXPERIMENTAL RESULTS SHOWING THE PERFORMANCE OF THE STRATEGY ARE PRESENTED DURING UNBALANCED VOLTAGE SAG AND SWELLS.