Andrzej Mondzik

Results of Investigation of Multicell Converters With Balancing Circuit—Part II

This paper presents the results of an investigation of the multilevel multicell converters with a passive RLC balancing circuit applied for the maintenance of the voltage sharing on the capacitive sources of the converters. The topologies of DC/DC, AC/AC, DC/AC, and AC/DC multicell converters were analyzed. For the purpose of multilevel modulation, a multicell converter employs several capacitors that are connected to every cell-the flying capacitors, charged to a given level of voltage. An inadequate relation between the voltages across the flying capacitors (the unbalance state) results in the increase of the voltages above their rated values across the switches. An RLC series circuit (a balancing circuit) with the properly selected resonance frequency is connected in parallel to the load in order to eliminate the unbalance. The balancing process with the use of passive RLC depends on the configuration and parameters of the balancing circuit, the parameters of the converter, as well as on the operating conditions. This paper presents the mathematical description of both the converter and the balancing process, the balancing circuit approach in the different topologies of the multicell converters, a selection of the balancing circuit parameters, and the analysis of the improper control conditions.

High-Power Thyristor-Based DC–DC Switched-Capacitor Voltage Multipliers: Basic Concept and Novel Derived Topology With Reduced Number of Switches

This paper presents concepts and results of an investigation of power electronic thyristor-based switched-capacitor voltage multipliers (SCVMs). A concept of the SCVM power converters assumes the utilization of resonant circuits for the zero-current switching operation. The topology makes it possible to apply thyristors as active switches that create the possibility of composing the resonant switch-mode converters for high-voltage gain, high power, and low cost, and opens a huge area of applications. This paper presents an in-depth analysis of the SCVM configured as the resonant high-power thyristor-based converter. The operation with regard to the specific switching conditions of thyristors, as well as efficiency of the converter is analyzed providing the unique relationship important for the converter design, optimization, and efficiency improvement. An experimental validation confirms the feasibility and the operation concept of the SCVM and demonstrates the efficiency range. The SCVM converter can be optimized to the topology with a decreased number of switches. This paper also presents a novel topology of the resonant converter with a reduced number of switches, resonant switched capacitor voltage multiplier (RSCVM), dedicated for thyristor implementation. The RSCVM requires the specific component selection and control. The analysis of the configuration, operation, efficiency, and component selection of the RSCVM converter, as well as simulation and experimental results are presented.

Multicell DC/DC Converter with DSP/CPLD Control. Practical Results

The paper presents practical investigations of DC/DC multilevel, multicell converter with DSP/CPLD control. A flying capacitors topology, natural balancing process and method of control of three-cell DC/DC converter are presented. Practical realization of the controller with use of programmable logic, discrete regulators in signal processor, procedures of initial flying capacitors charging, protection and turn-off the converter are described

Switched Capacitor-Based Power Electronic Converter—Optimization of High Frequency Resonant Circuit Components

This chapter presents issues of optimization of the resonant circuit components’ volume in a switched-capacitor voltage multiplier (SCVM). The SCVM is derived from chip-scale technology but can effectively operate as a power electronic converter in a zero current switching mode when the recharging of switched capacitors occurs in a resonant circuit supported by an inductance. Selection of the passive LC components is not strictly determined, and depends on the optimization strategy according to the volume, efficiency or cost of the converter. Optimization of the volume of LC components is limited by the energy transfer ability via switched capacitors, thus by the rated power of the converter and switching frequency. Depending on the LC values, the converter operates in some specific states that determine the efficiency of the converter and voltage stress on semiconductor switches and diodes. This chapter presents analysis of the converter parameters and operation in the cases of optimization of the resonant circuit components’ values. The analytical discussion is also supported by the simulation and experimental results. All the results are provided for the SCVM but can be useful for a variety of switched-capacitor resonant power converters.

Small-signal model and control of the interleaved two-phase coupled-inductor boost converter

Coupled-inductor boost converters are under development for high-current, high-power applications ranging from automotive fuel cells to photovoltaics. This paper presents the small-signal analysis of a coupled-inductor boost converter operating in both CCM and DCM. Due to the complexity of operation of a coupled-inductor boost converter operating in DCM, several small-signal models must be derived. Controllers for the converter are developed using the resulting small-signal models. Experimental validation of these controllers is presented from a 1 kW coupled-inductor boost converter laboratory prototype.

High efficiency switched capacitor voltage doubler with planar core-based resonant choke

This paper presents the research results of an optimized DC-DC voltage doubler based on a high-frequency resonant switched-capacitor (SC) topology. The converter utilizes a low weight PCB-type planar choke, and can be attractive for fuel cell-or battery-supplied systems which operate from low voltage where a voltage boost is needed. The optimization aims at minimizing power losses in the converter by an adequate selection of components, whereas low weight and small size are also advantageous. The problem is to minimize the resistance of the components and at the same time optimize the parameters of the resonant circuits. Improved efficiency in the switched-capacitor multipliers can also have the benefit of reducing voltage gain sensitivity for power variation. These types of converters are constant voltage gain circuits, but parasitic resistances can cause a substantial voltage gain drop as power rises, which can significantly limit the rated power. The paper contains an analytical discussion, an engineering assessment and experimental results of optimization issues in a MOSFET-based switched-capacitor voltage doubler (SCD) with a ferrite-based planar choke.

Experimental study of a multicell ac/ac converter balancing circuit

The paper presents the experimental study of the balancing process forced by passive RLC circuit in a multicell AC/AC converter. To ensure its proper operation the converter employs voltages over the capacitors within its internal topology. Appropriate charging and reversing charge of cellspsila capacitors is achieved by means of the passive balancing circuit - a series RLC circuit connected at the converter output. The main issue is the correct choice of the balancing circuit wave impedance and the converter parameters (switching frequency, capacitances of cells capacitors) that allows maintaining a correct shape and proportion of voltages across cells capacitors at minimum balancing current.

Efficiency Analysis of MOSFET-Based Air-Choke Resonant DC–DC Step-Up Switched-Capacitor Voltage Multipliers

This paper presents the investigation results of the efficiency of power electronic resonant zero-current switching dc–dc switched-capacitor voltage multipliers (SCVMs) in three topologies. The analytical model of efficiency shows the impact of the converters’ particular parameters on their properties and gives indications for an adequate design. The impact of the parameters of the semiconductor devices, parasitic resistances, switched capacitance value, number of switching cells, switching frequency, and choke design on the converters’ efficiency is demonstrated. The converters are investigated analytically with the use of computer-based simulations and experimentally as a three-cell MOSFET-based SCVM dc–dc resonant boost converter. The in-depth analysis and the results obtained are some novel contributions to the existing knowledge of switched-capacitor-based power electronic conversion. Moreover, the presented method of analysis can be useful for analyzing other types of SC power converters comprising resonant switching circuits.

An Analysis Of Overload Conditions In Mosfet-Based Power Resonant DC-DC Step-Up Converters In Switched Capacitor Voltage Multiplier Topology

This paper presents an analysis of operation of resonant DC-DC converter in topology of Switched Capacitor Voltage Multiplier (SCVM) under overload conditions. The SCVM operates as a charge pump, thus the energy transfer rate is limited and depends on the switched capacitance and the switching frequency. However an overload of the converter introduces specific operation conditions that can require a special control. The presented research results have an important significance for selection of components of SCVM as well as switching strategy, because the overload can occur as a result of load decrease as well as during the start of the converter. In the paper analytical, simulation and experimental results are presented for the Mosfet-based 200 Watt SCVM. Streszczenie. W artykule przedstawiono analize mozliwości pracy w stanie przeciązenia ukladu rezonansowego przeksztaltnika mocy DC-DC podwyzszającego napiecie w topologii powielacza napiecie (SCVM – Switched Capacitor Voltage Multiplier). Uklad o przelączanych kondensatorach dzialający na zasadzie pompy ladunku ma ograniczaną moc zdeterminowaną pojemnością przelączanych kondensatorow oraz czestotliwością przelączen. Jednak przeciązenie przeksztaltnika wywoluje specyficzny stan pracy, ktory moze wymagac specjalnego sterowania. Badania mają istotny wplyw na dobor sterowania w ukladzie SCVM, poniewaz przeciązenie moze wystepowac jako skutek wplywu odbiornika, ale rowniez przy starcie ukladu. W artykule przedstawiono badania analityczne, symulacyjne oraz eksperymentalne przeksztaltnika tranzystorowego SCVM z tranzystorami Mosfet, w zakresie mocy do 200 watow. (Analiza stanu przeciązenia przeksztaltnikow rezonansowych DC-DC o przelączanych kondensatorach podwyzszających napiecie zrealizowanych w technice Mosfet w topologii powielacza napiecia). Slowa kluczowe: Przeksztaltnik wielopoziomowy, przeksztaltnik DC-DC, przelączane kondensatory, pompa ladunku

A Synchronous Resonant Switched-Capacitor DC-DC Boost Converter - Experimental Results And Feasibility Model

This paper presents results of experimental research of a resonant switched capacitor voltage multiplier (SCVM) in the synchronous topology (SYSCVM). The classical SCVM utilizes diodes in the branches responsible for charging the switched capacitors. In the SYSCVM, additional MOSFET switches are connected in parallel with the diodes. Therefore, an improvement of efficiency is achieved. The paper presents experimental results of operation and efficiency of the SYSCVM. Furthermore, the issues related to the design of the converter with synchronous switches and the problems of the supply of the gate drivers are discussed. Streszczenie. W artykule przedstawiono wyniki badań eksperymentalnych rezonansowego przekształtnika DC-DC o przełączanych kondensatora powielającego napięcie stałe w topologii synchronicznej (SYSCVM – Synchronous Switched Capacitor Voltage Multiplier). W klasycznym rozwiązaniu analizowany przekształtnik o przełączanych kondensatorach wykorzystuje diody w obwodach ładowania przełączanych kondensatorów. W układzie SYSCVM diody połączone są równolegle z tranzystorami MOSFET dla uzyskania większej sprawności układu. Artykuł przedstawia wyniki pomiarów eksperymentalnych układu dotyczących weryfikacji działania układu oraz jego sprawności. Ponadto, problemy związane z praktyczną implementacją koncepcji synchronicznego układu (SYSCVM) zostają również omówione. (Układ powielacza napięcia w technice przełączanych kondensatorów w topologii synchronicznej badania eksperymentalne i studium wykonalności). Słowa kluczowe: Przekształtnik wielopoziomowy, przekształtnik DC-DC, przełączane kondensatory, powielacz napięcia, pompa ładunku