Bidirectional positive buck-boost converter

In a positive buck-boost (PBB) converter, inductor current and capacitor voltage can be decoupled which may improve system stability. In fact for a specific level of capacitor voltage, the inductor current can be adjusted at different levels and can be utilized to increase the robustness of the converter against input voltage and load disturbances. But when demand is a fast response with respect to step change in reference voltage, this topology needs to be modified. In this paper, a family of topologies based on a positive buck boost converter are presented which have a fast response and bidirectional power flow capability. This feature leads to some applications in hybrid vehicle systems and telecommunications. Simulations have been carried out to validate fast response of the proposed converters

Voltage-sharing converter to supply single-phase asymmetrical four-level diode-clamped inverter with high power factor loads

The output voltage quality of some of the single-phase multilevel inverters can be improved when their dc-link voltages are regulated asymmetrically. Symmetrical and asymmetrical multilevel diode-clamped inverters have the problem of dc-link capacitor voltage balancing, especially when power factor of the load is close to unity. In this paper, a new single-inductor multi-output dc/dc converter is proposed that can control the dc-link voltages of a single-phase diode-clamped inverter asymmetrically to achievevoltage quality enhancement. The circuit of the presented converter is explained and themain equations are developed. A control strategy is proposed and explained in details. To validate the versatilityof the proposed combination of the suggested dc–dc converter and the asymmetrical four-level diode-clamped inverter (ADCI), simulations and experiments have been directed. It is concluded that theproposed combination of introduced multioutput dc–dc converter and single-phase ADCI is a good candidate for power conversion in residential photovoltaic (PV) utilization

A New DC-DC Converter with Multi Output: Topology and Control Strategies

This paper presents a new topology based on a Positive Buck-Boost converter with multi output (MOPBB). A single output positive Buck-Boost converter consists of a Buck and Boost converters in cascade which can be controlled against input voltage fluctuation and load changes. In this paper, the steady state and dynamic analyses of the proposed topology are presented along with simulation results. A control algorithm is presented to control output voltages against input voltage fluctuation and step change in load with a purely logic control system that is based on hysteresis current and voltage control. This topology is suitable for a high power multilevel converter with diode-clamped topology where a series of capacitors are required to generate different voltage levels and capacitors voltage control is an important issue in this application

Common-mode voltage reduction in a motor drive system with a power factor correction

Common-mode voltage generated by a power converter in combination with parasitic capacitive couplings is a potential source of shaft voltage in an AC motor drive system. In this study, a three-phase motor drive system supplied with a single-phase AC-DC diode rectifier is investigated in order to reduce shaft voltage in a three-phase AC motor drive system. In this topology, the AC-DC diode rectifier influences the common-mode voltage generated by the inverter because the placement of the neutral point is changing in different rectifier circuit states. A pulse width modulation technique is presented by a proper placement of the zero vectors to reduce the common-mode voltage level, which leads to a cost-effective shaft voltage reduction technique without load current distortion, while keeping the switching frequency constant. Analysis, simulations and experimental implementation have been presented to investigate the proposed method

A Novel Configuration for Voltage Sharing in DC-DC Converters

This paper presents a new multi-output voltage sharing (MOVS) converter. A high voltage application has been considered in this paper, where a novel DC-DC converter is being used as interface in high power renewable energy systems based on diode-clamped multilevel inverter, in which high quality regulated DC voltage is generated for DC link capacitors. Different output voltage sharing can be achieved by a given duty cycle for low and high power applications. Meanwhile, capacitor unbalancing problem in diode-clamped converters could be avoided as the voltage across each capacitor is controlled to the desired voltage level which decreases in complexity of inverter control. The topology easily can be extended to give multiple outputs. In order to verify the proposed topology, steady state and dynamic analysis have been studied. Simulation results are presented to show the operation of the proposed converters