Search

A circuit structure, topological family, and unipolar phase-shift SPWM master-slave power distribution energy management control strategy (EMCS) of the single-stage Buck type multi-input high-frequency (HF) link's inverters with multiwinding time-sharing power supply are proposed in this article, in order to reduce the power conversion stage, volume and weight, and increase conversion efficiency and reliability. The key technologies of this kind of inverter, such as circuit structure and topological family, EMCS, power supply mode (PSM), and steady-state principle characteristics, are deeply studied. The circuit structure is composed of multiple isolated HF inverting bridges, a HF transformer with multi-input single-output, a cycloconverter and an output LC filter. The EMCS is to generate the bipolar tristate multilevel SPWM waves by phase-shift between the right arm and the left arm of multiple HF inverting bridges; the cycloconverter demodulates it into the unipolar tristate multilevel SPWM wave, and performs zero voltage commutation. The experimental results of the designed and developed 1kVA multi-input inverter prototype have shown it has the advantages of single-stage power conversion, HF electrical isolation, high conversion efficiency, small volume and weight, high reliability, stable output voltage, multi-input source master-slave power distribution, and smooth switching of different PSMs. [ABSTRACT FROM AUTHOR]

A class of single-stage multi-input Buck type high-frequency link's inverters with series and simultaneous power supply are proposed in this article, and the key technologies such as circuit structures and topological family, energy management control strategy (EMCS), power supply modes, steady-state principle characteristics are studied in depth, from which some important conclusions are obtained. The circuit structure is composed of a multi-input-single-output high-frequency inverter, high-frequency transformer, cycloconverter, and output filter in sequence. The EMCS is to generate bipolar tri-state multilevel sinusoidal pulse width modulation (SPWM) waves by phase shifting between right and left arms of the high-frequency inverting bridge, and the cycloconverter demodulates it into a unipolar tristate multilevel SPWM wave and performs commutation when the unipolar tristate multilevel SPWM wave is zero. In addition, the EMCS realizes the, smooth switching of different power supply modes and the stability of output voltage. 1 kVA multi-input inverter prototype is designed and developed, which has the advantages of single-stage power conversion, high-frequency electrical isolation, small volume and weight, wide duty cycle regulation range, high conversion efficiency, high output voltage waveform quality and strong load adaptability. It provides a kind of effective method for a variety of new energy joint power supply. [ABSTRACT FROM AUTHOR]

With the characteristics of module-level maximum power point tracking, module-level monitoring, and panel shut-off, single-phase cascaded H-bridge (CHB) inverter has outstanding advantages applied to household photovoltaic (PV) power generation occasion. However, unbalanced output powers among PV panels is an inherent problem of single-phase CHB PV inverter, which will make the H-bridges (HBs) with higher powers overmodulation, resulting in deteriorated grid current and even system instability. Aiming at this issue, this article proposes a power adaptive control strategy, which divides system operation into three modes, and calculates modulation waveforms by using different methods in different modes. By flexibly adjusting the transmission power of HBs in different modes, all the HBs are able to avoid overmodulation, and single-phase CHB PV grid-connected inverter can still operate normally even if the maximum powers among PV panels are seriously unbalanced. The effectiveness of the proposed control strategy is verified by simulation and experimental results. [ABSTRACT FROM AUTHOR]

A nonlinear pulse width modulation-controlled single-phase boost mode photovoltaic grid-connected inverter with limited storage inductance current is proposed in this paper. The circuit topology, control strategy, steady-state principle characteristic, and design criterion for the key circuit parameters of this kind of inverter are investigated in depth, and important conclusions are obtained. The inverter's regenerating energy duty ratio 1–D which decreases with the decline of the grid-connected voltage is real time adapted by sampling and feeding back the inverting bridge modulation current, and the average value of the modulation current in each switching cycle tracks the reference sinusoidal signal to get high-quality grid-connected current. The active control of the energy storage inductance current and the balance of the voltage step-up ratio are realized by adding a bypass switch connected in parallel with the energy storage inductance and using two kinds of switching pattern namely boost pattern and freewheeling pattern. The theoretical analysis and experimental results of the 1 kVA 110 VDC/220 V50 Hz photovoltaic grid-connected inverter prototype show that it has the advantages such as single-stage boost conversion, high conversion efficiency, high quality of grid-connected current waveform, low value of energy storage inductance, simple control, etc. [ABSTRACT FROM AUTHOR]

A circuit configuration, a circuit topological family, a buck-mode active clamped circuit, and an instantaneous output voltage feedback control strategy of combined bidirectional buck–boost dc–dc chopper-mode inverter with high-frequency (HF) link (HFL) were proposed and fully investigated in this paper. The steady principle characteristic and the design criteria for the key circuit parameters were given in this paper. The circuit configuration is composed of two identical isolated bidirectional buck–boost dc–dc choppers with the same input and output filters. These two choppers in parallel at input end and in series at output end generate unipolarity sinusoidal pulsewidth modulation current waveforms with positive and negative half low-frequency cycles separately. The circuit topological family includes four circuit topologies, such as one-transistor mode. Taking the one-transistor mode circuit topology as an example, the 750VA48VDC/220V50HzAC prototype is designed and implemented. The theoretical analysis and principle test show the inverters have excellent performance. [ABSTRACT FROM PUBLISHER]

A circuit configuration and a circuit topological family of differential buck dc–dc chopper mode inverter with high-frequency link are proposed in this paper. The circuit configuration, the topology family, the instantaneous output voltage and the capacitance current feedback control strategy, the steady principle characteristic, and the design criteria for the key circuit parameters are fully investigated in this paper. The circuit configuration is differentially composed of two identical isolated bidirectional buck dc–dc choppers with the same input and output LC filters. These two choppers generate unipolarity sinusoidal pulse width modulation voltage waveforms with positive and negative half low-frequency cycle separately. Each dc–dc chopper consists of high frequency inverter, high frequency transformer, and high frequency rectifier. The circuit topological family includes six circuit topologies, namely, one-transistor forward mode, push–pull mode, push–pull forward mode, two-transistor forward mode, half-bridge mode, and full-bridge mode. Taking one-transistor mode circuit topology as example, the prototype is designed and implemented. The results from the theoretical analysis and principle test indicate that the inverters have advantages of high frequency galvanic isolation, simple topology, bidirectional power flow, single-stage power conversion, high conversion efficiency, high-quality output voltage waveform, and strong adaptability to various loads. [ABSTRACT FROM AUTHOR]