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In the distributed generation system with multiple new energy joint supply, using a multi-input DC-DC converter instead of multiple single input DC-DC converters can simplify the circuit structure and reduce the cost. The circuit topology, maximum power output energy management control strategy and steady-state principle characteristics of the time-sharing power supply full bridge buck mode dual input DC-DC converter are analyzed and studied. The experimental results are given. The circuit topology is composed of two parallel selection branches and a buck mode converter in cascade. The control strategy indirectly realizes the maximum power output energy management control by controlling the instantaneous value of output current and the ratio of output power of two input sources. The 3 kW double input DC converter designed and developed has the advantages of small volume and weight, low cost and so on, which verifies the correctness and feasibility of the converter.

A hybrid computing method for predicting the magnetic field of line-start permanent magnet synchronous motor is presented in this article. The vector magnetic potential (VMP) is selected to be the primary objective of the calculation. For the convenience of expressing the VMP in the polar coordinate system, the topology of each motor component is replaced by the assembly of radial sectors. Along with the topology approximation, the VMPs of the stator and air gap are determined analytically, whereas the finite difference method is used to calculate the VMP of the rotor with the eddy current. Combining the numerical technique with the analytical method not only enables solution efficiency higher than using the former one merely but also keeps away from the inefficacy of using the latter one solely to predict magnetic fields with complex geometry. The presented approach is validated by the finite-element analysis and prototyping tests. [ABSTRACT FROM AUTHOR]

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]

Harmonic injection is commonly used in permanent magnet synchronous motor torque ripple minimization (TRM) of electric vehicle. Traditional inverter switching frequency limits TRM application at high speed due to harmonic modulation accuracy and inverter loss. To achieve TRM in the whole speed range and reduce inverter loss, a novel online calculated low carrier ratio pulsewidth modulation (LCRPWM) is proposed in this article. The carrier ratio determining regular according to the injected harmonics is established first. The relationship between injected harmonics and LCRPWM switching angle is revealed and a set of nonlinear equations is established. Thus, the problem is transformed from solving nonlinear equations into optimization by establishing a cost function. The analytical solutions of nonlinear equations are obtained, which avoids iterative operation and plunging into local minimum. Therefore, the switch angle solution method is suitable for online calculation. The LCRPWM is verified in simulation compared with the traditional regularly sampled space vector PWM, which achieves better results in voltage harmonic injection and flux tracking at a much lower switching frequency. At last, the LCRPWM is used in a test bench experiment that shows good TRM effects. The influence of sideband harmonics on torque ripple is analyzed. [ABSTRACT FROM AUTHOR]

Miniaturization and low cost contribute to the development and popularization of wireless power transfer (WPT). Reducing the number of power conversion stages can reduce the volume and cost of the WPT converter, and even make it possible to improve the efficiency. A single-stage WPT converter with constant current (CC) and constant voltage (CV) output and its asymmetric modulation method are proposed in this paper. A direct AC-AC converter is applied to the primary side of the WPT converter to directly convert line-frequency AC to high-frequency AC. The applied direct AC-AC converter that can replace the commonly used multi-stage primary converter reduces the number of circuit devices, thereby reducing the volume and cost of primary converter. The proposed WPT converter can realize zero voltage switching (ZVS) and power factor correction (PFC). In order to achieve CC and CV output, a switchable hybrid compensation topology is applied to the proposed WPT converter. A 720-W experimental prototype was manufactured to verify the rationality of the proposed WPT converter and the correctness of the theoretical analysis. [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]

A novel circuit-topology family of the current-mode ac/ac converter with high-frequency ac link, based on a Fly-back converter, is proposed. These circuit topologies, which can transfer one unregulated sinusoidal voltage with high total harmonic distortion (THD) into another regulated constant-frequency sinusoidal voltage with low THD, are composed of input cycloconverter, high-frequency storage transformer, and output cycloconverter. The circuit-topology family includes single four-quadrant power switch mode, push-pull mode, half-bridge mode, and full-bridge mode circuits. The single four-quadrant power switch mode and push-pull mode converters are suitable for low input voltage fields, but the half-bridge mode and full-bridge mode converters are suitable for high input voltage fields. The operational mode, steady principle, and transient voltage feedback control strategy of the kind of converter are investigated. The output characteristic curve, its relation to internal resistance, and the design criteria for the key circuit parameters are given. The theoretical analysis and the test result of the 500 VA 220 V [+ or -] 15% 50 HzAC/220 V 50 HzAC prototype have shown that the converters have advantages such as high-frequency galvanic isolation, simple topology, two-stage power conversion [low frequency alternating current (LFAC)/high frequency alternating current (HFAC)/LFAC], bidirectional power flow, high efficiency, high power density, low THD of the output voltage, strong adaptability to various loads, higher line power factor, low audio noise, etc. Index Terms--AC/AC converter, current mode, cycloconverter, Flyback converter, high-frequency ac link, transient voltage feedback control.

A circuit configuration and circuit topological family of voltage mode ac-ac converters with high frequency ac links, which are based on forward converters, and a uni-polarity phase-shifted control strategy are proposed and deeply investigated. These kinds of converters consist of a input cycloconveter, a high frequency transformer, an output cycloconverter, input and output filters, and can transfer an unsteady ac voltage with a high harmonic into steady same-frequency ac sinusoidal voltage with a low harmonic. By using uni-polarity phase-shifted control strategy, output filtering inductance current is naturally commutated, and zero voltage switching of the output cycloconverter is realized. The converters' averaging model, the output characteristic curve, and design criteria for the key circuit parameters are given. The theoretical analysis and test result of 1 kVA 220 V [+ or -] 10% 50 Hz ac/110 V 50 Hz ac prototype have shown that the converters have such advantages as high frequency electrical isolation, simple topology, two-stage power conversion (LFAC/HFAC/LFAC), bidirectional power flow, uni-polarity synchronized pulsewidth modulation waveform, high efficiency, high power density, high steady precision, low total harmonic distortion of the output voltage, strong adaptability to various loads, high line power factor, and low audio noise etc. Index Terms--AC-AC converters, cycloconverter, forward converter, high frequency ac link, soft commutation, uni-polarity phase-shifted control, voltage mode.

A novel combined soft switching technique and a novel topological family of the static inverter with high frequency pulse dc link are proposed in this paper. The topological structure is constituted of isolated high frequency pulse dc link circuit and inverter. In order to overcome the duty cycle D of the one transistor forward mode Static Inverter less than 0.5 and the topology of the interleaved forward mode Static Inverter more complicated, the duty cycle extension of high frequency pulse dc voltage is proposed in this paper. The steady operation principle of the active clamp forward mode high frequency pulse dc link static inverter with duty cycle extension and the control strategy of three-state discrete pulse modulation hysteresis current are deeply investigated. The design criteria for the key circuit parameters are gained. By using combined soft switching technique and the duty cycle extension of high frequency pulse dc voltage, a designed and developed 750 VA 27 V dc/115 V 400 Hz ac prototype has the advantages such as high efficiency, high power density, high reliability, high steady precision, fast dynamical response, low THD of output voltage, strong ability of over-load and short-circuit. Index Terms--Active clamp forward converter, combined soft-switching technique, duty cycle extension, high frequency link inverter, high frequency pulse dc link, static inverter, three states discrete pulse modulation.

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]

Different from the conventional photovoltaic (PV) inverters, a three-phase PV solid-state transformer (SST) based on the cascaded H-bridge (CHB) topology can be regarded as consisting of three single-phase CHB inverters in essence. During the low-voltage ride through (LVRT), some phases of three-phase PV SST may inversely absorb active power from ac grid affected by negative-sequence voltages, resulting in that the dc bus voltages of all H-bridges in these phases continue to rise, and that the system will shut down due to overvoltage protection. To deal with this problem, in this article, we study the mechanism of active power backflow during LVRT, analyzes and compares the main methods for suppressing active power backflow, and then proposes an LVRT control strategy based on the zero-sequence voltage compensation, which not only ensures that all modules in three-phase PV SST transmit the almost same active power but also can avoid effectively active power backflow problem even if the total output active of PV array is relatively low. The validity of the proposed method is verified by the simulation and experimental results. [ABSTRACT FROM AUTHOR]

Conventional dc–dc boost converters have limited boosting capabilities, and the main switching device may suffer relatively high voltage stress and current stress. A novel transformerless dc‐dc boost converter is proposed in this paper. The proposed topology, which combines the traditional active switch‐inductor and quasi‐Z‐source network, can increase the voltage gain without limiting the duty cycle or increasing the voltage and current stresses of the power switches. The detailed analysis including working principles, steady‐state characteristics, non‐ideal element analysis and a comprehensive comparison is also presented in this paper. To verify the proposed converter's performance, a prototype circuit with 20–30 V input voltage, 200 V output voltage, and 200 W output power is implemented in the laboratory. Experiment results confirm the theoretical analysis and advantages of the proposed converter. [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]

Solar energy is one of the most promising energy types, but photovoltaic (PV) mismatches have several negative effects. Finding an efficient and low-cost method to reduce or eliminate the power loss caused by the mismatch in PV power generation systems is necessary. In this paper, we propose a PV submodule-distributed maximum power point tracking (DMPPT) scheme based on a multi-port DC converter. In-depth analysis and research are performed on the PV model and mismatch characteristics, the PV module voltage equalization (VE) strategy, and implementation with the multi-port buck–boost converter. We discuss the trade-off between true DMPPT and VE on control overhead and tracking accuracy, and a detailed derivation is created to illustrate the differences between them. The VE can reduce the cost and complexity of the system at the expense of a small PV energy capture. The proposed implementation reduces the number of semiconductor components and current sensors, which is conducive to the integrated design of the hardware. A prototype based on a multi-port buck–boost converter for a 36 V/200 W PV module was designed and built. The feasibility and progress of the proposed scheme were verified through experiments. [ABSTRACT FROM AUTHOR]