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Vienna rectifier is widely employed in the electric vehicle charging system and wind turbine system due to its higher efficiency and lower total harmonic distortion. However, the Vienna rectifier with the LCL filter has the challenge of resonant current mitigation, current zero-crossing distortion elimination, neutral point (NP) voltage balance and switching loss reduction. Moreover, these problems are mutually coupled. To overcome these issues, the causes of resonant current with the conventional discontinuous pulsewidth modulation (PWM) (DPWM) method is analyzed, which reveals that the abrupt change of reference voltage has a wide range harmonics band and easily induces the resonant current at resonant frequency. Then, based on the analysis, a novel three-layer DPWM method with three offset voltages injection is proposed. In the first layer, the NP voltage balance is realized by injecting the first offset voltage. In the second layer, the second offset voltage, which makes the discontinuous reference voltages smooth is presented to reduce the losses and suppress the resonant current. In the third layer, the third offset voltage is elaborated to eliminate current zero-crossing distortion caused by different power factor and the LCL filter. Based on the proposed method, resonant current mitigation, current zero-crossing distortion elimination, NP voltage balance are realized simultaneously with reduced switching losses. The effectiveness and performance of the proposed method are verified by simulation and experiment. [ABSTRACT FROM AUTHOR]

The inherent neutral-point (NP) voltage fluctuation of the Vienna rectifier could have side effects on the input current quality. However, such effects have not been thoroughly analyzed in the literature yet. In this article, based on the three-level to two-level space vector modulation transformation, a novel method to evaluate the influence of the NP voltage fluctuation on the input current quality is introduced, which could optimize the NP control parameters. The proposed method superimposes the NP voltage fluctuation on the basis vectors, thereby establishing the correlation between the NP voltage fluctuation and the square root mean square of the input current ripple. The detailed model of the NP oscillation under two-level coordinates is presented. By combining the two-level modulation, NP voltage hysteresis control is adopted to simplify NP voltage control and suppress the NP low-frequency oscillation. The comprehensive influence of the NP compensation coefficient on the input current quality under NP hysteresis control is obtained, and the hysteresis control parameters are optimized by using the proposed evaluation method. The simulation and experimental results verify the correctness and effectiveness of the proposed evaluation method. [ABSTRACT FROM AUTHOR]

This article proposes a harmonic voltage injection pulsewidth modulation (PWM) method for a Vienna rectifier with an LCL filter. Existing PWM methods for Vienna rectifiers with full power factor can lead to resonance problems. It generates current oscillation at the resonant frequency. It is analyzed that why the resonance problem occurs in Vienna rectifier with the existing PWM methods. To solve these resonance problems, the proposed method injects a sinusoidal harmonic voltage into the sinusoidal reference voltage. The magnitude and phase of the injection voltage are determined by the power factor of the rectifier-side. Compared to other PWM methods, the proposed PWM method eliminates the possibility of resonant problems. Considering the operation characteristics of the proposed PWM method, this article suggests a design process for an LCL filter. The effectiveness and performance of the proposed PWM method and the design process for an LCL filter are verified by simulation and experiment. [ABSTRACT FROM AUTHOR]

The main standard for avionic equipment DO-160G defines a set of tests that require compliance before the employment of a device in aircraft. An important test involves the generator voltage and consequential current distortion of the three-phase load in the variable 360–800 Hz frequency grid. The main purpose of this paper is to present and analyze a systematic design methodology for three-phase boost and buck rectifiers in order to meet with the voltage distortion test requirement. For a given voltage harmonic profile, the current harmonic limits that have to be satisfied are translated into equivalent per-harmonic admittances and a profile of maximum rectifier input admittance versus frequency is obtained. The defined profile, due to normalization, is applicable to arbitrary power level with simple shifting by the base admittance governed by the converter nominal power. It is shown that for boost-type rectifiers there is a tradeoff between current controller bandwidth and input inductor size, while for the buck-type rectifiers main limitation lies in the input LC filter design used for differential electromagnetic interference filtering. The experimental results conducted on an SiC three-phase 10 kW VIENNA rectifier are tightly backing up the proposed theoretical analysis. This paper is accompanied by three videos demonstrating experimental measurement of d-axis open-loop duty cycle to inductor current transfer function, loop-gain of d-axis current controller with 3.8 kHz bandwidth and variable grid frequency 360–800 Hz operation of the converter under 0% and 10% input three-phase voltage total harmonic distortion. [ABSTRACT FROM AUTHOR]

The limited hours of availability and fluctuating behavior of solar insolation severely impact the reliability of solar photovoltaic (PV) integrated system. This article proposes a new topology of grid interactive solar water pumping (SWP) system to deal with the issue of frequent variation in insolation, related to solar power generation. Such intermittency affects the system performance and makes it unreliable for industrial and commercial applications. In contrary to the conventional voltage source converter, the proposed topology utilizes a reduced switch Vienna rectifier for utility grid integration. Although utility grid integration appears to be a viable solution, however, as most of the grid in underdeveloped and developing countries are generally weak, such integration faces the additional power quality challenges, like voltage sag, voltage swell, dc offset, harmonics distortion, etc. To deal with the problems associated with weak grid condition, a novel mix multiresonant generalized integrator (MMRGI) control structure is proposed in this article. Along with the selective harmonic elimination capability, the proposed MMRGI structure offers a high dc offset and higher-order harmonic rejection capability. The proposed control approach is also capable of effectively extracting the balanced positive sequence components from unbalanced distorted grid voltages, thereby, keeping the grid currents balanced. The proposed system uses a sensor-less vector control technique to drive the permanent magnet synchronous motor used for rotating the pump. A perturb and observe algorithm is used for optimum power harvesting from the solar PV array. A prototype of proposed system is developed and performance is investigated experimentally using a digital signal processor DS1202. [ABSTRACT FROM AUTHOR]

This paper investigates a Vienna rectifier as a charger for series-connected battery packs. Focusing on carrier-based pulsewidth modulation (CBPWM), the ripple current flowing through the neutral point (NP) results in the voltage oscillation if the loads are resistive. To reduce the ripple of average NP current with mitigated distortion under balanced and unbalanced dc-link voltages conditions, a novel CBPWM with segmented component injection scheme (SCIS) is proposed in this paper. After dc component injection, continuous intervals for optimized component injection and clamping intervals for compensation component injection are identified. Optimized components are calculated originally based on unbalanced factor to make the average NP current zero-size in one switching period. Moreover, unique compensation components generate suitable NP current to shape the sinusoidal input currents according to the circuit analysis. In consequence, the SCIS not only keeps the input current with low-harmonic distortion, but also minimizes the oscillation of dc-link voltage under balanced and unbalanced conditions. In addition, the value of the NP current during the clamping intervals is analyzed under various operating conditions. The effectiveness and the performance of the proposed SCIS are verified by simulation and experiments. [ABSTRACT FROM AUTHOR]