Vienna-type Rectifier Research Articles

Generalized Clarke Transformation and Enhanced Dual-Loop Control Scheme for Three-Phase PWM Converters Under the Unbalanced Utility Grid

Three-phase grids imbalance causes serious alternating input current distortion in three-phase pulsewidth modulation (PWM) rectifiers where the conventional control scheme is employed. In this article, a generalized Clarke transformation is proposed to convert three-phase unbalanced sinusoidal quantities to two orthogonal sinusoidal quantities with equal amplitudes. Then, these two orthogonal sinusoidal quantities could be converted to two direct quantities by the Park transformation. Furthermore, based on the generalized Clarke transformation, an enhanced dual-loop control (EDLC) scheme is proposed to control the three-phase PWM rectifier in the synchronous rotating frame. Finally, a 5-kW Vienna-type rectifier prototype was built to verify the proposed generalized Clarke transformation and the proposed EDLC control scheme. Experimental results show that, by using the proposed EDLC scheme, the low current total harmonic distortion is achieved even both the amplitude and phase of the utility grid voltages are unbalanced.

Improved control scheme for simultaneous reduction of common-mode voltage and current harmonic distortion of the Vienna-type rectifier with balanced and unbalanced neutral-point voltages

As a non-generative-boost rectifier, the Vienna-type rectifier has been proposed and applied in several applications, such as wind power generation systems, battery charging system, etc. This paper further proposes an improved control scheme for reducing common-mode voltage (CMV) and input current harmonic distortions under balanced and unbalanced neutral-point (NP) voltages. At first, the operating fundamentals of the Vienna-type rectifier are presented. The zero-sequence voltage and its corresponding ranges are carefully derived to control the dc-link capacitor voltages separately. Considering the specific constraint of this rectifier, the zero-sequence voltage is further revised to reduce the current harmonic distortions around the zero-crossing points. Doing so, the simultaneous reduction of CMV and input current harmonic distortions can be realized, which is applicable to balanced and unbalanced NP voltages. The comparisons of the proposed scheme, the conventional zero-sequence voltage injection scheme, and the CMV reduction method under balanced NP voltage condition are conducted, which demonstrate the salient advantages of the presented scheme.

A Hybrid Carrier-Based DPWM With Controllable NP Voltage for Three-Phase Vienna Rectifiers

In this article, a hybrid carrier-based discontinuous pulsewidth modulation (HCB-DPWM) scheme is proposed for Vienna-type rectifiers. By injecting modified zero sequence components (ZSCs), the proposed HCB-DPWM-I scheme solves the issue of alternating input current distortion under unbalanced neutral point (NP) voltage conditions. The proposed HCB-DPWM-II scheme can also active NP voltage balancing control in case of extreme imbalance NP voltages. The flexible transition between the HCB-DPWM-I and the HCB-DPWM-II is also analyzed. Finally, a 10-kW prototype was built to conduct experiments. Experimental results demonstrate that the HCB-DPWM-I can be preferred to run Vienna-type rectifiers without regulating the NP voltage, and the HCB-DPWM-II can balance the NP voltage under severe NP voltage imbalance conditions. Compared with existing DPWM schemes, both the current THD performance and efficiencies can be significantly improved by the proposed HCB-DPWM scheme, especially under unbalanced NP voltage conditions.

Performance Analysis of Three Levels Three Switches Vienna-Type Rectifier Based on Direct Power Control

The Vienna-type rectifier is broadly employed in various implementations thanks to realizable three-level operation, simple structure and controllable DC-link voltage. This paper proposes an adaptive proportional integral (PI) with anti-windup based direct power control (DPC) to improve dynamic response during load change, DC-link voltage step change and start up and to reduce current tracking errors. An adaptive PI with anti-windup DC-link voltage control is utilized to enhance dynamic response of the DC-link voltage and the instantaneous power because the PI regulator affected by the load change and system parameter variations. The PI based conventional power control is used to indicate the availability and accuracy of the proposed control strategy. The proposed control strategy performs outstanding performance and copes with vigorous disturbances in contrast to the conventional strategy. A detailed theoretical analysis of the proposed approach has been performed. Extensive case studies carried out by PSIM software are performed to validate the excellent behavior of the proposed control strategy.

A Hybrid Control Strategy Based on Lagging Reactive Power Compensation for Vienna-Type Rectifier

The Vienna-type rectifier is widely used in many applications due to the merits of controllable dc-link voltage, realizable three-level operation, and compact size. However, the input currents near the zero-crossing point are distorted inevitably due to its special topology. Based on the analysis of the causes of current distortion, a lagging reactive power compensation method is proposed. The d-q-axis current models are developed, and two finite-time current controllers are designed to enhance the interference suppression performance. The asymptotic convergence of the d-q-axis current systems is proved, respectively. In addition, neutral point potential balancing is achieved by employing a proportional controller without increasing the cost of the system. The validity of the proposed hybrid control strategy has been verified by simulation and experimental results. Compared with the conventional strategy, this new hybrid control strategy can help to achieve excellent performance and stronger disturbance rejection.

Multi-objective Design and Optimization of Power Electronics Converters With Uncertainty Quantification—Part II: Model-Form Uncertainty

The second part of the multi-objective design and optimization with parametric and model-form uncertainty quantification (MDO with P&MF-UQ) is dedicated to incorporating MF-UQ into the MDO framework. MF-UQ is used to estimate the error due to modeling inaccuracies and to validate the mathematical models used in the MDO framework. In this approach, the sensitivity index introduced in the first part of the article is modified too so that it is a quantitative measure of system design robustness with regards to modeling inaccuracies as well as the manufacturing variability in the design of systems with multiple performance functions. The optimum design solution is finally realized by exploring the Pareto Front of the enhanced performance space, where the model-form error associated with each design is used to modify the estimated performance measures and the parametric sensitivity of each design point is considered to discern between cases and help identify the most parametrically robust of the Pareto-optimal design solutions. To demonstrate the benefits of incorporating uncertainty quantification analysis into the design optimization from a more practical standpoint, design of a robust high-efficiency high-power-density 1.25 kW Vienna-type rectifier is used as a case study to compare the theoretical analysis with a comprehensive experimental validation. It is shown that the final design selected using the MDO with P&MF-UQ reduces the design sensitivity and system loss by 33% and 5%, respectively, compared to the optimal design selected using the conventional MDO.

Multi-objective Design and Optimization of Power Electronics Converters With Uncertainty Quantification—Part I: Parametric Uncertainty

This article presents a robust multi-objective design and optimization approach with parametric and model-form uncertainty quantification (MDO with P&MF-UQ). The first part of the article focuses on incorporating parametric uncertainty quantification (P-UQ) into the MDO framework, where a sensitivity index is defined as a quantitative measure of system design robustness with regards to manufacturing variability in the design of systems with multiple performance functions. To demonstrate the benefits of incorporating P-UQ analysis into the design optimization framework, this article presents the design and optimization of a robust high-efficiency high-power-density 1.25 kW Vienna-type rectifier. The optimum design solution is realized by exploring the Pareto Front of the enhanced performance space where the parametric sensitivity of each design point is considered to discern between cases and help identify the most parametrically-robust of the Pareto-optimal design solutions. It is shown that the design sensitivity is reduced by 39% when the optimum design is selected using MDO with P-UQ rather than the conventional MDO.

A Modified DPWM With Neutral Point Voltage Balance Capability for Three-Phase Vienna Rectifiers

Compared with continuous pulsewidth modulation (PWM), discontinuous PWM (DPWM) is a preferred solution in high-frequency Vienna-type rectifiers due to its inherent characteristics of less commutation number and higher efficiency. In this article, redundant clamping modes at the same subsector with opposite effects on the neutral point (NP) voltage are presented. Then, a modified DPWM (MDPWM) scheme is proposed to regulate the NP voltage by using redundant clamping modes. Thus, the NP voltage can be controlled in each switching period to lower the NP voltage fluctuation. The implementation of the proposed MDPWM is given with variable power factors analysis. Further, the switching loss comparison of conventional space vector PWM (SVPWM), hybrid DPWM (HDPWM), and proposed MDPWM is presented as well. A simulation model was built to verify the proposed NP voltage balance with different modulation indices and variable power factors. Finally, a 10-kW prototype is built to evaluate the proposed MDPWM scheme at conversion efficiency and current total harmonic distortion (THD). Experimental results and analysis show that comparing conventional SVPWM and HDPWM, the efficiency of MDPWM is the highest. The THD of DPWM is slightly higher than that of SVPWM, and it is only 2.5% at rated output power.

Effects of Junction Capacitances and Commutation Loops Associated With Line-Frequency Devices in Three-Level AC/DC Converters

This paper identifies extra junction capacitances and switching commutation loops introduced by line-frequency devices (i.e., non-active every other half line cycle) in three-level ac/dc converters and investigates the corresponding effects. Junction capacitances and power loops are well known as the key factors that impact converter switching loss and device stress, thus influence device selection, power stage layout, and thermal design. By examining switching transients of the commonly used T-shaped and I-shaped three-level converters, the cause and mechanism of the extra junction capacitances and power loops are presented. The impacts on switching loss, device voltage stress, and ac-side voltage/current distortion are respectively reported and analyzed. A loss calculation scheme for the three-level converter to include that extra loss is proposed. A power layout scheme to mitigate the device voltage stress is provided. Compensation and modeling of the voltage and current distortion are also proposed. Experimental results conducted on several types of three-level converter prototypes including a gallium nitride based 115 $V_{{\text{ac}}}{\text{/650}}$ V dc/1.5-kW/450-kHz Vienna-type rectifier and a SiC mosfet based 1-kV/10-kW/280-kHz three-level active neutral-point-clamped inverter confirm the presented effects and verify the associated analysis and solutions.

Two methods for controlling three‐time fundamental frequency neutral‐point voltage oscillation in a hybrid VIENNA rectifier

This study presents two methods of controlling neutral-point voltage oscillation in a hybrid VIENNA rectifier, which is composed of the parallel association of a three-phase single-switch Boost rectifier with a VIENNA-type rectifier. The neutral-point oscillation reason has been analysed with a mathematical model. Meanwhile, the two neutral-point control methods of a simplified method based on a zero-sequence component injection and a dual-carrier pulse-width modulation (PWM) method are proposed to control the voltage deviation of the split DC-link and three-time fundamental frequency neutral-point voltage fluctuation with a decrease from ±1.6 to ±1 V, respectively. Moreover, the significant oscillation in the neutral-point voltage caused by unbalanced loads or asymmetric capacitor parameters can also be effectively suppressed by using the dual-carrier PWM method. Furthermore, the performance comparison between these two methods is provided. The experimental results show that the system after being introduced the proposed two methods still exhibits a low-order input current harmonic such as second, third, and fourth harmonics as well as the input current total harmonic distortion is lower than the standard 5%.

Research on Carried-Based PWM with Zero-Sequence Component Injection for Vienna Type Rectifiers

Research on Carried-Based PWM with Zero-Sequence Component Injection for Vienna Type Rectifiers

A Modulation Compensation Scheme to Reduce Input Current Distortion in GaN-Based High Switching Frequency Three-Phase Three-Level Vienna-Type Rectifiers

Wide bandgap semiconductors are gradually being adopted in high power-density high efficiency applications, providing faster switching and lower loss, and at the same time imposing new challenges in control and hardware design. In this paper, a gallium nitride-based Vienna-type rectifier with SiC diodes is proposed to serve as the power factor correction stage in a high-density battery charger system targeting for aircraft applications with 800 Hz ac system and 600 V level dc link, where power quality is required according to DO160E standard. To meet the current harmonic requirement, PWM voltage distortion during the turn-off transient, is studied as the main harmonics contributor. The distortion mechanism caused by different junction capacitances of the switching devices is presented. A mitigation scheme considering the nonlinear voltage-dependent characteristics of these capacitances is proposed and then simplified from a pulse-based turn-off compensation method to a general modulation scheme. Simulation and experimental results with a 450 kHz Vienna-type rectifier demonstrate the performance of the proposed approach, showing a THD reduction from 10% to 3% with a relatively low-speed controller.

Design and Implementation of a Two-Channel Interleaved Vienna-Type Rectifier With >99% Efficiency

In this paper, the design and implementation of a 3 kW, three-phase, two-channel interleaved Vienna-type rectifier with greater than 99% efficiency is presented. The operating principle of the interleaved Vienna-type rectifier is introduced, with particular attention paid to the switching-frequency circulating current generated by the interleaved operation, as well as effective mitigation methods. An optimized design procedure for the converter is then presented to achieve maximum efficiency, for which detailed loss calculation models and hardware design guidelines are developed and introduced. Finally, experimental results obtained with a 3 kW experimental prototype are presented for validation purposes, demonstrating the 99.28% extreme efficiency attained by the converter at nominal load, in close agreement with the 99.32% predicted by the design procedure developed.

Improved direct power control for Vienna‐type rectifiers based on sliding mode control

This study proposes an improved direct power control (DPC) strategy based on sliding mode control (SMC) with dual closed loop for the Vienna-type rectifier to improve transient response during both start-up and load step-change periods and to guarantee stability in steady state. The inner power closed-loop utilises SMC–DPC controller to directly regulate the required rectifier's control voltage without transforming to synchronous rotating coordinate reference frame or tracking phase angle of the grid voltage, which simplifies the control system. In addition, the outer loop employs a novel sliding mode controller to improve the dynamic performance of the dc output voltage and the instantaneous power. Finally, the dynamic and steady-state performances of the grid current, dc output voltage, active/reactive power are experimentally investigated and compared with the conventional proportional–integral-DPC scheme, both the simulation and the experimental results demonstrated the dynamic performance and stability of the proposed control scheme.

Three-Phase Multilevel PFC Rectifier Based on Multistate Switching Cells

This paper presents a three-phase multilevel power factor correction (PFC) rectifier employing multistate switching cells. A generalized converter structure is presented based on the connection of switching networks of Vienna-type rectifier topologies through multiinterphase transformers (MIPTs). The resulting rectifier presents the intrinsic benefits to the employed building blocks and the ones added by a modular construction that enables the reduction of passive components and overall losses. The operation of the PFC rectifier is described, including appropriate modulation and control strategies. Design guidelines for the magnetic components are derived for the MIPTs, boost inductors, and power semiconductor devices. Finally, a lab prototype is used to present experimental results. This prototype is rated at 7.5 kW and uses a modular structure to assemble a four legs per phase rectifier. Efficiency above 98% from 40% load and IEC61000-3-2 requirements are observed.

A Novel Control Strategy Based on Natural Frame for Vienna-Type Rectifier Under Light Unbalanced-Grid Conditions

In order to reduce the dc-link voltage ripple and the dc component of the reactive power under unbalanced input conditions, a novel natural-frame-based control scheme for a Vienna rectifier is proposed in this paper. First, by applying an early-developed direct decoupled synchronization method, the fundamental positive/negative-sequence voltage components are derived. Then, a natural-frame-based current control loop is designed based on the mathematical modeling of the Vienna rectifier under unbalanced input conditions. Based on the natural abc frame, the proposed control scheme considerably reduces total algorithm complexity and helps reduce the dc reactive components and total loss in comparison to the traditional dual-hybrid current control schemes. In addition, the stationary operation region of the Vienna-type rectifiers is analyzed, and the scheme is claimed to work out of the stationary operation region with severe voltage unbalance. The dynamic response of unbalanced input is presented. The experimental results are given to demonstrate the effectiveness of the proposed control scheme. In addition, the performance comparison between the traditional controller and the proposed controller is given by experimental results.

Modeling and Direct Power Control Method of Vienna Rectifiers Using the Sliding Mode Control Approach

This paper uses the switching function approach to present a simple state model of the Vienna-type rectifier. The approach introduces the relationship between the DC-link neutral point voltage and the AC side phase currents. A novel direct power control (DPC) strategy, which is based on the sliding mode control (SMC) for Vienna I rectifiers, is developed using the proposed power model in the stationary <TEX>${\alpha}-{\beta}$</TEX> reference frames. The SMC-based DPC methodology directly regulates instantaneous active and reactive powers without transforming to a synchronous rotating coordinate reference frame or a tracking phase angle of grid voltage. Moreover, the required rectifier control voltages are directly calculated by utilizing the non-linear SMC scheme. Theoretically, active and reactive power flows are controlled without ripple or cross coupling. Furthermore, the fixed-switching frequency is obtained by employing the simplified space vector modulation (SVM). SVM solves the complicated designing problem of the AC harmonic filter. The simplified SVM is based on the simplification of the space vector diagram of a three-level converter into that of a two-level converter. The dwelling time calculation and switching sequence selection are easily implemented like those in the conventional two-level rectifier. Replacing the current control loops with power control loops simplifies the system design and enhances the transient performance. The simulation models in MATLAB/Simulink and the digital signal processor-controlled 1.5 kW Vienna-type rectifier are used to verify the fast responses and robustness of the proposed control scheme.

Constant power control‐based strategy for Vienna‐type rectifiers to expand operating area under severe unbalanced grid

For a Vienna type rectifier, unbalanced grids introduce twice the fundamental frequency ripples in dc-link voltage and input active/reactive power. To eliminate the input power ripple, the common current reference generation strategy, such as dual-frame hybrid vector control, can be adopted to maintain constant input power and eliminate ripples in dc-link voltage under light unbalanced grids. However, this control method does not work when under severe unbalanced grids. The theoretical operation area of the constant power control method under unbalanced grids is analysed in this study, furthermore, a compromised control method, which injects a small amount of input power ripple and makes a compromise between the working area and the output voltage ripples, is proposed. The control method can work when the grids have severe unbalance. The experimental operating area of constant power control is presented. The performance comparison and waveforms of three control strategies under different unbalanced grids are given.

Natural frame‐based strategy for Vienna‐type rectifier with light unbalanced input voltages

When the Vienna-type rectifier works at unbalanced input operation conditions, the dc-link voltage ripples and the dc component of the reactive power will be introduced. Therefore a novel control scheme based on natural frame is proposed. The fundamental positive-/negative-sequence voltage components are derived by applying an early developed direct decoupled synchronisation method. A natural abc frame-based current control loop, which considerably reduces total algorithm complexity and also helps to reduce the reactive components size and total loss in comparison with the traditional dual current control schemes, is proposed based on the mathematical modelling of Vienna rectifier under unbalanced input conditions. In addition, the static operation region of the Vienna-type rectifiers is analysed and derived. Finally, the experimental results are given to verify the effectiveness of the proposed control scheme and the conclusion. Performance comparison between the traditional controller and proposed controller is demonstrated by the experimental results.

Study of Conducted EMI Reduction for Three-Phase Active Front-End Rectifier

The problem of electromagnetic interference (EMI) plays an important role in the design of power electronic converters, especially for airplane electrical systems. This paper explores techniques to reduce EMI noise in three-phase active front-end rectifier. The Vienna-type rectifier is used as the object. The design approach introduced in this paper is using a high-density EMI filter to satisfy the EMI standard. Design methodology is introduced in the paper by a three-stage LC- LC-L filter structure. In particular, the cause of high noise at high frequencies is studied in experiments, and the coupling effect of the final-stage capacitor and inductors is investigated. In order to reduce the EMI noise in the mid-frequency range, the application of random pulsewidth modulation (PWM) is also presented. The performance of random PWM in a Vienna-type rectifier is verified by theoretical analysis and experimental results. The approaches discussed in this paper significantly reduce the EMI noise in the Vienna-type rectifier, and therefore, the filter size can also be reduced.