Pulse Width Modulation Rectifier Research Articles

Implementation on the dSPACE 1104 of VOC-SVM based anti-windup PI Controller of a three-phase PWM rectifier

<p><span>The study made in this paper concerns the use of the voltage-oriented control (VOC) of three-phase pulse width modulation (PWM) rectifier with constant switching frequency. This control method, called voltage-oriented controlwith space vector modulation (VOC-SVM). The proposed control scheme has been founded on the transformation between stationary (α-β) and and synchronously rotating (d-q) coordinate system, it is based on two cascaded control loops so that a fast inner loop controls the grid current and an external loop DC-link voltage, while the DC-bus voltage is maintained at the desired level and ansured the unity power factor operation. So, the stable state performance and robustness against the load’s disturbance of PWM rectifiers are boths improved. The proposed scheme has been implemented and simulated in MATLAB/Simulink environment. The control system of the VOC-SVM strategy has been built based on dSPACE system with DS1104 controller board. The results obtained show the validity of the model and its control method. Compared with the conventional SPWM method, the VOC-SVM ensures high performance and fast transient response.</span></p>

A new switching look-up table for direct power control of grid connected 3L-NPC PWM rectifier

This paper presents a comprehensive and systematic approach in developing a new switching look-up table for direct power control (DPC) strategy applied to the three-phase grid connected three-level neutral-point clamped (3L-NPC) pulse width modulated (PWM) rectifier. The term of PWM rectifier used in this paper is also known as AC-DC converter. The approach provides detailed information regarding the effects of each multilevel converter space vector to the distribution of input active and reactive power in the converter system. Thus, the most optimal converter space vectors are able to be selected by the switching look-up table, allowing smooth control of the active and reactive powers for each sector. In addition, the proposed DPC utilizes an NPC capacitor balanced strategy to enhance the performance of front-end AC-DC converter during load and supply voltage disturbances. The steady state as well as the dynamic performances of the proposed DPC are presented and analyzed by using MATLAB/Simulink software. The results show that the AC-DC converter utilizing the new look-up table is able to produce almost sinusoidal line currents with lower current total harmonic distortion, unity power factor operation, adjustable DC-link output voltage and good dynamic response during load disturbance.

고조파 및 불평형 성분을 가지는 계통 환경에 따른 3상 펄스폭변조정류기 성능 비교 연구

In this paper, the input and output performance of a three-phase pulse width modulation (PWM) rectifier operated by each of three different control techniques based on current control and power control in the grid with harmonics and unbalanced components are compared and analyzed. Regardless of the basic and high-efficiency types, the same current-controlled and power-controlled techniques showed similar performance in the harmonics and unbalanced grid conditions. In all grid conditions with harmonics and unbalanced components, the output voltage by the power-controlled rectifier has a lower ripple value than the output voltage by the current-controlled rectifier. Therefore, in terms of output voltage ripple, it is confirmed that the power-controlled rectifier shows more robust characteristics in harmonics and unbalanced grid condition.

COMPARATIVE STUDY OF SINGLE-PHASE PWM RECTIFIER CONTROL TECHNIQUES

In this study, 2.5 kW single-phase pulse-width modulated rectifier is simulated with three different control techniques to investigate the performance of controllers. Rectifier simulation is performed in Matlab / Simulink environment by using hysteresis current control, sinusoidal pulse width modulation and voltage oriented control techniques. In the performance comparison of the control techniques, considering the switching frequencies, the total harmonic content of the current drawn from the grid, the phase difference between the grid voltage and the grid current, and the DC bus voltage regulation at the output are considered as comparison criteria. The switching frequency is set to 35 kHz in sinusoidal pulse width modulation and voltage oriented control techniques. Since the switching frequency is variable in the hysteresis current control technique, the average and instantaneous switching frequency are calculated for different hysteresis band values. In the results with the technique, the switching frequency varies between 18.52 kHz and 47.6 kHz, while the average switching frequency is 34.6 kHz. As a result, the total harmonic distortion of the grid current with hysteresis current control, sinusoidal pulse width modulation and voltage oriented control techniques is 3.69%, 1.12% and 1.82%, respectively. The synchronization with the grid voltage is achieved with all techniques, and the DC voltage is regulated with active power.

Lyapunov Function Based Flux and Speed Observer Using Advanced Non-linear Backstepping DVC for PWM-Rectifier Connected Wind-turbine-driven PM Generator

In this paper, modeling, and speed/position sensor-less designed Direct Voltage Control (DVC) approach based on the Lyapunov function are studied for three-phase voltage source Space Vector Pulse Width Modulation (SVPWM) Rectifier Connected to a Permanent Magnet Synchronous Generator (PMSG) Variable Speed Wind Power Generation System (VS-WPGS). This control strategy is based on voltage orientation technique without mechanical speed sensor. Advanced Non-linear Integral Backstepping Control (IBSC) of the Generator Side Converter (GSC) has the ability to have a good regulation of the DC link voltage to meet the requirements necessary to achieve optimal system operation, regardless of the disturbances caused by the characteristics of the drive train or some changes into the DC load. The estimation of the speed is based on Model Reference Adaptive System (MRAS) method. This method consists in developing two models one of reference and the other adjustable for the estimation of the two d-q axis components of the stator flux from the measurement of currents, the speed estimated is obtained by canceling the difference between the reference stator flux and the adjustable one using Lyapunov criterion of hyper-stability. Some results of simulation using Matlab/Simulink® are presented, discussed to prove the efficiency and robustness of the system control policy for WPGS against external and internal perturbations.

Harmonics Analysis of Input Current of 3-Phase PWM Rectifier

Rectifier is a non-linier load that causes harmonic distortion in the power system. Pulse-width modulation (PWM) method is an effective method in pressing the magnitude of harmonics in a rectifier application, it provides an almost sinusoidal input current. However, the variation of loads that supplied by a rectifier cause the harmonics that arise can still beyond the applicable standard. The amount of harmonics in the operating range of a rectifier need to be identified to determine the filter on the input side. In this research article, 3-phase PWM rectifier was designed with hysteresis current control technique using PSCAD software simulation. Harmonic compensation was carried out by applying an active filter based on P-Q theory to reduce the harmonic distortion that occurs in the input current, thus giving a low total harmonic distortion (THD) value. Based on the simulation, 3-phase PWM rectifier operation starting at a power level of 150 kW, giving a THD value above 5-10% by the increasing the amount of load supplied by the rectifier. The application of active filter based on the P-Q theory is able to compensate harmonics in the input current wave with a THD value below 5% in the rectifier operating range.

A Review on Direct Power Control of Pulsewidth Modulation Converters

Starting from the principle of instantaneous power theory, this article explores various direct power control (DPC) strategies for three-phase two-level pulsewidth modulation (PWM) converters. After summarizing the fundamental power formula of PWM rectifiers, this article studies the operating principle of the conventional table-based approach and its related improvements. It further looks into the advanced counterparts employing space vector modulation and different nonlinear control strategies. The emphasis is put on the prevailing predictive DPC. Besides, the voltage-sensorless and robust DPC methods based on the virtual flux concept and the state observer or estimator are investigated. Critical issues, including the sample delay, constant switching frequency, duty cycle optimization, objective function, and unbalanced operation are examined.

Voltage Sensorless Direct Power Control for PWM Rectifier Under Distorted Network Using Improved Virtual Flux Estimator

Generally, AC-DC conversion system in the power system use the diode-bridge based rectifiers that cannot be reversible and causes high current distortion. Besides, they reduce the power factor and energy quality. recently, the application of three-phase pulse width modulation (PWM) rectifier has been risen quickly due to breakthrough advancement in the power devices. This converter offers sinusoidal input currents and minimized harmonic distortion and unity power factor. This work presents an improved sensorless control for performance enhancement purpose of the PWM-rectifier. The proposed control strategy uses the virtual flux principle with second-order generalized integrator (SOGI) in order to overcome the accompanying drawbacks of using pure integrator of low-pass filters for estimation. The integration of improved virtual flux estimator with direct power control saves the cost of using many voltage sensors which can increase the reliability and effectivity of the control system. Moreover, it improves control robustness and against highly distorted network. The different proposed approaches have been investigated through simulation using MATLAB/Simulink software.

A Dual-Vector Model Predictive Control Method With Minimum Current THD

This letter proposes a dual-vector model predictive control method to minimize the current total harmonic distortion (THD). The definition of current THD shows that it is proportional to the area enclosed by the actual current and the current fundamental wave. The lowest current THD is achieved by minimizing the area enclosed by the actual current and the reference current in the control period. This method is implemented on a single-phase neutral-point clamped three-level pulsewidth modulation rectifier, and the advantages of the proposed control method are verified through experiments.

Research on three‐phase VSR segmented PI synergetic control strategy based on LCL filter

In view of the resonance phenomenon caused by LCL filter introduced by voltage pulse width modulation (PWM) rectifier as well as the inability of traditional PI adjustment to meet the needs of different load changes, this article proposed a segmented PI synergetic control strategy for the LCL filter rectifier based on the proportional-integral manifold form synergetic control strategy. First of all, a synergetic controller based on the proportional-integral manifold was constructed; secondly, particle swarm optimization was used to optimize PI parameters under different load conditions; thirdly, the optimized PI parameters were used to establish a segmented trigger database, taking load impedance as the trigger condition. The control strategy made full use of the LCL filter's ability to suppress higher harmonics and the PI adjustment is simple and fast under specific loads. The synergetic control theory has a lot of advantages, including chatter-free, simple control ideas, easy implementation, etc. Simulation experiments verified that the control strategy could effectively reduce the harmonic content, avoid resonance phenomena and improve system stability, and it was characterized by high control accuracy and simple structure.

Generalized Predictive dc-Link Voltage Control for Grid-Connected Converter

The main function of the grid-connected converter in many applications is to control the dc-link voltage with high performance, i.e., strong disturbance rejection capability and good dynamic response. Take the grid-connected pulsewidth modulation (PWM) rectifier of a motor drive system as an example, good disturbance rejection capability is essential for the dc-link voltage control to address the varying loads on the motor side, and the dynamic process of the dc-link voltage control is preferred to be fast and overshoot-free, so as to adaptively adjust the dc-link voltage according to the motor speed and reduce the switching losses. However, the performance of the conventional proportional-integral (PI)-based dc-link voltage control is not always satisfying and can be further improved. In this article, the generalized predictive control (GPC) method is applied to the dc-link voltage control of a grid-connected converter for the first time, which can provide both good disturbance rejection capability and satisfying dynamic performance. Moreover, stability analysis of the proposed GPC-based dc-link voltage control strategy is theoretically studied, and a parameter tuning guideline is provided. The effectiveness and advantages of the proposed method are validated with experimental results.

An Enhanced Model-Free Predictive Control to Eliminate Stagnant Current Variation Update for PWM Rectifiers

In model-free predictive control (MFPC), high active power spikes and grid current notches are induced when applied to pulsewidth modulation (PWM) rectifiers. To overcome these problems, we develop an enhanced MFPC to eliminate the stagnant current variation update for PWM rectifiers. In the proposed MFPC, only four variables are estimated to remove the stagnant current variation update, and the grid current variations are obtained directly from these four estimated variables. Therefore, there is no need to identify any voltage vector combination, and a lookup table to store grid current variations is not needed in contrast to the previous method. Thanks to the elimination of the stagnant current variation update, the prediction accuracy of the proposed MFPC is significantly improved without complexity compared with that of the conventional MFPC. As a result, the active power spikes and grid current notches are eliminated with the proposed MFPC. Both simulation and experiment are implemented to verify the effectiveness of the proposed MFPC.

Reconfigurable Control of PWM AC-DC-DC Converter without Redundancy Leg Supplying an AC Motor Drive

The purpose of this paper is the study by simulation of a fault tolerant control with Pulse Width Modulation (PWM) AC-DC-AC converter supplying a three-phase rotor field oriented induction motor. The back to back converter, is supplied with three-phase network and composed of a PWM rectifier and a voltage source inverter. Fault tolerant topology of AC-DC-AC converter that without redundancy have been studied and associated with affective and fast method of fault detection and compensation to guarantee the continuity of service, in the presence of a possible open circuit failure on the level of one of their legs. Although of the presence of open circuit on the level of one of the converter legs the control based on the Zero Sequence Signal (ZSS) assure the service continuity, the simulation results obtained prove that it is possible to maintain the good performance of the drive without redundancy leg (6/5 topology).

Data‐driven design of fault diagnosis for three‐phase PWM rectifier using random forests technique with transient synthetic features

A three-phase pulse-width modulation (PWM) rectifier can usually maintain operation when open-circuit faults occur in insulated-gate bipolar transistors (IGBTs), which will lead the system to be unstable and unsafe. Aiming at this problem, based on random forests with transient synthetic features, a data-driven online fault diagnosis method is proposed to locate the open-circuit faults of IGBTs timely and effectively in this study. Firstly, by analysing the open-circuit fault features of IGBTs in the three-phase PWM rectifier, it is found that the occurrence of the fault features is related to the fault location and time, and the fault features do not always appear immediately with the occurrence of the fault. Secondly, different data-driven fault diagnosis methods are compared and evaluated, the performance of random forests algorithm is better than that of support vector machine or artificial neural networks. Meanwhile, the accuracy of fault diagnosis classifier trained by transient synthetic features is higher than that trained by original features. Also, the random forests fault diagnosis classifier trained by multiplicative features is the best with fault diagnosis accuracy can reach 98.32%. Finally, the online fault diagnosis experiments are carried out and the results demonstrate the effectiveness of the proposed method, which can accurately locate the open-circuit faults in IGBTs while ensuring system safety.

Current sensor fault diagnosis and fault‐tolerant control for single‐phase PWM rectifier based on a hybrid model‐based and data‐driven method

In this study, a hybrid model-based and data-driven method is proposed for the current sensor fault diagnosis used in single-phase pulse width modulation (PWM) rectifier. According to the principle of model-based methods, the proposed diagnostic method is based on signal prediction and residual generation. Differently, instead of a mathematical model, the signal prediction model is developed based on a data-driven method. Non-linear autoregressive exogenous learning model, randomised learning technique, and extreme learning machine are utilised to generate the data-driven prediction model. Once the fault is detected, fault-tolerant control is activated by substituting the predicted signal for the information of faulty sensors. The offline test shows that the proposed method is able to predict the sensor signal accurately with the root mean square error of 4.276 × 10−5. In addition, hardware-in-the-loop tests are conducted to verify the feasibility and reliability of the proposed method in the real-time application.

First‐order integral switching surface sliding‐mode control method of active front end rectifier for fast charger applications

This study proposes a control technique based on integral switching surface sliding-mode control for three-phase pulse-width modulation (PWM) rectifier. The proposed control system is based on the combination of a conventional proportional–integral (PI) controller and with two decoupled first-order sliding-mode (PI-FOSM) current controller. A set of integral switching surfaces based on the state-space equation are designed in the internal loop to force the grid currents to track their desired values. The proposed control approach improves the transient response and minimises the steady-state error under uncertainty. In addition, a conventional PI controller is also employed for the voltage regulation loop and generating the current reference of inner loops. In the controller design, all parameters of the system are considered with bounded perturbations in the design of control law. The main advantage of the proposed controller is robustness property against variations of entertained PWM rectifier parameters and external disturbances. The proposed PI-FOSM can improve transient performance and can decrease of the harmonic components under steady-state condition. In order to validate the theoretical contributions of this study, the performance of the proposed controller has been investigated by using a prototype laboratory.

Robust current control scheme for single‐phase PWM rectifiers based on improved μ ‐synthesis in electric locomotive

The parameter perturbation of grid-side equivalent inductance is a significant feature of the uncertainty in the single-phase pulse-width modulation rectifiers system for the electric locomotive. This characteristic tends to reduce the robustness of the rectifier system. This study handles these problems in the framework of the structured singular value, which helps to reduce the influence of model parameter perturbation, caused by measurement error and operation condition change, on the robustness. However, the conventional μ-synthesis robust controls only reflect tracking and anti-disturbance performance by weighting functions and ignoring the dynamic response performance. Herein, a direct current control (DCC) scheme based on improved μ-synthesis is proposed. A desired closed-loop transfer function is introduced to the conventional μ-synthesis control structure to ameliorate the performance of the dynamic response. Furthermore, considering the external disturbances on the system control output, a suitable weighting function is used to restrict the external disturbance. The input–output relationship of the generalised open-loop plant can thus be constructed accordingly. The proposed control scheme is compared with the widely applied proportional–integral-based DCC scheme and the conventional μ-synthesis DCC scheme. Hardware-in-the-loop experiment results show promising dynamic performance as well as stronger robustness against parameter perturbation and external disturbances.

Controlled Rectifier for Improved Harmonic Performance of a Pulse Step Modulated High Voltage Power Supply

Research in ITER grade magnetic confinement fusion uses high power radio frequency sources and accelerated neutral particles to heat the plasma to fusion temperature. These devices require high voltage DC power supplies in the range of several tens of kilovolts at a power level of few megawatts. Pulse step modulation technique is widely used to generate high voltage by cascading bulk numbers of low voltage switched power modules, offers a minimum ripple with microsecond order transient response and low let-through energy in case of load fault. However, the power quality and reliability of these systems still need enhancement for compatibility with an industrial environment. In a conventional diode rectifier-based switched power module, current drawn from the multisecondary transformer is highly distorted affecting transformer performance, leading to deploy higher capacity with enhanced thermal management. A novel concept of pulsewidth modulated (PWM) rectifiers in pulse step modulated power supplies is attempted for the first time with comparative analysis over conventional diode rectifiers, quoting an example of dual output high voltage power supply. Articles also discuss the development of a laboratory-scale prototype of the switched power supply module utilizing a PWM rectifier.

Design and Performance Analysis of Segmented Three-Phase IPMSM for EVs Integrated Battery Charger

A segmented three-phase interior permanent magnet synchronous motor (IPMSM) can bring a significant advantage in the development of electric vehicles (EVs) since it can be used as a simple inductor filter for an integrated battery charger without torque production during charging/vehicle-to-gird (V2G) mode. However, unlike an induction machine, majority of IPMSMs have low value of stator inductance, possibly below the minimum limit of the pulsewidth modulation rectifier requirement; therefore, the integrated battery chargers based on these types of IPMSMs may have difficulty dealing with grid current harmonics during charging/V2G mode. This article presents the method to design a suitable segmented three-phase IPMSM with nine windings (S3-IPMSM-9W) for integrated battery chargers. The optimization of stator winding inductance is proposed in order to get a large stator inductance capable of achieving acceptable ripple during charging and does not degrade the traction mode performance. Therefore, an optimized inductance, which is eight times greater than the nonoptimized stator inductance value was obtained. 96% of the efficiency of the optimized machine was achieved during the motoring mode. Moreover, with the help of optimized leakage inductance acting as a grid-side filter, the total harmonic distortion below 5% is reached during charging. Simulation and experimental results are provided to validate the theoretical analysis.

Modeling and analysis of a single-phase fractional-order voltage source pulse width modulation rectifier

A fractional-order voltage source pulse width modulation (PWM) rectifier (FOVSR) is that a voltage source PWM rectifier (VSR) with fractional-order inductors (FOIs) and fractional-order capacitors (FOCs). This paper deals with the modeling and analysis of a single-phase FOVSR, aiming to extend the single-phase VSRs from integer-order domain to fractional-order domain, and to reveal the influence mechanism of the FOI and the FOC on the operating characteristics of a single-phase FOVSR. Firstly, the model of a single-phase FOVSR is established based on the Caputo fractional calculus. On this foundation, the alternating current (AC) side steady-state operating characteristics are presented in detail by applying phasor analysis. Then the instantaneous power and secondary ripple expressions are derived. Additionally, the changing laws of the PWM operating waveforms of the AC side and the direct current (DC) side are analyzed. In order to control the operation of a single-phase FOVSR, a fractional-order proportional-integral-differential (FOPID) based dual closed-loop transient current controller is proposed. Finally, theoretical analysis is favorably verified by digital simulations. Compared with a single-phase integer-order VSR, a single-phase FOVSR presents more flexible and diversified operating characteristics, and it can operate in a wider range with good dynamic and static performance.