LINE SIDE HARMONIC ANALYSIS OF SINGLE-PHASE DIODE BRIDGE RECTIFIER WITH A DC FILTER CAPACITOR

Jinjun Liu,Zhaoan Wang 전력전자학회 1998 ICPE(ISPE)논문집 Vol.- No.-

Single-phase diode bridge rectifiers with dc filter capacitor usually operate in discontinuous mode and generate large amounts of harmonic currents. This paper presents a precise harmonic analysis of the line side current in the case that both the filter inductor and the filter capacitor are not infinite. The analytical expressions of the line side performance parameters associated with harmonics are derived The curves that show the relationship of these parameters as the functions of circuit parameters are illustrated. By simulation the results are verified to be accurate and the conclusion clearly reveals the relations between the line side performance parameters and circuit parameters.

A Family of New Zero-Voltage-Transition PWM Converter with Zero-Current Turnoff Auxiliary Switch

Xu Yang,Zhaoan Wang 전력전자학회 1998 ICPE(ISPE)논문집 Vol.- No.-

The shortcomings of zero-volltage-transition PWM converter is discussed ,and a new family of topologies of zero-voltage-transition PWM converter with soft-switched auxiliary switch is introduced The experiments on a 290W boost converter and a 100W forward converter are carried out to prove the circuit The efficiency increment of the new circuits are 2-5% comparing to hard switching circuits,and the switching noise is also greatly reduced.<br/>

CONTROL STRATEGIES FOR SHUNT ACTIVE POWER FILTERS IN DISTORTION SOURCE VOLTAGE SITUATION

Jun Yang,Zhaoan Wang 전력전자학회 1998 ICPE(ISPE)논문집 Vol.- No.-

The compensation strategy of shunt active power filters is one of the most important link that determine its compensation characteristics In this paper, a new interpretation of the instantaneous reactive power theory in three-phase circuits was proposed A compensation strategy (l_p, l_q mode) was introduced on the basis of the new interpretation. This compensation strategy was compared with other two compensation strategies (p, q mode and UPF mode). When source voltage is sinusoidal, the three compensation strategies are equivalent to each other When source voltage is distorted, a sinusoidal source current may result only by using l_p, l_q mode This js the advantage of l_p, l_q mode. The result is verified by simulation.

New Control Strategy for Reducing Switching Losses in Three-Phase Voltage-Source PWM Converters

Dong Xiaopeng,Wang Zhaoan 전력전자학회 1998 ICPE(ISPE)논문집 Vol.- No.-

In this paper, a new control strategy to reduce switching losses in three-phase voltage-source PWM converters is proposed according to Modified-Period-Average-Model (MPAM). The basic concept of this strategy is aimed at calculating the phase control voltages for controlling the source currents to be sinusoidal and in phase with the source voltages, and reducing the number of switching in each period.<br/> The phase control voltages of Period-Average-Model(PAM) is obtained according to analyzing the operation of PWM converter In order to reduce the sensitivity to system parameters in PAM, MPAM is deduced Then a square wave whose frequency is three times of utility frequency is added to the phase control voltages derived from MPAM The control strategy reduces the switching losses since there exists about one-third blanking time for every phase in one period. The theoretical derivation and the control strategy are experimentally verified on a 2.5 kW three-phase voltage source converter.

A PI Control Algorithm with Zero Static Misadjustment for Tracking the Harmonic Current of Three-Level APFs

Yingjie He,Jinjun Liu,Zhaoan Wang,Yunping Zou 전력전자학회 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.1

Tracking harmonic current quickly and precisely is one of the keys to designing active power filters (APF). In the past, the current state feedback decoupling PI control was an effective means for three-phase systems in the current control of constant voltage constant frequency inverters and high frequency PWM reversible rectifiers. This paper analyzes in detail the limitation of the conventional PI conditioner in the APF application field and presents a novel PI control method. Canceling the delay of one sampling period and the misadjustment for tracking the harmonic current is the key problem of this PI control. In this PI control, the predictive output current value is obtained by a state observer. The delay of one sampling period is remedied in this digital control system by the state observer. The predictive harmonic command current value is obtained by a repetitive predictor synchronously. The repetitive predictor can achieve better predictions of the harmonic current. By this means, the misadjustment of the conventional PI control for tracking the harmonic current is cancelled. The experiment results with a three-level NPC APF indicate that the steady-state accuracy and dynamic response of this method are satisfying when the proposed control scheme is implemented.

Deadbeat Control with a Repetitive Predictor for Three-Level Active Power Filters

Yingjie He,Jinjun Liu,Jian Tang,Zhaoan Wang,Yunping Zou 전력전자학회 2011 JOURNAL OF POWER ELECTRONICS Vol.11 No.4

Three-level NPC inverters have been put into practical use for years especially in high voltage high power grids. This paper researches three-level active power filters (APFs). In this paper a mathematical model in the d-q coordinates is presented for 3-phase 3-wire NPC APFs. The deadbeat control scheme is obtained by using state equations. Canceling the delay of one sampling period and providing the predictive value of the harmonic current is a key problem of the deadbeat control. Based on this deadbeat control, the predictive output current value is obtained by the state observer. The delay of one sampling period is remedied in this digital control system by the state observer. The predictive harmonic command current value is obtained by the repetitive predictor synchronously. The repetitive predictor can achieve a better prediction of the harmonic current with the same sampling frequency, thus improving the overall performance of the system. The experiment results indicate that the steady-state accuracy and the dynamic response are both satisfying when the proposed control scheme is implemented.

Theoretical Analysis and Control of DC Neutral-point Voltage Balance of Three-level Inverters in Active Power Filters

He, Yingjie,Liu, Jinjun,Tang, Jian,Wang, Zhaoan,Zou, Yunping The Korean Institute of Power Electronics 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.2

In recent years, multilevel technology has become an effective and practical solution in the field of moderate and high voltage applications. This paper discusses an APF with a three-level NPC inverter. Obviously, the application of such converter to APFs is hindered by the problem of the voltage unbalance of DC capacitors, which leads to system instability. This paper comprehensively analyzes the theoretical limitations of the neutral-point voltage balancing problem for tracking different harmonic currents utilizing current switching functions from the space vector PWM (SVPWM) point of view. The fluctuation of the neutral point caused by the load currents of certain order harmonic frequency is reported and quantified. Furthermore, this paper presents a close-loop digital control algorithm of the DC voltage for this APF. A PI controller regulates the DC voltage in the outer-loop controller. In the current-loop controller, this paper proposes a simple neutral-point voltage control method. The neutral-point voltage imbalance is restrained by selecting small vectors that will move the neutral-point voltage in the direction opposite the direction of the unbalance. The experiment results illustrate that the performance of the proposed approach is satisfactory.

Small-Signal Modeling and control of Three-Phase Bridge Boost Rectifiers under Non-Sinusoidal Conditions

Yuan Chang,Liu Jinjun,Wang Xiaoyu,Wang Zhaoan 전력전자학회 2009 JOURNAL OF POWER ELECTRONICS Vol.9 No.5

This paper proposes a systematic approach to the modeling of the small-signal characteristics of three-phase bridge boost rectifiers under non-simusoidal conditions. The main obstacle to the conventional synchronous d-q frame modeling approach is that it is unable to identify a steady-state under non-sinusoidal conditions. However, for most applications under non-sinusoidal conditions, the current loops of boost rectifiers are designed to have a bandwidth that is much higher than typical harmonics frequencies in order to achieve good current control for these harmonic components. Therefore a quasi-static method is applied to the proposed modeling approach. The converter small-signal characteristics developed from conventional synchronous frame modeling under different operating points are investigated and a worst case point is then located for the current loop design. Both qualitative and quantitative analyses are presented. It is observed that operating points influence the converter low frequency characteristics but hardly affect the dominant poles. The relationship between power stage parameters, system poles and zeroes is also presented which offers good support for the system design. Both the simulation and experimental results verified the analysis and proposed modeling approach. Finally, the practical case of a parallel active power filter is studied to present the modeling approach and the resultant regulator design procedure. The system performance further verifies the whole analysis.

A PI Control Algorithm with Zero Static Misadjustment for Tracking the Harmonic Current of Three-Level APFs

He, Yingjie,Liu, Jinjun,Wang, Zhaoan,Zou, Yunping The Korean Institute of Power Electronics 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.1

Tracking harmonic current quickly and precisely is one of the keys to designing active power filters (APF). In the past, the current state feedback decoupling PI control was an effective means for three-phase systems in the current control of constant voltage constant frequency inverters and high frequency PWM reversible rectifiers. This paper analyzes in detail the limitation of the conventional PI conditioner in the APF application field and presents a novel PI control method. Canceling the delay of one sampling period and the misadjustment for tracking the harmonic current is the key problem of this PI control. In this PI control, the predictive output current value is obtained by a state observer. The delay of one sampling period is remedied in this digital control system by the state observer. The predictive harmonic command current value is obtained by a repetitive predictor synchronously. The repetitive predictor can achieve better predictions of the harmonic current. By this means, the misadjustment of the conventional PI control for tracking the harmonic current is cancelled. The experiment results with a three-level NPC APF indicate that the steady-state accuracy and dynamic response of this method are satisfying when the proposed control scheme is implemented.

Small-Signal Modeling and Control of Three-Phase Bridge Boost Rectifiers under Non-Sinusoidal Conditions

Chang, Yuan,Jinjun, Liu,Xiaoyu, Wang,Zhaoan, Wang The Korean Institute of Power Electronics 2009 JOURNAL OF POWER ELECTRONICS Vol.9 No.5

This paper proposes a systematic approach to the modeling of the small-signal characteristics of three-phase bridge boost rectifiers under non-sinusoidal conditions. The main obstacle to the conventional synchronous d-q frame modeling approach is that it is unable to identify a steady-state under non-sinusoidal conditions. However, for most applications under non-sinusoidal conditions, the current loops of boost rectifiers are designed to have a bandwidth that is much higher than typical harmonics frequencies in order to achieve good current control for these harmonic components. Therefore a quasi-static method is applied to the proposed modeling approach. The converter small-signal characteristics developed from conventional synchronous frame modeling under different operating points are investigated and a worst case point is then located for the current loop design. Both qualitative and quantitative analyses are presented. It is observed that operating points influence the converter low frequency characteristics but hardly affect the dominant poles. The relationship between power stage parameters, system poles and zeroes is also presented which offers good support for the system design. Both the simulation and experimental results verified the analysis and proposed modeling approach. Finally, the practical case of a parallel active power filter is studied to present the modeling approach and the resultant regulator design procedure. The system performance further verifies the whole analysis.