Pursuing seamlessly charging world: Exploring high frequency wireless power transfer technology

Dianguo Xu 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

Improved Control Method of Grid-connected Converter Based on Voltage Perturbation Compensation Under Weak Grid Conditions

Sida Fu,Xueguang Zhang,Dianguo Xu 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

The three-phase grid-connected converter control system and the grid impedance are coupled with each other under weak grid conditions, which brings in negative influence on the system. In this paper, the impedance model of a three-phase grid-connected converter including current loop, PLL and DC voltage loop is established in d-q frame. The influence of PLL and DC voltage loop proportional coefficient on system stability is analyzed. According to the transfer relationship of each variable in the impedance model, the PCC voltage perturbation paths to the PLL and DC voltage loop are analyzed respectively. On the basis of voltage perturbation paths, a compensation control strategy is proposed. The impedance analysis results show that the proposed method can effectively improve the system stability under weak. The experimental results verify the correctness of the theoretical analysis and the effectiveness of the proposed method.

A Novel Frequency Characteristic Model and Noise Shaping Method for Encoder-Based Speed Measurement in Motor Drive

Yangyang Chen,Ming Yang,Dianguo Xu,Frede Blaabjerg 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

The performance of the closed-loop control system is determined by the accuracy of the feedback signal to some extent. In most motor drive systems, the position and speed signals come from the optical encoder. Thus, to reduce the quantization error from encoder and achieve better speed measurement results are the focuses of scholars and engineers. Although many improved speed measurement methods have been proposed, there are still few literatures discussed about the frequency characteristic of the encoder quantization noise. Even in some algorithms like Kalman filter based speed measurement methods usually regard the quantization noise as white noise. In this paper, a noise frequency characteristic model of encoder-based speed measurement in motor drive is built up. According to this model, the variation rule of the noise frequency is found. Besides, a variable-period noise shaping method is proposed to reduce the impact of quantization noise. Both the notch filter and a finite impulse response (FIR) filter are used to cope with the quantization noise. The frequency model and noise shaping method are verified by experiment results.

A High-Reliability Soft-Start Igniter for HPS Lamps

Wang Yifeng,Xu Dianguo,Wang Yijie,Zhang Xiangjun 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

In this paper, the analysis and design of a new igniter based on half bridge inverter is presented. The proposed igniters can tolerant of the leakage inductance and the parasitic capacitor influence inherent in the transformer. the location of the ignition pulses is near the edge of the square wave automatically. Meanwhile there are enough ignition pulses during a switching period that can ignite high-pressure-sodium (HPS) lamps without any voltage shock. The parameters are given by theoretical calculation, and then verified by PSpice simulation results. At last experimental results of the igniter are presented. Due to the location of ignition pulses, the optimized waveform and high frequency of pulse voltage, the proposed igniter can reliably start most of the 1㎾ HPS lamps without voltage or current surge.

Application of HHT for Online Detection of Inter-Area Short Circuits of Rotor Windings of Turbo-Generators Based on the Thermodynamics Modeling Method

Liguo Wang,Yi Wang,Dianguo Xu,Bo Fang,Qinghe Liu,Jing Zou 전력전자학회 2011 JOURNAL OF POWER ELECTRONICS Vol.11 No.5

This paper focuses on monitoring and predicting the short circuit faults of the rotor windings of large turbo-generator systems. For the purpose of increasing efficiency and decreasing maintenance cost, a method that combines the HHT (Hilbert Huang Transform) with a wavelet has been studied. This method is based on analyzing a classical Albright detecting coil. Due to the Empirical Mode Decomposition (EMD) and the Intrinsic Mode Functions (IMF) of the HHT the exact location of a short circuit of rotor windings may be given. However, a part of the useful information is eliminated by the unreasonable decomposing scale of the wavelet. Based on the thermodynamics modeling method, this study was illustrated with a 50㎿ turbo-generator system that is installed in Northern China. The analysis results, which have very good agreement with those of a previous study, show that the method of combining the HHT with a wavelet is an effective way to analyze and predict the short circuit faults of the rotor windings of large generators, such as supercritical turbo-generator systems and wind turbo-generator systems. This work can offer a useful reference for analyzing smart grids by improving the power quality of a distribution network that is supplied by a turbo-generator system.

Circulating Current Harmonics Suppression for Modular Multilevel Converters Based on Repetitive Control

Binbin Li,Dandan Xu,Dianguo Xu 전력전자학회 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.6

Modular multilevel converters (MMCs) have emerged as the most promising topology for high and medium voltage applications for the coming years. However, one particular negative characteristic of MMCs is the existence of circulating current, which contains a dc component and a series of low-frequency even-order ac harmonics. If not suppressed, these ac harmonics will distort the arm currents, increase the power loses, and cause higher current stresses on the semiconductor devices. Repetitive control (RC) is well known due to its distinctive capabilities in tracking periodic signals and eliminating periodic errors. In this paper, a novel circulating current control scheme base on RC is proposed to effectively track the dc component and to restrain the low-frequency ac harmonics. The integrating function is inherently embedded in the RC controller. Therefore, the proposed circulating current control only parallels the RC controller with a proportional controller. Thus, conflicts between the RC controller and the traditional proportional integral (PI) controller can be avoided. The design methodologies of the RC controller and a stability analysis are also introduced. The validity of the proposed circulating current control approach has been verified by simulation and experimental results based on a three-phase MMC downscaled prototype.

Speed and Current Sensor Fault Detection and Isolation Based on Adaptive Observers for IM Drives

Yong Yu,Ziyuan Wang,Dianguo Xu,Tao Zhou,Rong Xu 전력전자학회 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.5

This paper focuses on speed and current sensor fault detection and isolation (FDI) for induction motor (IM) drives. A new, accurate and high-efficiency FDI approach is proposed so that a system can continue operating with good performance even in the presence of speed sensor faults, current sensor faults or both. The proposed three paralleled adaptive observers are capable of current sensor fault detection and localization. By using observers, the rotor flux and rotor speed can be estimated which allows the system to run under the speed sensorless vector control mode when a speed sensor fault occurs. In order to detect speed sensor faults, a threshold-based scheme is proposed. To verify the feasibility and effectiveness of the proposed FDI strategy, experiments are carried out under different conditions based on a dSPACE DS1104 induction motor drive platform.

Recognition and Classification of Power Quality Disturbances on the basis of Pattern Linguistic Values

XiaoSheng Liu,Bo Liu,DianGuo Xu 대한전기학회 2016 Journal of Electrical Engineering & Technology Vol.11 No.2

This paper presents a new recognition and classification method for power quality (PQ) disturbances on the basis of pattern linguistic values. This method solves the difficulty of recognizing disturbances rapidly and accurately by using fuzzy logic. This method uses classification disturbance patterns to define the linguistic values of fuzzy input variables and used the input variables of corresponding disturbance pattern to set membership functions. This method also sets the fuzzy rules by analyzing the distribution regularities of the input variable values. One characteristic of this method is that the linguistic values of fuzzy input variables and the setting of membership functions are not only related to the input variables but also to the character of classification disturbance and the classification results. Furthermore, the number of fuzzy rules is equal to the number of disturbance patterns. By using this method for disturbance classification, the membership function and design of fuzzy rules are directly related to the objective of classification, thus effectively reducing the complexity of the design process and yielding accurate classification results. The classification results of the simulation and measured data verify the feasibility and effectiveness of this method.

Novel Interleaved Single-Stage AC/DC Converter with a High Power Factor and High Efficiency

Wang, Yijie,Wang, Wei,Zhang, Xiangjun,Xu, Dianguo The Korean Institute of Power Electronics 2011 JOURNAL OF POWER ELECTRONICS Vol.11 No.3

A novel single-stage AC/DC converter with the soft-switching characteristic based on interleaving technology and an LLC topology is proposed here. The converter is integrated by an interleaved cell and an LLC cell. Because the components of the system are reduced as a result of integrating, the cost decreases. Since interleaving technology is adopted, the converter can work in a high voltage input state. The LLC topology chosen here ensures that the switches on the primary side work in the ZVS condition and that the diodes on the secondary side work in the ZCS condition, which decreases the switching loss of the system. A theoretical analysis and the design procedures of the proposed converter are proposed and discussed in detail. Simulations and experimental studies with a 100W prototype are done to prove the analysis.

Speed and Current Sensor Fault Detection and Isolation Based on Adaptive Observers for IM Drives

Yu, Yong,Wang, Ziyuan,Xu, Dianguo,Zhou, Tao,Xu, Rong The Korean Institute of Power Electronics 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.5

This paper focuses on speed and current sensor fault detection and isolation (FDI) for induction motor (IM) drives. A new, accurate and high-efficiency FDI approach is proposed so that a system can continue operating with good performance even in the presence of speed sensor faults, current sensor faults or both. The proposed three paralleled adaptive observers are capable of current sensor fault detection and localization. By using observers, the rotor flux and rotor speed can be estimated which allows the system to run under the speed sensorless vector control mode when a speed sensor fault occurs. In order to detect speed sensor faults, a threshold-based scheme is proposed. To verify the feasibility and effectiveness of the proposed FDI strategy, experiments are carried out under different conditions based on a dSPACE DS1104 induction motor drive platform.