Improved Model Predictive Control for H-bridge Cascaded STATCOM

Xu Rong,Yu Yong,Wu Jian,Yang Rongfeng,Xu Dianguo,Chen He,Yu Yannan,Ni Ronggang 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

H-bridge cascaded static synchronous compensator (STATCOM) is often used to compensate the harmonic and reactive current derived from non-linear load. In order to improve the performance of STATCOM, an improved model predictive control (MPC) method is put forward in this paper. In the proposed MPC, the difference equations which are derived from the transfer functions of controlling variables and controlled variables in STATCOM are used as the predictive control model, the error between the output of STATCOM and predictive model is used to design feedback correction controller and rolling optimization controller. Meanwhile, the introduced repetitive controller is used to eliminate the inherent steady error. The actual H-bridge cascaded STATCOM is constructed and a series of verification tests are executed. The experimental results prove that the output voltage and current of H-bridge cascaded STATCOM with the proposed MPC have smaller distortion and better sinusoidal shape than those of the traditional Proportion Integral (PI) control. Moreover, the performance of H-bridge cascaded STATCOM is great in high power experiment.

Performance Evaluation of an Integrated Starter-Alternator with an IPM Synchronous Machine under Sensor-less Operation

Xu, Zhuang,Rahman, M.F.,Wang, G.,Xu, Dianguo The Korean Institute of Power Electronics 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.1

This paper presents performance evaluation of an Integrated Starter-Alternator (ISA) prototype with an Interior Permanent Magnet (IPM) synchronous machine under sensor-less operation. To attain a high starting torque at zero speed and in subsequent extremely low speed range, a hybrid signal injection method is proposed. At higher speed, an improved stator flux observer is used for the stator flux estimation. This observer is able to produce accurately-estimated stator flux linkage for high performance Direct Torque and Flux Control (DTFC) implementation. The sensor-less DTFC IPM synchronous machine drive takes full advantage of the capacity of the power converter and fulfills the control specifications for the ISA. The trajectory control algorithm responds rapidly and in a well behaved manner over a wide range of operating conditions. The experimental results verify the feasibility and advantages of the system.

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

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

Performance Evaluation of an Integrated Starter-Alternator with an IPM Synchronous Machine under Sensor-less Operation

Zhuang Xu,M. F. Rahman,G. Wang,Dianguo Xu 전력전자학회 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.1

This paper presents performance evaluation of an Integrated Starter-Alternator (ISA) prototype with an Interior Permanent Magnet (IPM) synchronous machine under sensor-less operation. To attain a high starting torque at zero speed and in subsequent extremely low speed range, a hybrid signal injection method is proposed. At higher speed, an improved stator flux observer is used for the stator flux estimation. This observer is able to produce accurately-estimated stator flux linkage for high performance Direct Torque and Flux Control (DTFC) implementation. The sensor-less DTFC IPM synchronous machine drive takes full advantage of the capacity of the power converter and fulfills the control specifications for the ISA. The trajectory control algorithm responds rapidly and in a well behaved manner over a wide range of operating conditions. The experimental results verify the feasibility and advantages of the system.

Optimal Stator-Current Trajectory Control of an IPM Synchronous Machine for Hybrid Electric Vehicles

Z. Xu,R. Datta,G. X.Yin,Dianguo Xu 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

This paper describes an optimal stator-current control strategy for an Integrated Starter-Alternator (ISA) prototype. Based on the applications of hybrid electric vehicles with wide constant power speed range, this paper investigates the various operation stages for the interior permanent magnet machine, including the maximum torque per ampere (MTPA), flux weakening control and maximum output power stage. A control algorithm was proposed to optimize the stator-current trajectories. Through the algorithm, the d-axis and q-axis components of the stator current were driven on the optimal trajectories to produce the desired torque and to maintain system stability under the voltage limit and current limit. The system takes full advantage of the capacity of the driving converter, and the maximum output torque was generated by the motor at any time. The reliability and dynamic performance of system were rather satisfactory. Energy optimization was achieved. The results from simulation and the real platform experiment verify the feasibility and advantages of the system.

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

Li, Binbin,Xu, Dandan,Xu, Dianguo The Korean Institute of Power Electronics 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.

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.

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

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.

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.