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4. Output Voltage Ripple Suppression of PPSS-LCC Converter for Medical X-Ray Application Based on Repetitive Control

Author

Lin, Chudi, He, Liqun, Fan, Mingdi, Li, Xiaohui, Fan, Shengfang, Wang, Cheng, and Xue, Yaosuo

Abstract

The primary-parallel-secondary-series LCC resonant high voltage (HV) power supply with single-phase ac input has been widely applied for medical X-ray application. It requires extremely low ripple (<0.5%) for hundreds of kilovolts output voltage, which is quite challenging. Large capacitance is often utilized at the dc bus to absorb the second-order ripple power introduced by the single-phase input, which deteriorates the power density of the system. To address this issue, this article proposes an output voltage ripple suppression strategy based on plug-in repetitive control combined with pulse-frequency modulation. It can realize voltage ripple suppression and zero-voltage switching ( of the LCC converter at the same time. The dc-bus capacitance can, therefore, be remarkably reduced. This strategy has the advantages of no additional hardware costs, directly implemented in digital controller, and insensitive to accuracy of system parameters. Experiments are carried out on a practical 120 kV/900 W HV power supply and confirm the effectiveness of the proposed strategy. The peak–peak output voltage ripple is suppressed to only 0.36%, while the DC capacitance is significantly reduced to 1/12. Comparison of X-ray does prove that the image quality of X-ray machine is consequently greatly improved.

Published
2024
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23. Grid Impedance Detection Based On Complex Coefficient Filter and Full-order Capacitor Current Observer for Three-phase Grid-connected Inverters.

Author

Wang, Kaixin, Yang, Yong, Fan, Mingdi, Tang, Yuhang, Li, Haoyang, Chen, Rong, Hu, Jiefeng, Zeng, Weibo, and Rodriguez, Jose

Abstract

This article proposes a new grid impedance detection method incorporating the complex coefficient filter (CCF) with full-order capacitor current observer for a T-type three-level grid-connected inverter controlled by the inverter output current feedback. Compared with conventional CCF impedance detection algorithms, the proposed method reduces the number of current sensors and detects the grid impedance accurately. First, based on the sampled inverter output current and grid-connected voltage signals, the grid-connected current is estimated. Then, the CCF method is used to extract harmonics from the grid-connected current and voltage signals to calculate the grid impedance. Finally, the correctness of the full-order capacitor current observer is verified by simulation and the feasibility and effectiveness of the proposed algorithm are verified experimentally based on a laboratory prototype. [ABSTRACT FROM AUTHOR]

Published
2023
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32. An Improved Space Vector Modulation Method for the Reduction of Common-Mode Voltages in PMSM Control System

Author

Liqun He, Xin Jiang, Xiaohui Li, Wei Zhang, Yong Yang, Fan Mingdi, and Aiming Ji

Subjects
Reduction (complexity), Physics, Modulation, Control theory, Dynamic range, Control system, Common-mode signal, Pulse-width modulation, Space vector modulation, Voltage
Abstract

In order to suppress the negative effects of the common-mode voltage (CMV) generated in the permanent magnet synchronous motor (PMSM) control system, an improved space vector modulation method for CMV reduction is proposed in this paper. Compared with traditional space vector pulse width modulation (SVPWM), it has same modulation range and has great dynamic and steady-state performance when used in the PMSM control system. In addition, it can reduce the amplitude of CMV from V DC /2 to V DC /6. Comparisons with existing modulation methods, as well as, experimental results are provided to verify feasibility and stability of the proposed method.

Published
2021
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40. Implicit Model Predictive Control with Continuous Control Set of PMSM Drive Systems

Author

Yong Yang, Fan Mingdi, Xin Jiang, Rong Chen, Menxi Xie, and Aiming Ji

Subjects
0209 industrial biotechnology, Electronic speed control, Computer science, 020208 electrical & electronic engineering, 02 engineering and technology, Function (mathematics), Model predictive control, 020901 industrial engineering & automation, Control theory, Power electronics, 0202 electrical engineering, electronic engineering, information engineering, Quadratic programming, Current loop, Pulse-width modulation
Abstract

In this paper, a predictive speed controller based on continuous control set model predictive control (CCS-MPC) is developed for permanent magnet synchronous motor (PMSM) driver. The controller overcomes limitations of cascaded speed loop and current loop. To minimize the cost function, the conventional implicit CCS-MPC requires complex algorithms to solve the quadratic program. This controller obtains the optimization modulation reference for PWM that can be easily implemented for the PMSM drive systems. In the simulation study, the proposed controller achieves excellent dynamic and steady-state performance.

Published
2020
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41. An Optimized Start-up Method for Modular Cascaded AC/DC Power Electronic Transformer with Minimized Input-Inrush Current in Dual Active Bridge

Author

Menxi Xie, Shengfang Fan, Xiaohui Li, Linqian Cheng, Liqun He, Yong Yang, and Fan Mingdi

Subjects
business.industry, Computer science, 020208 electrical & electronic engineering, Electrical engineering, 020206 networking & telecommunications, 02 engineering and technology, Modular design, Inrush current, law.invention, Power (physics), law, Duty cycle, Interfacing, Power electronics, 0202 electrical engineering, electronic engineering, information engineering, Power semiconductor device, Transformer, business
Abstract

The modular cascaded power electronic transformers (PETs) designed for interfacing AC and DC grids are mostly composed of active front end (AFE) and dual active bridges (DABs). Due to the remarkable difference between primary side and secondary side capacitor voltages of DAB at start-up, high input-inrush current will occur if the phase-shift-control (PSC) of DAB is directly employed, which can pose damage to power devices. This paper proposes a novel soft start-up method for DABs in PET with fast pre-charge process. The duty cycle of primary bridge is dynamically adjusted to precisely limit the peak of input-inrush current, and the regulating range is also enlarged.

Published
2020
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42. Power based Single-phase PLL with in-loop Fix Delay Filter under Distortion

Author

Menxi Xie, Yong Yang, Fan Mingdi, and Liqun He

Subjects
Phase-locked loop, Filter (video), Control theory, Cascade, Computer science, Distortion, Power electronics, 020208 electrical & electronic engineering, Phase distortion, 0202 electrical engineering, electronic engineering, information engineering, 02 engineering and technology, Phase detector, Power (physics)
Abstract

Precise voltage phase information is of great importance for grid-connected converter control. For single-phase system, product-type based Power Phase-Locked Loop (pPLL) has high order disturbs in phase detector when the grid voltage is distorted. To obtain zero steady state phase detected error, this paper presents a cascade fix delay filter applied in loop of pPLL. The configuration of cascade filter unit is analyzed, also the parameter design guidelines and digital implementation of the methods are provided. The simulation and experimental tests are carried out to verify the correctness and effectiveness of the filter.

Published
2020
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50. Rail potential control with train diagram optimization in multitrain DC traction power system

Author

Zhu, Chengqian, Du, Guifu, Ding, Yawen, Huang, Weiguo, Wang, Jun, Fan, Mingdi, and Zhu, Zhongkui

Abstract

ABSTRACTCurrently, abnormally elevated rail potential exists in the DC traction power system, which greatly threatens the safe operation of the line. In order to realize the reflux safety, timetable optimization of multitrain based on improved Seeker Optimization Algorithm (SOA) is proposed to suppress the rail potential of the system. Firstly, the simulation model of the system is built and the calculation process of rail potential is proposed. Secondly, an optimization model based on maximum rail potential is formulated, where the dwell time is the decision variable and is adjusted to change the regenerative power distribution of the system. Finally, the improved SOA is used to handle the optimization model. Compared with the maximum rail potential before optimization, the simulation results demonstrate that the maximum rail potential is reduced by 55.5% with the proposed method, which greatly improves the reflux safety of the multi-train subway system.

Published
2022
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