An Improved Control Method for Suppressing Capacitor Voltage Fluctuation of Medium-Voltage Motor Drives based on Cascaded H-Bridge

2020 ◽  
Author(s):  
Shifeng Zhao ◽  
Jinjun Liu ◽  
Sixing Du
Keyword(s):  
Control Method ◽  
Motor Drives ◽  
Voltage Fluctuation ◽  
Medium Voltage ◽  
Capacitor Voltage

Hybrid modular multilevel converter with cascaded full bridges for medium-voltage motor drives

2019 ◽  
Vol 41 (12) ◽  
pp. 3279-3291 ◽  
Author(s):  
Yu Jiali ◽  
Xia Chaoying
Keyword(s):  
High Frequency ◽  
Stable State ◽  
High Amplitude ◽  
Motor Drives ◽  
Modular Multilevel Converter ◽  
Multilevel Converter ◽  
Voltage Fluctuation ◽  
Constant Frequency ◽  
Medium Voltage ◽  
Capacitor Voltage

Modular multilevel converter (MMC) is especially appropriate in high-voltage constant-frequency systems due to its modularity and scalability. But, so far MMC has not been widely used in motor drives applications. Since the capacitor voltage fluctuation is proportional to the output current amplitude and inversely proportional to the output frequency under constant torque load, at the low-speed, the excessive sub-module (SM) capacitor voltage fluctuation is one of the major obstacles for MMC applied in motor drives. To suppress the SM capacitor voltage fluctuation, an effective solution is to inject a high frequency zero sequence voltage to the three-phase output voltages of MMC and control the circulating current per phase reasonably. However, the introduced high frequency and high amplitude common voltage at the motor side is harmful. In this paper, a hybrid MMC with cascaded full-bridge SMs (HMMC-CFB) topology is used in the medium-voltage motor drives. The high frequency and high amplitude common mode voltage is absorbed by the cascaded full-bridge SMs. Besides, the capacitor voltage fluctuations of each arm and the cascaded full-bridge SMs is easily limited within a reasonable range. Finally, the state space model of HMMC-CFB system is established and a stable state-error feedback control law is given. By the passive theory, the necessary and sufficient condition for the globally uniformly asymptotical stability of the HMMC-CFB closed-loop system is deduced. Simulation results confirm the superiority of this novel topology and the validity of the proposed control strategy.

scholarly journals Voltage Jump Suppression and Capacitor Voltage Fluctuation Analysis for a Four-Level Hybrid Flying Capacitor T-Type Converter

Energies ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 698 ◽  
Author(s):  
Chen Wei ◽  
Xibo Yuan ◽  
Juan Zhou ◽  
Kangan Wang ◽  
Yonglei Zhang ◽  
...  
Keyword(s):  
Dead Time ◽  
Fluctuation Analysis ◽  
Voltage Fluctuation ◽  
Multilevel Converters ◽  
Medium Voltage ◽  
Time Period ◽  
Capacitor Voltage ◽  
And Control ◽  
Laboratory Prototype ◽  
Voltage Jump

In low and medium voltage power conversion systems, multilevel converters are becoming more and more attractive due to improved power density. However, the complexity of topology and control is a big challenge for the application of multilevel converters. In this paper, a four-level (4L) hybrid flying capacitor (FC) T-type converter has been researched in detail. The topological advantage of the converter is displayed in comparison to existing four-level converters. According to the feature of the topology, the operating status has been analyzed and the reason for the voltage jump is researched in detail during the dead-time period. A strategy to reduce voltage jump by adjusting the switching states has be presented. The FC voltages can be balanced by selecting the appropriate switching states. The relationships between the fluctuations of FC voltages and the modulation index and power factor (PF) have been analyzed by simulation results. The performance of the 4L converter has been investigated in MATLAB/Simulink as well as on a down-scaled laboratory prototype.

scholarly journals A novel sliding mode single-loop speed control method based on disturbance observer for permanent magnet synchronous motor drives

2018 ◽  
Vol 10 (12) ◽  
pp. 168781401881527 ◽  
Author(s):  
Xudong Liu ◽  
Ke Li
Keyword(s):  
Permanent Magnet ◽  
Disturbance Observer ◽  
Control Structure ◽  
Control Method ◽  
Sliding Mode ◽  
Permanent Magnet Synchronous Motor ◽  
Speed Control ◽  
Synchronous Motor ◽  
Motor Drives ◽  
Sliding Mode Controller

A novel speed control method based on sliding mode control and disturbance observer is studied for permanent magnet synchronous motor drives. Different from the conventional speed and current cascade control structure in the field-oriented vector control, the new controller adopts the single-loop control structure, in which the speed and quadrate axes current controllers are combined together. First, a multiple-surface sliding mode controller is designed for the speed control system of permanent magnet synchronous motor. Although the sliding mode controller has the strong robustness for the matched disturbance in the system, it still cannot deal with mismatched disturbance effectively, such as external load disturbance and some parameter variations. Thus, the disturbance observer is introduced to estimate the disturbance in the motor, which is designed by combining the proposed sliding mode controller. Finally, the effectiveness is tested under various conditions by both simulation and experiment. The results show that the designed controller has the fast transient response and robustness under different operating conditions.

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