电工技术学报  2023, Vol. 38 Issue (16): 4376-4390    DOI: 10.19595/j.cnki.1000-6753.tces.221041
电力电子 |
并联级联H桥电源电流跟踪优化与环流抑制的模型预测控制
黄海宏, 颜碧琛, 王海欣
合肥工业大学电气与自动化工程学院 合肥 230000
Model Predictive Control of Current Tracking Optimization and Circulating Current Suppression for Multi-Parallel Cascaded H-Bridge Power Supplies
Huang Haihong, Yan Bichen, Wang Haixin
School of Electrical Engineering and Automation Hefei University of Technology Hefei 230000 China
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摘要 分布式控制在级联H桥(CHB)变换器并联的电源中可提升输出容量及可靠性。然而,常规分布式控制器可能由于硬件或控制参数的不匹配而导致输出功率不平衡,从而在CHB支路之间形成不稳定的环流,这将导致:①支路电流的稳定性与跟踪性能变差;②均流电抗器易饱和。对此该文提出一种基于Luenberger观测器状态重构的主从模型预测控制,所提策略可以实现参考电流跟踪和环流抑制的控制优化。此外,通过载波可以轻松实现级联H桥交错和并联控制器同步,从而固定开关频率。基于推导出的电流预测模型,当多个并联CHB支路具有不同的输出功率时,可以实现优化的电流跟踪响应并消除环流。仿真和实验结果验证了所提方法的有效性。
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黄海宏
颜碧琛
王海欣
关键词 预测控制级联H桥变换器并联主从控制结构电流跟踪环流观测器    
Abstract:When the cascaded H-bridge (CHB) converter with an isolated DC-link is used as a power supply in parallel through the current-sharing reactor, the distributed controller will form an unstable circulating current between the parallel branches due to the parameter difference. However, when the output power is unbalanced, the conventional linear controller cannot actively suppress the circulating current, resulting in degraded reference tracking performances. Recent studies have proposed parallel methods based on improved master-slave predictive control. However, the problems of more stable circulating current observation and a large amount of computation still exist. Therefore, this paper proposes a parallel method of carrier-based model predictive control (MPC) and improved master-slave control. When the output power is unbalanced, the reference tracking and a circulating current suppression are realized by optimizing the global control value through the proposed prediction model.
Firstly, the master controller reconstructs the branch current into the common load inductor current and the branch circulating current through the Luenberger observer. Secondly, a global cost function is established to optimize the reference tracking and the circulating current suppression. Finally, the globally optimized control values are sent to the slave controllers, and the interleaved H-bridges are managed by the respective carrier phase shifted pulse width modulation (CPSPWM) modulator. The master and slave controllers have similar optimized timing based on the carrier, and slave controllers only communicate with the master controller. In the proposed method, the Luenberger outputs stable state observations, the MPC solves the global optimal control values, the CPSPWM modulator fixes the switching frequency of the interleaved H-bridge, and the improved master-slave control reduces the communication resource. Therefore, the proposed method can realize stable reference tracking and the circulating current suppression in the parallel CHB power supply.
The results show that when the current-sharing reactor is 2 mH or 1mH and the current reference difference reaches 50 %, the proposed method quickly tracks the steady-state reference after a small overshoot. The steady-state deviation is much smaller than the conventional linear controller. It is shown that the proposed method has a more stable dynamic tracking performance, with the reference suddenly changing when the amplitude step mutation of the reference signal is added. A 5 % mismatching of the current-sharing reactor is operated in the simulated test. The results show that the proposed method can effectively suppress the circulating current caused by the difference in hardware parameters. Observation errors of the proposed Luenberger observer are measured in simulation. The maximum deviation of the branch current is 0.83 A, almost following the sampling current. The program time of the proposed method is about 23 μs in DSP28335, which is less than the sampling period of 20 kHz.
The analysis of the results leads to the conclusion that: (1) Compared with the parallel scheme of the conventional linear controller, the branch's current reference tracking performance is improved. Specifically in terms of high steady-state tracking accuracy and short dynamic adjustment time. (2) The circulating current caused by the unbalanced output power is effectively suppressed. (3) The proposed algorithm can be extended to any number of the multi-parallel CHB branches if the sampling period is sufficient to operate the program.
Key wordsPredictive control    cascaded H-bridge converter    parallel    master-slave control structure    current tracking    circulating current    observer   
收稿日期: 2022-06-06     
PACS: TL62  
  TM46  
基金资助:区域创新发展联合基金资助项目(重点支持项目)(U22A20225)
通讯作者: 颜碧琛, 男,1995年生,博士研究生,研究方向为电力电子技术和预测控制。E-mail: yanbichen@mail.hfut.edu.cn   
作者简介: 黄海宏 男,1973年生,教授,博士生导师,研究方向为电力电子技术和自动控制。E-mail: hhaihong741@126.com
引用本文:   
黄海宏, 颜碧琛, 王海欣. 并联级联H桥电源电流跟踪优化与环流抑制的模型预测控制[J]. 电工技术学报, 2023, 38(16): 4376-4390. Huang Haihong, Yan Bichen, Wang Haixin. Model Predictive Control of Current Tracking Optimization and Circulating Current Suppression for Multi-Parallel Cascaded H-Bridge Power Supplies. Transactions of China Electrotechnical Society, 2023, 38(16): 4376-4390.
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