单相CHBR改进型无网压传感器直接功率控制

Improved grid voltage sensorless direct power control for single-phase CHBR

以降低单相级联H桥整流器(CHBR)系统硬件成本、改善控制系统性能为目的,提出一种改进型无网压传感器直接功率控制方法。首先,建立单相CHBR的数学模型,并通过混合逻辑动态方法估算出网侧输入电压。针对已有虚拟磁链观测器存在的缺点,提出改进型的虚拟磁链观测器,并给出详细的频域分析过程。所提观测器可以有效地解决幅、值相位误差和直流偏置问题,并且能够有效地抑制谐波。此外,提出一种基于比例积分(PI)控制器的CHBR改进型直接功率控制(DPC)方法。相较于传统DPC方法,改进型DPC取消了旋转坐标变换,不需要网压相位信息,改善了系统动态响应速度。最后,在实验样机上对已有的虚拟磁链观测器方法、直接功率控制方法以及所提改进型控制方法展开对比实验研究,结果验证了所提方法的可行性和有效性。

To reduce the hardware cost of the single-phase cascaded H-bridge rectifier(CHBR)system and optimize the performance of control system,an improved grid voltage sensorless direct power control method was proposed.Firstly,the mathematical model of CHBR was established,and the input voltage on the grid side was estimated by the mixed logic dynamic method.Considering the shortcomings of existing virtual flux observer,an improved virtual flux observer was proposed,and the detailed frequency domain analysis process was given.The proposed observer can effectively solve the problems of amplitude and phase errors,DC offset and harmonics suppression.In addition,a CHBR modified direct power control(DPC)method based on proportional-integral(PI)controller was proposed.Compared with the traditional DPC method,the modified DPC method eliminates the rotation coordinate transformation,does not need the grid voltage phase information,and improves the system dynamic response speed.Finally,the existing virtual flux observer method,the direct power control method and the proposed control method were compared and studied on the experimental prototype.The results demonstrate feasibility and effectiveness of the proposed method.