基于子模块瞬时功率跟随模块化多电平矩阵变换器控制策略

Control Strategy for Modular Multilevel Matrix Converters Based on Submodule Instantaneous Power Tracking

通过特殊矩阵结构下各桥臂级联子模块的瞬时功率特性分析,提出了一种基于子模块瞬时功率跟随的三相六桥臂模块化多电平矩阵变换器控制策略。桥臂间电容电压均衡控制环采用电容电压直流量偏差值及差频纹波的混合反馈,实时跟随瞬时功率幅值包络线注入高频共模电流,经由同一闭环实现二者的整体控制,可解决桥臂间无功分配差异和差频电压波动对变换器应用范围的限制;在单一环流路径约束下,叠加输出频率环流调节桥臂间非零序有功偏差,叠加输入频率环流调节相间平衡,环流闭环合成方式不影响控制独立性且易于实现。桥臂电流控制环可实现交流两侧端口电流及内部环流的解耦控制,无需复杂的矢量变换。最后通过不同工况实验验证了该方法的有效性。

By an instantaneous power characteristics analysis of cascaded sub-modules of each arm in the special matrix topology,a control strategy for novel modular multilevel matrix converters based on submodule instantaneous power tracking is proposed.The capacitor voltage DC deviation and differential-frequency voltage ripple mixed is fed back direct and controlled as a whole in the balancing control loop between arms,the high frequency circulation being injected by tracking the instantaneous power amplitude envelope to solve converters＇ application range restriction from reactive power distribution and too high a differential-frequency voltage ripple.Under the constraint of a single circulation path,the output-frequency circulation superimposed adjusts the nonzero sequence active power deviation between arms,while realizing interphase balancing control by the input-frequency circulation.The mode of circulation synthesis does not affect control independence and is easy to carry out.The arm current loop can realize the decoupling control of both AC-side current and internal circulation without complicated vector transformation.Finally,the effectiveness of the proposed control scheme under different working conditions is verified by experimental results.