电网电压不平衡条件下VIENNA整流器滑模控制策略

三相VIENNA整流器作为新型的三电平拓扑结构，因其功率密度高、电压应力小和实现单位功率因数运行等特点在大功率整流场合中运用广泛。针对电网不平衡时直流侧电压产生的二倍频波动，设计了一种在两相静止坐标系下的改进型不平衡控制策略。首先利用双同步坐标系的解耦软件锁相环实现电网电压正负序分量的分离，然后基于正负序双电流环独立控制结构将滑模控制SMC（sliding mode control）引入到电流控制器中，通过所设跟踪误差选取合适的滑模面及滑模趋近律，有效实现了直流电压纹波抑制以及输入电流谐波含量的最小化。最后在Matlab/Simulink软件中搭建了电网不平衡下VIENNA整流器控制系统的仿真模型，验证了所提控制策略的正确性和可行性。

Sliding Mode Control Strategy for VIENNA Rectifier under Unbalanced Grid Voltage Conditions

As a novel three-level topology, the three-phase VIENNA rectifier is widely applied in high-power rectification scenarios owing to its characteristics such as high power density, low voltage stress and unity power factor operation. Aimed at the double-frequency fluctuation generated by DC-link voltage when the grid is unbalanced, an improved unbalanced control strategy is designed under the two-phase stationary reference frame. First, the separation between the positive- and negative-sequence components of grid voltage is realized by means of the decoupled double synchronous reference frame PLL. Then, based on the positive- and negative-sequence dual-current loop independent control structure, sliding mode control(SMC) is introduced into the current controller. By selecting an appropriate sliding surface according to the set tracking error and the sliding mode approach law, the DC-link voltage ripple is suppressed and the input current harmonic component is minimized. Finally, a simulation model of VIENNA rectifier control system under unbalanced grid conditions is built in Matlab/Simulink, which verifies the correctness and feasibility of the proposed control strategy.