不平衡负载下四桥臂逆变器双重准比例复数积分控制策略

Dual quasi-proportional complex integral control strategy of the four-leg inverter with unbalanced load

逆变器输出特性易受负载影响,负载不平衡时会导致逆变器三相输出电压不平衡。为了解决电压不平衡问题,提出了一种双重准比例复数积分(Dual quasi-proportional complex integral, DQPCI)控制器。此控制器不仅可将交流稳态误差控制在较小范围内,还可有效抑制电压不平衡分量。首先,基于αβ0静止坐标系下四桥臂逆变器的数学模型,分析了逆变器的控制原理及DQPCI控制器的控制特点。其次,根据准比例谐振控制器、准比例复数积分控制器及DQPCI控制器的数学模型及电路模型,对比分析了三者之间的异同点及工作性能。此外,采用伯德图分析了控制器各参数及负载对系统性能影响,并在空载条件下进行了参数设计及校验。最后利用PSCAD进行仿真,结果验证了所提出控制策略的正确性和有效性。

The output characteristics of the inverter are easily affected by the load, and unbalanced load will cause three-phase output voltages unbalance of the inverter. In order to solve the problem of voltage unbalance, the Dual Quasi-Proportional Complex Integral(DQPCI) controller is proposed in this paper. The DQPCI controller can not only control the steady-state error of the AC signal in a small range, but also effectively suppress voltage unbalance components. Firstly, based on the mathematical model of the four-leg inverter, the control principle of the inverter and working characteristics of the DQPCI controller are analyzed in αβ0 stationary frame. Secondly, based on the mathematical models and electric circuit models of the quasi-proportional resonant controller, quasi-proportional complex integral controller and dual quasi-proportional complex integral controller, the similarities and differences of working performances among the three controllers are compared and analyzed. In addition, the influences of controller parameters and the load on the system performance are analyzed by the bode diagrams, and the design and verification of the parameters are also carried out under no-load condition. Finally, simulative results with PSCAD verify the correctness and validity of the proposed control strategy.