一种基于双矢量恒定开关频率的三电平ANPC型全桥逆变器模型预测控制方法

A Model Predictive Control Method of Three-level ANPC Type Full-bridge Inverter Based on Dual Vector Constant Switching Frequency

针对三电平有源中点箝位型(activeneutral-pointclamped,ANPC)全桥逆变器在使用有限集模型预测控制(finite control set mode predictive control,FCS-MPC)方法时,存在开关频率不固定、电流谐波大、多目标优化复杂、对处理器运算效率要求高等问题,该文首先提出一种双矢量恒定开关频率FCS-MPC方法,该方法以逆变器输出电压矢量而非开关矢量为有限集进行模型预测,降低模型计算量;然后,通过代价函数寻优以确定最优和次优电压矢量,消除多目标优化问题;根据代价函数值计算矢量作用时间,并在下一控制周期中同时输出2种电压矢量,实现恒定开关频率,降低输出电流谐波;再次,推导基于不同变量约束实现所提方法的原理;最后,该文提出基于比例积分控制器调整冗余矢量作用时间来实现直流侧电容电压均衡控制的方法,此方法具有很快的调节速度。仿真和实验验证所提方法的良好性能。

For three-level active neutral-point-clamped(ANPC)type full-bridge inverters,there are some problems in finite control set mode predictive control(FCS-MPC)method,such as unfixed switching frequency,large harmonics of current,complex multi-objective optimization problems and high requirements on computing efficiency of processor.Firstly,this paper proposed a multi-vector constant switching frequency FCS-MPC method.Model prediction was performed by taking the output voltage of inverter instead of switching vectors as the control set,reducing the amount of model calculations;determining the optimal and sub-optimal voltage vectors through cost function optimization,eliminating multi-objective optimization problems;calculating the vector duration according to cost-function value,and outputs two voltage vectors at the same time to achieve a constant switching frequency and reduce the output current harmonics.Then,the principle of implementing the method in this paper based on different variable constraints is derived.Finally,the redundant vector based on a proportional integral controller is proposed,for balancing the voltage of the DC side capacitor,which has a faster adjustment speed.Simulation and experiment contrast and analyze different FCS-MPC methods,verifying the good performance of the proposed method.