【作者】 李飞；

【导师】 游国栋； 朱德涛；

【作者基本信息】 天津科技大学 ， 控制工程（专业学位）， 2022， 硕士

【摘要】 NPC型三电平逆变器作为目前应用比较广泛的逆变器类型之一,中点电压不平衡和共模电压幅值高的问题关系到了逆变器的性能及实际应用。中点电压不平衡是该类型逆变器固有的问题,其直接影响到了逆变器的输出电压波形的质量以及器件的寿命等;共模电压虽然不会对逆变器的性能产生明显的影响,但是高的共模电压会对周围的操作人员以及设备造成危害还会降低逆变器的稳定性等。这两个问题如果不加以控制,会给逆变器的运行产生很大的影响,甚至会阻碍逆变器向前发展和广泛应用。针对NPC型三电平逆变器的发展现状,结合中点电压平衡和共模电压抑制的控制需求,本文通过对传统的虚拟空间矢量调制方法进行改进,设计了IVSVPWM方法,并引入基于遗传粒子群算法的闭环控制,有效实现了中点电压平衡以及抑制共模电压幅值的效果。首先,本文以NPC型三电平逆变器为研究目标,详细分析了其拓扑结构、工作原理以及动态换相原理,并对其进行基于空间矢量的数学模型的建立,详细分析该类型逆变器产生中点电压不平衡、共模电压幅值高问题的原因及危害。其次,详细研究推算传统的空间矢量调制方法以及虚拟矢量调制方法的实现过程,针对传统方法在90°坐标系下存在大量三角函数运算问题,又引入了60°坐标系,利用坐标变换、矢量的标幺化来大大的简化算法的运算量;针对传统的虚拟矢量调制方法共模电压幅值高的问题,定义新的虚拟矢量,实现了NPC三电平逆变器中点电压平衡的同时又降低了共模电压幅值。然后,针对NPC逆变器在实际运行中因为一些原因而可能会出现的中点电压波动问题,又引入动态调节参数,并引入基于GA-PSO的闭环控制策略,实现了对中点电压的实时调节。最后在Matlab/Simulink中搭建仿真模型,对传统的VSVPWM方法以及本文设计的IVSVPWM方法以及引入基于GA-PSO的闭环控制策略之后的方法进行仿真,结果表明本文设计的方法具有更好的中点电压平衡以及共模电压抑制效果,证明了本文设计方法的有效性。更多还原

【Abstract】 The NPC three-level inverter is one of the most widely used inverter types.The problems of unbalanced midpoint voltage and high common-mode voltage amplitude are related to the performance and practical application of the inverter.The midpoint voltage imbalance is an inherent problem of this type of inverter,which directly affects the quality of the output voltage waveform of the inverter and the life of the device;although the common mode voltage does not have a significant impact on the performance of the inverter,but the high common-mode voltage will cause harm to the surrounding operators and equipment,and also reduce the stability of the inverter.If these two problems are not controlled,it will have a great impact on the operation of the inverter,and even hinder the development and wide application of the inverter.In view of the development status of NPC three-level inverters,combined with the control requirements of midpoint voltage balance and common-mode voltage suppression,this paper proposes an IVSVPWM method by improving the traditional virtual space vector modulation method,and introduces a method based on genetic particles.The closed-loop control of the group algorithm effectively realizes the midpoint voltage balance and the effect of suppressing the common mode voltage amplitude.First of all,this paper takes the NPC type three-level inverter as the research goal,analyzes its topology,working principle and dynamic commutation principle in detail,and establishes a mathematical model based on space vector,and analyzes this type of inverter in detail.The causes and hazards of the problem of unbalanced midpoint voltage and high common-mode voltage amplitude.Secondly,the implementation process of the traditional space vector modulation method and the virtual vector modulation method is studied in detail.In view of the large number of trigonometric function operations in the90°coordinate system of the traditional method,the60°coordinate system is introduced,and the coordinate transformation and the per-unitization of the vector are used to calculate the The computational complexity of the algorithm is greatly simplified;Aiming at the problem of high common-mode voltage amplitude in the traditional virtual vector modulation method,a new virtual vector is defined,which realizes the balance of the midpoint voltage of the NPC three-level inverter and reduces the common-mode voltage amplitude.Then,in view of the midpoint voltage fluctuation problem that may occur in the actual operation of the NPC inverter due to some reasons,dynamic adjustment parameters are introduced,and a closed-loop control strategy based on GA-PSO is introduced to realize the real-time monitoring of the midpoint voltage.Finally,a simulation model is built in Matlab/Simulink to simulate the traditional VSVPWM method,the IVSVPWM method proposed in this paper,and the method after introducing the closed-loop control strategy based on GA-PSO.The results show that the method proposed in this paper has better midpoint voltage Balance and common-mode voltage suppression effects prove the effectiveness of the method proposed in this paper.更多还原