近年来，在我国1140V电压等级下，具有自主知识产权的多电平逆变器产品日益增多，多电平逆变器在输出电压谐波含量、功率管耐压等方面相比于两电平逆变器优势明显，现已成为电力传动领域的研究热点。 本文对三电平逆变器的基本工作原理进行了阐述，对异步电机按转子磁链定向的矢量控制系统进行了研究。详细分析了异步电机动态数学模型，设计控制原理框图，对转子磁链幅值和空间角度的具体参数，采用间接磁场定向法进行分析。搭建了异步电机矢量控制系统仿真电路，在此基础上，对比分析了基于a-b 坐标系的空间矢量调制算法和简化60°坐标系的空间矢量调制算法，仿真结果表明异步电机矢量控制系统具有良好的性能。简化60°坐标系下的空间矢量调制算法，更易于实现数字控制。 对于二极管钳位型三电平逆变器，在运行过程中出现的电压不平衡现象，本文做了定性定量的分析，通过在小矢量对中引入分配因子对中点电位有效抑制，但该控制算法仍存在一定的电位波动问题，本文在此基础上进行了改进，加入电荷控制法，建立控制算法切换函数，实现了对中点电位在偏移和波动两方面有效控制。搭建中点电位平衡控制仿真平台，输出结果与理论相符。 在实验室环境下完成三电平逆变系统实验样机平台搭建，以DSP为核心控制单元，主要包括系统主电路、驱动电路、中点电位检测电路、电压电流采样电路等。测试了相关实验波形。实验结果进一步验证了所设计简化SVPWM算法及中点电位平衡控制策略的有效性与可行性。

Recent years, product of under the 1140V voltage multi-level inverter with independent intellectual property rights increasingly grow in China, the multi-level inverter’s advantage of less output voltage harmonic content, power tube pressure resistance and other aspects compared to two-level inverter is obvious, currently it has become a research hotspot in the field of power transmission. In this paper, described the basic working principle of three-level inverter and studied the vector control system of asynchronous motor oriented by rotor flux. The dynamic mathematical model of asynchronous motor is analyzed in detail, and designed the block diagram of control principle. the specific parameters of rotor flux amplitude and space angle are analyzed by indirect magnetic field orientation method. The simulation circuit of asynchronous motor vector control system is built. on this basis, the space vector modulation algorithm based on a~b coordinate system and the space vector modulation algorithm based on simplified 60° coordinate system are compared and analyzed. The simulation results show that the vector control system of asynchronous motor has good performance. The simplified space vector modulation algorithm in 60° coordinate system is easier to realize digital control. For the diode clamp three-level inverter, this paper makes a qualitative and quantitative analysis to the voltage imbalance in the course of operation, by introducing the distribution factor into the small vector pair to effectively suppress the Neutral-Point Potential offset problem, but there are still some potential fluctuations, this paper performed appropriate improvement on the basis, adding of charge control method, the switching function of the control algorithm is established so that the Neutral-Point Potential is effectively suppressed in terms of offset and fluctuation. The simulation platform of Neutral-Point Potential balance control is built, and the output results are consistent with the theory. The experimental prototype platform of the three-level inverter system is completed in the laboratory environment, and the DSP is the core control unit, which mainly includes themain circuit of the system, the driving circuit, the Neutral-Point Potential detection circuit, the voltage and current sampling circuit and so on. The relevant experimental waveforms were tested. The experimental results further verified the validity and feasibility of the designed simplified SVPWM algorithm and the Neutral-Point Potential balance control strategy.