基于SVPWM过调制策略的SRG风力发电系统并网逆变器

Grid-connected inverter of SRG wind power system based on SVPWM over-modulation scheme

以四相8/6极开关磁阻发电机(SRG)为例,介绍了SRG工作原理以及实际工作中的饱和非线性,以傅里叶级数为工具建立非线性数学模型,并针对SRG发电系统的应用场合,采用了一种基于基波电压幅值线性输出控制的SVPWM过调制算法:在过调制区域内,引入幅值系数的概念,基于幅值系数和空间矢量图的顶点电压矢量,计算逆变器输出电压矢量与参考电压矢量的关系,并进一步推导出过调制区的基本电压矢量作用时间。该算法能有效解决对于SRG小功率发电系统,多电平逆变技术不适用,传统的两电平SVPWM算法控制精度又不够理想的问题。在Matlab平台进行仿真,结果表明,基于SVPWM过调制算法的逆变电路能将SRG的输出电能回馈电网,在动、静态环境中均能得到理想的输出电能质量。

The four-phase SRG（Switched Reluctance Generator） with 8 stator poles ＆ 6 rotor poles is taken as an example for introducing the operating principle and actual nonlinearity of SRG. Its nonlinear mathe- matical model is established with Fourier series tool. As the multi-level inverter technology is not suitable for SRG generation system and the control precision of two-level SVPWM is not perfect ,a SVPWM over -modulation control algorithm based on fundamental vohage amplitude linear output control is presented：the amplitude modulation index is introduced to over-modulation area;based on the index and the vertex voltage vector of space vector chart,the relationship between inverter output voltage vector and reference voltage vector is calculated;and the turn-on time of the effective vector of over-modulation area is then derived. Results of simulation with Matlab show that,the inverter based on SVPWM over-modulation control algorithm feeds the SRG output energy back to grid,achieving perfect electric energy quality in both dynamic and static conditions.