新型五电平逆变器三维PWM控制

多电平逆变器已广泛应用于动态电能质量补偿，但因其电平增加，控制算法变得更为复杂。文中介绍了一种简单有效的新型控制算法——二层三维脉宽调制(3 Dimensional PWM)滞环控制算法。二层3DPWM滞环控制使控制算法大为简化，降低了对控制系统硬件和软件的要求，从而提高了系统的控制性能。很多三相四线制系统中中性线电流的补偿需要附加一桥臂分支来实现，使得原有的三桥臂逆变器变为四桥臂逆变系统，增加了系统的造价。利用三桥臂中线分开逆变器，可以减少四桥臂多电平逆变器中需要的绝缘栅双极晶体管(IGBT)的数量，降低成本，其补偿效果优于二电平或三电平的滞环算法。系统仿真结果表明，二层3DPWM滞环控制算法应用于五电平的控制是有效的和可行的。

A NOVEL 3-DIMENSIONAL PWM CONTROL FOR 5-LEVEL INVERTER

A novel PWM control method, which combined 3-dimension voltage vector PWM and Double-level Hysteresis method, is introduced into the 5-level inverter PWM system. In the 5-level inverters, the 5-level space vector PWM control method is one of the most popular methods. However, it needs many computational steps and it has to determine the corresponding space vector according to the complex algorithm. By the way, the hardware DSP's requirement is high too. The control of 5-level inverter is more complex than the 3-level one not only due to structure but also the complicated algorithm.The proposed algorithm simplifies the control algorithm in 5-level inverter and also has the common advantages of multi-level inverters. In 3-Phase 4-Wire System, there is the neutral line current. 4-Arms Inverters are needed and one arm of them is dedicated to compensating the zero-sequence current. However, three-dimensional PWM is a novel technique in handling 3-phase 4-wire system and was proposed in 2001. The conventional 3-Arms Inverter can be used in 3-Phase 4-Wire System when the 3DPWM control algorithm is used. The novel control algorithm is proposed with 3DPWM in 5-level 3-Phase 4-Wire Inverter. The mathematical model of 5-level inverter is described in detail. The shunt-connected 5-level power inverter in 3-phase 4-wire system as an active filter, which uses the 3-dimensional voltage vectors pulse width modulation technique, is illustrated. The simulation results demonstrate the validity of the proposed method.