五电平逆变器直流侧电容电压的平衡与控制

DC bus voltage balancing and control in five-level inverters

多电平逆变器能产生多阶梯、低失真电压波形,特别适合于大功率高电压场合。而二极管箝位式多电平逆变器(DCMLI)因无需独立的直流电源来维持每级电压而备受人们青睐。然而,该逆变器存在直流侧电容电压的不平衡问题,因而还未能在有功功率变换中得到广泛应用。针对这一问题,本文提出一种电容电压动态平衡控制算法。该算法基于空间矢量脉宽调制法(SVPWM),通过选取合适的冗余开关状态,控制电容电流,从而达到控制电容电压的平衡目的。仿真验证了该算法的有效性。

Multilevel inverters that provide more than two voltage levels and less distorted waveform offer many benefits for higher power /or higher voltage applications. The Diode-Clamped Multilevel Inverter (DCMLI) does not require a separate dc power source to maintain each voltage level and has been attracting wide industrial interests recently. However, it suffers from problems such as DC bus voltage unbalance and is not widely used in active power transfer. A dynamic control algorithm based on Space Vector Pulse-width Modulation (SVPWM) methods and utilizing proper redundant switching states is described which balances the voltage across the DC Bus capacitors in 5-level DCMLI. Simulation results are used to verify the effectiveness of the control algorithm.