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针对二极管中点钳位型单相级联变换器直流侧电压不平衡问题，提出一种新型空间矢量脉宽调制(space vector pulse width modulation，SVPWM)策略。其核心为在冗余矢量选择时引入过渡开关状态，使当前矢量逐渐切换到均压能力最强的矢量，避免开关动作时模块端口电压发生越级跳变所带来的危害，降低了变换器的开关频率。文章分析了该调制策略的计算方法，给出最优路径选择步骤，并设计了基于可编程逻辑器件的 SVPWM 算法的控制核心。最后，通过级联两模块实验系统验证了所提调制策略的均压能力及系统的动静态性能。“,”An space vector pulse width modulation (SVPWM) modulation was proposed to solve the problem of DC voltage imbalance in the single-phase cascaded neutral-point-clamped H-bridge inverter. To avoid the harm of module port voltage level-skip, the transition states were introduced in the redundant vector selection, which made the current vector gradually switching to the vector with the strongest voltage balance ability, and reduced the switching frequency of the converter. The selection method of the optimal transition was given. Meanwhile, a digital SVPWM algorithm based on the programmable logic device was designed. Finally, the experimental results of two-cascade-module based prototype were presented to verify the voltage balance ability and the steady-state and dynamic performances of this modulation strategy.