中点箝位型(neutral point clamped,NPC)三电平逆变器已被广泛应用,中点电位的平衡是其关键技术之一。首先建立基于零序电压注入的中点电位的数学模型,然后根据模型分析采用三种不同零序电压注入的计算方法。在实验室搭建三电平并网逆...中点箝位型(neutral point clamped,NPC)三电平逆变器已被广泛应用,中点电位的平衡是其关键技术之一。首先建立基于零序电压注入的中点电位的数学模型,然后根据模型分析采用三种不同零序电压注入的计算方法。在实验室搭建三电平并网逆变器实验样机,比较在不同功率因数下,3种不同零序电压注入方法的中点电位动稳态平衡能力。结果表明,3种方法均能很好地平衡中点电位。此外,在实际条件下,上下电容值常会不相等,因此有必要补充在上下电容值误差为12%条件下的实验。实验验证了3种不同零序电压注入方法在上下电容值误差较大时仍能很好地控制中点电位的平衡。展开更多
二极管中点箝位(neutral point clamped,NPC)型三电平换流器具有开关器件承受电压小、谐波特性好、冲击电压小等优点,但由于中点电流的存在,中点电位平衡成为该类型换流器固有的问题。从中点电流的角度分析了中点电位不平衡的原因,提出...二极管中点箝位(neutral point clamped,NPC)型三电平换流器具有开关器件承受电压小、谐波特性好、冲击电压小等优点,但由于中点电流的存在,中点电位平衡成为该类型换流器固有的问题。从中点电流的角度分析了中点电位不平衡的原因,提出了从直流偏差和交流波动两个方面对中点电位分别进行控制的思路,通过在参考电压中引入一个微小零序分量,很好地解决了中点电位的直流偏差问题,在换流器四象限运行时皆不会出现直流偏差,最后通过PSCAD/EMTDC仿真算例验证了该方法的有效性。展开更多
This paper presents a mathematical model of three-level voltage PWM rectifier,and derives a power control model from the theory of instantaneous power.In the vector-space,the influences on instantaneous power exercise...This paper presents a mathematical model of three-level voltage PWM rectifier,and derives a power control model from the theory of instantaneous power.In the vector-space,the influences on instantaneous power exercised by all the switching vectors are studied and illustrated separately,then a direct power control(DPC) scheme for three-level PWM rectifier which uses multistage band hysteresis comparator is proposed,and a novel switching table is designed.Meanwhile,the neutralpoint voltage unbalance is inhibited by selecting the redundancy switching states of small voltage vectors.Simulation and experimental results show that the proposed strategy can not only stabilize the DC bus voltage but also realize the unity power factor operation and the balance of neutral-point voltage.Moreover,the proposed method can improve the performance of the three-level rectifier.展开更多
文摘中点箝位型(neutral point clamped,NPC)三电平逆变器已被广泛应用,中点电位的平衡是其关键技术之一。首先建立基于零序电压注入的中点电位的数学模型,然后根据模型分析采用三种不同零序电压注入的计算方法。在实验室搭建三电平并网逆变器实验样机,比较在不同功率因数下,3种不同零序电压注入方法的中点电位动稳态平衡能力。结果表明,3种方法均能很好地平衡中点电位。此外,在实际条件下,上下电容值常会不相等,因此有必要补充在上下电容值误差为12%条件下的实验。实验验证了3种不同零序电压注入方法在上下电容值误差较大时仍能很好地控制中点电位的平衡。
文摘二极管中点箝位(neutral point clamped,NPC)型三电平换流器具有开关器件承受电压小、谐波特性好、冲击电压小等优点,但由于中点电流的存在,中点电位平衡成为该类型换流器固有的问题。从中点电流的角度分析了中点电位不平衡的原因,提出了从直流偏差和交流波动两个方面对中点电位分别进行控制的思路,通过在参考电压中引入一个微小零序分量,很好地解决了中点电位的直流偏差问题,在换流器四象限运行时皆不会出现直流偏差,最后通过PSCAD/EMTDC仿真算例验证了该方法的有效性。
基金supported by the Key Program of National Natural Science Foundation of China (Grant No. 51037004)the National Natural Science Foundation of China (Grant No. 51077097)the Key Technologies Research and Development Program of Tianjin (Grant No.11ZCKFGX03300)
文摘This paper presents a mathematical model of three-level voltage PWM rectifier,and derives a power control model from the theory of instantaneous power.In the vector-space,the influences on instantaneous power exercised by all the switching vectors are studied and illustrated separately,then a direct power control(DPC) scheme for three-level PWM rectifier which uses multistage band hysteresis comparator is proposed,and a novel switching table is designed.Meanwhile,the neutralpoint voltage unbalance is inhibited by selecting the redundancy switching states of small voltage vectors.Simulation and experimental results show that the proposed strategy can not only stabilize the DC bus voltage but also realize the unity power factor operation and the balance of neutral-point voltage.Moreover,the proposed method can improve the performance of the three-level rectifier.
