电机与控制学报
電機與控製學報
전궤여공제학보
Electric Machines and Control
2015年
9期
61-66
,共6页
袁庆庆%伍小杰%戴鹏%夏鲲
袁慶慶%伍小傑%戴鵬%夏鯤
원경경%오소걸%대붕%하곤
三电平%低开关频率%中点电位%分段调制分界点%桥臂优化选取
三電平%低開關頻率%中點電位%分段調製分界點%橋臂優化選取
삼전평%저개관빈솔%중점전위%분단조제분계점%교비우화선취
three-level%low switching frequency%neutral point potential%demarcation point of subsection modulation%optimal selection of sub-bridges
为减少大功率变换器功耗,需降低器件开关频率,但将造成输出侧电流谐波含量显著增加,影响三电平逆变器中点电位控制精度. 为解决这一问题,以二极管箝位型三电平逆变器为对象,在分析低开关频率对中点电位影响的基础上,明确了三电平逆变器低开关频率分段调制的理论分界点. 针对低调制度区域所采用的常规SVPWM算法,提出了一种基于桥臂优化选取的中点电位控制方法,该方法只需判断中点电位差,无需引入输出侧电流,从而避免了低开关频率下电流畸变严重对电流极性的影响,有效保证了中点电位平衡. 仿真及实验验证了该中点控制方案在开关频率500 Hz时,仍能保持较好的中点电位误差在1%Vdc之内.
為減少大功率變換器功耗,需降低器件開關頻率,但將造成輸齣側電流諧波含量顯著增加,影響三電平逆變器中點電位控製精度. 為解決這一問題,以二極管箝位型三電平逆變器為對象,在分析低開關頻率對中點電位影響的基礎上,明確瞭三電平逆變器低開關頻率分段調製的理論分界點. 針對低調製度區域所採用的常規SVPWM算法,提齣瞭一種基于橋臂優化選取的中點電位控製方法,該方法隻需判斷中點電位差,無需引入輸齣側電流,從而避免瞭低開關頻率下電流畸變嚴重對電流極性的影響,有效保證瞭中點電位平衡. 倣真及實驗驗證瞭該中點控製方案在開關頻率500 Hz時,仍能保持較好的中點電位誤差在1%Vdc之內.
위감소대공솔변환기공모,수강저기건개관빈솔,단장조성수출측전류해파함량현저증가,영향삼전평역변기중점전위공제정도. 위해결저일문제,이이겁관겸위형삼전평역변기위대상,재분석저개관빈솔대중점전위영향적기출상,명학료삼전평역변기저개관빈솔분단조제적이론분계점. 침대저조제도구역소채용적상규SVPWM산법,제출료일충기우교비우화선취적중점전위공제방법,해방법지수판단중점전위차,무수인입수출측전류,종이피면료저개관빈솔하전류기변엄중대전류겁성적영향,유효보증료중점전위평형. 방진급실험험증료해중점공제방안재개관빈솔500 Hz시,잉능보지교호적중점전위오차재1%Vdc지내.
The switching frequency of the three-level inverters is usually kept low to reduce the dynamic losses of the high-power inverters and which results in an increase in the harmonic components of the out-put current, and affects the control difficulties of the neutral point potential. According to these prob-lems, the influence on the neutral point potential by the output current was analyzed, as well as the first proposing of the demarcation point for the subsection modulation. For low modulation index, the normal pulse width modulation would be more appropriate. A novel approach controlling the neutral point poten-tial for the low modulation index was proposed based on the optimal selection of the sub-bridges. This new method doesn' t need the output current as a feedback signal, which avoids the affect from the severe distortion of the output current at low switching frequency. Experimental results verify that method can maintain the neutral point potential balancing with the switching frequency as low as 500Hz.