农业工程学报
農業工程學報
농업공정학보
2013年
22期
189-195
,共7页
刘国海%钱鹏%陈兆岭%沈跃%廖志凌
劉國海%錢鵬%陳兆嶺%瀋躍%廖誌凌
류국해%전붕%진조령%침약%료지릉
拓扑%电压%设计%三电平逆变器%二极管箝位式%中点电压%平衡
拓撲%電壓%設計%三電平逆變器%二極管箝位式%中點電壓%平衡
탁복%전압%설계%삼전평역변기%이겁관겸위식%중점전압%평형
topology%voltage%design%three-level inverter%neutral point clamped%neutral-point voltage%balance
传统的二极管箝位式(NPC)三电平逆变器结构中,中点电压波动过大将导致输出电压的谐波总畸变率(total harmonic distortion,THD)增大及开关器件损坏,影响了该结构在农业机电中的应用。该文提出了一种带中点电压自平衡的NPC三电平逆变器拓扑结构,通过在传统NPC三电平逆变器结构中加入一套由单相全桥逆变电路组成的电压主动补偿装置,对三相桥臂中点电压的波动进行主动补偿。实时检测三相桥臂中点电压,与给定值比较后,控制补偿装置实时产生补偿电压。不需要坐标变换,控制方案简单。同时对系统的稳定性进行了理论分析。仿真结果表明提出的拓扑结构能够将三相桥臂中点电压的波动控制在3%以下,并且在负载突变时,仍然能快速的平衡中点电压的波动,具有良好的动态性能。
傳統的二極管箝位式(NPC)三電平逆變器結構中,中點電壓波動過大將導緻輸齣電壓的諧波總畸變率(total harmonic distortion,THD)增大及開關器件損壞,影響瞭該結構在農業機電中的應用。該文提齣瞭一種帶中點電壓自平衡的NPC三電平逆變器拓撲結構,通過在傳統NPC三電平逆變器結構中加入一套由單相全橋逆變電路組成的電壓主動補償裝置,對三相橋臂中點電壓的波動進行主動補償。實時檢測三相橋臂中點電壓,與給定值比較後,控製補償裝置實時產生補償電壓。不需要坐標變換,控製方案簡單。同時對繫統的穩定性進行瞭理論分析。倣真結果錶明提齣的拓撲結構能夠將三相橋臂中點電壓的波動控製在3%以下,併且在負載突變時,仍然能快速的平衡中點電壓的波動,具有良好的動態性能。
전통적이겁관겸위식(NPC)삼전평역변기결구중,중점전압파동과대장도치수출전압적해파총기변솔(total harmonic distortion,THD)증대급개관기건손배,영향료해결구재농업궤전중적응용。해문제출료일충대중점전압자평형적NPC삼전평역변기탁복결구,통과재전통NPC삼전평역변기결구중가입일투유단상전교역변전로조성적전압주동보상장치,대삼상교비중점전압적파동진행주동보상。실시검측삼상교비중점전압,여급정치비교후,공제보상장치실시산생보상전압。불수요좌표변환,공제방안간단。동시대계통적은정성진행료이론분석。방진결과표명제출적탁복결구능구장삼상교비중점전압적파동공제재3%이하,병차재부재돌변시,잉연능쾌속적평형중점전압적파동,구유량호적동태성능。
A NPC three-level inverter is suitable to be used in the field of high power, high voltage. A DC side neutral-point N and three-phase bridge arm neutral-point O of a traditional NPC three-level inverter were linked together. The voltage of the three-phase bridge arm neutral-point would fluctuate, because of the DC side neutral-point voltage fluctuation. It would influence the efficiency of the NPC three-level inverter’s work. The neutral-point voltage excessive fluctuation of the traditional neutral point clamped (NPC) three-level inverter would cause the total harmonic distortion (THD) of output voltage increase and switch devices damage. This problem limits its engineering applications in the field of agriculture. A NPC three-level inverter topology with a neutral-point voltage self-balancing function was proposed. It consisted of two parts. Part 1 was the traditional NPC three-level inverter. Part 2 was the active compensation voltage device, and was composed of a single-phase full-bridge inverter circuit, which was used to compensate for the voltage fluctuation of a three-phase bridge arm neutral-point in a traditional NPC three-level inverter. The active compensation voltage device is similar to a controllable voltage source. It was used in a series between point O and point N in a traditional NPC three-level inverter. The three-phase bridge arm neutral-point real-time voltage value was detected and compared with a given value. Then, a real-time compensation voltage was generated by the active compensation voltage device. The voltage of the three-phase bridge arm neutral-point was uo, the voltage of the DC side neutral-point was un, and the voltage of the DC side was us. The real-time compensation voltage was ub, o n bu =u ?u . When the neutral-point voltage of part 1 fluctuates excessively, the active compensation voltage device would generate a real-time compensation voltage to keep neutral-point voltage stability, o su =0.5u . Because coordinate transformation is not required, the control scheme is simple. Further, a theoretical analysis of the system stability was achieved. In order to verify the proposed control method, the system was simulated by using the “Power system Blockset”in the Matlab/Simulink environment. The parameters used for simulation are defined as follows:us=3000 V,udc=500 V, dc link capacitor, C=1000 uF, L=0.4 mH, the switching frequency of the NPC three-level inverter was 3kHz, and the switching frequency of the active compensation voltage device was 10 kHz. After the compensation, a voltage fluctuation value of the three-phase bridge arm neutral-point in the traditional NPC three-level inverter was limited under 3%. In addition, simulation results showed that the proposed topology has good dynamic performance. In conclusion, a NPC three-level inverter with a neutral-point voltage self-balancing function was proposed due to the problem of neutral-point voltage excessive fluctuation of a traditional neutral point clamped (NPC) three-level inverter. This structure consisted of an active compensation voltage device to eliminate the neutral-point voltage excessive fluctuation. Simulation results have shown that no matter how the load varies, the presented circuit structure can eliminate the three-phase bridge arm neutral-point voltage fluctuation effectively with quick response and good dynamic performance.