In medium voltage-high power(MV-HP)applications,the high switching frequency of power converter will result in unnecessary energy losses,which directly affect efficiency.To resolve this issue,a novel finite control se...In medium voltage-high power(MV-HP)applications,the high switching frequency of power converter will result in unnecessary energy losses,which directly affect efficiency.To resolve this issue,a novel finite control set-model predictive control(FCS-MPC)with low switching frequency for three-level neutral point clamped-active front-end converters(NPC-AFEs)is proposed.With this approach,the prediction model of three-level NPC-AFEs is established inα-βreference frame,and the control objective of low average switching frequency is introduced into a cost function.The proposed method not only achieves the desired control performance under low switching frequency,but also performs the efficient operation for the three-level NPC-AFEs.The simulation results are provided to verify the effectiveness of proposed control scheme.展开更多
This paper presents a novel and efficient control scheme for unified power quality conditioner （UPQC） based on three-level neutral point clamped （NPC） inverter using fuzzy logic techniques. The proposed UPQC is ca...This paper presents a novel and efficient control scheme for unified power quality conditioner （UPQC） based on three-level neutral point clamped （NPC） inverter using fuzzy logic techniques. The proposed UPQC is capable of mitigating source current harmonics and compensate all voltage disturbances such as voltage sags, swells, unbalances and harmonics. It is designed by the integration of series and shunt active filters （AFs） sharing a common DC bus capacitor. The DC voltage is maintained constant using proportional integral voltage controller. The synchronous reference frame （SRF） theory is used to get the reference signals for shunt active power filters （APFs） and the power reactive theory （p-q theory） for series APFs. The shunt and series APF reference signals derived from the control algorithm and sensed signals are injected in two controllers to generate switching signals. To improve the UPQC capability, fuzzy logic techniques are introduced to control the series APF. The performances of the proposed UPQC system are evaluated in terms of power factor correction, mitigation of voltage or current harmonics and all other voltage disturbances compensation using Matlab-Simulink software and SimPowerSystem toolbox. The simulation results illustrate the performance of the proposed UPQC at the common connection point of the nonlinear load to improve the power energy quality.展开更多
To improve the quality and efficiency of peanut half-feed harvesting in clay hilly areas in South China and address problems such as excessive soil clumps,broken branches,and seedlings in pods,difficulty in cleaning i...To improve the quality and efficiency of peanut half-feed harvesting in clay hilly areas in South China and address problems such as excessive soil clumps,broken branches,and seedlings in pods,difficulty in cleaning impurities,and the need for manual picking owing to the high soil viscosity and easy hardening,a new half-feed peanut cleaning picker suitable for southern clay hilly areas,including its overall structure and transmission system,was designed.The picker can perform the operations of soil removal,clamping and conveying of seedlings,and orderly pod picking and pod gathering.The structural design of key components and the analysis and determination of key parameters were carried out.By adopting a crank rocker mechanism,a soil removal device was designed.A single-side chain clamping conveying device,which consists of a clamping chain,a pretightening spring,and a guide rail,was designed.A phase tangent configuration of opposite rollers was used to design a pod picking device.Thus,the functions of the half-feed peanut picker,such as cleaning and removing soil,smooth and reliable clamping and conveying,and flexible pod picking,were realized.The field test revealed that when the picking rate was greater than 97%,the soil removal pods drop rate was less than 10%,and the soil removal rate was greater than 50%.The performance indicators meet the design requirements.This study provides a technical reference for the research and development of clean picking technology for upright peanuts in the clay hilly areas of southern China.展开更多
文摘In medium voltage-high power(MV-HP)applications,the high switching frequency of power converter will result in unnecessary energy losses,which directly affect efficiency.To resolve this issue,a novel finite control set-model predictive control(FCS-MPC)with low switching frequency for three-level neutral point clamped-active front-end converters(NPC-AFEs)is proposed.With this approach,the prediction model of three-level NPC-AFEs is established inα-βreference frame,and the control objective of low average switching frequency is introduced into a cost function.The proposed method not only achieves the desired control performance under low switching frequency,but also performs the efficient operation for the three-level NPC-AFEs.The simulation results are provided to verify the effectiveness of proposed control scheme.
文摘This paper presents a novel and efficient control scheme for unified power quality conditioner （UPQC） based on three-level neutral point clamped （NPC） inverter using fuzzy logic techniques. The proposed UPQC is capable of mitigating source current harmonics and compensate all voltage disturbances such as voltage sags, swells, unbalances and harmonics. It is designed by the integration of series and shunt active filters （AFs） sharing a common DC bus capacitor. The DC voltage is maintained constant using proportional integral voltage controller. The synchronous reference frame （SRF） theory is used to get the reference signals for shunt active power filters （APFs） and the power reactive theory （p-q theory） for series APFs. The shunt and series APF reference signals derived from the control algorithm and sensed signals are injected in two controllers to generate switching signals. To improve the UPQC capability, fuzzy logic techniques are introduced to control the series APF. The performances of the proposed UPQC system are evaluated in terms of power factor correction, mitigation of voltage or current harmonics and all other voltage disturbances compensation using Matlab-Simulink software and SimPowerSystem toolbox. The simulation results illustrate the performance of the proposed UPQC at the common connection point of the nonlinear load to improve the power energy quality.
基金financially supported by National Natural Science Foundation of China(Grant No.52105263)Jiangsu Agricultural Science and Technology Innovation Fund(Grant No.CX(23)3028)+2 种基金Key Laboratory of Modern Agricultural Intelligent Equipment in South China,Ministry of Agriculture and Rural Affairs,China(Grant No.HNZJ202201)Key Laboratory of Agricultural Equipment for Hilly and Mountainous Areas in Southeastern China(Co-construction by Ministry and Province)Ministry of Agriculture and Rural Affairs(Grant No.QSKF202304).
文摘To improve the quality and efficiency of peanut half-feed harvesting in clay hilly areas in South China and address problems such as excessive soil clumps,broken branches,and seedlings in pods,difficulty in cleaning impurities,and the need for manual picking owing to the high soil viscosity and easy hardening,a new half-feed peanut cleaning picker suitable for southern clay hilly areas,including its overall structure and transmission system,was designed.The picker can perform the operations of soil removal,clamping and conveying of seedlings,and orderly pod picking and pod gathering.The structural design of key components and the analysis and determination of key parameters were carried out.By adopting a crank rocker mechanism,a soil removal device was designed.A single-side chain clamping conveying device,which consists of a clamping chain,a pretightening spring,and a guide rail,was designed.A phase tangent configuration of opposite rollers was used to design a pod picking device.Thus,the functions of the half-feed peanut picker,such as cleaning and removing soil,smooth and reliable clamping and conveying,and flexible pod picking,were realized.The field test revealed that when the picking rate was greater than 97%,the soil removal pods drop rate was less than 10%,and the soil removal rate was greater than 50%.The performance indicators meet the design requirements.This study provides a technical reference for the research and development of clean picking technology for upright peanuts in the clay hilly areas of southern China.
