风机驱动电动机由于工作环境和频繁启停的工作要求,常由变频器控制,其运行中谐波含量大,发热严重。为研究其温升分布规律,以一台4 500 k W电动机为例,基于电磁学及传热学理论,建立三维半域通风冷却物理模型。应用有限元法,对额定工况下...风机驱动电动机由于工作环境和频繁启停的工作要求,常由变频器控制,其运行中谐波含量大,发热严重。为研究其温升分布规律,以一台4 500 k W电动机为例,基于电磁学及传热学理论,建立三维半域通风冷却物理模型。应用有限元法,对额定工况下电动机内电磁场进行仿真计算,把非均布的损耗分布以热源形式映射到温度场中,通过电磁场与温度场双向耦合,准确计算电动机各部分的温升分布。此外,为更具对比性,对同种工况下体积均布热源的方法进行仿真计算,通过与试验结果的对比分析,验证双向耦合的方法较均布热源的方法更接近真实值,表明双向耦合的方法更具科学性。展开更多
针对舰用风机电动机的特点和运行要求,研制了一台10 k W风机电动机样机,试验结果表明性能满足要求,尤其振动噪声远低于指标要求,验证了优化设计的可行性和正确性。该方案采取的减振降噪措施和分析方法对舰用辅机减振降噪设计有良好的指...针对舰用风机电动机的特点和运行要求,研制了一台10 k W风机电动机样机,试验结果表明性能满足要求,尤其振动噪声远低于指标要求,验证了优化设计的可行性和正确性。该方案采取的减振降噪措施和分析方法对舰用辅机减振降噪设计有良好的指导作用。展开更多
This serial research has proposed the hybrid power system combined the wind power unit with the counter-rotating type pump-turbine unit, to provide the constant output for the grid system, even at the suddenly fluctua...This serial research has proposed the hybrid power system combined the wind power unit with the counter-rotating type pump-turbine unit, to provide the constant output for the grid system, even at the suddenly fluctuating/turbulent wind circumstance. In this paper, the tandem impellers prepared for the counter-rotating type pumping unit were operated at the turbine mode, and the performances and the flow conditions were investigated numerically with accompanying the experimental results. Even though providing the pumping unit for the turbine mode, the maximum hydraulic efficiency is close to one of the counter-rotating type hydroelectric unit designed exclusively for the turbine mode. Besides, the runners/impellers of the unit work evidently so as to coincide the angular momentum change through the front runners/impellers with that through the rear runners/impellers, namely to take the axial flow at not only the inlet but also the outlet, without the guide vanes. From these results, it can be concluded that this type unit is effective to work at not only the pumping but also the turbine modes.展开更多
This paper presents an electronic VSD （variable speed drive） for three-phase IM （induction motor） using a microcontroller. The VSD is designed for cooling applications where the 1M is coupled to a cooling fan. The...This paper presents an electronic VSD （variable speed drive） for three-phase IM （induction motor） using a microcontroller. The VSD is designed for cooling applications where the 1M is coupled to a cooling fan. The drive receives temperature feedback from objects to be cooled and output a corresponding frequency to the IM. A prototype of the VSD is constructed to control a 175 W, four pole, squirrel cage three-phase IM. The heart of the control circuit is a low-cost microchip＇s PICI6F777 microcontroller which is programmed using C language to generate variable frequency SPWM （sinusoidal pulse width modulation） switching signals. These switching signals are fed to an 1GBT inverter. The VSD constructed can be switched between two modes of speed control＂ automatic temperature-controlled mode and manual user-controlled mode. Cost savings using the prototype are demonstrated.展开更多
This paper describes a small wind turbine generation system with SynRG （synchronous reluctance generator）. SynRGs are robust and inexpensive. In addition, SynRG has no cogging torque. Hence, wind turbine generation ...This paper describes a small wind turbine generation system with SynRG （synchronous reluctance generator）. SynRGs are robust and inexpensive. In addition, SynRG has no cogging torque. Hence, wind turbine generation system with SynRG can achieve smooth start at low wind velocity. The rotor design of proposed SynRG is multi flux barrier type. With FEA （finite element analysis） software, the characteristics of SynRG are brought out, and the performance of wind turbine generation system with SynRG including copper loss and iron loss is simulated by FEA coupled with the motion equation of the wind turbine generation system under the maximum power point tracking control. In this paper, the constant wind test and the quasi-natural wind test are conducted. In conclusion, the results of these simulations indicate that the wind turbine generation system with SynRG has good performance, especially in starting phenomena.展开更多
This paper has attempted to study a mechanism of three-dimensional flow around a horizontal axis wind turbine(HAWT) rotor blade. An experimental study of the flow phenomenon in the vicinity of the wind turbine blade i...This paper has attempted to study a mechanism of three-dimensional flow around a horizontal axis wind turbine(HAWT) rotor blade. An experimental study of the flow phenomenon in the vicinity of the wind turbine blade is a challenging endeavor. In this research, the HAWT model with 2.4 m diameter was tested in the large wind tunnel. The flow around the rotating blade surface was measured simultaneously for three velocity components, and two probes were used for the synchronized measurement of three-dimensional flow components. The local velocity was detected for the single seeding particle measured in the point where three pairs of laser beams intersected. Blade sections of interest in this study are composed of radial positions r/R = 0.3, 0.5 and 0.7. Optimum and low tip speed ratio flow characteristics were also compared. The velocity flow vector, skin friction coefficient and bound circulation were calculated from LDV measurements, and the experimental research showed reasonably and clearly the experimental results.展开更多
文摘风机驱动电动机由于工作环境和频繁启停的工作要求,常由变频器控制,其运行中谐波含量大,发热严重。为研究其温升分布规律,以一台4 500 k W电动机为例,基于电磁学及传热学理论,建立三维半域通风冷却物理模型。应用有限元法,对额定工况下电动机内电磁场进行仿真计算,把非均布的损耗分布以热源形式映射到温度场中,通过电磁场与温度场双向耦合,准确计算电动机各部分的温升分布。此外,为更具对比性,对同种工况下体积均布热源的方法进行仿真计算,通过与试验结果的对比分析,验证双向耦合的方法较均布热源的方法更接近真实值,表明双向耦合的方法更具科学性。
文摘This serial research has proposed the hybrid power system combined the wind power unit with the counter-rotating type pump-turbine unit, to provide the constant output for the grid system, even at the suddenly fluctuating/turbulent wind circumstance. In this paper, the tandem impellers prepared for the counter-rotating type pumping unit were operated at the turbine mode, and the performances and the flow conditions were investigated numerically with accompanying the experimental results. Even though providing the pumping unit for the turbine mode, the maximum hydraulic efficiency is close to one of the counter-rotating type hydroelectric unit designed exclusively for the turbine mode. Besides, the runners/impellers of the unit work evidently so as to coincide the angular momentum change through the front runners/impellers with that through the rear runners/impellers, namely to take the axial flow at not only the inlet but also the outlet, without the guide vanes. From these results, it can be concluded that this type unit is effective to work at not only the pumping but also the turbine modes.
文摘This paper presents an electronic VSD （variable speed drive） for three-phase IM （induction motor） using a microcontroller. The VSD is designed for cooling applications where the 1M is coupled to a cooling fan. The drive receives temperature feedback from objects to be cooled and output a corresponding frequency to the IM. A prototype of the VSD is constructed to control a 175 W, four pole, squirrel cage three-phase IM. The heart of the control circuit is a low-cost microchip＇s PICI6F777 microcontroller which is programmed using C language to generate variable frequency SPWM （sinusoidal pulse width modulation） switching signals. These switching signals are fed to an 1GBT inverter. The VSD constructed can be switched between two modes of speed control＂ automatic temperature-controlled mode and manual user-controlled mode. Cost savings using the prototype are demonstrated.
文摘This paper describes a small wind turbine generation system with SynRG （synchronous reluctance generator）. SynRGs are robust and inexpensive. In addition, SynRG has no cogging torque. Hence, wind turbine generation system with SynRG can achieve smooth start at low wind velocity. The rotor design of proposed SynRG is multi flux barrier type. With FEA （finite element analysis） software, the characteristics of SynRG are brought out, and the performance of wind turbine generation system with SynRG including copper loss and iron loss is simulated by FEA coupled with the motion equation of the wind turbine generation system under the maximum power point tracking control. In this paper, the constant wind test and the quasi-natural wind test are conducted. In conclusion, the results of these simulations indicate that the wind turbine generation system with SynRG has good performance, especially in starting phenomena.
文摘This paper has attempted to study a mechanism of three-dimensional flow around a horizontal axis wind turbine(HAWT) rotor blade. An experimental study of the flow phenomenon in the vicinity of the wind turbine blade is a challenging endeavor. In this research, the HAWT model with 2.4 m diameter was tested in the large wind tunnel. The flow around the rotating blade surface was measured simultaneously for three velocity components, and two probes were used for the synchronized measurement of three-dimensional flow components. The local velocity was detected for the single seeding particle measured in the point where three pairs of laser beams intersected. Blade sections of interest in this study are composed of radial positions r/R = 0.3, 0.5 and 0.7. Optimum and low tip speed ratio flow characteristics were also compared. The velocity flow vector, skin friction coefficient and bound circulation were calculated from LDV measurements, and the experimental research showed reasonably and clearly the experimental results.
