To improve the accuracy of the stator winding fault diagnosis in induction motor,a new diagnostic method based on the Hilbert-Huang transform(HHT)was proposed.The ratio of fundamental zero sequence voltage to positive...To improve the accuracy of the stator winding fault diagnosis in induction motor,a new diagnostic method based on the Hilbert-Huang transform(HHT)was proposed.The ratio of fundamental zero sequence voltage to positive sequence voltage after switch-off was selected as the stator fault characteristic,which could effectively avoid the influence of the supply unbalance and the load fluctuation,and directly represent the asymmetry in the stator.Using the empirical mode decomposition(EMD)based on HHT,the zero sequence voltage after switch-off was decomposed and the fundamental component was extracted.Then,the fault characteristic can be acquired.Experimental results on a 4-kW induction motor demonstrate the feasibility and effectiveness of this method.展开更多
The way of neutral point to earth via full compensation arc suppression coil can solve the problem of residual current compensation in coal mine power network effectively. Based on the analysis on the grounding curren...The way of neutral point to earth via full compensation arc suppression coil can solve the problem of residual current compensation in coal mine power network effectively. Based on the analysis on the grounding current detection results of Xieqiao coal mine, the conclusion that harmonic component of grounding current is dominated by higher harmonics with complex harmonic sources in coal mine power network system was obtained. The influences of harmonic source type and fault point position on harmonic voltage and harmonic current were analyzed theoretically. The influences of earthed fault feeder detection result and the estimation errors of parameters to earth on residual current compensation were analyzed. A new thought of residual current prediction and the selections of model method and control method were proposed on this basis. The simulation results prove that harmonic amplitudes of zero sequence voltage and zero sequence current are determined by harmonic source type as well as fault point position in coal mine power network, and also prove that zero sequence voltage detection can avoid the unstable problem of coal mine power network system caused by undercompensation of capacitive current. Finally, the experimental device of full compensation arc suppression coil is introduced.展开更多
Dual inverter fed open end winding induction motor(IM)drive offers many advantages over other multilevel inverter fed IM drives.Pulse width modulation(PWM)techniques are employed for the control of output voltage and ...Dual inverter fed open end winding induction motor(IM)drive offers many advantages over other multilevel inverter fed IM drives.Pulse width modulation(PWM)techniques are employed for the control of output voltage and frequency.Space vector base PWM techniques are popular among all the PWM techniques.A simplified space vector PWM method with simple and small look-up table approach is presented for dual inverter configuration.Moreover the proposed space vector based PWM technique provides freedom in selecting the center voltage vector(CVV)by which different PWM techniques will be derived.The implementation of all these PWM techniques is generalized by using a constant ao.The derived PWM techniques show superior performance in reducing the zero sequence voltage(ZSV)by maintaining the same quality of output voltage.The performance of all these PWM techniques are evaluated theoretically and verified in real time through dSPACE 1104 control board.展开更多
基金Project (No. 50677060) supported by the National Natural ScienceFoundation of China
文摘To improve the accuracy of the stator winding fault diagnosis in induction motor,a new diagnostic method based on the Hilbert-Huang transform(HHT)was proposed.The ratio of fundamental zero sequence voltage to positive sequence voltage after switch-off was selected as the stator fault characteristic,which could effectively avoid the influence of the supply unbalance and the load fluctuation,and directly represent the asymmetry in the stator.Using the empirical mode decomposition(EMD)based on HHT,the zero sequence voltage after switch-off was decomposed and the fundamental component was extracted.Then,the fault characteristic can be acquired.Experimental results on a 4-kW induction motor demonstrate the feasibility and effectiveness of this method.
基金The financial support from the National Natural Science Foundation of China (No. 51107143)
文摘The way of neutral point to earth via full compensation arc suppression coil can solve the problem of residual current compensation in coal mine power network effectively. Based on the analysis on the grounding current detection results of Xieqiao coal mine, the conclusion that harmonic component of grounding current is dominated by higher harmonics with complex harmonic sources in coal mine power network system was obtained. The influences of harmonic source type and fault point position on harmonic voltage and harmonic current were analyzed theoretically. The influences of earthed fault feeder detection result and the estimation errors of parameters to earth on residual current compensation were analyzed. A new thought of residual current prediction and the selections of model method and control method were proposed on this basis. The simulation results prove that harmonic amplitudes of zero sequence voltage and zero sequence current are determined by harmonic source type as well as fault point position in coal mine power network, and also prove that zero sequence voltage detection can avoid the unstable problem of coal mine power network system caused by undercompensation of capacitive current. Finally, the experimental device of full compensation arc suppression coil is introduced.
文摘Dual inverter fed open end winding induction motor(IM)drive offers many advantages over other multilevel inverter fed IM drives.Pulse width modulation(PWM)techniques are employed for the control of output voltage and frequency.Space vector base PWM techniques are popular among all the PWM techniques.A simplified space vector PWM method with simple and small look-up table approach is presented for dual inverter configuration.Moreover the proposed space vector based PWM technique provides freedom in selecting the center voltage vector(CVV)by which different PWM techniques will be derived.The implementation of all these PWM techniques is generalized by using a constant ao.The derived PWM techniques show superior performance in reducing the zero sequence voltage(ZSV)by maintaining the same quality of output voltage.The performance of all these PWM techniques are evaluated theoretically and verified in real time through dSPACE 1104 control board.
