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
Electrical pole-changing technology leads to torque ripple and speed fluctuation despite broadening the constant power speed range of the multiphase induction machine （IM） system. To reduce the torque ripple and spe...Electrical pole-changing technology leads to torque ripple and speed fluctuation despite broadening the constant power speed range of the multiphase induction machine （IM） system. To reduce the torque ripple and speed fluctuation of the machine, we investigate an exponential response electrical pole-changing method for five-phase IM with a current sliding-mode control strategy. This control strategy employs the dual-plane （dr-q1 and d2-q2） vector control method, which allows the IM to operate under different pole modes. Current sliding-mode controllers are applied instead of conventional proportional integral （PI） controllers to adjust the current vectors, and exponential current response achieves a smooth transition between the d1-q1 and d2-q2 planes. Compared with the step response pole-changing with PI control method, the proposed pole-changing method greatly reduces the torque ripple and speed fluctuation of the IM during the pole-changing process. Experimental results verify the ex- ceptional performance of the proposed electrical pole-changing strategy.展开更多
Properties of the current controller are essential for permanent magnet synchronous machine(PMSM)drives,but the conventional continuous-time current controller cannot fully decouple the cross-coupling terms when appli...Properties of the current controller are essential for permanent magnet synchronous machine(PMSM)drives,but the conventional continuous-time current controller cannot fully decouple the cross-coupling terms when applied in the digital processor.Its performance is related closely to the rotational speed.To improve the performance of the current loop,the direct design method in the discrete-time domain is adopted using the accurate discrete-time complex vector model.An integrated accurate hold-equivalent discrete model for PMSM is derived considering the difference between the output of the voltage source inverter and the back electro-motive force.Then an accurate two-degree-of-freedom(2DOF)current controller with a third-order closed-loop transfer function is designed.The 2DOF controller has more freedom in pole placement,and two schemes with a different cancelled pole-zero pair are investigated.Analysis is conducted by the robust root locus method via the complex vector root locus and sensitivity functions,showing properties in disturbance rejection and sensitivity to parameter variation of two schemes.Both schemes have their own advantages.Finally,the dynamic performance and flexibility of the proposed current controller is verified on a 2.5-kW PMSM test bench.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Project supported by the National Basic Research Program(973)of China(No.2013CB035600)
文摘Electrical pole-changing technology leads to torque ripple and speed fluctuation despite broadening the constant power speed range of the multiphase induction machine （IM） system. To reduce the torque ripple and speed fluctuation of the machine, we investigate an exponential response electrical pole-changing method for five-phase IM with a current sliding-mode control strategy. This control strategy employs the dual-plane （dr-q1 and d2-q2） vector control method, which allows the IM to operate under different pole modes. Current sliding-mode controllers are applied instead of conventional proportional integral （PI） controllers to adjust the current vectors, and exponential current response achieves a smooth transition between the d1-q1 and d2-q2 planes. Compared with the step response pole-changing with PI control method, the proposed pole-changing method greatly reduces the torque ripple and speed fluctuation of the IM during the pole-changing process. Experimental results verify the ex- ceptional performance of the proposed electrical pole-changing strategy.
基金Project supported by the National Natural Science Foundation of China(No.51777191)the Natural Science Foundation of Zhejiang Province,China(No.LZ13E070001)the Collaborative Innovation Center for Advanced Aero-engine,China
文摘Properties of the current controller are essential for permanent magnet synchronous machine(PMSM)drives,but the conventional continuous-time current controller cannot fully decouple the cross-coupling terms when applied in the digital processor.Its performance is related closely to the rotational speed.To improve the performance of the current loop,the direct design method in the discrete-time domain is adopted using the accurate discrete-time complex vector model.An integrated accurate hold-equivalent discrete model for PMSM is derived considering the difference between the output of the voltage source inverter and the back electro-motive force.Then an accurate two-degree-of-freedom(2DOF)current controller with a third-order closed-loop transfer function is designed.The 2DOF controller has more freedom in pole placement,and two schemes with a different cancelled pole-zero pair are investigated.Analysis is conducted by the robust root locus method via the complex vector root locus and sensitivity functions,showing properties in disturbance rejection and sensitivity to parameter variation of two schemes.Both schemes have their own advantages.Finally,the dynamic performance and flexibility of the proposed current controller is verified on a 2.5-kW PMSM test bench.
