Hydrological events should be described through several correlated variables, so multivariate HFA has gained popularity and become an active research field during recent years. However, at present multivariate HFA mai...Hydrological events should be described through several correlated variables, so multivariate HFA has gained popularity and become an active research field during recent years. However, at present multivariate HFA mainly focuses directly on fitting the frequency distribution without confirming whether the assumptions are satisfied. Neglecting testing these assumptions could get severely wrong frequency distribution. This paper uses multivariate Mann-Kendal testing to detect the multivariate trends of annual flood peak and annual maximum 15 day volume for four control hydrological stations in the?Upper Yangtze River Basin. Results indicate that multivariate test could detect the trends of joint variables, whereas univariate tests can only detect the univariate trends. Therefore, it is recommended to jointly apply univariate and multivariate trend tests to capture all the existing trends.展开更多
Permanent magnet synchronous motor(PMSM)has the advantages of high efficiency,high power density and high reliability.It has been widely used in electric vehicles,rail transit,industrial transmission and other fields....Permanent magnet synchronous motor(PMSM)has the advantages of high efficiency,high power density and high reliability.It has been widely used in electric vehicles,rail transit,industrial transmission and other fields.Compared with the traditional PMSM control strategy,the Indirect stator-quantities control(ISC)of low torque ripple induction motor has high dynamic response performance in the whole speed range,with high stability and strong security.However,due to the inherent characteristics of PMSM,there are still some difficulties in applying ISC strategy,such as solving the load angle corresponding to the current torque,realizing the maximum torque per ampere(MTPA)control and flux weakening control method in the stator field oriented control algorithm of PMSM.In this paper,theoretical analysis and discussion are carried out for the above difficulties,and an indirect stator vector control(ISC)method for PMSM is proposed.Finally,combined with the electric drive application platform of electric vehicle,the simulation and experimental results verify that the proposed ISC control strategy of PMSM also has good dynamic and steady-state performance in the whole speed range.展开更多
文摘Hydrological events should be described through several correlated variables, so multivariate HFA has gained popularity and become an active research field during recent years. However, at present multivariate HFA mainly focuses directly on fitting the frequency distribution without confirming whether the assumptions are satisfied. Neglecting testing these assumptions could get severely wrong frequency distribution. This paper uses multivariate Mann-Kendal testing to detect the multivariate trends of annual flood peak and annual maximum 15 day volume for four control hydrological stations in the?Upper Yangtze River Basin. Results indicate that multivariate test could detect the trends of joint variables, whereas univariate tests can only detect the univariate trends. Therefore, it is recommended to jointly apply univariate and multivariate trend tests to capture all the existing trends.
文摘Permanent magnet synchronous motor(PMSM)has the advantages of high efficiency,high power density and high reliability.It has been widely used in electric vehicles,rail transit,industrial transmission and other fields.Compared with the traditional PMSM control strategy,the Indirect stator-quantities control(ISC)of low torque ripple induction motor has high dynamic response performance in the whole speed range,with high stability and strong security.However,due to the inherent characteristics of PMSM,there are still some difficulties in applying ISC strategy,such as solving the load angle corresponding to the current torque,realizing the maximum torque per ampere(MTPA)control and flux weakening control method in the stator field oriented control algorithm of PMSM.In this paper,theoretical analysis and discussion are carried out for the above difficulties,and an indirect stator vector control(ISC)method for PMSM is proposed.Finally,combined with the electric drive application platform of electric vehicle,the simulation and experimental results verify that the proposed ISC control strategy of PMSM also has good dynamic and steady-state performance in the whole speed range.
