PM machine or Permanent magnet synchronous motorPMSMis a nonlinear system with multivariable couplings.To achieve the sensorless control of a PMSM with high inertial load,a modified curre...PM machine or Permanent magnet synchronous motorPMSMis a nonlinear system with multivariable couplings.To achieve the sensorless control of a PMSM with high inertial load,a modified current observer,using PI regulator instead of sliding mode switching function,is proposed in this paper.The modified current observer can solve the chattering and phase delay problem while still maintaining the robust advantages of sliding mode system in position estimation.In addition,a new phase-locked loop(PLL)based angle switching strategy is designed to ensure the motor can smoothly switch from I-F control to closed-loop sensorless vector control in startup stage with a high inertial load.The simulation and experimental results show that the control system of PMSM with proposed ideas has fast response speed,accurate rotor position estimation,stable state switching and good system robustness under high inertia load.展开更多
The dynamic effects of inertial loads on the interface stresses between a residual limb and the trans-tibial prosthetic socket were investigated. A 3-D nonlinear finite element model, based on the actual geometry of t...The dynamic effects of inertial loads on the interface stresses between a residual limb and the trans-tibial prosthetic socket were investigated. A 3-D nonlinear finite element model, based on the actual geometry of the residual limb, including internal bones and socket liner, was developed to study the mechanical interaction between the socket and the residual limb during walking. To simulate the friction/slip boundary conditions between the skin and liner, automated surface-to-surface contact was used. The results show that interface pressure and shear stress have a similar double-peaked waveform shape in the stance phase. The average difference in interface stresses between the cases with and without consideration of inertial forces is 8.4% in the stance phase and 20.1% in the swing phase. The results suggest that the dynamic effects of inertial loads on interface stress distribution during walking must be considered in prosthetic socket design.展开更多
文摘PM machine or Permanent magnet synchronous motorPMSMis a nonlinear system with multivariable couplings.To achieve the sensorless control of a PMSM with high inertial load,a modified current observer,using PI regulator instead of sliding mode switching function,is proposed in this paper.The modified current observer can solve the chattering and phase delay problem while still maintaining the robust advantages of sliding mode system in position estimation.In addition,a new phase-locked loop(PLL)based angle switching strategy is designed to ensure the motor can smoothly switch from I-F control to closed-loop sensorless vector control in startup stage with a high inertial load.The simulation and experimental results show that the control system of PMSM with proposed ideas has fast response speed,accurate rotor position estimation,stable state switching and good system robustness under high inertia load.
文摘The dynamic effects of inertial loads on the interface stresses between a residual limb and the trans-tibial prosthetic socket were investigated. A 3-D nonlinear finite element model, based on the actual geometry of the residual limb, including internal bones and socket liner, was developed to study the mechanical interaction between the socket and the residual limb during walking. To simulate the friction/slip boundary conditions between the skin and liner, automated surface-to-surface contact was used. The results show that interface pressure and shear stress have a similar double-peaked waveform shape in the stance phase. The average difference in interface stresses between the cases with and without consideration of inertial forces is 8.4% in the stance phase and 20.1% in the swing phase. The results suggest that the dynamic effects of inertial loads on interface stress distribution during walking must be considered in prosthetic socket design.
