Aiming at the difficulty of setting the weight coefficient in the value function of model predictive torque control(MPTC)for permanent magnet synchronous motor(PMSM)driven by three-level inverter,a fine-division model...Aiming at the difficulty of setting the weight coefficient in the value function of model predictive torque control(MPTC)for permanent magnet synchronous motor(PMSM)driven by three-level inverter,a fine-division model predictive flux control(MPFC)method is proposed.First,establish a mathematical model between the motor torque and the stator flux linkage according to the mathematical equations of PMSM.Thus,the control of the motor torque and stator flux linkage in the MPTC is transformed into the control of a single stator flux linkage vector,omitting the cumbersome weight setting process in the traditional MPTC.The midpoint potential control strategy is proposed,which uses the characteristics of redundant small vectors to balance the midpoint potential.After that,a fine-division strategy is proposed,which effectively reduces the number of candidate vectors and the computational burden of the system.Finally,the proposed MPFC is compared with MPTC by simulation.The results show that the proposed fine-division MPFC effectively reduces the system calculation,and has the advantages of simple principle and better dynamic and steady-state control performance.The feasibility of the control strategy is verified.展开更多
A comprehensive predictive strategy was proposed for the neutral-point balancing control of back-to-back three-level converters. The phase currents at both sides and the DC-link capacitor voltages were measured for th...A comprehensive predictive strategy was proposed for the neutral-point balancing control of back-to-back three-level converters. The phase currents at both sides and the DC-link capacitor voltages were measured for the prediction of the neutral-point current. A quality function was found to balance the neutral-point, and a metabolic on-times distribution factor was used as a predicator to minimize the quality function at each switching state. Simulation results show that the proposed method produces smaller ripples in tested signals compared with the established one, namely, 9.15% less in a total harmonic distortion(THD) of line-to-line voltage, 1.08% less in the THD of phase current, and 0.9 V less in the ripple of the neutral-point voltage. The obtained experimental results show that the main harmonics of the line-to-line voltage and the phase current in the proposed method are improved by 10 d B and 6 d B, respectively, and the ripple of neutral-point voltage is halved compared to the established one.展开更多
The solid state transformer(SST) can be viewed as an energy router in energy internet. This work presents sliding mode control(SMC) to improve dynamic state and steady state performance of a three-stage(rectifier stag...The solid state transformer(SST) can be viewed as an energy router in energy internet. This work presents sliding mode control(SMC) to improve dynamic state and steady state performance of a three-stage(rectifier stage, isolated stage and inverter stage) SST for energy internet. SMC with three-level hysteresis sliding functions is presented to control the input current of rectifier stage and output voltage of inverter stage to improve the robustness under external disturbance and parametric uncertainties and reduce the switching frequency. A modified feedback linearization technique using isolated stage simplified model is presented to achieve satisfactory regulation of output voltage of the isolated stage. The system is tested for steady state operation, reactive power control, dynamic load change and voltage sag simulations, respectively. The switching model of SST is implemented in Matlab/ Simulink to verify the SST control algorithms.展开更多
This paper proposes the control of a grid side converter under unbalance voltage conditions for wind turbine system. The control technique is designed to operate under unbalance voltage by independent control between ...This paper proposes the control of a grid side converter under unbalance voltage conditions for wind turbine system. The control technique is designed to operate under unbalance voltage by independent control between positive and negative components. The converter will regulate the DC link voltage at the specific value （650 V）. To verify an operation of the proposed control, the simulation is conducted by MATLAB/SIMULINK program. The experiments are conducted on a 5 kW system composed of wind turbine simulator, machine side converter and the propose grid side converter for operation under unbalance voltage. By comparing the simulation experimentation results, it can be shown that the proposed control can be continuously operating through an extremely sag voltage without damage. Moreover the proposed control can deliver power to the grid and regulate DC link voltage under unbalance voltage.展开更多
This paper presents a mathematical model of three-level voltage PWM rectifier,and derives a power control model from the theory of instantaneous power.In the vector-space,the influences on instantaneous power exercise...This paper presents a mathematical model of three-level voltage PWM rectifier,and derives a power control model from the theory of instantaneous power.In the vector-space,the influences on instantaneous power exercised by all the switching vectors are studied and illustrated separately,then a direct power control(DPC) scheme for three-level PWM rectifier which uses multistage band hysteresis comparator is proposed,and a novel switching table is designed.Meanwhile,the neutralpoint voltage unbalance is inhibited by selecting the redundancy switching states of small voltage vectors.Simulation and experimental results show that the proposed strategy can not only stabilize the DC bus voltage but also realize the unity power factor operation and the balance of neutral-point voltage.Moreover,the proposed method can improve the performance of the three-level rectifier.展开更多
基金National Natural Science Foundation of China(No.51867012)。
文摘Aiming at the difficulty of setting the weight coefficient in the value function of model predictive torque control(MPTC)for permanent magnet synchronous motor(PMSM)driven by three-level inverter,a fine-division model predictive flux control(MPFC)method is proposed.First,establish a mathematical model between the motor torque and the stator flux linkage according to the mathematical equations of PMSM.Thus,the control of the motor torque and stator flux linkage in the MPTC is transformed into the control of a single stator flux linkage vector,omitting the cumbersome weight setting process in the traditional MPTC.The midpoint potential control strategy is proposed,which uses the characteristics of redundant small vectors to balance the midpoint potential.After that,a fine-division strategy is proposed,which effectively reduces the number of candidate vectors and the computational burden of the system.Finally,the proposed MPFC is compared with MPTC by simulation.The results show that the proposed fine-division MPFC effectively reduces the system calculation,and has the advantages of simple principle and better dynamic and steady-state control performance.The feasibility of the control strategy is verified.
基金Project(61074018)supported by the National Natural Science Foundation of ChinaProject(2012kfjj06)supported by Hunan Province Key Laboratory of Smart Grids Operation and Control(Changsha University of Science and Technology),China
文摘A comprehensive predictive strategy was proposed for the neutral-point balancing control of back-to-back three-level converters. The phase currents at both sides and the DC-link capacitor voltages were measured for the prediction of the neutral-point current. A quality function was found to balance the neutral-point, and a metabolic on-times distribution factor was used as a predicator to minimize the quality function at each switching state. Simulation results show that the proposed method produces smaller ripples in tested signals compared with the established one, namely, 9.15% less in a total harmonic distortion(THD) of line-to-line voltage, 1.08% less in the THD of phase current, and 0.9 V less in the ripple of the neutral-point voltage. The obtained experimental results show that the main harmonics of the line-to-line voltage and the phase current in the proposed method are improved by 10 d B and 6 d B, respectively, and the ripple of neutral-point voltage is halved compared to the established one.
基金Projects(61403404,71571187)supported by the National Natural Science Foundation of China
文摘The solid state transformer(SST) can be viewed as an energy router in energy internet. This work presents sliding mode control(SMC) to improve dynamic state and steady state performance of a three-stage(rectifier stage, isolated stage and inverter stage) SST for energy internet. SMC with three-level hysteresis sliding functions is presented to control the input current of rectifier stage and output voltage of inverter stage to improve the robustness under external disturbance and parametric uncertainties and reduce the switching frequency. A modified feedback linearization technique using isolated stage simplified model is presented to achieve satisfactory regulation of output voltage of the isolated stage. The system is tested for steady state operation, reactive power control, dynamic load change and voltage sag simulations, respectively. The switching model of SST is implemented in Matlab/ Simulink to verify the SST control algorithms.
文摘This paper proposes the control of a grid side converter under unbalance voltage conditions for wind turbine system. The control technique is designed to operate under unbalance voltage by independent control between positive and negative components. The converter will regulate the DC link voltage at the specific value （650 V）. To verify an operation of the proposed control, the simulation is conducted by MATLAB/SIMULINK program. The experiments are conducted on a 5 kW system composed of wind turbine simulator, machine side converter and the propose grid side converter for operation under unbalance voltage. By comparing the simulation experimentation results, it can be shown that the proposed control can be continuously operating through an extremely sag voltage without damage. Moreover the proposed control can deliver power to the grid and regulate DC link voltage under unbalance voltage.
基金supported by the Key Program of National Natural Science Foundation of China (Grant No. 51037004)the National Natural Science Foundation of China (Grant No. 51077097)the Key Technologies Research and Development Program of Tianjin (Grant No.11ZCKFGX03300)
文摘This paper presents a mathematical model of three-level voltage PWM rectifier,and derives a power control model from the theory of instantaneous power.In the vector-space,the influences on instantaneous power exercised by all the switching vectors are studied and illustrated separately,then a direct power control(DPC) scheme for three-level PWM rectifier which uses multistage band hysteresis comparator is proposed,and a novel switching table is designed.Meanwhile,the neutralpoint voltage unbalance is inhibited by selecting the redundancy switching states of small voltage vectors.Simulation and experimental results show that the proposed strategy can not only stabilize the DC bus voltage but also realize the unity power factor operation and the balance of neutral-point voltage.Moreover,the proposed method can improve the performance of the three-level rectifier.
