According to the fact that the actual inductor and actual capacitor are fractional, the mathematical and state-space averaging models of fractional order Buck converters in continuous conduction mode(CCM) are construc...According to the fact that the actual inductor and actual capacitor are fractional, the mathematical and state-space averaging models of fractional order Buck converters in continuous conduction mode(CCM) are constructed by using fractional calculus theory. Firstly, the parameter conditions that ensure that the converter working in CCM is given and transfer functions are derived. Also, the inductor current and the output voltage are analyzed. Then the difference between the mathematical model and the circuit model are analyzed, and the effect of fractional order is studied by comparing the integer order with fractional order model. Finally, the dynamic behavior of the current-controlled Buck converter is investigated. Simulation experiments are achieved via the use of Matlab/Simulink. The experimental results verify the correctness of theoretical analysis, the order should be taken as a significant parameter. When the order is taken as a bifurcation parameter, the dynamic behavior of the converter will be affected and bifurcation points will be changed as order varies.展开更多
48MnV-C non-heat treatment crankshaft steel is specially used for making crankshafts of Cummings C engines.It mainly adopts the technology of V—N micro-alloying,at present,it has been successfully used in making cran...48MnV-C non-heat treatment crankshaft steel is specially used for making crankshafts of Cummings C engines.It mainly adopts the technology of V—N micro-alloying,at present,it has been successfully used in making crankshaft of heavy duty truck engines.BX STEEL made trial production by means of converter→secondary metallurgy(RH+LF)→rectangular slab caster→hot rolling process,and studied the T[O],T[N],[H]and non-metal inclusion in 48MnV-C steel under continuous casting process condition,the actual grain size and the slab quality.All the chemical compositions and test results met the needs of Cummings Crankshaft Steel Standard.In order to ensure the mechanical properties of the non-heat treatment steel,a certain amount of nitrogen is added to it,also a small amount of sulfur is added to improve the cutting property of the steel.This process route can make full use of the de-hydrogen function of RH,and during RH treatment,rough adjustment of alloy elements may be made while the adjustment of Nitride Manganese nitrogen pick up and adjusting Mn,as well as Ca treatment and S content adjustment may be done during LF treatment so as to ensure the requirement of high nitrogen,low hydrogen,low oxygen content in 48MnV-C steel.Magnetic marks are defects shown in magnetic powder testing after the steel was used to make finished crankshafts.The 48MnV-C non-heat treatment crankshaft steel produced by means of the above-mentioned process route has not only relatively high robust performance which meets the needs of truck crankshaft safety,but also high qualification rate and basically no"magnetic marks"are found after being made into finished crankshafts,which meets the crankshaft standard.Therefore,this steel has been widely used in domestic crankshaft industry.展开更多
A proven beam-track contact model was used to analyze the track-structure interaction of CWR (continuously welded track) on bridge. Considering the impact of adjacent bridges, the tower-cable-track-beam-pier-pile fini...A proven beam-track contact model was used to analyze the track-structure interaction of CWR (continuously welded track) on bridge. Considering the impact of adjacent bridges, the tower-cable-track-beam-pier-pile finite element model of the cable-stayed bridge was established. Taking a bridge group including 40-32m simply-supported beam and (32+80+112)m single-tower cable-stayed bridge and 17-32m simply-supported beam on the Kunming-Shanghai high-speed railway as an example, the characteristics of CWR longitudinal force on the cable-stayed bridge were studied. It is shown that adjacent bridges must be considered in the calculation of the track expansion force and bending force on cable-stayed bridge. When the span amount of adjacent bridges is too numerous, it can be simplified as six spans; the fixed bearing of adjacent simply-supported beams should be placed on the side near the cable-stayed bridge; the track expansion device should be set at the bridge tower to reduce the track force near the bridge abutment.展开更多
a Pole voltage waveforms (VA20 and VA40) for modulation index 0.4 (middle trace is A-phase voltage waveform) x-axis: 1 div.=10ms, y-axis: 1 div.= 100V b Normalized harmonic spectrum for pole voltage of Fig. 9a c A-pha...a Pole voltage waveforms (VA20 and VA40) for modulation index 0.4 (middle trace is A-phase voltage waveform) x-axis: 1 div.=10ms, y-axis: 1 div.= 100V b Normalized harmonic spectrum for pole voltage of Fig. 9a c A-phase current and phase voltage for modulation index 0.4 (reference space vector is in inner layer)展开更多
In this paper, we proposed an output voltage stabilization of a DC-DC Zeta converter using hybrid control. We modeled the Zeta converter under continuous conduction mode operation. We derived a switching control law t...In this paper, we proposed an output voltage stabilization of a DC-DC Zeta converter using hybrid control. We modeled the Zeta converter under continuous conduction mode operation. We derived a switching control law that brings the output voltage to the desired level. Due to infinite switching occurring at the desired level, we enhanced the switching control law by allowing a sizeable output voltage ripple. We derived mathematical models that allow one to choose the desired switching frequency. In practice, the existence of the non-ideal properties of the Zeta converter results in steady-state output voltage error. By analyzing the power loss in the zeta converter, we proposed an improved switching control law that eliminates the steady-state output voltage error. The effectiveness of the proposed method is illustrated with simulation results.展开更多
Dear Editor,This letter investigates the grid-forming control for power converters.Recently,grid-forming control based on matching of synchronous machines was suggested by using continuous measurements.In the present ...Dear Editor,This letter investigates the grid-forming control for power converters.Recently,grid-forming control based on matching of synchronous machines was suggested by using continuous measurements.In the present letter,we suggest a digital implementation using artificial delays where the controller employs the discrete-time measurements only.展开更多
This paper proposes a continuous control set model predictive control(CCS-MPC)algorithm of a modular multilevel matrix converter(M3C)for low-frequency AC transmission(LFAC),via which the offshore wind farm(OWF)is inte...This paper proposes a continuous control set model predictive control(CCS-MPC)algorithm of a modular multilevel matrix converter(M3C)for low-frequency AC transmission(LFAC),via which the offshore wind farm(OWF)is integrated.The M3C is operated with a 16.7 Hz frequency at the OWF side and a 50 Hz frequency at the onshore grid side.The balance of the capacitor voltages and the regulation of circulating currents in the M3C are performed using the proposed CCSMPC algorithm,which is based on the online solution of a cost function with constraints.Simulation and experimental work(with a 5 kW M3C prototype)are provided,showing the performance of the LFAC system to operate with symmetrical and asymmetrical voltage dips,active and reactive power steps,and optimal limitation of currents and voltages using constraints.Unlike previous publications,the predictive control system in this paper allows seamless operation under balanced and unbalanced conditions,for instance,during asymmetrical voltage dips.展开更多
The Objective of this paper is to give more insight into CCM Operation of the LCL Converter to obtain op-timum design using state-space analysis and to verify the results using PSPICE Simulation for wide variation in ...The Objective of this paper is to give more insight into CCM Operation of the LCL Converter to obtain op-timum design using state-space analysis and to verify the results using PSPICE Simulation for wide variation in loading conditions. LCL Resonant Full Bridge Converter (RFB) is a new, high performance DC-DC con-verter. High frequency dc-dc resonant converters are widely used in many space and radar power supplies owing to their small size and lightweight. The limitations of two element resonant topologies can be over-come by adding a third reactive element termed as modified series resonant converter (SRC). A three ele-ment resonant converter capable of driving voltage type load with load independent operation is presented. We have used embedded based triggering circuit and the embedded ‘C’ Program is checked in Keil Software and also triggering circuit is simulated in PSPICE Software. To compare the simulated results with hardware results and designed resonant converter is 200W and the switching frequency is 50 KHz.展开更多
Tangent bifurcation is a special bifurcation in nonlinear dynamic systems. The investigation of the mechanism of the tangent bifurcation in current mode controlled boost converters operating in continuous conduction m...Tangent bifurcation is a special bifurcation in nonlinear dynamic systems. The investigation of the mechanism of the tangent bifurcation in current mode controlled boost converters operating in continuous conduction mode (CCM) is performed. The one-dimensional discrete iterative map of the boost converter is derived. Based on the tangent bifurcation theorem, the conditions of producing the tangent bifurcation in CCM boost converters are deduced mathematically. The mechanism of the tangent bifurcation in CCM boost is exposed from the viewpoint of nonlinear dynamic systems. The tangent bifurcation in the boost converter is verified by numerical simulations such as discrete iterative maps, bifurcation map and Lyapunov exponent. The simulation results are in agreement with the theoretical analysis, thus validating the correctness of the theory.展开更多
This paper proposes the design and experimentation of digital control of soft-switched interleaved boost converter using FPGA for Telecommunication System. The switching devices in the proposed converter are turned on...This paper proposes the design and experimentation of digital control of soft-switched interleaved boost converter using FPGA for Telecommunication System. The switching devices in the proposed converter are turned on and off with Zero Voltage Switching (ZVS) and Zero Current Switching (ZCS) respectively. The circuit is operated in Continuous Conduction Mode (CCM) with various load ranges having duty cycle of more than 50%. The proposed converter is studied by developing the simulation module in MATLAB/SIMULINK. A PI controller is designed and implemented in FPGA to obtain a regulated DC output for line and load variations. Simulation and experimentation results are verified with a prototype development of the proposed converter. The results indicate that the converter performance is enhanced with closed loop control.展开更多
The adapted DC-DC converters should be smaller in size and have a small output current ripple to meet the increasing demand for low voltages with high performance and high density micro processors for several microele...The adapted DC-DC converters should be smaller in size and have a small output current ripple to meet the increasing demand for low voltages with high performance and high density micro processors for several microelectronic load applications. This paper proposes a DC-DC converter using variable on-time and variable switching frequency control enhanced constant ripple current control and reduced magnetic components. The proposed converter is realized by making the turn-offtime proportional to the on-time of the converter, according to the input and output voltage, thereby reducing the corresponding current ripple on output voltage in the continuous conduction mode. A Buck DC-DC converter using the proposed control strategy is analyzed in detail, along with some experimental results to show the performance and effectiveness of this converter.展开更多
基金Sponsored by the National Natural Sciences Foundation of China(Grant No.61201227)
文摘According to the fact that the actual inductor and actual capacitor are fractional, the mathematical and state-space averaging models of fractional order Buck converters in continuous conduction mode(CCM) are constructed by using fractional calculus theory. Firstly, the parameter conditions that ensure that the converter working in CCM is given and transfer functions are derived. Also, the inductor current and the output voltage are analyzed. Then the difference between the mathematical model and the circuit model are analyzed, and the effect of fractional order is studied by comparing the integer order with fractional order model. Finally, the dynamic behavior of the current-controlled Buck converter is investigated. Simulation experiments are achieved via the use of Matlab/Simulink. The experimental results verify the correctness of theoretical analysis, the order should be taken as a significant parameter. When the order is taken as a bifurcation parameter, the dynamic behavior of the converter will be affected and bifurcation points will be changed as order varies.
文摘48MnV-C non-heat treatment crankshaft steel is specially used for making crankshafts of Cummings C engines.It mainly adopts the technology of V—N micro-alloying,at present,it has been successfully used in making crankshaft of heavy duty truck engines.BX STEEL made trial production by means of converter→secondary metallurgy(RH+LF)→rectangular slab caster→hot rolling process,and studied the T[O],T[N],[H]and non-metal inclusion in 48MnV-C steel under continuous casting process condition,the actual grain size and the slab quality.All the chemical compositions and test results met the needs of Cummings Crankshaft Steel Standard.In order to ensure the mechanical properties of the non-heat treatment steel,a certain amount of nitrogen is added to it,also a small amount of sulfur is added to improve the cutting property of the steel.This process route can make full use of the de-hydrogen function of RH,and during RH treatment,rough adjustment of alloy elements may be made while the adjustment of Nitride Manganese nitrogen pick up and adjusting Mn,as well as Ca treatment and S content adjustment may be done during LF treatment so as to ensure the requirement of high nitrogen,low hydrogen,low oxygen content in 48MnV-C steel.Magnetic marks are defects shown in magnetic powder testing after the steel was used to make finished crankshafts.The 48MnV-C non-heat treatment crankshaft steel produced by means of the above-mentioned process route has not only relatively high robust performance which meets the needs of truck crankshaft safety,but also high qualification rate and basically no"magnetic marks"are found after being made into finished crankshafts,which meets the crankshaft standard.Therefore,this steel has been widely used in domestic crankshaft industry.
基金Project(51178469) supported by the National Natural Science Foundation of China
文摘A proven beam-track contact model was used to analyze the track-structure interaction of CWR (continuously welded track) on bridge. Considering the impact of adjacent bridges, the tower-cable-track-beam-pier-pile finite element model of the cable-stayed bridge was established. Taking a bridge group including 40-32m simply-supported beam and (32+80+112)m single-tower cable-stayed bridge and 17-32m simply-supported beam on the Kunming-Shanghai high-speed railway as an example, the characteristics of CWR longitudinal force on the cable-stayed bridge were studied. It is shown that adjacent bridges must be considered in the calculation of the track expansion force and bending force on cable-stayed bridge. When the span amount of adjacent bridges is too numerous, it can be simplified as six spans; the fixed bearing of adjacent simply-supported beams should be placed on the side near the cable-stayed bridge; the track expansion device should be set at the bridge tower to reduce the track force near the bridge abutment.
文摘a Pole voltage waveforms (VA20 and VA40) for modulation index 0.4 (middle trace is A-phase voltage waveform) x-axis: 1 div.=10ms, y-axis: 1 div.= 100V b Normalized harmonic spectrum for pole voltage of Fig. 9a c A-phase current and phase voltage for modulation index 0.4 (reference space vector is in inner layer)
文摘In this paper, we proposed an output voltage stabilization of a DC-DC Zeta converter using hybrid control. We modeled the Zeta converter under continuous conduction mode operation. We derived a switching control law that brings the output voltage to the desired level. Due to infinite switching occurring at the desired level, we enhanced the switching control law by allowing a sizeable output voltage ripple. We derived mathematical models that allow one to choose the desired switching frequency. In practice, the existence of the non-ideal properties of the Zeta converter results in steady-state output voltage error. By analyzing the power loss in the zeta converter, we proposed an improved switching control law that eliminates the steady-state output voltage error. The effectiveness of the proposed method is illustrated with simulation results.
基金supported by the National Natural Science Foundation of China(62403296,62303292,62173218).
文摘Dear Editor,This letter investigates the grid-forming control for power converters.Recently,grid-forming control based on matching of synchronous machines was suggested by using continuous measurements.In the present letter,we suggest a digital implementation using artificial delays where the controller employs the discrete-time measurements only.
基金supported by ANID BECAS/DOCTORADO NACIONAL 21230608supported by the Projects Fondecyt Nr.1221392,Anillo grant ATE230035,and Basal project FB0008(AC3E)supported by Fondecyt Nr.1230596 and Fondequip EQM200234.
文摘This paper proposes a continuous control set model predictive control(CCS-MPC)algorithm of a modular multilevel matrix converter(M3C)for low-frequency AC transmission(LFAC),via which the offshore wind farm(OWF)is integrated.The M3C is operated with a 16.7 Hz frequency at the OWF side and a 50 Hz frequency at the onshore grid side.The balance of the capacitor voltages and the regulation of circulating currents in the M3C are performed using the proposed CCSMPC algorithm,which is based on the online solution of a cost function with constraints.Simulation and experimental work(with a 5 kW M3C prototype)are provided,showing the performance of the LFAC system to operate with symmetrical and asymmetrical voltage dips,active and reactive power steps,and optimal limitation of currents and voltages using constraints.Unlike previous publications,the predictive control system in this paper allows seamless operation under balanced and unbalanced conditions,for instance,during asymmetrical voltage dips.
文摘The Objective of this paper is to give more insight into CCM Operation of the LCL Converter to obtain op-timum design using state-space analysis and to verify the results using PSPICE Simulation for wide variation in loading conditions. LCL Resonant Full Bridge Converter (RFB) is a new, high performance DC-DC con-verter. High frequency dc-dc resonant converters are widely used in many space and radar power supplies owing to their small size and lightweight. The limitations of two element resonant topologies can be over-come by adding a third reactive element termed as modified series resonant converter (SRC). A three ele-ment resonant converter capable of driving voltage type load with load independent operation is presented. We have used embedded based triggering circuit and the embedded ‘C’ Program is checked in Keil Software and also triggering circuit is simulated in PSPICE Software. To compare the simulated results with hardware results and designed resonant converter is 200W and the switching frequency is 50 KHz.
文摘Tangent bifurcation is a special bifurcation in nonlinear dynamic systems. The investigation of the mechanism of the tangent bifurcation in current mode controlled boost converters operating in continuous conduction mode (CCM) is performed. The one-dimensional discrete iterative map of the boost converter is derived. Based on the tangent bifurcation theorem, the conditions of producing the tangent bifurcation in CCM boost converters are deduced mathematically. The mechanism of the tangent bifurcation in CCM boost is exposed from the viewpoint of nonlinear dynamic systems. The tangent bifurcation in the boost converter is verified by numerical simulations such as discrete iterative maps, bifurcation map and Lyapunov exponent. The simulation results are in agreement with the theoretical analysis, thus validating the correctness of the theory.
文摘This paper proposes the design and experimentation of digital control of soft-switched interleaved boost converter using FPGA for Telecommunication System. The switching devices in the proposed converter are turned on and off with Zero Voltage Switching (ZVS) and Zero Current Switching (ZCS) respectively. The circuit is operated in Continuous Conduction Mode (CCM) with various load ranges having duty cycle of more than 50%. The proposed converter is studied by developing the simulation module in MATLAB/SIMULINK. A PI controller is designed and implemented in FPGA to obtain a regulated DC output for line and load variations. Simulation and experimentation results are verified with a prototype development of the proposed converter. The results indicate that the converter performance is enhanced with closed loop control.
文摘The adapted DC-DC converters should be smaller in size and have a small output current ripple to meet the increasing demand for low voltages with high performance and high density micro processors for several microelectronic load applications. This paper proposes a DC-DC converter using variable on-time and variable switching frequency control enhanced constant ripple current control and reduced magnetic components. The proposed converter is realized by making the turn-offtime proportional to the on-time of the converter, according to the input and output voltage, thereby reducing the corresponding current ripple on output voltage in the continuous conduction mode. A Buck DC-DC converter using the proposed control strategy is analyzed in detail, along with some experimental results to show the performance and effectiveness of this converter.
