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Switching Frequency Improvement of a High Speed on/off Valve Based on Pre-excitation Control Algorithm
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作者 Qi Zhong Xiaotian Li +4 位作者 Yongxin Mao Enguang Xu Tiwei Jia Yanbiao Li Huayong Yang 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2024年第4期94-106,共13页
The high-speed on/off valve(HSV)serves as the fundamental component responsible for generating discrete fluids within digital hydraulic systems.As the switching frequency of the HSV increases,the properties of the gen... The high-speed on/off valve(HSV)serves as the fundamental component responsible for generating discrete fluids within digital hydraulic systems.As the switching frequency of the HSV increases,the properties of the generated discrete fluid approach those of continuous fluids.Therefore,a higher frequency response characteristic of HSV is the key to ensure the control accuracy of digital hydraulic systems.However,the current research mainly focuses on its dynamic performance,but neglect its FRC.This paper presents a theoretical analysis demonstrating that the FRC of the HSV can be enhanced by minimizing its switching time.The maximum switching frequency(MSF)is mainly determined by opening dynamic performance when HSV operates with low switching duty ratio(SDR),whereas the closing dynamic performance limits the MSF when HSV operates with high SDR.Building upon these findings,the pre-excitation control algorithm(PECA)is proposed to reduce the switching time of the HSV,and consequently enhance its FRC.Experimental results demonstrate that PECA shortens the opening delay time of HSV by 1.12 ms,the closing delay time by 2.54 ms,and the closing moving time by 0.47 ms in comparison to the existing advanced control algorithms.As a result,a larger MSF of 417 Hz and a wider controllable SDR range from 20%to 70%were achieved at a switching frequency of 250 Hz.Thus,the proposed PFCA in this paper has been verified as an effective and promising approach for enhancing the control performance of digital hydraulic systems. 展开更多
关键词 High speed on/off valve switching frequency Pre-excitation Dynamic performance switching duty ratio
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Model predictive control of three-level active front-end converter with low switching frequency
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作者 YANG Li WANG Lang-zhu +1 位作者 FENG Bo WANG Hong-lin 《Journal of Measurement Science and Instrumentation》 CAS CSCD 2018年第2期153-159,共7页
In medium voltage-high power(MV-HP)applications,the high switching frequency of power converter will result in unnecessary energy losses,which directly affect efficiency.To resolve this issue,a novel finite control se... In medium voltage-high power(MV-HP)applications,the high switching frequency of power converter will result in unnecessary energy losses,which directly affect efficiency.To resolve this issue,a novel finite control set-model predictive control(FCS-MPC)with low switching frequency for three-level neutral point clamped-active front-end converters(NPC-AFEs)is proposed.With this approach,the prediction model of three-level NPC-AFEs is established inα-βreference frame,and the control objective of low average switching frequency is introduced into a cost function.The proposed method not only achieves the desired control performance under low switching frequency,but also performs the efficient operation for the three-level NPC-AFEs.The simulation results are provided to verify the effectiveness of proposed control scheme. 展开更多
关键词 finite control set-model predictive control(FCS-MPC) three-level neutral point clamped active front-end converters(NPC-AFEs) switching frequency
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Periodic Variation in the Effect of Switching Frequency on the Harmonics of Power Electronic Converters 被引量:5
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作者 Qiao Li Jianan Chen Dong Jiang 《Chinese Journal of Electrical Engineering》 CSCD 2020年第3期35-45,共11页
Switching frequency is an important factor in the performance control of power electronic converters.It can help optimize switching losses,switching ripples and electromagnetic interference,especially for newly develo... Switching frequency is an important factor in the performance control of power electronic converters.It can help optimize switching losses,switching ripples and electromagnetic interference,especially for newly developed high-switching-frequency silicon carbide converters.Periodic variation in the switching-frequency methods has been developed for this purpose,especially the model-predictive variable switching-frequency pulse width modulation(VSFPWM)method.The effect of periodic switching-frequency variation on the harmonics of a converter using double Fourier analysis and simulations are investigated.This work verifies that the switching harmonics can be reduced by periodic variation in the switching frequency,and the low-frequency(baseband)harmonics only incur a slight change.The analysis provides a theoretical foundation for the application of VSFPWM in power electronic converters. 展开更多
关键词 switching frequency PWM HARMONICS EMI
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Adaptive switching frequency buck DC-DC converter with high-accuracy on-chip current sensor 被引量:1
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作者 江金光 黄飞 熊智慧 《Journal of Semiconductors》 EI CAS CSCD 2015年第5期111-119,共9页
A current-mode PWM buck DC-DC converter is proposed. With the high-accuracy on-chip current sen- sor, the switching frequency can be selected automatically according to load requirements. This method improves efficien... A current-mode PWM buck DC-DC converter is proposed. With the high-accuracy on-chip current sen- sor, the switching frequency can be selected automatically according to load requirements. This method improves efficiency and obtains an excellent transient response. The high accuracy of the current sensor is achieved by a simple switch technique without an amplifier. This has the direct benefit of reducing power dissipation and die size. Additionally, a novel soft-start circuit is presented to avoid the inrush current at the starting up state. Finally, this DC-DC converter is fabricated with the 0.5μm standard CMOS process. The chip occupies 3.38 mm2. The accuracy of the proposed current sensor can achieve 99.5% @ 200 mA. Experimental results show that the peak efficiency is 91.8%. The input voltage ranges from 5 to 18 V, while a 2 A load current can be obtained. 展开更多
关键词 DC-DC switching frequency current sensor soft-start wide load range
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Design of a constant-voltage and constant-current controller with dual-loop and adaptive switching frequency control
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作者 陈映平 李志谦 《Journal of Semiconductors》 EI CAS CSCD 2015年第5期104-110,共7页
A 5.0-V 2.0-A flyback power supply controller providing constant-voltage (CV) and constant-current (CC) output regulation without the use of an optical coupler is presented. Dual-close-loop control is proposed her... A 5.0-V 2.0-A flyback power supply controller providing constant-voltage (CV) and constant-current (CC) output regulation without the use of an optical coupler is presented. Dual-close-loop control is proposed here due to its better regulation performance of tolerance over process and temperature compared with open loop control used in common. At the same time, the two modes, CC and CV, could switch to each other automatically and smoothly according to the output voltage level not sacrificing the regulation accuracy at the switching phase, which overcomes the drawback of the digital control scheme depending on a hysteresis comparator to change the mode. On-chip compensation using active capacitor multiplier technique is applied to stabilize the voltage loop, eliminate an additional package pin, and save on the die area. The system consumes as little as 100 mW at no-load condition without degrading the transient response performance by utilizing the adaptive switching frequency control mode. The proposed controller has been implemented in a commercial 0.35μm 40-V BCD process, and the active chip area is 1.5×1.0 mm^2. The total error of the output voltage due to line and load variations is less than 4-1.7%. 展开更多
关键词 constant voltage constant current DUAL-LOOP adaptive switching frequency
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Adjust or Synchronize LM2586/88 Switching Frequency
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作者 National Semiconductor 《电源世界》 2003年第1期50-,49,共2页
INTRODUCTIONSwitching frequency is a very important parameter in switchingpower converters. As the switching frequency increases, the physicalsize of magnetic elements and other components in the circuit reducesignifi... INTRODUCTIONSwitching frequency is a very important parameter in switchingpower converters. As the switching frequency increases, the physicalsize of magnetic elements and other components in the circuit reducesignificantly. Switching frequency also plays a great role incontrol loop gain and compensation design. Switching frequency determinesthe maximum allowable bandwidth of the control loop.Switching frequency is also important parameter for EMI and noiseissues. The EMI spectrum is a direct function of the switching fre- 展开更多
关键词 LM IS Adjust or Synchronize LM2586/88 switching frequency FIGURE EMI BE of or
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Dependence of Switching Current Distribution of a Current-Biased Josephson Junction on Microwave Frequency
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作者 翟计全 李永超 +5 位作者 史建新 周渝 李小虎 许伟伟 孙国柱 吴培亨 《Chinese Physics Letters》 SCIE CAS CSCD 2015年第4期118-121,共4页
We investigate the distribution of the switching current of a current-biased Josephson junction (CBJJ) and its dependence on the microwave frequency using two theoretical methods, one of which is the quantum traject... We investigate the distribution of the switching current of a current-biased Josephson junction (CBJJ) and its dependence on the microwave frequency using two theoretical methods, one of which is the quantum trajectory method and the other is the master equation method. Both the methods show that the distribution of the switching current of CBJJ will exhibit double peaks in a certain range of microwave frequency if proper microwave power is given, and the gap between the two peaks will increase with the microwave frequency. The obtained results can be used to identify the energy difference of the ground and first excited states in a Josephson junction for any bias current. 展开更多
关键词 Dependence of switching Current Distribution of a Current-Biased Josephson Junction on Microwave frequency
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Impact of switching frequencies on the TID response of SiC power MOSFETs 被引量:2
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作者 Sheng Yang Xiaowen Liang +9 位作者 Jiangwei Cui Qiwen Zheng Jing Sun Mohan Liu Dang Zhang Haonan Feng Xuefeng Yu Chuanfeng Xiang Yudong Li Qi Guo 《Journal of Semiconductors》 EI CAS CSCD 2021年第8期73-76,共4页
Different switching frequencies are required when SiC metal-oxide-semiconductor field-effect transistors(MOSFETs)are switching in a space environment.In this study,the total ionizing dose(TID)responses of SiC power MO... Different switching frequencies are required when SiC metal-oxide-semiconductor field-effect transistors(MOSFETs)are switching in a space environment.In this study,the total ionizing dose(TID)responses of SiC power MOSFETs are investigated under different switching frequencies from 1 kHz to 10 MHz.A significant shift was observed in the threshold voltage as the frequency increased,which resulted in premature failure of the drain-source breakdown voltage and drain-source leakage current.The degradation is attributed to the high activation and low recovery rates of traps at high frequencies.The results of this study suggest that a targeted TID irradiation test evaluation method can be developed according to the actual switching frequency of SiC power MOSFETs. 展开更多
关键词 SiC power MOSFET switching frequency oxide trap total ionizing dose TRANSISTOR semiconductor theory
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Fast-transient techniques for high-frequency DC–DC converters 被引量:2
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作者 Lin Cheng Kui Tang +1 位作者 Wang-Hung Ki Feng Su 《Journal of Semiconductors》 EI CAS CSCD 2020年第11期92-102,共11页
A 30 MHz voltage-mode controlled buck converter with fast transient responses is presented.An improved differential difference amplifier(DDA)-based Type-III compensator is proposed to reduce the settling times of the ... A 30 MHz voltage-mode controlled buck converter with fast transient responses is presented.An improved differential difference amplifier(DDA)-based Type-III compensator is proposed to reduce the settling times of the converter during load transients,and to achieve near-optimal transient responses with simple PWM control only.Moreover,a hybrid scheme using a digital linear regulator with automatic transient detection and seamless loop transition is proposed to further improve the transient responses.By monitoring the output voltage of the compensator instead of the output voltage of the converter,the proposed hybrid scheme can reduce undershoot and overshoot effectively with good noise immunity and without interrupting the PWM loop.The converter was fabricated in a 0.13μm standard CMOS process using 3.3 V devices.With an input voltage of 3.3 V,the measured peak efficiencies at the output voltages of 2.4,1.8,and 1.2 V are 90.7%,88%,and 83.6%,respectively.With a load step of 1.25 A and rise and fall times of 2 ns,the measured 1%settling times were 220 and 230 ns,with undershoot and overshoot with PWM control of 72 and 76 mV,respectively.They were further reduced to 36 and 38 mV by using the proposed hybrid scheme,and 1%settling times were also reduced to 125 ns. 展开更多
关键词 differential difference amplifier(DDA) Type-III compensator fast transient responses hybrid scheme high switching frequency overshoot/undershoot
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Constant Ripple Current Control for Switching DC-DC Converter
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作者 Gwo-Tarng Chern Jenn-Jong Shieh 《Journal of Energy and Power Engineering》 2012年第9期1437-1441,共5页
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
关键词 Constant ripple current DC-DC converter variable switching frequency continuous conduction mode indirect currentsensor magnetic component.
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Frequency Switches at Transition Temperature in Voltage-Gated Ion Channel Dynamics of Neural Oscillators
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作者 Yasuomi D.Sato 《Chinese Physics Letters》 SCIE CAS CSCD 2018年第5期152-155,共4页
Understanding of the mechanisms of neural phase transitions is crucial for clarifying cognitive processes in the brain. We investigate a neural oscillator that undergoes different bifurcation transitions from the big ... Understanding of the mechanisms of neural phase transitions is crucial for clarifying cognitive processes in the brain. We investigate a neural oscillator that undergoes different bifurcation transitions from the big saddle homoclinic orbit type to the saddle node on an invariant circle type, and the saddle node on an invariant circle type to the small saddle homoclinic orbit type. The bifurcation transitions are accompanied by an increase in thermodynamic temperature that affects the voltage-gated ion channel in the neural oscillator. We show that nonlinear and thermodynamical mechanisms are responsible for different switches of the frequency in the neural oscillator. We report a dynamical role of the phase response curve in switches of the frequency, in terms of slopes of frequency-temperature curve at each bifurcation transition. Adopting the transition state theory of voltagegated ion channel dynamics, we confirm that switches of the frequency occur in the first-order phase transition temperature states and exhibit different features of their potential energy derivatives in the ion channel. Each bifurcation transition also creates a discontinuity in the Arrhenius plot used to compute the time constant of the ion channel. 展开更多
关键词 frequency Switches at Transition Temperature in Voltage-Gated Ion Channel Dynamics of Neural Oscillators
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Finite-Control-Set Model Predictive Control of Permanent Magnet Synchronous Motor Drive Systems——An Overview 被引量:6
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作者 Teng Li Xiaodong Sun +3 位作者 Gang Lei Zebin Yang Youguang Guo Jianguo Zhu 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2022年第12期2087-2105,共19页
Permanent magnet synchronous motors(PMSMs)have been widely employed in the industry. Finite-control-set model predictive control(FCS-MPC), as an advanced control scheme, has been developed and applied to improve the p... Permanent magnet synchronous motors(PMSMs)have been widely employed in the industry. Finite-control-set model predictive control(FCS-MPC), as an advanced control scheme, has been developed and applied to improve the performance and efficiency of the holistic PMSM drive systems. Based on the three elements of model predictive control, this paper provides an overview of the superiority of the FCS-MPC control scheme and its shortcomings in current applications. The problems of parameter mismatch, computational burden, and unfixed switching frequency are summarized. Moreover, other performance improvement schemes, such as the multi-vector application strategy, delay compensation scheme, and weight factor adjustment, are reviewed. Finally, future trends in this field is discussed, and several promising research topics are highlighted. 展开更多
关键词 Computational burden finite control set(FCS) model predictive control(MPC) permanent magnet synchronous motor(PMSM) robust operation switching frequency
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Development of High-Speed On-Of Valves and Their Applications 被引量:3
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作者 He Wang Zhen Chen +2 位作者 Jiahai Huang Long Quan Bin Zhao 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2022年第4期21-41,共21页
With the widespread application of the computer and microelectronic technology in the industry,digitization becomes the inevitable developing trend of the hydraulic technology.Digitization of the hydraulic components ... With the widespread application of the computer and microelectronic technology in the industry,digitization becomes the inevitable developing trend of the hydraulic technology.Digitization of the hydraulic components is critical in the digital hydraulic technology.High-speed on-of valves(HSVs)which convert a train of input pulses into the fast and accurate switching between the on and of states belong to widely used basic digital hydraulic elements.In some ways,the characteristics of the HSVs determine the performance of the digital hydraulic systems.This paper discusses the development of HSVs and their applications.First,the HSVs with innovative structures which is classifed into direct drive valves and pilot operated valves are discussed,with the emphasis on their performance.Then,an overview of HSVs with intelligent materials is presented with considering of the switching frequency and fow capacity.Finally,the applications of the HSVs are reviewed,including digital hydraulic components with the integration of the HSVs and digital hydraulic systems controlled by the HSVs. 展开更多
关键词 High-speed on-of valve Digital hydraulic component switching frequency Flow rate Innovative structure Intelligent material
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An Approach towards Pulse Data Transmission Using Modified Negative Luo Converter (MNLC) for Telecoms
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作者 V. Chamundeeswari Dr. R. Seyezhai 《Circuits and Systems》 2016年第9期2712-2728,共17页
Telecom sectors generally operate at negative voltages to reduce the effect of corrosion caused in the metallic wire due to electrochemical reaction while communicating signals. To feed those lines and to have an effe... Telecom sectors generally operate at negative voltages to reduce the effect of corrosion caused in the metallic wire due to electrochemical reaction while communicating signals. To feed those lines and to have an effective digital data transmission, a power electronic converter referred as Modified Negative Luo Converter (MNLC) is proposed in this paper. MNLC is a high gain converter in which the output voltage increases in geometric progression. This paper portrays a novel concept of a 50 Hz pulse data transmission through RLCG (Resistance-inductance-capacitance with a shunt conductance) transmission line using MNLC. Signal frequency of 50 Hz to be transmitted is anded with a high frequency pulse that charges and discharges MNLC and produces the boosted negative output voltage. The boosted output is again transmitted through the RLCG transmission line from which 50 Hz data pulse is retrieved at the output of the transmission line by comparing with a comparator signal. This sort of MNLC aided data transmission not only introduces less loss in its transmitted data but also overcomes various health hazards of conventional radio frequency (RF) communication. This technique also proves that any data bit stream can be transmitted and retrieved using the proposed high gain DC-DC converter. The simulation model of the proposed system is implemented in MATLAB for various switching frequencies with its prototype of the converter developed and the results are verified. 展开更多
关键词 Pulse Data Transmission MNLC RLCG Line switching frequency High Gain Converter
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Load Torque Compensator for Model Predictive Direct Current Control in High Power PMSM Drive Systems
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作者 M. Preindl E. Schaltz 《Journal of Energy and Power Engineering》 2011年第6期554-561,共8页
The widely used cascade speed and torque controllers have a limited control performance in most high power applications due to the low switching frequency of power electronic converters and the convenience to avoid sp... The widely used cascade speed and torque controllers have a limited control performance in most high power applications due to the low switching frequency of power electronic converters and the convenience to avoid speed overshoots and oscillations for lifetime considerations. Model Predictive Direct Current Control (MPDCC) leads to an increase of torque control performance taking into account the discrete nature of inverters but temporary offsets and poor responses to load torque variations are still issues in speed control. A load torque estimator is proposed in this paper in order to further improve dynamic behavior. It compensates the load torque influence on the speed control setting a feed forward torque reference value. The benefits are twice; the speed controller reaches the speed reference value without offsets which would need to be compensated by an integrator and a better response to load torque variations is obtained since they are detected and compensated leading to small speed variations. Moreover, the influence of pararneter errors and disturbances has been analyzed and limited so that they play a minor role in operation. 展开更多
关键词 Drive systems model predictive control (MPC) current control switching frequency optimization.
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ANALYSIS AND MEASUREMENT OF LARGE DYNAMIC RANGE RF SWITCH INTER-MODULATION
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作者 Han Zhouan 《Journal of Electronics(China)》 2008年第3期422-427,共6页
Radio Frequency (RF) switch circuit is the basic part of microwave devices and systems. The non-linearity distortion figure is necessary in the field of large dynamic range of signal. This letter analyzes the basic sw... Radio Frequency (RF) switch circuit is the basic part of microwave devices and systems. The non-linearity distortion figure is necessary in the field of large dynamic range of signal. This letter analyzes the basic switch circuit and its inter-modulation, and studies in detail the measurement methods and systems of RF switch intercept point. It has provided cascaded simulation testing methods, which can accurately measure the PF switch, of which the second or third order intercept point value is above 75dB and 60dB, respectively. As the testing results are consistent with the theoretical analyses, it proves that the validity of the method satisfies the requirements of large scaled linearity measurement in engineering. 展开更多
关键词 Large dynamic range Radio frequency (RF) switch Intercept point MEASUREMENT
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An Improved Modulation Strategy for Single-phase Three-level Neutral-point-clamped Converter in Critical Conduction Mode
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作者 Ning Li Yujie Cao +4 位作者 Xiaokang Liu Yan Zhang Ruotong Wang Lin Jiang Xiao-Ping Zhang 《Journal of Modern Power Systems and Clean Energy》 SCIE EI CSCD 2024年第3期981-990,共10页
Two-level totem-pole power factor correction(PFC)converters in critical conduction mode(CRM)suffer from the wide regulation range of switching frequency.Besides,in highfrequency applications,the number of switching ti... Two-level totem-pole power factor correction(PFC)converters in critical conduction mode(CRM)suffer from the wide regulation range of switching frequency.Besides,in highfrequency applications,the number of switching times increases,resulting in significant switching losses.To solve these issues,this paper proposes an improved modulation strategy for the single-phase three-level neutral-point-clamped(NPC)converter in CRM with PFC.By optimizing the discharging strategy and switching state sequence,the switching frequency and its variation range have been efficiently reduced.The detailed performance analysis is also presented regarding the switching frequency,the average switching times,and the effect of voltage gain.A 2 k W prototype is built to verify the effectiveness of the proposed modulation strategy and analysis results.Compared with the totem-pole PFC converter,the switching frequency regulation range of the three-level PFC converter is reduced by 36.48%and the average switching times is reduced by 45.10%.The experimental result also shows a 1.2%higher efficiency for the three-level PFC converter in the full load range. 展开更多
关键词 Critical conduction mode(CRM) on-board charger switching frequency range switching times power factor correction(PFC) three-level converter
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Mixed Dead-time Effect Suppression Strategy for Modular Multilevel Converters
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作者 Zhi Geng Minxiao Han 《CSEE Journal of Power and Energy Systems》 SCIE EI CSCD 2024年第3期1075-1084,共10页
Dead time is necessary for the coupled power switches to prevent shoot-through,especially in the modular multilevel converters(MMCs)with a large number of power switches.This paper proposes a dead-time effect suppress... Dead time is necessary for the coupled power switches to prevent shoot-through,especially in the modular multilevel converters(MMCs)with a large number of power switches.This paper proposes a dead-time effect suppression strategy for MMCs with nearest level modulation.The operational principles of MMCs are first analyzed.According to the operational features of MMCs,the method that removes a switching signal from the coupled switches and the reduced switching frequency voltage balancing algorithms(RSFVBAs)are mixed in the proposed method.In the intervals that are furthest away from the zerocrossing points(ZCP)of arm currents,the single switching signal method can completely eliminate the dead-time effect(DTE).Alternatively,the DTE is suppressed by the RSFVBA in intervals that are close to the ZCP.By the combination of the two methods,the dependence of the DTE suppression method on currents is reduced and the influences of ZCP are also released without degrading the normal operation performance of MMCs.Moreover,the output performance of MMCs is improved and the voltage stress on the arm inductor dramatically decreases.Finally,the validation of the method is verified by the simulation results with the professional tool Matlab/Simulink. 展开更多
关键词 Dead-time effect modular multilevel converters switching frequency voltage balancing algorithm
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Direct Power Control Based on Dead-beat Function and Extended Kalman Filter for PV Systems
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作者 Mostafa Ahmed Ibrahim Harbi +1 位作者 Ralph Kennel Mohamed Abdelrahem 《Journal of Modern Power Systems and Clean Energy》 SCIE EI CSCD 2023年第3期863-872,共10页
In this paper,a new proposal for the implementation of the well-known direct power control(DPC)technique in grid-connected photovoltaic(PV)systems is suggested.Normally,the DPC is executed using a look-up table proced... In this paper,a new proposal for the implementation of the well-known direct power control(DPC)technique in grid-connected photovoltaic(PV)systems is suggested.Normally,the DPC is executed using a look-up table procedure based on the error between the actual and reference values of the active and reactive power.Thus,the structure of the DPC is simple and results in a fast transient behavior of the inner current loop(injected currents).Therefore,in the current study,the DPC is reformulated using a dead-beat function.In this formulation,the reference voltage vector(RVV)is obtained in theα-βreference frame.Consequently,the switching states for the inverter can be obtained based on the sign of the components of the RVV.The suggested DPC is compared with the conventional one and other switching tables,which are intended for performance enhancement.Furthermore,an extended Kalman filter(EKF)is utilized to eliminate all grid-voltage sensors.Moreover,the switching frequency of the proposed technique is minimized without any need for weighting factors or cost function evaluation.The overall control technique is validated using a hardware-in-the-loop(HIL)experimental set-up and compared with other schemes under different operating conditions. 展开更多
关键词 Photovoltaic(PV)system direct power control(DPC) sensorless control switching frequency minimization weighting factor
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Monte-Carlo simulation of effective stiffness of time-sharing optical tweezers 被引量:1
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作者 任煜轩 吴建光 +1 位作者 钟敏成 李银妹 《Chinese Optics Letters》 SCIE EI CAS CSCD 2010年第2期170-172,共3页
The Brownian motion of a polystyrene bead trapped in a time-sharing optical tweezers (TSOT) is numerically simulated by adopting Monte-Carlo technique. By analyzing the Brownian motion signal, the effective stiffnes... The Brownian motion of a polystyrene bead trapped in a time-sharing optical tweezers (TSOT) is numerically simulated by adopting Monte-Carlo technique. By analyzing the Brownian motion signal, the effective stiffness of a TSOT is acquired at different switching frequencies. Simulation results confirm that for a specific laser power and duty ratio, the effective stiffness varies with the frequency at low frequency range, while at high frequency range it keeps constant. Our results reveal that the switching frequency can be used to control the stability of time-sharing optical tweezers in a range. 展开更多
关键词 Brownian movement Electric power supplies to apparatus Interference suppression Optical instruments POLYSTYRENES STIFFNESS switching frequency
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