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Microelectromechanical system (MEMS) oscillators are conventionally designed so that the resonator is operated within the linear regime. This paper investigates an optimal low noise point for a nonlinear MEMS oscillator where phase noise to frequency noise conversion is minimized. A closed loop oscillator consisting of a digitally controlled phase shifter is implemented and measurements of frequency stability are conducted under varying phase feedback conditions. The measured results show that for a specific value of feedback phase, the oscillation frequency is independent of phase fluctuations. Enhanced frequency stability is achieved when the MEMS resonator is biased at the optimal phase feedback condition in the non-linear regime.

This paper proposes an enhanced sensorless vector control strategy using the predictive deadbeat algorithm for a direct-driven permanent magnet synchronous generator (PMSG). To derive favorable sensorless control performances, an enhanced predictive deadbeat algorithm is proposed. First, the estimated back electromotive force (EMF), corrected by a cascade compensator, was put into a deadbeat controller in order to improve the system stability, while realize the null-error tracking of the stator current at the same time. Subsequently, an advance prediction of the stator current based on the Luenberger algorithm was used to compensate the one-step-delay caused by digital control. Maintaining the system stability, parameters of the controller were optimized based on discrete models in order to improve the dynamic responses and robustness against changes in generator parameters. In such cases, the proposed methodology of synchronous rotating frame phase lock loop (SRF-PLL), which applies the estimated back EMF, can observe the rotor position angle and speed without encoders, realizing the flux orientation and speed feedback regulation. Finally, the simulation and experimental results, based on a 10-kW PMSG-based direct-driven power generation system, are both shown to verify the effectiveness and feasibility of the proposed sensorless vector control strategy.

The WD40 proteins, often acting as scaffolds to form functional complexes in fundamental cellular processes, are one of the largest families encoded by the eukaryotic genomes. Systematic studies of this family on genome scale are highly required for understanding their detailed functions, but are currently lacking in the animal lineage. Here we present a comprehensive in silico study of the human WD40 family. We have identified 262 non-redundant WD40 proteins, and grouped them into 21 classes according to their domain architectures. Among them, 11 animal-specific domain architectures have been recognized. Sequence alignment indicates the complicated duplication and recombination events in the evolution of this family. Through further phylogenetic analysis, we have revealed that the WD40 family underwent more expansion than the overall average in the evolutionary early stage, and the early emerged WD40 proteins are prone to domain architectures with fundamental cellular roles and more interactions. While most widely and highly expressed human WD40 genes originated early, the tissue-specific ones often have late origin. These results provide a landscape of the human WD40 family concerning their classification, evolution, and expression, serving as a valuable complement to the previous studies in the plant lineage.

In this paper, the influence of different environmental conditions, substrates, micromachining processes, areas and patternings on the performances of PECVD SiO2/Si3N4 double-layer electrets were studied for its application in micro-devices. Various samples were prepared and then charged by the negatively corona charging method. The charge decays at either 250°C or 95%RH were observed to reveal the chargeability and charge stability. Finally, a micro power generator with patterned PECVD SiO2/Si3N4 double-layer electret was presented briefly as demonstration. The results show that all these conditions that conventionally or even unavoidably happen in the fabrication process of electret micro-devices had more or less impact on the electret performance. It is crucial that the electret should be as large area as possible and kept from the micromachining processes and humid condition to the best. Our micro power generator with 2mm rectangular array of PECVD SiO2/Si3N4 double-layer electret had the 5μW output power at 20Hz and 0.7g.

For doubly fed induction generator (DFIG)-based wind turbine (WT), large electromotive force will be induced in the rotor circuit under grid faults, and the rotor side of DFIG is prone to suffering from overcurrent and overvoltage. To mitigate this problem, an inductance-simulating control strategy is proposed to enhance its low-voltage ride through (LVRT) capability. In this method, the rotor side converter (RSC) is controlled to simulating as an inductance. Furthermore, under proper inductance value, both the required rotor voltage and postfault rotor current can be reduced within the permissible range. In addition, the electromagnetic torque ripple can be effectively eliminated. Finally, the simulation and experimental results clearly demonstrate the effectiveness of the proposed method.

This paper presents a control strategy to improve the low-voltage ride-through capability of a doubly fed induction generator (DFIG); since the stator of a DFIG is directly connected to a grid, this sort of machine is very sensitive to grid disturbance. Grid voltage sag causes overcurrents and overvoltages in rotor windings, which can damage the rotor-side converter (RSC). In order to protect the RSC, a classical solution based on installation of the so-called crowbar is adopted; however, as the DFIG absorbs reactive power from the grid, this type of solution deteriorates grid voltage sags and cannot meet the requirements of a new grid code. An improved control strategy which uses virtual resistance to limit rotor side overcurrents is proposed in this paper, which can make a crowbar inactive and supply reactive power to fulfill the latest grid code requirement during voltage sags. In order to validate the proposed strategy, simulations and experiments have been carried out, and the results demonstrate the effectiveness of the proposed strategy.

In this paper, performance of PECVD SiO2/Si3N4 double layers electrets with different thicknesses were investigated detailedly in respect of chargeability, storage charge stability in high temperature and reliability in high humidity environment. Samples with different thicknesses of Si3N4 and SiO2 were prepared on Pyrex 7740 glass substrates and characterized by isothermal and high humidity charge decay. The results of experiment approved that the PECVD SiO2/Si3N4 double layers electrets on glass substrate has as good chargeability and charge stability in high temperature and high humidity environment as thermal oxidation or APCVD/LPCVD ones on silicon substrates. The experiment results indicated that a Si3N4 layer no less than 50 nm is necessary for good charge stability in high temperature and a Si3N4 layer thicker than 500 nm decreases the chargeability. Even a 2 nm Si3N4 layer is enough to significantly improve the charge stability in high humidity environment. Thick SiO2 layer can increase the surface potential of electrets under the same charging condition and its charge stability in high temperature. However, the electrets with high surface potential also exhibit poor uniformity of charge stability in high humidity environment.

In this paper, multiple approaches were attempted to improve the performance of PECVD SiO2/Si3N4 double-layer electrets on glass, including different electrode structures, as well as various corona charging conditions. Both chargeability and charge stability of the PECVD SiO2/Si3N4 double-layer electret at high temperature and high humidity were investigated. It is proven that samples with both lower and back electrodes has simpler process but exhibits similar chargeability and charge stability to those having lower electrode contact with ground directly by welding lead. High charging temperature can increase chargeability but has no effect on charge stability melioration. Long-term observation implies that if the electrets have to work outside properly, heat treatment will be necessary, although hermetic packaging is the best option. PECVD SiO2/Si3N4 double-layer electrets can endure high temperature lower than 250°C and shows good charge stability under high humidity.

We report on the characterization of a high-resolution micromachined resonant accelerometer fabricated in an SoI-microelectromechanical (MEMS) foundry process. A prototype device demonstrated scale factor of 142.8 Hz/m/s 2 , dynamic range of >140 dB, and noise-limited resolution that is comparable with existing high-resolution macroscale seismometers. Experimental characterisation detailing the benchmarking of the MEMS prototype relative to an existing macroscale seismometer shows that the MEMS device tracks the passive ambient seismic response measured by a macroscale seismometer (Guralp systems CMG-3TD) over a measurement bandwidth extending from near dc (0.02 Hz) up to 100 Hz.

Dual-loop PI control strategy for LCL type grid-connected converter is usually used in wind power generation. Serious inrush current will be caused when grid-connected converter runs on the rectified status at the start time if no effective control strategy is taken, so it is necessary to improve the startup control performance and the grid voltage feedforward method is usually used. However, in wind power generation, the grid voltage of the transformer's high voltage side can't be directly sampled. To deal with it, a method is proposed based on the feedforward of filter capacitor branch's voltage. Firstly, the mathematical model of LCL type grid-connected converter, under the synchronous rotating reference frame, is established. And the cause of inrush current at the rectified start time of grid-connected converter is analyzed in detail. Then, the feedforward of capacitor branch's voltage is introduced into the output of current loop, and the theoretical analysis on its effectiveness of inrush current suppression is made. Finally, the simulation analysis based on the 10kW LCL type grid-connected converter and the experiments based on the 10kW direct drive wind power grid-connected converter prototype are carried out. The results verify that this method can effectively suppress startup inrush current and improve dynamic response of the grid current control.

For doubly fed induction generation (DFIG) based wind turbine, large electromotive force will be induced in the rotor circuit under severe grid faults, and it usually far exceeds the DC-bus voltage. In that case, it is necessary to inject transient and negative-sequence components into rotor current reference to fulfill controllable low-voltage ride through (LVRT). On the synchronous reference frame of vector control system, such current references are 50 Hz and 100 Hz AC items, respectively. Thus, the classical proportional-integral (PI) controller cannot accurately track this AC reference. To solve this problem, a feedforward current reference (FFCR) control scheme is proposed to improve the tracking capability of AC reference. Hence, it unearths the characteristics of such reference. The proposed FFCR control scheme will not alter the stability of original current loop. Furthermore, it has strong robustness for frequency fluctuations of grid voltage and DFIG parameters drift. Finally, simulation and experimental results are presented to demonstrate the effectiveness of the proposed control scheme.

Brushless Doubly-Fed Induction Generator (BDFIG) is potential for power generation applications for its high reliability and low maintenance-cost. There are two operation modes for BDFIG: grid-tied and stand-alone modes. The grid-tied mode usually uses the power winding (PW) synchronous and orientation frame since PW is connected to the grid; however in stand-alone mode, the PW is connected to the load rather than the grid, the control winding (CW) synchronous and orientation frame would be preferred. In order to improve the performance of stand-alone power generation system, this paper presents the CW synchronous frame model of BDFIG, and three kinds of orientation methods aiming to further simplify the BDFIG control are deduced and compared. Based on the derivations, the proper current inner-loop and voltage outer-loop structures (dual-loops) are also designed and compared. The experimental system based on one of the orientation methods is also built, and experimental results show the validity of the mathematical model and the adapted control structure.

This paper proposed a positive sequence detector (PSD) based on cascaded delayed quadrature signal cancellation (CDQSC). The delayed quadrature signal cancellation (DQSC) operator based on two orthogonal signals in dq-frame or αβ-frame can be tailored to eliminate any specified harmonic. The proposed DQSC operator can be further cascaded to stepwise reject all undesired harmonics. Then the conditioned voltage signal can be used in phase locked loop (PLL) to obtain the positive sequence component accurately and fast. When the frequency of the three-phase signal is variable, the detector also realizes frequency adaptability by introducing a frequency feedback loop (FFL). Experimental results show that the proposed PSD is effective and feasible.

This paper reports on a vacuum packaged resonant MEMS accelerometer that demonstrates some of the highest sensitivities reported to-date and a ∼7x scale factor enhancement relative to a recently reported prototype, benefiting from a larger proof mass and improved leverage amplification factor. The device describes a scale factor of 960 Hz/m/s2 over a dynamic range of approximately +/− 0.5 m/s2. The experimentally measured intrinsic noise limited resolution of the accelerometer is less than 150 ng/√Hz in the frequency range from < 1 Hz up to 50 Hz.

It is necessary to insert a dead-time in sinusoidal pulse width modulation (SPWM) voltage source inverter (VSI) to prevent a short circuit in the DC link. However, this will cause the dead-time effect, drop the fundamental voltage and introduce the 3rd, 5th and 7th low-order harmonics into the output voltage. Conventional dead-time compensation methods either average voltage based or inductor current feedback compensation cannot be adopted in the case of high inductor ripple current. Moreover, even with high-precision detection of the inductor current polarity, the conventional methods are still not suitable when unipolar frequency doubling SPWM method is adopted. Dead-time effect is different when different SPWM methods are used. In this paper, dead-time effect of unipolar frequency doubling SPWM is analyzed and a new approach for eliminating low-order harmonics is proposed. Simulation and experiment on a 400-Hz prototype both show satisfactory results and verify the validity of the analysis and the effectiveness of the proposed control method.

Three-phase active damping LCL-type grid-connected converters are usually used in distributed power generation systems. However, serious inrush current will be aroused when the grid-connected converter starts, especially in rectifier mode, if no effective control method is taken. The point of common coupling (PCC) voltage feedforward is usually used to suppress start-up inrush current. Unfortunately, it will introduce a positive feedback loop related to the grid current and grid impedance under weak grid conditions, and therefore, the grid current will be distorted and the system stability margin will be significantly reduced. To solve the above problems, this paper proposes a simple method based on a d-axis fundamental positive-sequence component of filter capacitor voltage feedforward, without extra sensors and software resources. With the proposed method, it is possible to suppress the start-up inrush current and maintain the grid current quality and system stability under weak grid conditions. The mechanism of start-up inrush current and the effectiveness of the method for inrush current suppression are analyzed in detail. Then, the influences of different feedforward methods on system stability are analyzed under weak grid conditions by the impedance model of grid-connected converter. Finally, experimental results verify the validity of the proposed method.

DFIG is very sensitive to grid voltage disturbance, grid voltage dip and recovery may cause overcurrents an overvoltages in rotor windings, which can damage the rotor side converter(RSC). The transient behavior of DFIG under voltage dip has been studied in many literatures, but the behavior of DFIG under voltage recovery after voltage dip is seldom reported, the transient behavior of DFIG during voltage recovery after balanced and unbalanced voltage dip are theoretically analyzed in this paper, in order to validate theory analysis, simulations have been carried out, the results are consistent with proposed theoretical analysis.

In order to protect the converter of doubly fed induction generator(DFIG) and realize low voltage ride through(LVRT) during grid faults, the crowbar is usually used , since the resistor value of the crowbar effects DFIG's rotor current, reactive power output and electrical torque, it 's design is very crucial for LVRT.A novel optimal design of DFIG crowbar resistor for fault ride-through is proposed in this paper, simulations have been carried out to validate the proposed optimal design, the results demonstrate its effectiveness.

Non-isolated single-inductor three-port converters (SI-TPCs) are the cost-effective way to connect the renewable source, energy-stored component and load for those stand-alone applications without isolation requirements. However, the dynamic features of SI-TPCs are complicated due to the multiport, bidirectional energy flowing and a variety of energy management modes. To facilitate the control-loop design, this paper deduces the general average equations for the SI-TPCs, and then proposes the available small-signal models for different energy management modes. According to the analysis results, the smoothing switching among different energy management modes is also presented. The experimental results are also given to verify the validity of the analysis.

This paper reports a high-resolution frequency-output MEMS tilt sensor based on resonant sensing principles. The tilt sensor measures orientation by sensing the component of gravitational acceleration along a specified input axis. A combination of design enhancements enables significantly higher sensitivity for this device as compared to previously reported prototype sensors. The MEMS tilt sensor is calibrated on a manual tilt table over tilt angles ranging over 0-90 degrees with a relatively linear response measured in the range of ±20°(linearity error

This paper has proposed a sensor-less control strategy for direct-driven permanent magnet synchronous generator (PMSG). Synchronous rotating frame phase lock loop (SRF-PLL) that employs model based back elector-motive force (EMF) estimation is utilized to derive rotor position angle and speed. To steadily achieve the sensor-less vector control, a first order compensator is applied in cascade with the estimated back EMF. Then, an improved dead-beat controller based on luenberger predictive algorithm is presented to compensate for the one-step delay, further enhancing the robustness against motor parameter deviations and whole sensor-less control performance. Finally, experimental results are shown to illustrate that proposed sensor-less strategy and controller design scheme could well achieve high performance vector control of the PMSG.

The AC power source can be tested by the PEL (Power Electronic Load) expediently and economically. The GCC(Grid-Connection Converter) of the PEL should send back the recycling energy to the utility grid with high power factor and low harmonics components. Considering that the single phase PEL can be widely used to test the single phase or three phase power source, the single phase PEL is analyzed in the paper. The paper gives the electrical model and the control scheme based on the GCC's circuits, and analyzes the harmonic components based on the structure and the function of the PEL. The effects of the notch filter, low-pass filter and mean filter are compared, and the mean filter has been chosen to filter the harmonics components mixed with the dc voltage, for its perfect steady-state characteristics. Large inertia links such as DC capacitor with large capacity and means filter deteriorate the dynamic characteristics, a small signal model based on active power balance is constructed, and feedforward control strategy is applied to ensure the whole system with perfect dynamic response when the input voltage, input current and grid voltage flicker fluctuate. The improved repetitive controller is employed to ensure the inner current loop with zero-errors track characters and hold the GCC with near unity power factor. The experimental and simulation results show that the analysis in the paper is right and the new control scheme is effective. The conclusion can be applied in the control strategy of GCCs, which are used in the distributed power supply system such as Photovoltaic power generations.

This paper proposes a novel 3-D space vector modulation scheme for three-level three-leg neutral point clamped converter used in the three-phase four-wire active power filter towards the performance optimization among load harmonic current compensation, mid-point voltage balancing, and Suppression of switching loss increase. Optimization functions for different objectives are analyzed based on the detailed state space equations of the system. Furthermore, a multi-objective optimization process is presented to show how the compensation for the load harmonic current, mid-point balancing control, and switching losses reduction can be optimized based on the solution space of linear equations. Lastly, the simulation and experimental results are given for verification purpose.

This paper presents a control strategy to enhance the capability of doubly-fed induction generator(DFIG) based system during grid voltage unbalance, in which the model of DFIG is derived and analyzed. Active power, reactive power and generator torque are also defined under these conditions, based on these analyses, the control targets of RSC are discussed and positive and negative components are controlled in positive and negative synchronous reference frame respectively. Traditionally, low pass or band stop filter is used to extract positive and negative component, but the intrinsic time delay may cause slow response speed and make the system unstable. Hence, a fast decomposition algorithm instead of using low pass or notch filter is used to decompose positive and negative sequence, in order to validate the proposed strategy, simulations have been carried out, the results demonstrate the effectiveness of the proposed strategy.

According to the situation that the power system can only defense the fault passively, a new FACTS device, which is called flexible power conditioner (FPC), based on flywheel energy storage system is proposed.. This device, which employed new technologies such as AC excitation, VSCF and vector control, combines the flywheel energy storage with the traditional phase synchronization technology. FPC can modulate phase, store and generate energy, which can stabilize power system actively. The control strategy and method of FPC is discussed. A 10kVA excitation control system of FPC was developed. Experiment results reflect that this device can quickly and enormously modulate the active power and reactive power in four-quadrant, which makes power system stability possible. Ill. 9, bibl. 12, tabl. 1 (in English; abstracts in English and Lithuanian). http://dx.doi.org/10.5755/j01.eee.115.9.739

Conventional adaptive current detection methods are always terribly disturbed by the “mutual erroneous impacts”, which are due to the low SNR (Signal-to-Noise Ratio) utility conditions, so it is difficult to make an optimal tradeoff between the speed and accuracy of those adaptive methods. This paper has proposed a novel adaptive current detection method, where a sliding integration filter (SIF) was applied to eliminate the disturbances by other current components and to derive the real amplitude estimation errors of target current components. Then, adaptive detection closed-loop systems were constructed based on the internal model theory so as to extract the target current components from the distorted load current rapidly and accurately. The mathematical model of the proposed adaptive method was presented, and its performances including system convergence, dynamic and steady-state responses were also illustrated by analytic methods of control theory so that theoretical instructions could be provide for designing the adaptive current detection method. Finally, simulation and experimental results of the proposed novel detection method and previous methods are compared, which verify the correctness and effectiveness of the proposed theory and method.

According to software and hardware requirements of brake test-bed structure, this paper introduced overall plan and main parameters selecting method of related equipments, provided control strategy for variable electrical inertia. Authors had established automobile brake test-bed which is based on electrical inertia simulation technology, and had completed the simulation test and result analysis. The analysis results indicate that the margin between simulation of brake process and actual braking process is small, electrical inertia could simulate mechanical inertia. Applying the electrical inertia simulation technology could simplify structure of the traditional mechanical inertia test-bed which formerly is complicated, could expand the measuring scope and measuring accuracy of the test-bed, and could provide tools and platform for the brake performance test and experiment teaching.

From software demand analysis on brake test-bed that based on the electric inertia technology, the problems and the main ideas of testing software development were described. The software was divided into foreground interaction and background processing in accordance with software structure. The functions of the two parts were defined respectively. According to specific functional demands of the software, the detailed function modules of the software were described. The function analysis and graphics code of the test software was presented.

In a Flywheel Energy Storage system (FESS), the power conditioning system is the key component of controlling power transfer between the Flywheel and the power system. The dynamics of the power conditioning system directly affect the effect of FESS in dynamic regulation of power system. In this paper, power conditioning system which is made up of a doubly-fed induction machine (DFIM) connected with flywheel, a back-to-back converter for AC excitation and an excitation vector control system is studied. The excitation control strategy is presented for FESS DFIM to improve transient stability and increase transfer capability of power systems. The proposed control method has good dynamics that can respond to the system power demand quickly and accurately. Moreover, the proposed control method has good robust characteristic and applicability to improve the performance of power conditioning system. Simulation and experiment results are performed to evaluate the performance of the proposed control method.

This paper reports on a switchable multi-band filter response achieved within a single micro-electro-mechanical device. A prototype device fabricated in a SOI process demonstrates a voltage programmable and tunable, dual-band, band-pass/band-stop response. Both analytical and finite element models are introduced in this paper to elucidate the operating principle of the filter and to guide filter design. Voltage programmability of the filter characteristic is demonstrated with the ability to independently tune the centre frequency and bandwidth for each band. A representative measurement shows that the minimum 3 dB-bandwidth (BW) is 155 Hz, 140Hz, and 20 dB-BW is 216 Hz, 203Hz for the upper-band and lower-band center frequencies located at 131.5 kHz and 130.7 kHz, respectively.

This paper main focus on the 3-D modulation scheme and neutral-point unbalance problem of 3-level 3-leg converter for Active Power Filters. The neutral point unbalance problem is a key issue for this topology based APFs. To date there hasn't any perfect 3-D modulation solutions to tackle with neutral point unbalance problem well. In this paper, a detailed discussion on this issue is carried out. The relationship between the neutral point potential and the relative voltages and currents is analyzed in this paper. Then a new concept named Factor of neutral-point balance (Fn) is proposed and the calculation formula is derived. Basing on Fn, a novel 3-D modulation scheme is proposed in a-b-c coordinates. By measuring the output currents and DC voltages, Fn is calculated in every sampling period and the most fit space vectors are selected to approximate the reference vector. In addition, a concept called Neutral Point Control Grade (NPCG) and another concept named average-NPCF (A-NPCG) are utilized in this paper to evaluate the control capability of neutral point potential control scheme. The simulation and experiment results verified the correctness and validity of this novel 3DSVM scheme.

This paper presents a 4-bit RF microelectromechanical system (MEMS) wide-band tunable filter at the 10–14GHz frequency range. Open-ended shunt stubs is utilized to load RF MEMS capacitive switches and MAM capacitors acting as the tunable cells, and leads to lower loss and more flexibility of design. The simulation results obtained by 3D electromagnetic simulation tool show that the tuning range is about 30% (from 10.5GHz to 13.5GHz) and the insertion loss is from −4.8dB to −5.2dB.

Vehicle guidance system (VGS) is one of important contents of intelligent transportation system (ITS). However, in many developing countries, VGS is backward. To heighten level of VGS of China, the composition of VGS, the functions of subsystems were studied, and critical technologies, such as geographic information system (GIS), global positioning system (GPS), were applied into the systems. In order to reduce storage space of road network, the storage mode is improved by adjacent node relation matrix and adjacent node weight matrix. The classical shortest path algorithm, Dijkstra algorithm, was optimized with dynamic adjacent node relation matrix and dynamic adjacent node weight matrix, which enhance the efficiency of calculation for shortest path, and the specific algorithm is presented. The studied VGS based on GIS, GPS, and other technologies was realized. Preliminary application of the VGS show the system can exactly position vehicle, real-timely display running track of vehicle, effectively calculate shortest path, rightly guide diver driving and so on.

In this paper, charge decay of PECVD SiO2/Si3N4 double layers electrets with different thicknesses of Si3N4 under different environmental conditions was investigated. Single layers of PECVD prepared SiO2 and Si3N4 were also studied. Double layers electrets exhibits better charge stability than single layer under different conditions. As for the double layers with 2 nm-100 nm Si3N4, their charge stability at 250°C is as good as each other. However, if the Si3N4 thickness continues to increase, the charge stability will be decreased. Thicker layer of Si3N4 leads to better charge stability under 95%RH. Heat treatment at 250°C can improve charge stability under high humidity condition, especially for double layers electrets with thin Si3N4. After heat treatment at 250°C for 3hrs, the PECVD SiO2/Si3N4 double layers electrets with 50 nm Si3N4 show the optimized charge stability under different conditions.

The conventional modulation strategies for diode-clamped three-phase three-level inverter have some disadvantages, such as switching loss of switching device. This paper presents a novel space vector pulse width modulation (SVPWM) scheme to reduce switching loss. Using this novel modulation strategy, the changing of switch states cause only one single phase voltage change every time. In this way, the inverter generates similar output voltage as that under the common strategies, whereas the switching loss is reduced. The proposed scheme has been digitally implemented by using TMS320F240 and its feasibility has been verified by the experimental results.

Pulse power supply applications usually require short and intense bursts of energy that may be derived by rapidly discharging an energy storage capacitor. Series resonant topology is used in capacitor charging power supply because of its approximate constant current characteristic from zero volts to maximum voltage. But the series resonant topology with open-loop control is not accurate constant current charging characteristic because the DC bus voltage is variable and the transformer is not ideal. Furthermore, the high voltage rectifier diodes are also not ideal. This paper presents the current characteristic of series resonant power supply with ideal and actual components, respectively. And moreover, some valuable figures given in this paper can be used during the course of designing and debugging.

This paper describes a simplified model of induction motor based on voltage decoupling control principle for speed sensorless vector-controlled induction drive system. The model consists of two subsystems, the rotor flux and torque current subsystems, and is conveniently to solve the problems of voltage coupling. According to this model, a speed identification method is presented for a speed sensorless vector-controlled induction motor drive system, which uses t axis flux to obtain rotor speed. The validity of the proposed method is verified by computer simulation and experiment results.