二冲程汽油机多传感器电控倒行驶变换装置

利用二冲程汽油机做动力的超微型汽车大都不设倒档,即使设倒挡也是靠附加一个倒档箱来实现,这种方式的缺点是倒档箱串联在动力传递环节中,始终消耗着车辆本来就不很充足的功率,同时还得多一个倒车控制杆。早期出现过的双触点倒转装置也由于全电子点火装置的普及而被淘汰,因而必须寻求一种新的办法来解决这个问题。

Speed Sensorless Vector Control of Induction Motor Based on Reduced Order Extended Kalman Filter

A speed sensorless vector control system of induction motor with estimated rotor speed and rotor flux using a new reduced order extended Kalman filter is proposed. With this method, two rotor flux components are selected as the state variables, and the rotor speed as an estimated parameter is regarded as an augmented state variable. The algorithm with reduced order decreases the computational complexity and makes the proposed estimator feasible to be implemented in real time. The simulation results show high accuracy of the estimation algorithm and good performance of speed control, and verify the usefulness of the proposed algorithm.

Anti-reverse rotation startup method for sensorless brushless DC motor

In order to start up the brushless DC motor （BLDCM） without reverse rotation and smoothly switch the running state of the motor, a novel startup and smoothly switching method for a sensodess BLDCM is presented. Based on the saturation effect of the stator iron, six short voltage pulses are applied to determine the initial rotor position and the rotor can be found within 60°. After that, a series of short and long voltage pulses are used to accelerate the motor and the variation of the response current is utilized to detect the rotor position dynamically. When the motor reaches a certain speed at which the back-electromotive force （EMF） method can be applied, all the power devices are turned off and the running state of the motor is smoothly switched at the moment determined by the relationship between the terminal voltage waveform and the commutation phases. The experimental results verify the feasibility and validity of the proposed method.

NOVEL SENSORLESS VECTOR CONTROL SYSTEM OF INDUCTION MACHINE BASED ON FLUX OBSERVER IN FIELD WEAKENING

A speed-sensorless vector control system for induction machines （IMs）is presented, According to the vector control theory of IMs, the rotor flux is estimated based on a flux observer,and the speed is estimated through the method of q-axis rotor flux converging on zero with proportional integral regulator, A 0.75 kW,50 Hz,two-pole induction machine was used in the simulation and experimental verification, The simulation model was constructed in Matlab. A series of tests were performed in the field weakening region, for both no-load and loaded operation. The estimated speed tracks the actual speed well in the based speed region and field weakening region （ 1 per unit value to 4 per unit value）. The small estimation error of residual speed is due to the existence of slip.

Double ESOs-based field-oriented control for PMSM drive system with current sensorless

A novel double extended state observers(ESOs)-based field-oriented control(FOC)strategy is developed for three-phase permanent magnet synchronous motor(PMSM)drive systems without any phase current sensor.In principle,two current sensors are essential parts of the drive system for implementation of the feedback to achieve high accuracy control.For this purpose,the double ESOs are created to provide feedback stator currents instead of actual current sensors.The first one of the double ESOs is designed to estimate the benchmark value of q-axis stator current,which is a primary premise;While the second is designed to estimate real-time stator currents of d-axis and q-axis simultaneously.The resultant double ESOs can rapidly and accurately give estimation of the actual currents of a-axis,b-axis and c-axis,and the synthesized double ESOs-based FOC strategy for PMSM drive system without any current sensors has satisfactory control performance and strong robustness.Numerical experiments validate the feasibility and effectiveness of the proposed scheme.

Position Sensorless Control for Permanent Magnet Synchronous Motor Using Sliding Mode Observer

An approach of position sensorless control for permanent magnet synchronous motor （ PMSM ） is put forward based on a sliding mode observer. The mathematical model of PMSM in a stationary αβ reference frame is adopted, and the system is controlled by the digital signal processor （ DSP; TMS320LF2407 according to the control achieve closed loop operation of the motor, the stator theory of sliding mode observer. In order to magnetic field should be vertical with the rotor magnetic field and be synchronous with rotor rotating, so the position and speed of PMSM is estimated in real time and the estimated position is modified continuously. The simulation results indicate that the proposed observer has high precision is more robust to the parametric variation and load in estimation of PMSM position and speed, and torque disturbance.

Thermal Error Compensation for Telescopic Spindle of CNC Machine Tool Based on SIEMENS 840D System

In this paper, eddy current sensors and thermocouple sensors were employed to measure the thermal field and thermal deformation of a spindle of a telescopic CNC boring-milling machine tool, respectively. A linear regression method was proposed to establish the thermal error model. Furthermore, two compensation methods were implemented based on the SIEMENS 840D system by using the feed shaft of z direction and telescopic spindle respectively. Experimental results showed that the thermal error could be reduced by 73.79% when using the second compensation method, and the thermal error could be eliminated by using the two compensation methods effectively.

Control of a Rigid-Flexible Satellite Solar Panel with Non-collocated Sensor/Actuator

This paper presents a model and analysis for a flexible link with non-collocations of sensors and actuators. It shows the changes in the system dynamics and the appearance of zeroes in the right-plan complex, turning the system a non-minimum phase system. The performance of the PID （proportional-integral-derivative） and LQR （linear quadratic regulator） controller are discussed considering the zero dynamics of the system in three points of special interest： （I） the collocated case, when the sensor is in the base of the link; （2） the critical case, where the system starts to present zeroes in the right-plan complex and （3） the limit case, when the sensors are in the end point of the flexible link. Investigation for a simple rigid-flexible model with one mode, in the three cases, the PID and LQR controller performance are damage. To deal with this kind of problem, new control techniques should be developed.

Synchronization control for electro-hydraulic dual-cylinder system based on force/position switching

If the rigidity of a mechanism is stiff enough, the position synchronous error of the two cylinders driving one degree-of-freedom （DOF） of the mechanism may be less than the resolution of position sensors. To handle this synchronization problem this paper proposes a force/position switching scheme, which partitions the two cylinders into a master cylinder and a slave cylinder. The master cylinder is always position tracking controlled by a second-order sliding mode controller and the slave cylinder is integrated with a force tracking controller which is a first order sliding mode controller. When the position tracking error is less than a given value, the slave cylinder switches to be force controlled. Two synchronization control methods are presented based on the switching scheme： the master - master ＋ force/position switching control and the master - slave ＋ force/position switching control. Simulations show that the formance compared with two given proposed synchronization control position-based control methods. methods can get a better per-

A Fuzzy Control Based Intelligent Control System for Flower Greenhouse

In order to realize intelligent control of flower greenhouse＇ s parameters of atmospheric temperature and humidity, lighting intensity, CO2 concentration and soil water content, it carries out design with ZigBee network, embedded controller and intelligent fuzzy control algorithm as core. With advantages of high precision and stability, the design of sensor circuit mainly employs digital module sensors. In order to save energy, the sensor circuit is controlled by relay switch to work at the proper time. The gateway node is designed by employing high performance 32-digit embedded controller and WinCE6.0 embedded OS is self customized. And embedded SQlite database is realized on WinCE6.0 for effectively managing data. The closed loop control is realized by employing fuzzy control algorithm and the test result shows that the deviation of atmospheric temperature is controlled within ± 0.5° C, the deviation of illumination intensity is controlled within ± 283 LUX, the deviation of CO2 concentration is controlled within ± 24 PPM, the deviation of atmospheric humidity is controlled within ± 13% and that of soil water content is controlled within ± 0.9%, thus all parameters fully meet practical requirements of flower greenhouse.

The Least Order Observer Based Sensorless Control of PMSG in Direct-Drive Wind Turbines

Permanent magnet synchronous Generator （PMSG） based direct-drive wind energy conversion system （WECS） has been attracting wide attentions. For the special application, sensorless control for PMSG is desired. By widely studying the previous contributes, a novel estimator based on back-EMF is proposed. The estimator is composed of back-EMF observer and a phase-lock-loop （PLL） control to get the rotor-flux speed and position. The estimator not only can be used for interior and surface permanent magnet synchronous generators, but also has a compact and symmetrical structure, which makes it be beneficial for implementation. Compared with previous strategies, the EMF observer is independent of the PLL control, which would simplify the observer design. Meanwhile, the proposed estimator is less sensitive to parameter variations. Based on mathematic models of PMSG, the proposed estimator was analyzed in detail, and the realizing process was also presented. To validate the proposed estimator, the important experiment results are reported.

Performance Analysis of PMSM Equations Computation

The paper deals with the comparison of three different digital devices used for the computing of permanent magnet synchronous motor （PMSM） model. Model is used for virtual high frequency injection method （VHFIM） sensorless control, where injection and acting voltages are virtual ones. For computing the whole PMSM model, differential equations are used. The paper is focused on performance analysis of computing speed and accuracy of field-programmable gate array （FPGA） device, digital signal controller and Power PC microcontroller and results are compared.

Sensorless Control of Switched Reluctance Motor Drive Systems

This paper presents a sliding mode observer for sensorless operation of SRM （switched reluctance motor） drive. Design of such an observer depends mainly on the nonlinear model of SRM. In this technique, neither extra hardware nor huge memory space are not required but it only requires active phase measurements. Furthermore, PI （proportional integral） and adaptive FLPI （fuzzy logic PI） controllers are suggested to operate individually along with the SMO （sliding mode observer） to cover a full speed range of sensorless controller. Both controller schemes operate in PWM （pulse width modulation） control mode. The proposed observer is implemented and tested using a digital signal processor. All results obtained with both simulation and experimental investigations corroborate the superior performance of the adaptive fuzzy logic controller （FLPI） when compared with those of PI controller.

Low-cost sensorless control of four-switch,brushless DC motor drive with direct back-EMF detection

We propose a position sensorless control scheme for a four-switch,three-phase brushless DC motor drive,based on the zero crossing point detection of phase back-EMF voltages using newly defined error functions(EFs). The commutation in-stants are 30° after detected zero crossing points of the EFs. Developed EFs have greater magnitude rather than phase or line voltages so that the sensorless control can work at a lower speed range. Moreover,EFs have smooth transitions around zero voltage level that reduces the commutation errors. EFs are derived from the filtered terminal voltages vao and vbo of two low-pass filters,which are used to eliminate high frequency noises for calculation of the average terminal voltages. The feasibility of the proposed sensorless control is demonstrated by simulation and experimental results.

Transformer Partial Discharge Monitoring Based on Optical Fiber Sensing

The power transformer is the most important equipment of the high voltage power grid, however, some traditional methods of online partial discharge monitoring have some limitations. Based on many advantages of the optical fiber sensing technology, we have done some research on fiber optics Fabry-Perot （FP） sensing which can be useful for the transformer on online partial discharge monitoring. This research aimed at improving the reliability of power system safety monitoring. We have done some work as follows： designing a set for fiber optics FP sensor preparation, according to the fabrication procedure strictly making out the sensors, building a reasonable signal demodulation system for fiber optics FP sensing, doing a preliminary analysis about online partial discharge signal monitoring, including the research on different discharge intensities with the same measuring distance and different measuring distances with the same discharge intensity, and then making a detailed analysis of the experimental results.

A sensorless and simple controller for VSC based HVDC systems

Voltage source converter high-voltage direct current （VSC-HVDC） is a new power transmission technology pref- erable in small or medium power transmission. In this paper we discuss a new control system based on space vector modulation （SVM） without any voltage line sensors. Using direct power control （DPC） SVM and a new double synchronous reference frame phase-locked loop （DSRF-PLL） approach, the control system is resistant to the majority of line voltage disturbances. Also, the system response has accelerated by using a feed forward power decoupled loop. The operation of this control strategy was verified in a SIMULINK/MATLAB simulation environment. To validate this control system, a 5 kV.A prototype system was constructed. Compared to the original controllers, the current total harmonic distortion （THD）, the active and reactive deviations and the DC voltage overshoot were lowered by 2.5%, 6.2% and 8%, respectively. The rectifier power factor in the worst condition was 0.93 and the DC voltage settling time was 0.2 s.

Advances in organic micro/nanocrystals with tunable physicochemical properties

Organic micro/nanocrystals based on small organic molecules have drawn extensive attention due to their potential application in organic field-effect transistors,electrochemical sensors,solar cells,etc.Herein,the recent advances for organic micro/nanocrystals from the perspective of molecule aggregation mode,morphology modulation,and optical property modulation are reviewed.The stacking mode and the intermolecular interaction depend on the molecular structure,which eventually determines the morphology of organic micro/nanocrystals.The morphologies of the organic micro/nanocrystals make the aggregates exhibit photon confinement or light-guiding properties as organic miniaturized optoelectronic devices.In this review,we conclude with a summary and put forward our perspective on the current challenges and the future development of morphology and optical tunable direction for the organic micro/nanocrystals.

Optimized algorithm for balancing clusters in wireless sensor networks

Wireless sensor networks consist of hundreds or thousands of sensor nodes that involve numerous restrictions in-cluding computation capability and battery capacity.Topology control is an important issue for achieving a balanced placement of sensor nodes.The clustering scheme is a widely known and efficient means of topology control for transmitting information to the base station in two hops.The automatic routing scheme of the self-organizing technique is another critical element of wireless sensor networks.In this paper we propose an optimal algorithm with cluster balance taken into consideration,and compare it with three well known and widely used approaches,i.e.,LEACH,MEER,and VAP-E,in performance evaluation.Experimental results show that the proposed approach increases the overall network lifetime,indicating that the amount of energy required for com-munication to the base station will be reduced for locating an optimal cluster.

Thermal energy harvesting circuit with maximum power point tracking control for self-powered sensor node applications

We present a simple implementation of a thermal energy harvesting circuit with the maximum power point tracking（MPPT） control for self-powered miniature-sized sensor nodes. Complex start-up circuitry and direct current to direct current（DC-DC） boost converters are not required, because the output voltage of targeted thermoelectric generator（TEG） devices is high enough to drive the load applications directly. The circuit operates in the active/asleep mode to overcome the power mismatch between TEG devices and load applications. The proposed circuit was implemented using a 0.35-μm complementary metal-oxide semiconductor（CMOS） process. Experimental results confirmed correct circuit operation and demonstrated the performance of the MPPT scheme. The circuit achieved a peak power efficiency of 95.5% and an MPPT accuracy of higher than 99%.