Abstract:As the installed capacity of wind turbines grows rapidly and cumulative operation time continues extending, the maintenance issue of the wind turbines becomes increasingly prominent, it is necessary to develop effective wind turbine fault diagnosis and prognosis systems urgently. In this paper, the main fault characteristics of wind turbines are summarized from two aspects of fault diagnosis and fault prognosis. Aiming at the difficult problems in fault diagnosis, the research status of the fault diagnosis approaches based on vibration, electric signal analysis and pattern recognition algorithms for wind turbine fault diagnosis are analyzed and summarized. The technical characteristics, limitations and future development trends of different approaches are pointed out. Aiming at various characteristics of mechanical structure and electronic system degradation in wind turbines, current research development of the fault prognostic approaches for wind turbines are summarized. The fault prognostic approach fusing the physicsoffailure model and datadriven model is proposed. Finally, the new development and the problems requiring further study for the fault diagnosis and prognosis of wind turbines using supervisory control and data acquisition (SCADA) data are summarized.

Abstract:In the networked high precision measurement and localization, the requirements of growing measurement scale, enlarging communication constraints and increasing signal coordination processing bring great challenges in this domain. Based on the spatial localization principle, the information fusion estimation is investigated for uncertain networked systems with crosscorrelated noises and data transmission delays. A distributed fusion estimation scheme is proposed by distributed perception and centralized fusion based on Kalman filtering. The scheme designs an optimal weighted fusion estimator employing the measurement transformation and the twostage weighted fusion approaches. As a result, the communication burden and computational cost with networkinduced transmission delays can be alleviated, and the noisy disturbances can be decomposed, and robustness can be improved. Moreover, information redundancy can be reduce and the higher measurement accuracy can be maintained. An illustrative example is given to validate the effectiveness of the proposed method.

Abstract:Spherical multiprobe antenna nearfield measurement system has the advantages of fast test speed and being able to acquire the threedimensional nearfield data of the antenna to be tested. However, multiple probes form multiple channels, and different amplitude and phase characteristics of various channels will affect nearfield measurement accuracy. In order to eliminate the channel inconsistency, mechanical calibration of the multiprobe system is performed first, which reduces the angle and position errors of the probe. Then electrical calibration is performed through measuring the radiation signal from the center of sphere to each probe. Next, the influence of amplitude and phase errors caused by system errors and environment factors on the extrapolation of farfield radiation pattern from nearfield data is simulated and analyzed. A semispherical multiprobe antenna nearfield measurement system was built, and verification experiment was conducted. The results indicate the effectiveness of mechanical calibration and electrical calibration techniques. The calibrated nearfield data was extrapolated to obtain farfield radiation pattern, and the obtained radiation pattern was compared with the measured farfield radiation pattern. The comparison result verifies influence of amplitude and phase errors on extrapolated farfield radiation pattern.

Abstract:Due to the limited distance of beacon operating, stumbling block, etc. in long BaseLine (LBL) acoustic positioning system, the Unmanned Underwater Vehicle (UUV) may not receive the entire response signals, and cause the measurement update delay. The paper focuses the navigation filter algorithm for the above conditions. Combined the error model of Strapdown Inertial Navigation System (SINS) and the error of sound velocity, the SINS/LBL integrated navigation model is built. An asynchronous measurement sequential processing method is introduced into the SINS/LBL integrated navigation algorithm to optimize the filtering process and achieve measurement update in time. The positioning error between the sequential filter algorithm and the conventional algorithm in SINS/LBL integrated navigation is compared via lake trial data analysis. The results show that this method can perform measurement update timely using limited observed values of responding signal and guarantee the navigation precision, even when some responding signal is missing.

Abstract:Return voltage method is a nondestructive testing technique for studying the insulation aging state of power transformer. The return voltage contains abundant information about dielectric relaxation response reflecting the insulation aging status of transformer. In order to give full play to the advantages of return voltage method in diagnosing transformer oil paper insulation aging, a new method is proposed, which evaluates the insulation aging state of transformer using the quantity of relaxation charge. The quantitative relationship between the relative quantity of relaxation charge and the furfural content in the transformer oil is given. First of all, the return voltage curve is processed with the timedifferential unfolding and the relaxation response function of the return voltage is solved. Secondly, the relative quantity of relaxation charge in the measurement process of return voltage is calculated using the relationship between the quantity of relaxation charge and the relaxation response function. Finally, the relationship between the relative quantity of relaxation charge and insulation aging state is analyzed. Analysis results show that the quantity of relaxation charge is very sensitive to the aging of transformer oil paper insulation. There is a good linear relationship between furfural content and the relative quantities of relaxation charge Q1000 and Q500. The relative quantity of relaxation charge can be used for the quantitative evaluation of the aging of transformer oil paper insulation.

Abstract:Aiming at the problem of large impact force when the robot falls to the ground in jumping motion, in this paper facing to the vertical jumping movement, taking hydraulic quadruped robot single leg as research object, the single leg motion kinematics model of the hydraulic quadruped robot is established, and the trajectory planning when the single leg of the robot is in takeoff phase, flight phase and falling phase is carried out. According to the joint parameters, the driving function is obtained through inverse kinematics solution, and the simulation software ADAMS is used to simulate the vertical hopping gait. The experiment platform for single leg was set up and experiment verification was carried out. According to the obtained dynamic characteristics, the accuracy and rationality of gait planning are analyzed, which provides the design and control basis for the following study of the dynamic gait of hydraulic quadruped robot.

Abstract:To meet the requirements of indoor service robot working under unknown dynamic environments, an incremental sampling path planning based on local environments is proposed in this paper. At first, the estimation of collision risk in current environment is built by a probabilistic model. Then, during the searching tree expansion process, a novel cost function using the Euclidean distance and estimation of collision risk is constructed. Thus, the collision checking for new vertex and potential extensible edges in each iteration can be reduced, and then the algorithm efficiency can be increased. Meanwhile, the best extension in current structure of searching tree can be obtained by referred the rapidlyexploring random graph algorithm. In addition, the performance analysis is provided. Finally, the simulations and experimental results show that the proposed algorithm owns good planning performances and efficiency (less calculating time and iteration times) respectively, which satisfies the needs of real time path planning for indoor service robot.

Abstract:Nonlinear ultrasonic methods have distinct advantage in material microstructure features test, especially in material early damage test. Based on the development progress of nonlinear ultrasound, this paper describes the basic theories and mathematical models of nonlinear ultrasound, deeply analyzes the influence factors of nonlinear ultrasonic parameters, including dislocation monopole model, dislocation dipole model, precipitates and microcracks. This paper presents the details of available nonlinear ultrasonic measurement and analysis techniques, focusing on nonlinear ultrasonic longitudinal wave and Rayleigh wave methods. The main focus of this paper is a critical review of the literatures that utilize nonlinear ultrasound for nondestructive evaluation of closed crack, fatigue and early dislocation damage monitoring, thermal aging, creep damage and radiation damage in materials. Finally, the challenges and opportunities of the nonlinear ultrasonic testing technology in the application of material early damage diagnosis are outlined.

Abstract:The remote field eddy current (RFEC) technique is widely applied for nondestructive testing of metallic pipes, but it always requires shutting down equipment to place the probe inside the pipe. In order to meet the demands of inservice inspection for pressure piping whose elbow regions are prone to corrosion, a novel RFEC probe placed outside the elbow is designed in this paper. Firstly, the probe structure and the pattern of its exciting field are simulated and designed by using finite element software. Then, the simulation model of RFEC testing for elbow defect detection is established, and the quantitative relationship of the inner diameter (ID) and outer diameter (OD) defect depth to the signal characteristics is analyzed. Finally, a test platform is set up and the detecting prefabricated defect experiments are conducted. The results show that: i) the probe signal phase decreases almost linearly with the increase of ID or OD defect depth, which can be used to quantify defect depth; ii) the phase of ID defect signal decreases more rapidly, and therefore, the defect depth can be quantified in the presence of only one type (ID or OD) defect by using the phase feature, but cannot be quantified when both two types of defect exist simultaneously.

Abstract:In order to improve the holography accuracy of multiple sources on irregular structure surface, a Nearfield Acoustic Holography for multiple sources on irregular structure surface is presented based on spherical harmonic wave superposition and sound source identification. The positions of the sound sources are determined by the theory of sound source depth identification and localization, the 3D sound field distributions are described by spherical harmonic wave superposition from different sound sources location. Then the sound fields are reconstructed by the existing theory of spherical harmonic wave superposition from the same point. The methodology is validated and the accuracy of acoustic field reconstruction is examined numerically in the crowded sound field and the discrete sound field, respectively, and it is compared with the existing method which depict sound field with spherical waves from one local coordinate origin. The results show that when the sound sources are crowded together, the results of sound field reconstruction by the two methods are all satisfied and the reconstruction error is less than 5%. When the sound sources are discrete, the result of the existing method is failed, but the proposed method can generate sound pressure distribution precisely, and the reconstruction error is almost less than 20%. Further comparative experiments are carried out with three loudspeakers in anechoic box, the results show that the reconstruction error can be reduced by 14.08% averagely, and the holography accuracy of the multiple sources in irregular spatial position is improved significantly.

Abstract:Time domain electromagnetic (TDEM) method is widely used in detecting subsurface objects such as pipelines, unexploded ordnance (UXO) and archaeological studies. But the characteristics inversion of anomaly is still a challenging problem which causes the increase of false alarm rate and cost of labor. This paper proposes a threedimensional orthogonal equivalent magnetic dipole model and a target parameter synthesis method. With the proposed model and method, the target size, material and shape parameters can be synthesized by the time attenuation characteristics of the equivalent magnetic dipole. The proposed model and method is tested by the developed TDEM system. Experimental results indicate that the model can reproduce the response of subsurface objects, and the parameters of the dipoles can be used to estimate the characteristic of the object. These features can lay solid foundation for identifying subsurface objects.

Abstract:The bandwidth of the low pass filter in its signal conditioning circuits of the hard bearing dynamic balancing machine is less than that of the signal, so frequency characteristics of the circuits should be compensated. Generally, the compensated frequency characteristics are calculated with nominal values of the electronic components. To ensure the effect of compensation, dozens of filtering resistances and capacitors should be screened or matched strictly, which is of time consuming and cost ineffective. And the compensation effect will be degraded when temperature drift and time drift of element parameter occurs. This paper investigates an insitu and selfcontained frequency compensation method, to identify the frequency response characteristics of the third order lowpass filter circuit with the system’s original hardware and software resources. The selection of the exciting frequencies is investigated. The parameter estimation error caused by replacing the sine wave excitation with the square wave and triangular wave is analyzed. The frequency compensation experiments and performance verification of the hard bearing dynamic balancing machine are conducted. Experimental results prove the effectiveness of the proposed insitu frequency compensation method.

Abstract:The characteristic equations of the guided waves in free steel plate and water loaded steel plate are solved based on the Navier kinetic equation; then, the dispersion curves are drawn. After comparing and analyzing the dispersion characteristics of free plate and water loaded plate, it is found that a QuasiScholte modal guided wave exists in water loaded steel plate, which does not exist in free steel plate. Through numerical calculation, finite element simulation and experiment, the propagation characteristics and modals of the guided waves in free plate and water loaded plate are verified respectively. In lowfrequency region, A0 modal exists in the guided waves in free plate, and QuasiScholte modal only exists in the guided waves in water loaded plate. Using the propagation characteristics of the A0 modal and QuasiScholte modal guided waves, a water level measurement experiment was designed, which adopts pitchcatch PZT sensor deployment modal, and a 130Hz, 2.5period Hanning window modulated sine wave signal is used as the test signal. The results show that the water level and the guided wave propagation time exhibit a linear relationship, which can be potentially used for the estimation of water level in a container.

Abstract:Measuring accuracy of AACMM based on measuring force is focused in this work. The error of length measurement caused by measuring force is analyzed theoretically and experimentally. The local deformation of the probe and the measured object and the bending deformation of the measuring rod are the main factors affecting the accuracy of AACMM. The mathematical models of the local deformation and the bending deformation of the rod are established, with which the measuring results compensated with force error. Results show the error caused by measuring force can be compensated to a great extent: the average length measurement error is reduced about 82%, the maximum error is reduced by about 47um, which effectively improves the precision of AACCM.

Abstract:The redefinition of the unit of mass by tracing kilogram to Planck constant has been widely accepted in the field of metrology. In China, Joule balance method is proposed by NIM to measure the Planck constant and redefine the kilogram. Compared with the Watt balance method in other countries, Joule balance method benefits from the advantage of static measurement. The whole system experiments for the first generation of the Joule balance system have been finished. The whole measurement uncertainty was analyzed in detail, which will help us to further optimize the design scheme and improve the experiment process. Finally, we obtained that the whole measurement uncertainty is 2.5×10-6. Aiming at the major sources of the measurement uncertainty, several improvement methods are put forward for the next generation of the Joule balance system, which provides the ensuring measure for further reducing the measurement uncertainty.

Abstract:Aiming at the detection of grinding burn of high performance bevel gear after grinding, the automatic detection device for grinding burn of bevel gear tooth surface is developed. The detection device is composed of mechanical structure, Barkhausen noise detection module and test software. The detection device completely relies on the mechanical system and electrical system of bevel gear tester to realize automatic detection. The mechanical structure shares fixture with gears, by introducing flexible shaft design, which can meet the requirements of a variety of bevel gear detections. And the detection process of spiral bevel gear can be simplified. AST RollScan350 magnetic elastic instrument is employed to collect the Barkhausen noise signal of measured bevel gear. The collected signals are analyzed using detection software run in the host computer. Experimental results indicate the high repeatability of the detection device for quality control in gear production．

Abstract:The detection of angular positioning error on specific turntable shaft end cannot reflect its actual space angular position of working surface. Thus, a space angular position measuring device of turntable working surface is introduced with circular grating and horizontal capacitance sensor as its angle measuring components. The error factors of the measuring device are especially classified and analyzed in order to improve spatial angle measurement accuracy. Besides the angle measuring error of subsystem, the measuring device has error that the shafting or the sensitive direction of horizontal capacitance sensor is not parallel to the reference plane for measurement and others error terms. The mathematical model is established to analyze the factors of systematic errors and correct them according to the spatial geometrical relations of grating rotary surface, sensitive direction of sensor, rotation axis and reference plane for measurement. Then the measuring device is calibrated by using highprecision turntable with 0.3″ indexing error. And the mathematical model of error compensation is established based on radial basis function (RBF) neural network to improve precision with the maximum error value decreased to 2.9 ″ from 13.75 ″ to satisfy angular measuring accuracy within 3 ″ demand.

Abstract:The optomechanical structue of 300mm aperture visible light rough tracking and imaging lens was designed for a certain developing ground base optical telescope. The concave mirror structure contouring the rear surface was optimized and the primary mirror weight was reduced by 41.2%. Aiming at the deficiencies of the conventional cementing structure, the new primary mirror supporting structure with elastic compression was adopted. The Patran finite element method (FEM) simulation software was adopted to analyze the accuracy of the primary mirror surface figure with supporting structure at different tilt angle positions and different temperatures. The installation and test scheme was designed, Zygo interferometer was used to test the accuracy of the primary mirror surface figure with supporting structure indoor; and the test result of the surface figure is 0.04λ (RMS), the design reference value of the visible light wave length λ is 0.633 nm and the wavefront aberrations of the optical system both for longfocus lens and shortfocus lens are 0.132λ (RMS). The test results of the indoor collimator star test, resolution test and outdoor polaris imaging test indicate that the system imaging quality meets the telescope requirement. The results verify the reasonability of the new primary mirror supporting structure and lens optomechanical structure design, which provides the design basis and technical path for developing the optomechanical structure of similar lenses.

Abstract:Based on the working principle of giant magnetostrictive actuator (GMA), a mechanical structure with segmented bias magnetic field and oil cooling system is designed. The 3D model of the GMA is established and its magnetic field and temperature field are simulated with finite element analysis software. The simulation results show that the segmented bias magnetic field method can obtain better bias performance, the oil cooling system can greatly lower the GMA’s temperature. A force test platform is set up, then the static and dynamic output force characteristics of the GMA are studied, respectively. The experimental results indicate that the output force has positive correlation with the driving current. Excited by DC, the output force of the GMA has hysteresis nonlinearity and is greatly influenced by the GMA’s temperature but slightly influenced by the external mechanical constraint force. Meanwhile, the GMA can accurately track the signals without doublefrequency effect when driven by AC. This represents that segmented bias magnetic field has excellent bias effect, high precision and fast dynamic response speed.

Abstract:In order to realize rapid and high precision calibration of the standard scattering plate for visibility meter calibration, based on the calibration principle of standard scatter plate used in calibrating forward scattering visibility meter, we proposed a new type of calibration system for standard scatter plate used in calibrating forward scattering visibility meter. The main research focus was the alignment technology for the calibration system. According to composition and working principle of the calibration system, we established the alignment optical model. We also proposed the alignment scheme consist of the alignment of relative location between parabolic reflection mirror and panoramic imaging energy detection system and relative location between parabolic reflection mirror and low reflectivity spherical screen system. We established extremity error calculation model. In the situation of 45°pitching angle of incident light, we calculated the maximum alignment error of translation error and tilt error between parabolic reflection mirror and low reflectivity spherical screen system are 3.18°and 0.847° respectively, and the maximum alignment error of translation error and tilt error between parabolic reflection mirror and panoramic imaging energy detection system are both 2.14 pixels. The experimental results proved that the maximum angle detection error of the alignment standard scatter plate calibration system used in calibrating forward scattering visibility meter is 0.795°, which is less than 1° and satisfied the requirements of angle detection error of the calibration system.

Abstract:Aiming at the present situation of the contradiction existing between the decoupling difficulty and configuration complexity of sixaxis accelerometer, a new design scheme of prestressed parallel sixaxis accelerometer with 12 branch chains is presented, and the decoupling algorithm in four dimensional configurationspace is constructed. By recomposing the input parallel items and solving forward dynamics equations and force coordination equations, the ingredients of the outputs are dissected. Through introducing prematrix, postmatrix and aided angular velocity, the complex dynamic equations are transformed into two simple linear ordinary differential equations, and the explicit recursive formulas of key characteristic quantities are derived using trapezoidal method. ADAMS simulation is conducted to verify the decoupling algorithm, and the relative composite error between the decoupling algorithm and ADAMS simulation is only 0.62%, and the decoupling algorithm has higher calculation efficiency. Laboratory test results show that within one minute the composite error of the real physical prototype is 8.42%, which verifies the feasibility and correctness of the proposed design scheme. Through Taylor expansion around discrete nodes, the analytic formulas of local truncation error are derived, which provides a basis for improving the decoupling accuracy. Furthermore, the decoupling algorithm is generalized to be suitable for general configuration. Through introducing two theorems concerning vector independent elements, it is proved that the least number of branch chains for the prestressed parallel sixaxis accelerometer is 7, and the least degrees of freedom for corresponding topological configuration is 6.

Abstract:Abstract:Electro optic (EO) sensor is the core device for free space sampling technique. Conventional EO sensors are fabricated by inorganic crystal, whose EO coefficients are too low. This limits the detecting bandwidth of THz wave. Hostguest polymer possess higher EO coefficient and lower dielectric constant, which becomes the researching focus in related fields. However, phase separation often happens between the host polymer and the guest EO molecules, which leads to the properties decay. In this paper, two kinds of chromophoric groups are introduced into polymer main chains through a combination of chemical and physical methods. Polyphosphazene with double EO molecules, possessing not only high EO coefficient but also fine phasestability, is synthesized successfully and the EO coefficient of the product can be 64.8 pm/V under optimal conditions. Based on our product, a new kind of EO sensor with coplanar electrodes structure is designed and fabricated. On detecting the same THz wave, the amplitude of the new sensor can be enhanced by 50% and the sensibility by 50% compared with the conventional sandwich one. Meanwhile, the effect on detecting sensibility by incident angle can be avoided and the noise interference can be reduced, which makes the sensor with coplanar electrodes structure a more suitable device for THz applications.

Abstract:Multi hop communication is applied to underwater acoustic sensor networks, since nodes energy is limited. In order to balance load in communication process, this paper proposes an optimization mechanism based on nodes’ quality and distance for multihop communications, and designs an adaptive load balancing algorithm. The nodes communication quality and distance between each other are weighted for evaluating and selecting the next hop. Then balancedbased data transmission algorithm based Autonomous Underwater Vehicles is proposed. The performance of networks can be further optimized and the lifetime of networks can be maximized. Finally, the simulation results show the rationality and effectiveness of the proposed method.

Abstract:This work presents a new designed wheel force transducer which can decouple between the motion and force. Since the wheel force transducer is speciallydesigned and installed on the spinning wheel of a vehicle, the rotation and inertial couplings cause errors into the force measurement. With the introduced the motion measurement technique such as a MEMs unit, these errors can be eliminated with the combined algorithms including the rotation decoupling, inertial decoupling, and the initial error calibration, so the precision of force measurement can be improved for the transducer.

Abstract:The transverse flux sensor (TFS) is a new type of sensor designed for rotor radial displacement measurement. Compared with conventional eddy current or inductive sensors, relying on its unique probe design, TFS has the advantages of high costefficiency, high accuracy, high sensitivity and ultracompact structure. Through theoretical analysis, the factors influencing the sensitivity of the sensor are researched. With establishing the finite element model, the key points of the sensor probe PCB design are clarified with simulation, and then the design rules applied to TFS are summarized according to the simulation results. The experiment circuit was designed and optimized, the experiment platform was built, and the performance test of the sensor was completed. Experiment results show that the sensor has good sensitivity, linearity and very low XY coupling. The TFS was successfully applied to the rotor displacement measurement of an active magnetic bearing system, and a stable levitation at 12 000 r/min was achieved.

Abstract:The imaging performance of full polarization synthetic aperture radar (SAR) can be improved by applying the sparse reconstruction technology based on compressed sensing (CS) to different polarizationchannel data independently. However, with respectively independent processing the method cannot utilize the redundancy and complementarity of the polarization information, which may destroy the integrity of the polarization information. A new jointsparsity measure function is built according to the scattering characteristics of radar target in full polarization condition. Then, the full polarization SAR highresolution imaging can be mathematically converted to a multichannel joint sparse constraint optimal reconstruction problem, which can be solved via the improved orthogonal matching pursuit algorithm. Because of effectively using the full polarization information, compared with the singlechannel CS imaging, the multichannel joint CS imaging not only performs better with fewer measurements and obtains better imaging quality, but also fully and accurately reflects the fully polarization scattering characteristics of the target. Finally, the processing of the Backhoe excavator simulation data verifies the effectiveness of the proposed method; a full polarization SAR hardwareinloop system was constructed in an anechoic chamber, the full polarization test data obtained on the system further verify the engineering feasibility of the proposed method.

Abstract:The highspeed railway clearance intrusion detection system is used to detect whether there is object intruding the safety clearance of the highspeed railway. To enhance the reliability of the system, a new CNN based fast feature extraction algorithm is proposed. Aiming at the problem of slow feature calculation speed, a simplified full connected network structure is proposed, and the structure of the neural network is simplified to two full connected convolutional layers. To avoid the accuracy decreasing caused by simplifying network structure, the convolutional kernels of the convolutional layers are pretrained. Finally, in order to prevent the symmetric feature extraction caused by full connection, fast feature extraction algorithm with sparse parameters added is proposed, and the network is trained with sparse coding algorithm. The improved CNN accelerates the calculation speed while ensures the accuracy. At the same time, the new algorithm satisfies the requirements of real time capability and high accuracy. Experiment result shows that the speed of processing single image is 0.15 s and the accuracy is 99.5%.

Abstract:The geometry shape and parameters of highefficiency cutting tool directly affects the tool’s service life and product’s quality in advanced manufacturing technology. Thus, a noncontact measurement method based on surface structured light projection is adopted for geometry parameters of highefficiency cutting tool. This method can not only reconstruct the 3D model of the tool used for measure its geometry parameters, but also can directly detect the defects of the tool surface. This work mainly focuses on the basic ideal of surface structured light projection, mathematical model of measurement system and point cloud rotation registration. The transformation relation between tool turntable coordinate system and CCD camera imaging coordinate system is built. Meanwhile, the measure experiments on was carried out, the experimental results on straight shank twist drill show that the surface structured light projection is effective and precise in the tool measurement.

Abstract:The precise mathematical models of tooth surfaces and fillet surfaces of the hypoid gear are established. Three indexes of average semimajor axis of contact ellipses, the direction angle of contact path and the intersection of the transmission error curve are selected to evaluate the tooth contact pattern and the transmission error. Then, taking a hypoid gear for example, the finite element analysis model of hypoid gears transmission system is established which is suitable for tooth contact characteristics analysis under quasistatic condition. By the analysis of quasistatic motion and loaded tooth contact, the variations of bending stresses, contact stresses, and transmission error are investigated. Besides, the results are compared with the calculated results by empirical formula. Finally, a hypoid gear transmission performance test bed is developed, then the tooth contact pattern test and bending stress test are carried out, and the test results are well consistent with the simulation results.

Abstract:A novel composite control method is proposed in this paper aiming at the requirements of transient response and antiinterference performance in applications of transient energy feedback of girdconnected inverter. The method combines the advantages of repetitive control and sliding mode variable structure control. The tracking characteristic of sliding mode variable structure control is optimized using repetitive control, and the composite control method effectively suppresses the gridconnected current harmonics, speeds up the system dynamic response speed and improves the system antiinterference performance. Simulation and experiment results show that the fifth harmonic distortion of the gridconnected current is controlled to 1.5%, and the grid side power factor is close to 1. Furthermore, with the fast transient response of dynamic current, the effect of energy variation on dc bus voltage is effectively restrained, which proves the effectiveness of the proposed composite control method.