For the special requirements of grid-connected inverter used in wind power generation system, a kind of three-phase Z-Source inverter operational principle is analyzed in this paper. Formulas for the design of main parameters under the control of constant duty cycle of shoot-through switching state are derived. Then the simulation models of SVPWM with shoot-through zero vectors are established by using Matlab/Simulink in order to control the switches of Z-Source inverter on and off. The independent control strategy of d-axis and q-axis currents is used to achieve a unity power factor grid-connected aim. Simulation results show that the theoretical analysis and the simulation models are validity.

A kind of decoupling mathematical model of Permanent Magnet Synchronous Motor (PMSM) in two-phase rotated coordinate is established. According to the Space Vector Pulse Width Modulation (SVPWM) control strategy and optimum parameters scheme, the three closed-loop servo control system for Automobile Gear Fatigue Test (AGFT) is designed. Rapid and accurate positioning must meet the requirement of testing gear fatigue system. Simulation results show it can achieve the goal of linearization control and the scheme mentioned is feasible and effective.

On the basis of interior electromagnetism relationship and vector control principle, the vector control system of Permanent Magnet Synchronous Motor (PMSM) without position sensor is designed. There are two main identification methods are introduced to estimate the position and speed of PMSM. One scheme is based on the back Electromotive Force (EMF) and the other is Model Reference Adaptive Standard (MRAS). The former method achieves fast dynamic-state response while the later method obtains better steady-state performance. According to both of them advantages, an improved estimate method which combining the back EMF and the MARS is proposed. Simulation results show that the improved method is feasible and stable.

Slow traffic accounts for a great part of urban transportation, and is drawn more and more attention. However, the service system for this kind of traffic is rather inadequate, which seriously hampers the construction of smart city and digital urban. In this paper, beginning with the characteristics of slow travel persons, we design a multi-mode traffic information service platform for pedestrians and bicycle system specially. In our platform, non-interactive facilities for slow traffic are designed and deployed oriented pedestrians and cyclists. To provide customized information meeting pedestrians’ various demands and allow users’ feedback, the interactive service platform based intelligent mobile terminals and mobile internet is introduced instead of current electronic inquire equipments settled in public.

Taking TWERD frequency converter as research object, the working principle and fault types of three-phase SPWM inverter are analyzed. Its output line voltage waveform in normal operation and fault condition is studied. According to the fault information and the different data of input and load changes, the frequency converter output line voltage waveform is decomposed by wavelet transform. The low frequency energy value is picked-up and regards it as eigenvector. The mapping relationship between eigenvector and fault types are established by BP neural network, the fault bridge and fault location of frequency converter are found. Simulation results show that the diagnosis accuracy is 96.5% after training 46 times. Fast convergence speed and high precision is obtained.