Liu Zhenxing

Control for single-phase power inverter system based on lead signal and dq transform

In the control of inverter power system, with reference to the dq transform in three-phase inverter control system, a control method of single-phase power inverter system based on lead signal and dq transform is proposed. In this method, the αβ frame is constructed by the physical “Real Circuit” and the second “Imaginary Orthogonal Circuit”, which is constituted by the 90 degree lead signal, thus the control scheme based on dq transform is realized. Simulation model based on dq transform is constructed in the simulink of MATLAB, the effectiveness and viability of the method is verified by the simulation and experiment results.

Diagnosis simulation of broken rotor bars in squirrel cage induction motor fed with variable frequency power

The previous methods on broken rotor bars fault diagnosis of squirrel cage induction motor (SCIM) were just for motors fed with industry frequency power supply. In this paper, a simulation modeling of SCIM supplied with variable frequency power is introduced, which respectively in normal condition and in broken rotor bars conditions. Through the comparison and analysis of the one-phase stator current spectrum and the three-phase average instantaneous power spectrum, it is concluded that the latter has the better resolution from spectrum with abundant harmonics, so it can be an advisable criterion for the broken bars fault diagnosis.

Fault detection of networked multi-rate systems with probabilistic sensor failures

In this paper, the fault detection problem is investigated for a class of networked multi-rate systems (NMSs) with network-induced probabilistic sensor failures. By applying the lifting technique, the system model for the observer-based fault detection is established. With the aid of the stochastic analysis approach, sufficient conditions are established under which the stochastic stability of the error dynamics is guaranteed and the prescribed H∞ performance constraint is achieved. Based on the established conditions, the addressed fault detection problem of NMSs is recast as a convex optimization one that can be solved via the semi-definite program method, and the explicit expression of the desired fault detection filter is derived by means of the feasibility of certain matrix inequalities. Finally, an simulation example is utilized to illustrate the effectiveness of the proposed fault detection method.

A novel control method for single-phase power inverter systems based on Hilbert transform and DQ transform

In the control of 400Hz power inverter systems, a new method based on Hilbert transform and DQ transform is proposed. The αβ coordinate is structured according to actual measured voltage and its Hilbert transform. Then the DC quantities under the rotating coordinate is obtained by the DQ transform, followed which the double closed loop control model can be structured. Compared with the conventional method which the BETA data is structured by the 90° delay, the good performance of the proposed method is verified in the simulation results. In addition, on the circumstance of the sudden load adding to the system, the method eliminates the secondary subsidence of output voltage problems, which cannot be solved by the conventional 90° delay method.

A self-adaptive analysis method of fault diagnosis in roller bearing based on Local mean decomposition

In view of the nonlinear and non-stationary characteristics of fault vibration signal in roller bearing, a self-adaptive fault diagnosis method known as LMD (Local mean decomposition) is proposed. Initially the original vibration signal is decomposed into several stationary PF (product function) which possessed physical meaning and a residual component by using of LMD. Subsequently, the main components in fault signal are determined by calculation of correlation factor of each PF with the original signal aiming at obtaining amplitude and frequency information. LMD is applied in analysis of simulation signals and fault diagnosis of bearing outer-race. The results indicate that LMD method of fault diagnosis in roller bearing is equipped with high fault recognition and identification rate. The characteristics of mechanical fault signals can be effectively extracted.

Fault diagnosis way based on CLEAN algorithms in Squirrel Cage Induction Motors

Among the methods of fault diagnosis based on the current analysis for Squirrel Cage Induction Motors (SCIM), the fault characteristic components are often submerged by fundamental component and noises, especially for the broken rotor bars. The CLEAN algorithm is a kind of relaxant data processing algorithms for additive noises and system errors. A new approach based on CLEAN algorithms for fault diagnosis and monitoring in SCIM is proposed in this paper. the CLEAN algorithm is used to extract the characteristic components for the fundamental one of power, and estimates the discrete-time spectrum parameter of particular fault from the continuous spectrum of the noise and mixed waves, which can eliminate the effective of power and noise and highlight the fault characteristic components. At last experimental results have demonstrated the effectiveness and advantage of the proposed technique.

Fault Diagnosis Way Based on subsection Spectrum zoom analysis by CZT for Squirrel Cage Induction Motors

Among the methods of fault diagnosis based on the current analysis for squirrel cage induction motors (SCIM), the faultspsila characteristic components are often submerged by fundamental component and noises, especially for the broken rotor bars, and how to effectively eliminate the influences of the fundamental component and noises is essential for the diagnosis system. Fault diagnosis way based on subsection spectrum zoom analysis method by CZT for squirrel cage induction motors is proposed in this paper. using subsection spectrum zoom of CZT, the fault current is analyzed to eliminate the effective of power and yawp and to highlight the fault characteristic components.