Conducted interference test and simulation of alternator rectifier system

Conduction Interference Test and Simulation of Alternator Rectifier System of North China Electric Power University Meng Jin, Ma Weiming, Liu Dezhi, Zhang Lei (Institute of Power Electronics Technology Application, Naval University of Engineering, Wuhan 430033, China) A high frequency model of the generator was built, simplifying the system to a resonant circuit consisting of the main parasitic parameters. The dynamic electromagnetic simulation system Simulink of MATLAB software is used to simulate the conducted electromagnetic interference of the actual system. The simulation study of the conducted interference of the actual system was carried out. The maximum pulse of the LISN noise voltage and the generator ground current occurs at the moment of the switching action, and a large number of pulse spike voltages are generated at the commutation point of the DC output voltage K. It shows that the high-frequency oscillation caused by the switching action of the rectifying device is obviously different from the ordinary harmonic phenomenon, and these oscillations mainly depend on the parasitic capacitance and inductance of the system. Therefore, when analyzing and establishing the time domain simulation model of the system, the parasitic parameters of the dominant interference current path in the system must be considered.

analysis. Medium, Zir is the impedance modulus between the output and the generator casing, and Zm is the impedance modulus between the output and the midpoint of the winding. Ztr and two amplitude resonance curves are given by .

In the middle, / is the series resonant frequency of Z, f, and /2 and /3 are respectively the parallel resonant frequency of two. Have r\! C, such as. Where * and 1 are the resistance and inductance of the wire, CU is the coupling parasitic capacitance between the wire and the wire, which is the high frequency attenuation caused by the skin effect of the cable. The values ​​of Cb and 凡 are directly measured by the LCR measuring instrument. The DC load directly utilizes the load model in the simulation component library, and the parameters are also set according to the actual system operating conditions.

3 Results Verification To verify the correctness of the above analysis and model, the actual test system was simulated. According to the parameter extraction method introduced above, the specific parameters are 0=5): iw=280mf2, Lw=58HH, ic=70Q, Cc=0.44nF, C,=0.3nF, is=lmf2, C,= construction The mode is simulated by the de23s algorithm, and the obtained LISN noise voltage, generator ground current and DC output voltage waveform are as shown. The main oscillation characteristics of the medium voltage and current are accurately reflected here, and the simulated waveform is in good agreement with the actual tested waveform. The simulated LISN voltage time domain waveform is subjected to Fourier analysis to obtain a predicted spectrum of interference.

The measured and predicted spectrum of the noise voltage in the frequency band of 10 kHz to 3 MHz is more powerfully proved by the comparison of the two.

Noise Voltage Spectrum 4 Conclusion This paper studies the DC conduction interference of the alternator rectification system. Through the analysis of the test results, it is considered that the relatively high d*/d pulse voltage generated by the switching action in the circuit acts on a large number of parasitic capacitances such as generators, rectifiers and cable wires, thereby generating complex conducted noise interference. Based on the analysis, a time domain model for simulation analysis of system conducted EMI is established. The comparison between the experimental and simulation results proves the correctness of the model.

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