Traction Converter Electromagnetic Compatibility Analysis

With the traction converter and calculation of transmission control system of the railway in a wide range of applications, electric traction drive system of the electromagnetic compatibility problem is getting attention. Electric locomotive of electromagnetic pollution on the environment at home and abroad locomotives and rolling stock has been attached great importance to the manufacturing sector, while the traction converter is a serious source of electromagnetic interference, so traction converter technology of electromagnetic compatibility is especially important.Inverter through the analysis of the mechanism of harmonic generation, high-frequency harmonic interference channels and high harmonic hazards. Put forward a number of commonly used measures to inhibit electromagnetic interference, such as the increase in filter, shielding, grounding, isolation and so on. Analysis of inverter power supply when the motor common-mode voltage, shaft voltage and bearing current mechanism to study the shaft voltage, bearing current and common-mode voltage of the electrical nature of the relationship between. PWM pulses, the electrical voltage in the distribution of capacitance coupling constitutes the common-mode loop system, thus giving rise to motor shaft voltage and bearing current. The size of the main axis voltage-mode voltage and sharing within the various parts of the electrical capacitance of the coupling. Bearing current mainly composed of three kinds of current: EDM (Electric Discharge Machining, EDM) current, dv / dt current and loop current. SVPWM modulation strategy using SPWM modulation strategy than by common-mode voltage generated by even smaller; proposed three-phase four-leg inverter and the PWM inverter output feedforward active filter to suppress common-mode voltage.To electromagnetic field theory, analysis of four typical derivation of the line connecting loop inductance, given changes in structural parameters of wires connecting different circuit inductance formula. Analysis and Comparison of a typical four-loop electromagnetic interference of space, from the theory described in the design of power converter used to connect the conductor loop and the loop between the thickness of the insulating layer is thinner, the better. Through the rational distribution of the main circuit, reducing the converter to the circuit for the stray inductance and characteristic impedance, and can effectively reduce the over-voltage switch, electromagnetic interference energy, as well as the spread of electromagnetic interference energy.