Specific Harmonic Elimination Pulse Width Modulation Control Method and Device for Eliminating Dead Zone Effect

Abstract

The invention discloses a specific harmonic elimination pulse width modulation control method and device for eliminating the dead zone effect, which are used for diode-clamped NPC multi-level converters, including current and voltage for NPC multi-level converters Closed-loop control, real-time calculation of voltage modulation ratio and real-time phase; query the preset switching angle storage table according to the voltage modulation ratio, and obtain a set of standard switching angles corresponding to the voltage modulation ratio; according to the output current direction and delay of the NPC multi-level converter The radian value of on-time conduction and the radian value of early turn-off are used to correct the standard switching angle, eliminate the dead zone effect in the standard switching angle, and obtain a set of corrected standard switching angles; based on the corrected standard switching angle, determine the real-time phase. According to the angle interval at the angle interval and the preset correspondence table, the driving pulse with dead zone corresponding to the real-time angle is obtained to drive the NPC multilevel converter. The invention can eliminate the influence of the dead zone effect on the driving pulse of the converter, and optimize the harmonic level of the converter.

Description

Technical field [0001] The present invention relates to the technical field of converter control, in particular to a specific harmonic elimination pulse width modulation control method and device for eliminating dead zone effects. Background technique [0002] Diode clamped (NPC, Neutral point clamped) three-level converters are very suitable for medium voltage high-power industrial converter drives (such as locomotive traction, offshore wind power, metallurgical rolling mills, mine hoists, ship propellers, etc.). Combined with existing commercial high-voltage and high-power semiconductor devices (such as IGBT, IGCT, IEGT, etc.), the converter can achieve high withstand voltage and strong overcurrent performance. The three-phase topology of NPC three-level converter is as figure 1 Shown, where S 1 , S 2 , S 3 , S 4 It is a fully-controlled switching device, each switching device is connected in anti-parallel with a freewheeling diode (D 1 ~D 4 ), D 5 , D 6 Clamping diode, DC side...

AI Technical Summary

Problems solved by technology

The dead time will affect the obtained standard switching angle, which will cause the output voltage to deviate, cause output voltage distortion, increase the harmonic content of output voltage and current, and cause impact on the load or power supply network, such as causing the torque of the motor to occur violently. Fluctuation or even damage, total harmonic distortion (Total Harmonic Distortion, THD) of output current does not meet international or domestic grid-connected standards, etc., and the impact of wide dead zone is even worse

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