Suspended capacitor voltage control method of five-level ANPC (Active Neutral-Point-Clamped) converter

Abstract

The invention relates to a five-level ANPC (Active Neutral-Point-Clamped) converter, particularly to a suspended capacitor voltage control method of the five-level ANPC converter. The suspended capacitor voltage control method comprises the following steps of applying SHEPWM (Selective Harmonic Elimination Pulse Width Modulation) pulse waves to the five-level ANPC converter; performing real-time detection on a suspended capacitor voltage value of the five-level ANPC converter, performing comparison on the suspended capacitor voltage value and a reference value of the suspended capacitor voltage and determining whether a suspended capacitor needs to be charged or discharged; detecting whether the load current of the five-level ANPC converter is positive or negative and selecting the redundancy switch state which is suitable for the ANPC converter according to the positive or negative load current of the five-level ANPC converter and the determined charging and discharging state required by the suspended capacitor; performing charging and discharging on the suspended capacitor of the five-level ANPC converter through the selected switch state until that the variable quantity of the suspended capacitor voltage is zero within a sampling period and performing repeated detection on the suspended capacitor voltage value. According to the suspended capacitor voltage control method of the five-level ANPC converter, the appropriate redundancy switch state is selected according to the direction of the load current and the size of the suspended capacitor voltage so as to enable the suspended capacitor voltage to be fluctuated within a small range.

Description

technical field [0001] The invention relates to a five-level ANPC converter, in particular to a method for controlling the suspension capacitor voltage of the five-level ANPC converter. Background technique [0002] With the advancement of technology and the improvement of living standards, people's requirements for power quality are also constantly improving. The emergence of active neutral-point-clamped (ANPC) topology makes up for the diode-clamped topology and capacitor The shortcomings of the clamping topology are better suited for the high-voltage frequency conversion fields of 6 and 10kV. ANPC multi-level converters are more and more used in the fields of industry and social life to provide higher quality electric energy. At present, domestic selection of SHEPWM modulation method for five-level ANPC converters has not been published yet. Selecting SHEPWM control can effectively reduce low-order harmonics at high frequencies, improve waveform quality, and reduce requi...

AI Technical Summary

Problems solved by technology

One of the prerequisites for five-level and above ANPC topologies to work normally is that the floating capacitor voltage must remain stable. During SHEPWM control, if the key issue of the floating capacitor voltage is not considered, if the obtained SHEPWM switch state causes the floating capacitor voltage to be large fluctuations will lose practical significance

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