A Control Method for Eliminating Low Frequency Ripple of DC Midpoint Voltage of Three-level Inverter

A three-level inverter, mid-point technology, applied in the direction of converting AC power input to DC power output, electrical components, output power conversion devices, etc. Ripple, simple to implement, small amount of calculation

CN106533231BActive Publication Date: 2019-05-07NO 719 RES INST CHINA SHIPBUILDING IND
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Publication Date
2019-05-07

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Abstract

The invention discloses a control method for eliminating a low-frequency ripple of mid-point voltage of DC of a three-level inverter. According to the method, a mid-point voltage difference is detected in each switching period, and specific zero-sequence voltage is compensated in real time according to the mid-point voltage difference detected in real time, so that fast complete compensation is carried out on the mid-point voltage difference by mid-point current generated in the next switching period. The control method for eliminating the low-frequency ripple of the mid-point voltage of the DC of the three-level inverter has the advantages that (1) balancing of the mid-point voltage of the three-level inverter can be effectively and quickly achieved; (2) the low-frequency ripple of the mid-point voltage can be effectively eliminated; and (3) the control method is very simple to implement and small in computing quantity.
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Description

technical field

[0001] The invention relates to a three-level DC-AC power conversion device, in particular to a control method for a three-level DC-AC power conversion device for eliminating low-frequency ripples of a DC midpoint voltage. Background technique

[0002] Multilevel inverters can reduce the harmonic content of the output voltage and reduce the voltage stress of switching devices, and are widely used in high-voltage and high-power applications. Among them, the three-level neutral-point clamped inverter is the most extensively researched and applied. The prerequisite for the normal operation of the three-level neutral-point clamped inverter is that the neutral-point voltage remains balanced. The unbalanced midpoint voltage will lead to an increase in the harmonic content of the output voltage and current. If the voltage fluctuates sharply or there is a large steady-state deviation, it will lead to an increase in the voltage stress of the switch tube of the bridge...

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Embodiment Construction

[0028] The present invention will be described in detail below in conjunction with the accompanying drawings and the embodiments thereof, but the protection scope of the present invention is not limited to the scope described in the embodiments.

[0029] The present invention will be further described below in conjunction with accompanying drawing.

[0030] figure 1 It is the topological structure diagram of three-phase three-level inverter. Such as figure 1 As shown, the three-phase three-level inverter includes a DC power supply V dc , DC side voltage stabilizing capacitors C1 and C2, phase A switching tube S a1 ~S a4 , A phase embedding diode D a1 and D a2 , Phase B switch S b1 ~S b4 , Phase B embedded diode D b1 and D b2 , C-phase switch S c1 ~S c4 , C-phase embedding diode D c1 and D c2 , and three-phase AC loads. Phase A switch tube S a1 ~S a4 , A phase embedding diode D a1 and D a2 Form A-phase midpoint clamping type bridge arm; B-phase switch tube S ...