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Improved hybrid modulation method suitable for hybrid cascaded H bridge

A hybrid cascading and hybrid modulation technology, which is used in output power conversion devices, electrical components, and the conversion of AC power input to DC power output, etc. Equivalent switching frequency, the effect of improving the service life

Pending Publication Date: 2021-06-22
ANHUI UNIV OF SCI & TECH
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Problems solved by technology

The hybrid cascaded inverter with multiple low-voltage units often has more redundant switch states when the level jumps, and there is no need to design more carriers and additional logic reorganization, and the current backflow problem can be solved by reasonable selection , but there is a problem of unbalanced output power between low-voltage units

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  • Improved hybrid modulation method suitable for hybrid cascaded H bridge
  • Improved hybrid modulation method suitable for hybrid cascaded H bridge
  • Improved hybrid modulation method suitable for hybrid cascaded H bridge

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Embodiment Construction

[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention.

[0024] For a hybrid cascaded H-bridge inverter with a voltage ratio of 1:1:2, the DC side of the cascaded unit is a DC power supply, the voltage of the DC side of the low-voltage units H1 and H2 is E, and the output voltage of the AC side is u H1 , u H2 , the voltage on the DC side of the high-voltage unit H3 is 2E, and the output voltage on the AC side is u H3 , the inverter output voltage is u out , the output current is i o . The topological high-voltage unit and the output voltage of the low-voltage unit can be superimposed to output a maximum nine-level voltage waveform, and the equivalent switching frequency of the inverter output voltage increases.

[0025] For this topology, the modulation method of the present invention has three modulation waves: main modulation ...

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Abstract

The invention discloses an improved hybrid modulation method suitable for a hybrid cascaded H-bridge multi-level inverter with a voltage ratio of 1: 1: 2, and belongs to the technical field of PWM of multi-level converters. According to the method, a high-voltage unit and a low-voltage unit are independently controlled, a high-voltage part adopts the step wave modulation to obtain a pulse signal of the high-voltage unit, and a low-voltage part adopts the hybrid modulation combining step wave modulation and PWM modulation, wherein the PWM modulation adopts a single-carrier modulation mode similar to unipolar frequency multiplication. The two modulation methods are sequenced, and the low-voltage unit is modulated in a 1 / 4 period cycle manner to obtain an optimized pulse signal of the low-voltage unit. According to the method, the equivalent switching frequency of the output voltage of the inverter is improved, the power loss consistency of in-phase and inter-phase switching tubes of the low-voltage units is realized, meanwhile, the output power balance control among the low-voltage units is realized, and the practicability of the inverter is improved.

Description

technical field [0001] The invention belongs to the technical field of multilevel converter PWM, and in particular relates to an improved hybrid modulation method of a hybrid cascaded H-bridge inverter with a DC side voltage ratio of 1:1:2. Background technique [0002] With the rapid development of power electronic technology, the voltage and capacity levels of power electronic devices are also increasing day by day. The traditional two-level converter technology has been unable to adapt to high-power and high-voltage occasions due to the influence of device withstand voltage and output voltage performance. The emergence of multi-level inverter technology has reduced the voltage stress of power devices through topology changes, improved the waveform quality of the output voltage, and greatly reduced the rate of change of the output voltage, reducing electromagnetic interference. [0003] Among the multi-level inverters, the cascaded H-bridge inverter is widely used in the f...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02M7/5387H02M1/088H02M1/32
CPCH02M7/53871H02M1/088H02M1/32
Inventor 顾军宋飞许青春李平许天
Owner ANHUI UNIV OF SCI & TECH
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