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Calculation Method of Instantaneous Power of Each Unit in Cascaded H-bridge Multilevel Converter

A multi-level converter, instantaneous power technology, applied in the direction of converting AC power input to DC power output, electrical components, output power conversion devices, etc. Advanced problems, to achieve the effect of accurate and reliable calculation of power value, easy and accurate amplitude value, and strong versatility

Inactive Publication Date: 2019-07-12
SOUTHWEST JIAOTONG UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] However, the prior art lacks a method for calculating the unit power of each H-bridge unit of the cascaded H-bridge multilevel converter working under the nearest level approximation modulation method
If the AC side voltage and current information of each H-bridge unit is collected and the power of each unit is indirectly calculated, a large number of voltage sensors are required, which greatly increases the cost of system hardware and is not reliable.

Method used

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  • Calculation Method of Instantaneous Power of Each Unit in Cascaded H-bridge Multilevel Converter
  • Calculation Method of Instantaneous Power of Each Unit in Cascaded H-bridge Multilevel Converter
  • Calculation Method of Instantaneous Power of Each Unit in Cascaded H-bridge Multilevel Converter

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Embodiment Construction

[0029] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. The method of the invention only collects the power of the converter and the current amplitude of the AC side of the converter, and calculates the active power and reactive power distributed in each H-bridge unit on-line. The topology of the cascaded H-bridge multilevel converter is as attached figure 2 As shown, the principle of the nearest level approach modulation method is as attached image 3 shown. The method includes the following steps:

[0030] First, for a cascaded H-bridge converter with any number of units, the DC side voltage of each cascaded H-bridge multilevel converter unit is V DC , let the fundamental AC value v of the AC side voltage of the i-th H-bridge unit i Expressed as formula (1):

[0031] v i =V i sin ωt (1)

[0032] In the formula, V i is the fundamental AC amplitude of the AC side voltage of the i-...

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Abstract

The invention discloses a method for calculating the instantaneous power of each unit in a cascaded H-bridge multi-level converter, which includes the following steps: Step 1: each H-bridge unit is modulated according to the nearest level approximation of the cascaded H-bridge converter The electrical angle corresponding to the forward and reverse input moments of the AC side voltage and the DC side voltage of each H-bridge unit, establish the relationship between the AC side voltage of the H-bridge unit with respect to time; Step 2: Solve the equivalent sine of the AC voltage in step 1 by Fourier transform Quantitative expression; Step 3: Multiply the obtained H-bridge unit AC side voltage with the current relational expression flowing through each H-bridge unit to obtain the expression of the H-bridge unit instantaneous power with respect to time; Step 4: Solve the problem through the power proportional distribution relationship Active and reactive power of each H-bridge unit. The method of the invention has less information collection amount, higher calculation accuracy of each unit power value, simple and convenient algorithm realization, and strong versatility.

Description

technical field [0001] The invention relates to the technical field of electric energy conversion of high-power cascaded H-bridge multilevel converters, in particular to a method for calculating instantaneous power of each unit in a cascaded H-bridge multilevel converter. Background technique [0002] Cascaded H-bridge multilevel converters are widely used in high-power AC-DC and DC-AC conversion occasions due to their ability to output arbitrary level voltage waveforms and unitized structure. The modulation methods of cascaded H-bridge multilevel converters mainly include carrier phase shift modulation, space voltage vector modulation, nearest level approximation modulation and so on. Among them, the nearest level approximation modulation realizes the output of the ladder wave voltage through the rounding operation of the modulation voltage and the DC side voltage information, which is especially suitable for applications with a large number of cascaded units, such as the f...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02M7/00
CPCH02M7/00
Inventor 熊成林刁飞张笛雷海吴瑕杰宋文胜葛兴来冯晓云
Owner SOUTHWEST JIAOTONG UNIV