An improved carrier phase-shift modulation method based on three-module cascaded h-bridge
A modulation method and carrier phase-shifting technology, which are applied in the parallel feeding arrangement of a single network, the conversion device of output power, and the conversion of irreversible DC power input into AC power output, which can solve the problem of poor power quality and inability to eliminate inverter It can solve the problems of low frequency harmonic components of the output voltage of the device, so as to achieve the effect of simple algorithm, elimination of equivalent first harmonic components, and small amount of calculation.
Active Publication Date: 2019-11-26
合肥博鳌电气科技有限公司
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[0011] The purpose of the present invention is to provide an improved carrier phase-shift modulation method based on three-module cascaded H-bridges. The phase-shift modulation strategy cannot eliminate the low-frequency harmonic components of the inverter output voltage, resulting in poor power quality. It provides a method that can eliminate the output by correcting the phase-shift angle of the triangular carrier wave in real time without increasing power loss. An Improved Carrier Phase Shift Modulation Method for the Equivalent First Harmonic Component of Voltage
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[0048] Referring to the accompanying drawings, the topological diagram of the three-module cascaded H-bridge photovoltaic grid-connected inverter involved in the present invention is as follows figure 2 Shown:
[0049] The inverter includes three H-bridge modules. Among the three H-bridge modules, each H-bridge module is connected in parallel with a voltage stabilizing capacitor C k and a photovoltaic panel PV k , k=1, 2, 3; each module contains 4 switch tubes, respectively marked as switch S k1 , S k2 , S k3 , S k4 , k=1,2,3, switching tube S k1 with S k2 The front bridge arm of the kth H-bridge module is formed in series, and the switch tube S k1 with S k2 The connection point of is defined as the front-arm voltage output point of the kth H-bridge module, S k3 with S k4 The rear bridge arm of the kth H-bridge module is formed in series, and the switch tube S k3 with S k4 The connection point of is defined as the voltage output point of the rear bridge arm of the...
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The invention discloses an improved carrier phase-shift modulation method based on three-module cascaded H-bridges. The DC side voltage and modulation wave of each module are sampled, and the influence factor of each module on the equivalent first harmonic of the output voltage is calculated. According to the impact factor, the initial phase shift angle of the triangular carrier of each module is determined, so as to obtain two triangular carriers of each module. Finally, compare the modulated wave of each module with the triangular carrier to generate PWM wave to control the inverter. The invention can effectively eliminate the equivalent first harmonic component of the total output voltage of the three-module cascaded H-bridge inverter without increasing losses, improve the power quality of the output voltage, and reduce the DC side voltage and modulation wave imbalance of the H-bridge module Adverse effects on inverter output power quality. Because the algorithm is simple and the control is convenient, it is easy to be extended to practical engineering.
Description
technical field [0001] The invention relates to an improved carrier phase-shift modulation method, which is particularly suitable for a three-module cascaded H-bridge photovoltaic grid-connected inverter, and specifically relates to an improved carrier-wave phase-shift modulation method based on a three-module cascaded H-bridge. Background technique [0002] As a clean energy source, solar energy has attracted more and more attention in the current era of energy scarcity. In order to improve solar power generation, power generation efficiency and utilization rate, the research of photovoltaic grid-connected inverters is one of the most important. Heavy. Cascaded H-Bridge (CHB) multilevel inverter has the advantages of modularization, easy expansion, high efficiency, and high-quality grid-connected current, and has been applied to motor drives and static var compensators. , Active power filter and other occasions. Since the photovoltaic panel just solves the shortcoming tha...
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IPC IPC(8): H02M7/5387H02M7/49H02M1/12H02J3/38
CPCH02J3/385H02M1/12H02M7/49H02M7/53871H02M1/007Y02E10/56
Inventor 何立灿
Owner 合肥博鳌电气科技有限公司