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 direction of single-network parallel feeding arrangement, output power conversion device, irreversible DC power input conversion to AC power output, etc., can solve the problem of poor power quality and inability to eliminate inverter Problems such as low-frequency harmonic components of the output voltage of the device, to achieve the effect of simple algorithm, elimination of equivalent first-order harmonic components, and easy realization
Active Publication Date: 2018-09-28
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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[0045] 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: The inverter includes 3 H-bridge modules, and the DC side of each H-bridge module is connected in parallel with a capacitor C k and photovoltaic panels PV k ,, k=1, 2, 3, after cascading 3 H-bridge modules, the AC side is connected to the filter inductor L and the power grid V s , each H-bridge module contains 4 switch tubes, denoted as switch S k1 ,S k2 ,S k3 ,S k4 , k=1, 2, 3, switch tube S k1 with S k2 Connected in series to form the front bridge arm of the H-bridge module, S k3 with S k4 The rear bridge arm of the H-bridge module is formed in series, and the voltage at both ends of the capacitor of each H-bridge module and the output voltage are recorded as the DC side voltage V dck , k=1, 2, 3, AC side voltage V k , k=1, 2, 3, V T is the total output vol...
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The invention discloses an improved carrier phase shift modulation method based on a three-module cascaded H bridge. A DC side voltage and a modulating wave of each module are sampled, and an influence factor of each module on the equivalent first harmonic of an output voltage is calculated. An initial phase shift angle of each module is determined according to the influence factor to obtain two triangular carriers of each module. Finally, the modulating wave of each module is compared with the triangular carriers to generate a PWM wave control inverter. By adoption of the improved carrier phase shift modulation method disclosed by the invention, the equivalent first harmonic component of the total output voltage of the three-module cascaded H bridge inverter can be effectively eliminatedwithout increasing the loss, the power quality of the output voltage is improved, and the adverse effects of the imbalance of the DC side voltage and the modulating wave of the H bridge module on theoutput power quality of the inverter are reduced. As the algorithm is simple and the control is convenient, and the improved carrier phase shift modulation method can be easily promoted to actual projects.
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