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Simplified model forecasting control method of network voltage unbalance three-level rectifier

A technology of three-level rectification and grid voltage, which is applied in the direction of irreversible AC power input conversion to DC power output, etc., which can solve the problems of inability to realize stable operation of the system, influence of switching frequency PWM inertia link, and inability to accurately track current accuracy and response speed and other problems, to achieve the effect of simplifying the model predictive control algorithm, eliminating the double frequency pulsation, and reducing the number of optimization times

Inactive Publication Date: 2014-07-30
CHINA UNIV OF MINING & TECH
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Problems solved by technology

Existing solutions use proportional-integral (PI), proportional resonant (PR) controllers and some nonlinear controllers to control the current inner loop, but there are still problems of accurate tracking of current accuracy and response speed, especially in large In power applications, the reduction of switching frequency has a serious impact on the PWM inertial link, making it impossible to achieve stable operation of the system

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  • Simplified model forecasting control method of network voltage unbalance three-level rectifier
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Embodiment Construction

[0047] The present invention will be further described below in conjunction with accompanying drawing:

[0048] according to figure 1 It can be seen that in the topology of the main circuit of the three-level PWM rectifier, e a 、e b 、e c is a three-phase AC voltage source, i a i b i c is the three-phase AC side current, v a , v b , v c is the three-phase voltage at the input side of the rectifier bridge, V dc is the DC side voltage, L and R are the AC side incoming line inductance and its equivalent resistance, C 1 、C 2 is the DC side capacitor, and the DC side load uses R L To be equivalent, n is the midpoint of the power grid, o is the midpoint of the two capacitors connected to the midpoint of the clamping diode, and the voltages on the two capacitors are V dc1 , V dc2 , the capacitive current is i dc1 i dc2 .

[0049] according to figure 2 It can be seen that when the positive and negative sequence components are separated using the time delay method, the...

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Abstract

The invention belongs to the field of converter control, and relates to a simplified model forecasting control method of a network voltage unbalance three-level rectifier. The simplified model forecasting control method of the network voltage unbalance three-level rectifier comprises the steps that (1) positive and negative sequence separation is carried out on three-phase network voltage and current to obtain positive and negative sequence components; (2) coordinate transformation is carried out on three-phase positive sequence voltage and current to obtain positive sequence voltage and current under a two-phase static coordinate system; (3) according to the three-phase positive sequence voltage, three levels are changed into two levels in an order reduction mode through reference voltage; (4) an active power reference value and a current reference value are calculated; (5) a current forecasting value of the rectifier, a direct current side capacitance voltage forecasting value and the changing number of switching elements are calculated; (6) current control, neutral-point potential control and switching frequency control are forecast according to a model, and the best switching state is selected. The simplified model forecasting control method of the network voltage unbalance three-level rectifier can effectively suppress double-frequency fluctuation of input power of the rectifier, lower the switching frequency of the elements, shorten circulation calculation time, control neutral-point potential balance, and improve the operation efficiency of the system.

Description

technical field [0001] The invention relates to a control method for a grid voltage unbalanced three-level rectifier, in particular to a grid voltage unbalanced three-level rectifier low switching frequency simplified model predictive control method. Background technique [0002] With the rapid development of new power electronic devices and technologies, three-phase PWM rectifiers have the characteristics of sinusoidal grid-side voltage, unit power factor operation, and bidirectional energy flow, so they have good application prospects in high-voltage and high-power applications. Under the condition of obtaining the same control function, the switching frequency of the three-level PWM rectifier is doubled, and the current harmonics can be effectively reduced, so the research on high-power three-level PWM rectifier and its control has become a hot spot, and the model predictive control The algorithm is widely used in the design of the rectifier control system because of its ...

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Application Information

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IPC IPC(8): H02M7/12
Inventor 张婷婷苗文彬田桂林赵明龙张金科袁庆庆公铮吴强王钊朱茂森吴斌
Owner CHINA UNIV OF MINING & TECH
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