A Model Predictive Control Method for Direct Power Control of Three-Phase Four-Switch Rectifier

Abstract

The invention discloses a three-phase four-switch rectifier direct power control model prediction control method. The method includes: A, measuring the three-phase current, the three-phase grid voltage, and the voltages of two DC side capacitors through a current sensor and a voltage sensor in a rectifier; B, calculating the voltage vectors corresponding to four switch combinations (00, 01, 11, 10) through the measured voltages of the DC capacitors; C, predicting the active powers, the reactive powers, and the capacitor voltages which are corresponding to four voltage vectors according to the measured phase current, the measured phase voltage; E, calculating cost functions of the voltage vectors: subtracting a prediction value and a reference value, and then obtaining an absolute value, multiplying various values and weight coefficients, and finally adding the obtained values; and F, applying the switch state corresponding to the voltage vector having the minimum cost function to the rectifier. The method is suitable for various rectification systems and various active filtering systems which are driven by a three-phase four-switch.

Description

technical field [0001] The invention belongs to the field of rectification, and in particular relates to a model predictive control method for direct power control under the topology of a three-phase four-switch power converter. Background technique [0002] In recent years, the rectifier composed of six-switch three-phase fully-controlled power electronic devices has many advantages such as controlling the bidirectional flow of energy, controllable power factor, good DC voltage regulation performance, and sinusoidal input current. , wind energy and other renewable energy grid-connected power generation, active power filter, and frequency conversion speed regulation and other systems have been widely used. Among them, the energy density of the converter is high, and the power electronic devices are relatively "fragile". Once an open circuit or short circuit fault occurs in a power tube of the converter, the entire system will lose the ability to work normally, and even have ...

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Problems solved by technology

In many patents and literatures on the control strategy of the three-phase four-switch rectifier system, the general methods are divided into two categories: one is to assume that the DC capacitor voltage is constant, and design the control algorithm on this basis. The phase is directly connected to the neutral point of the capacitor, and the flow of the phase current will cause the fluctuation and drift of the capacitor voltage, so this type of method cannot be used in the actual system; the other is designed for the capacitor voltage fluctuation and drift based on some steady-state assumptions control algorithm, but this algorithm is generally a steady-state control strategy, and its dynamic performance in voltage regulation is poor

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