Direct power predictive control method based on load current observation of three-phase six-switch rectifier

Abstract

The invention provides a direct power prediction control method based on three-phase six-switch rectifier load current observation, and discloses a direct power prediction control technology for three-phase rectifier load current observation. The direct power prediction control method comprises the steps of: A, measuring three phases of currents, a three-phase power grid voltage and a DC side capacitor voltage through a current sensor and a voltage sensor respectively; B, calculating voltage vectors corresponding to eight kinds of switch combinations (000, 001, 010, 100, 011, 101, 110, 111) through the measured DC side capacitor voltage; C, passing a given DC voltage through a filter to obtain an instantaneous reference voltage of a sampling period at present, and acquiring an instantaneous reference value of active power according to a DC side and AC side power conservation principle, wherein the reference value of active power is calculated by adopting an observer to estimate a load current; D, predicting active power, reactive power and capacitor voltages corresponding to eight voltage vectors of a rectifier according to the measured phase currents and the phase voltages; E, and calculating a corresponding cost function F, and applying a switching state corresponding to the voltage vector with the minimal cost function value to the rectifier. The direct power prediction control method is applicable to various kinds of three-phase rectifiers and active filters.

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 with a load current observer under the topology of a three-phase 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. [0003] Among the many patents and literatures on the control strategy of the three-phase six-switch rectifier system, the general methods are divided into three categories: one is to use the voltage vector oriented control (VOC), and the coordinate axis ...

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Problems solved by technology

[0003] Among the many patents and literatures on the control strategy of the three-phase six-switch rectifier system, the general methods are divided into three categories: one is to use the voltage vector oriented control (VOC), and the coordinate axis is oriented to the voltage vector by rotating the coordinate transformation , to obtain decoupling control of active power and reactive power, but this type of algorithm requires coordinate transformation and modem, and its control parameters are too many to be adjusted; the other type is direct power control (DPC) by introducing the concept of instantaneous power, Directly calculate the active and reactive power of the rectifier, and obtain the optimal voltage vector through the switch table lookup method, but this type of algorithm cannot guarantee that all the optimal voltage vectors are obtained; the third type is the predictive control method of direct power control , but the reference value of its active power is often obtained through a proportional-integral (PI) regulator, which often has the problem of integral saturation, which affects the dynamic performance

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