Virtual flux linkage-based three-phase Vienna rectifier predictive direct power control method

Abstract

The invention discloses a virtual flux linkage-based three-phase Vienna rectifier predictive direct power control method. According to the method, a mathematic model of a Vienna rectifier under a two-phase static coordinate system is firstly established, and a cross compensation flux linkage observer is adopted to estimate a voltage value of a power grid; a predictive direct power model is deducedaccording to a dead beat prediction basic principle, and a Lagrange linear interpolation method is imported to estimate given values of active power and reactive power at a k+2 moment; and finally, aspace vector modulation technology is utilized to control a switch device of the rectifier. According to the method, a rotational coordinate transformation technology and a phase-locked loop technology do not need to be synchronized, and independent control for the active power and reactive power of the rectifier is directly realized under the two-phase static coordinate system, so that a relatively good control effect can be achieved under the condition that the power grid is unbalanced and distorted and has a relatively large harmonic content.

Description

technical field [0001] The invention belongs to the field of rectifier control, in particular to a three-phase Vienna rectifier prediction direct power control method based on virtual flux linkage. Background technique [0002] Three-level rectifiers are widely used in various high-voltage and high-power devices because the voltage stress of power switching devices is only half of the DC bus voltage. However, the traditional three-level rectifier is composed of 12 semiconductor switch tubes, which reduces the power density of the converter and increases the cost of the device. Compared with the traditional three-level rectifier, the three-phase Vienna rectifier can be composed of 3 semiconductor switching tubes and 18 low-loss silicon carbide diodes. The Vienna rectifier has attracted much attention due to its advantages of low voltage stress of switching devices, fewer semiconductor switches, low grid-side current harmonic content, and can achieve unity power factor. In re...

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Problems solved by technology

Hysteresis current control is a typical nonlinear control method. It obtains the current error by comparing the command current and the detection current in real time, and sends the obtained current error signal to the hysteresis comparator with a preset loop width. The control pulse signal of the converter switching device is obtained by comparing the wide value. The hysteresis current controller has the advantages of fast response, good robustness, and simplicity, but it has the disadvantages of unfixed switching frequency, mutual influence of current between lines, and Disadvantages such as load changes affecting switching frequency

The PI control method based on SVPWM is slow in response and has shortcomings such as overshoot

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