Three-phase PWM rectifier based on multi-sliding-mode variable structure control

Abstract

The invention discloses a three-phase PWM rectifier based on multi-sliding-mode variable structure control. The rectifier comprises three portions of a three-phase PWM rectifier main circuit, a voltage outer loop and a current inner loop. The current inner loop adopts the sliding-mode variable structure control of input and output feedback linearization. An input current follows an input voltage and a distortion is small so that a system is guaranteed to operate in a unit power factor mode and possess a low harmonic wave content. The voltage outer loop adopts a sliding-mode variable structurecontrol strategy based on an exponential approach law so as to increase a starting speed of the system. A stable state characteristic and a dynamic characteristic are further improved, and system jitter can be effectively reduced. By using the control strategy, a disadvantage that input and output feedback linearization control excessively depends on an accurate system mathematics model is effectively overcome; and when a system parameter changes, high robustness can be maintained so that the rectifier is suitable for actual engineering application.

Description

Technical field [0001] The invention relates to a three-phase PWM rectifier, in particular to a three-phase PWM rectifier based on multi-sliding mode variable structure control. Background technique [0002] The three-phase PWM rectifier has become one of the hot issues in the field of modern power electronics research due to its advantages of "green" energy and bidirectional flow, high grid-side power factor, small current distortion, and adjustable output voltage, and is widely used in active power Industrial fields such as filters, wind power generation, photovoltaic power generation, uninterruptible power supply (UPS) and charging stations for emerging hybrid vehicles. Various control strategies, such as: PI control, predictive control, hysteresis control, precise feedback linearization control, sliding mode variable structure control and passive control, have been applied to the control of rectifiers and have achieved certain results. [0003] The three-phase PWM recti...

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Problems solved by technology

[0003] The three-phase PWM rectifier is a nonlinear system with multiple variables and strong coupling between variables, which brings certain difficulties to the design of the controller.

The control strategies mentioned above have improved the performance of the rectifier to varying degrees, but there are also shortcomings such as slow system startup response, large output voltage fluctuations or oscillations when the load jumps, and slow dynamic response.

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