Control method for sliding mode converter control structure of active power filter containing parameter perturbation

Abstract

The invention discloses a control method for a sliding mode converter control structure of an active power filter containing a parameter perturbation, which comprises the following steps: firstly, building a state space mathematical model under an abc coordinate system; converting the state space mathematical model to be under a dq coordinate system to obtain a uniform mathematical model by taking dq components of harmonic current and capacitor voltage on a direct-current side as state variables; constructing a sliding mode surface; decoupling the sliding mode surface for control; defining a control rate; carrying out inverse transformation on the control rate to obtain an effective control rate; constructing an integral sliding mode surface; and redefining a new control rate, so as to finally obtain a PWM (Pulse-Width Modulation) signal for driving a switch tube. The control method adopts the sliding mode converter structure, so that current tracking and the capacitor voltage on the direct-current side are uniformly controlled. The sliding mode converter control structure is simple in design and is easy to realized, has good robustness on the internal parameter perturbation and internal interference of a system and has good dynamic performance, and the current variation can be quickly tracked when a load is suddenly changed.

Description

technical field [0001] The invention relates to a control method of an active power filter (APF), in particular adopting a sliding mode variable structure control method to uniformly control the current tracking and the DC side capacitor voltage of the active power filter. Background technique [0002] With the wide application of power electronic devices, the harmonics and reactive currents generated by various nonlinear loads have seriously affected the power grid. Active power filter has been widely researched and applied as an effective measure to suppress harmonics. The principle of parallel active power filter (APF) is to make the converter generate real-time tracking command current i c * The compensation current i c , so that the grid side current i s Does not contain harmonic and reactive components. [0003] Common current tracking control methods include hysteresis control, triangle carrier control, etc. Hysteresis control has the advantages of flexibilit...

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Problems solved by technology

Hysteresis control has the advantages of flexibility, fast response, and high precision, but it has high requirements for switching frequency, and the switching frequency is not fixed

The triangular carrier control is characterized by fixed switching frequency and simple circuit implementation, but when the triangular carrier is applied to the high-frequency component of the command current, the control performance decreases

The switching frequency of the ideal sliding mode variable structure control is infinite, and the control amount is also unlimited, so the sliding mode is smooth, but the above two requirements cannot be met in the actual system, and there are time and space lags, making the sliding mode The modulus variable structure system produces "chattering", and the robustness is not strong

[0005] In addition, for the control of the capacitor voltage on the DC side of the voltage-type active power filter, PI adjustment control is often used. The disadvantages of PI adjustment control are obvious: overshoot is easy to occur, parameters are difficult to set, and it is greatly affected by accurate mathematical models. Interference performance is poor

At present, for the current tracking control and the DC side capacitor voltage control in the voltage-type active power filter, most of the literature and practical applications design the two separately, and the process is cumbersome

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