DIRECT-CURRENT SIDE CONTROL METHOD FOR MIDLINE ARM CONTROL MODEL OF FOUR BRIDGE ARM PHOTOVOLTAIC INVERTER

摘要

Disclosed is a direct-current side control method for a midline arm control model of a four bridge arm photovoltaic inverter. The midline arm control model comprises a photovoltaic direct-current input (1), a stabilized voltage capacitor (CPV), a direct-current booster circuit (2), two groups of inverter side energy storage capacitors (CN+, CN-), two equivalent bleeder resistors connected in series, a midline inductor (LN) and a midline arm (3). In the control method, an average value (p) of signals in a switching period of a midline arm switching function is used as a control variable; an H8 controller is designed by adopting an H8 control method, so that the H-infinite range of the input midline current (iN), measurement error (n), equivalent external disturbance (V0), half of the sum (Vavc) of the output voltages of the two capacitors relative to a neutral point and midline arm midpoint voltage (UN) is minimum; and implementation of a corresponding generalized controlled object (P), a controller structure and a corresponding weighting function (Wu, Wv) selection method are provided. The control method ensures that the stability of the direct-current side midpoint of the four bridge arm photovoltaic inverter still can be kept in high midline current.