Abstract：With the high proportion of distributed photovoltaic power generation connected to the power grid，the single-phase grid connection of distributed power generation has exacerbated the imbalance of the power grid.In addition，the number of DC electrical equipment is increasing in the industrial and construction fields. Under the imbalance of the power grid，how to reduce the adverse impact of the AC second harmonic of the three-phase PWM rectifier on the stability of DC system power supply has become a problem that must be faced. Under voltage

imbalance in the power grid，conventional control strategies require the extraction of positive and negative

sequence components to calculate power compensation values. The extended reactive power theory was introduced

to reduce control complexity，reduce computational complexity，and achieve the same control objectives. To

address the issues of long rolling optimization time，large power ripple，and variable switching frequency in

traditional FCS-MPDPC，a fixed switching frequency FSF-MPDPC was used to calculate the optimal voltage

vector online. A control strategy was proposed to suppress the rate of change of reactive power，effectively reducing the high-frequency ripple and total harmonic distortion of the grid side current of the three-phase PWM rectifier，in response to the high-frequency oscillation phenomenon of actual reactive power under the optimal voltage vector of FSF-MPDPC. Finally，the effectiveness and feasibility of the algorithm were verified through experimental platforms built on Simulink simulation platform and laboratory conditions.

        Key words：three-phase PWM rectifier；voltage imbalance in the power grid；model predictive direct power

control（MPDPC）

     Format Citation:杨晓霞，曾飞，缪惠宇,等. 电网不平衡下三相PWM整流器模型预测直接控制策略[J].电气传动,2026,56(07):39-46. YANG Xiaoxia，ZENG Fei，MIAO Huiyu,et al. Model predictive direct control strategy for three-phase PWM rectifier under unbalanced power grid [J].Electric Drive, 2026,56(07):39-46