中文摘要：

恒频直接功率控制（constant switching frequency direct power control,CSF-DPC）具有开关频率固定、动态性能好、系统采样频率较低等优点。电网电压不平衡会在脉宽调制（pulse width modulation,PWM）型整流器交流侧产生大量谐波电流,使系统有功功率大幅波动,恶化系统性能。针对上述情况,提出一种新型恒频直接功率控制策略。该策略首先分离出电网电压和电流正、负序分量;然后在正、负序双旋转坐标系下计算瞬时功率与参考值之间的误差,根据误差生成整流器正、负序参考电压;合成后采用空间矢量调制（spacevector modulation,SVM）算法产生整流器电压,对功率进行补偿。该策略可有效抑制交流侧电流谐波,减小系统无功功率直流分量,稳定系统输出的有功功率,改善系统稳态性能。仿真与实验结果证明了该策略的正确性和有效性。

英文摘要：

Constant switching frequency direct power control（CSF-DPC） strategy has the advantages of fixed switching frequency,good dynamic performance and low system sampling frequency requirement.In this paper,a developed CSF-DPC strategy was proposed to solve the problems in pulse width modulation（PWM） rectifiers,such as current harmonics,significantly fluctuating active power and performance deterioration,caused by unbalanced grid voltage.The positive and negative sequence components of grid voltages and currents were calculated to obtain instantaneous power in two revolving coordinates,which rotate at positive and negative synchronous angular velocity respectively.The errors between reference values and calculated values of power were regulated to build the output voltage space vector.The duty cycle of rectifier was calculated by SVM method.The proposed strategy was finally verified by simulation and experimental results.It is proved to be effective on reducing input current harmonics and reactive power DC components,stabilizing output active power.