抑制共模电流的变频空调系统同步PWM控制方法

Synchronous PWM Control Method of Frequency Conversion Air Conditioning System for Suppressing Common Mode Current

为有效降低双变频空调(Air Conditioner,AC)系统中电压波动产生的共模电流,以便满足电磁干扰标准,提出了一种新的同步脉冲宽度调制(Pulse Width Modulation,PWM)控制方法。在由两个逆变器驱动(主从式控制模式)的AC系统中,通过在从模逆变器的矢量空间进行信号选择,以便减小相电流的畸变;采用矢量控制的方法来抑制风扇电机的不稳定性,并利用特殊的扇区选择方法减小电压误差,实验结果表明,相比现有的PWM方法,提出的同步PWM方法明显减小了相位电流的畸变,并有效降低了AC系统工作过程中的传导发射噪声,在170 kHz、1 MHz和10 MHz的频率下,噪声分别可降低23 dB、6 dB和1.5 dB,理论仿真和实机测试均验证了该方法的有效性。

In order to effectively reduce the common mode current caused by voltage fluctuation in air conditioner(AC)system and meet the electromagnetic interference standard,a new synchronous pulse width modulation(PWM)control method is proposed.In an AC system driven by two inverters(master-slave control mode),signal selection is carried out in the vector space of slave mode inverters in order to reduce the distortion of phase current.The vector control method is used to suppress the instability of fan motor,and the special sector selection method is used to reduce the voltage error.The experimental results show that compared with the existing PWM method,the proposed synchronous PWM method obviously reduces the distortion of phase current and effectively reduces the conducted emission noise in AC system.The noise can be reduced by 23 dB,6 dB and 1.5 dB at 170 kHz,1 MHz and 10 MHz,respectively.Theoretical simulation and real machine test verify the effectiveness of this method.