基于两相电流差检测的逆变器输出电压补偿新方法

Compensating Inverter Output Voltage Error Based on Two-Phase Currents Difference Detection

为了提高交流电动机变频调速系统的运行性能,提出了一种新的三相电流极性检测方法,用于对死区和开关器件非理想特性引起的逆变器输出电压误差进行补偿。该方法通过检测A、B两相电流差的过零点,对三相电流过零点进行预测;再根据A、B两相电流差过零时A相电流的极性,得到任意时刻的三相电流极性。这种方法的优点是避开了零电流钳位现象,且不受奇次谐波的影响。根据得到的电流极性对死区和IGBT非理想特性引起的电压误差进行补偿,此方法在异步电动机间接转矩控制系统上进行了实验验证。系统中通过计算误差电压等效时间对三相参考电压占空比进行前馈补偿,文中给出了补偿前后的实验结果对比,实验结果表明,补偿后的性能有了明显提高。

In order to improve the performance of AC variable frequency adjustable speed system, a new current polarity detection method is proposed, which is used to compensate the inverter output voltage error caused by the dead time and the non-ideal characteristic of the switch devices. The zero-crossings of the three-phase currents are forecasted in terms of detecting the zero-crossing of two-phase current difference, for example phase A and phase B. Together with the message of phase A current polarity detected at the time of zero-crossings of the two-phase current difference, the current polarities of three-phase at arbitrary moment can be achieved. This method avoids the zero-current clamped phenomenon, and the zero-crossing detection precision is not affected by the odd harmonics. Based on the above polarity detection results, the voltage error produced by the dead time and the non-ideal switching characteristic of IGBT is compensated in an induction motor indirect self control （ISC） system. The compensation of the three-phase voltages are implemented by calculation of the equal time of the voltage error and the feed-forward control of duty cycles of three-phase reference voltages in the real system. Some experiments are carried out, and the experiment results with and without compensation are compared. It shows that the performance of the system is remarkably improved with the proposed method.