3-레그형 2상 인버터에서의 전류 복원 영역 확장

초록

For measuring phase currents of two-phase motors driven by the three-leg inverters, the leg shunt resistors inserted between the lower switch of each inverter leg and the negative DC rail can be used instead of the expensive Hall-effect sensors. The two-leg shunt method using shunt resistors located on the two-phase legs has a limited current measurement range. In addition to this method, the three-leg shunt method can reconstruct the immeasurable phase currents by using an additional shunt resistor on a neutral leg. Therefore, the current measurement range can be wider than that in the two-leg shunt method. However, this method cannot properly reconstruct the currents in the specific areas where the voltage modulation index of the inverter is high, thereby decreasing the DC voltage utilization rate, and increasing the torque ripple of the motors. To improve this problem, this paper analyzed the current reconstruction areas of a three-leg type two-phase inverter applied CPWM(Continuous Pulse Width Modulation) method, and proposed a simple technique to expand the areas. The proposed technique can expand the current reconstruction areas by securing the turn-on time of the inverter lower switches utilizing the DPWM(Discontinuous PWM) method, which results in the improvement of DC voltage utilization rate

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