Expansion Technique of the Current Reconstruction Areas for Two-Phase Three-Leg Inverters

초록

When driving two-phase motors using the three-leg inverters, phase currents can be measured using shunt resistors inserted between a low-side switch on each leg of the inverter and the negative DC-link terminal. The current measuring scheme using shunt resistors on the only two inverter legs has a limited current measurement capability. In addition to this two-shunt scheme, the three-shunt scheme can reconstruct the immeasurable currents utilizing a shunt resistor located on a neutral leg of the inverter. Thus, the three-shunt scheme can widen the measurable areas of currents than those in the two-shunt scheme. However, this scheme cannot appropriately reconstruct the currents within the specific operating areas in which the sufficient turn-on time for the low-side switches cannot be guaranteed, resulting in the increased torque ripple of two-phase motors and the decreased DC voltage utilization of the inverter. In this paper, a simple technique for expanding the reconstruction areas of currents in the three-shunt scheme is proposed. The proposed technique can expand the reconstruction areas by utilizing the DPWM (Discontinuous Pulse Width Modulation) that can secure the turn-on time of the low-side switches longer than the CPWM (Continuous PWM), thereby improving the DC voltage utilization. © 2022 IEEE.

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