A Reliable Control Strategy for Dual Induction Motor Drive System Consisting of Five-Leg Inverter

This paper proposes a reliable control strategy for dual induction motor drives using a five-leg inverter (FLI). Since the FLI has the structural characteristic where both motors share a common leg, the current of the common leg can flow at twice the magnitude of the other leg currents. To prevent this overcurrent, this paper proposes a reliable integrated control strategy for both normal and open-circuit fault conditions in the FLI. Under normal conditions, overcurrent can occur when the phase and frequency of the current for both motors are distinct; therefore, the angle controller and current limitation prevent overcurrent. In contrast, an open-circuit fault in the FLI can cause overcurrent due to altered current paths. To ensure a safe shutdown, identifying the specific location of the faulty switch is essential. Therefore, fault diagnosis is required using the stator currents. Once the fault is located, a fault-tolerant method is applied to safely stop the motors, considering both the fault location and the rated current of the common leg. Consequently, the proposed system enables reliable operation of dual induction motor drives under various conditions. The experimental results verify the effectiveness of the proposed system.