Abstract
In this paper, a control method in fault-mode for three-phase voltage source inverters to drive AC motors is proposed. The proposed method does not require any additional switching devices and specially constructed motors with an external terminal of the neutral point. Thus, this method can be easily applied to conventional three-phase voltage source inverters. When the one leg of the inverters is lost by a trouble in the switching devices, the turn-on signals for the switching devices are removed. Then, the corresponding phase of the motor is connected to the neutral point of the DC link divided by the two series-connected DC smoothing capacitors. In this connection, the switching devices in the remaining two phases of the inverter can apply sinusoidal line-to-line voltage to produce the three-phase balanced currentin the motor. To realize the proposed method, a method to compensate the voltage fluctuation of the DC neutral point must be developed. The effectiveness of the proposed control strategy for the fault-mode three-phase voltage source inverters has been confirmed by the experimental results employing a test system.
