Delay Characteristics of Power Relay Operation in the Application of Phase Transfer Method for Failure Stability in Power Conversion Drive Systems

This paper analyzed the transient duration and maximum overshoot according to the operation delay time by applying the phase transfer method for power relay to secure fault stability in a power conversion drive system. The phase transfer method is a method of short-circuiting the faulty phase with two B-contact Power relays and connecting the neutral point to the DC link capacitor for continuous power supply. For the experiment in this study, hardware was manufactured and the power relay was synchronized to the DSP TMS320F28335. A delay was added between the operations of the B-contact power relay and the A-contact power relay to ensure stable power supply when a faulty phase occurs. The optimal relay operation sequence and operation delay time guide lines were presented. In conclusion, it is better to apply only the minimum delay when applying phase transfer method.