Bidirectional Over-Voltage Protection Circuit for Three-Phase Single-Stage Indirect Matrix Converter

Three-phase single-stage Indirect matrix converter (SSIMC) with bipolar output voltage enables three-phase to single-phase AC and to DC power conversion eliminating the need for bulky and heavy dc-link capacitor. However, the fundamental operating principle of SSIMC is identical to that of current-source rectifier with bidirectional switches, making it susceptible to open circuit faults with bipolar currents. To address this issue, a suitable model for SSIMC is developed to capture the switching events to study the open circuit faults along with the parasitic effects, which is, in turn, used for the evaluation of the proposed over-voltage protection (OVP) circuit. The effect of parasitics with the over-voltage clamping devices such as metal oxide varistor and transient voltage suppression diode is analyzed in determining the optimal configuration of the proposed OVP scheme. Consequently, a novel TRIAC-based over-voltage protection circuit is proposed, with a bidirectional capability, applicable to SSIMC. The proposed protection scheme only depends on the stored energy of the primary winding, without any sensors and gate drives.