The　high　penetration　of　distributed　power　sources　and　distributed　loads　in　new　power　systems　makes　dynamic　changes　in　system　topology　and　source-load　properties　the　norm.　The　breaking　capacity　of　AC　switches　is　newly　challenged　by　the　traditional　design　and　selection　methods.　For　the　distributed　power　supply　access,　there　is　a　mixed　AC　and　DC　power　supply　phenomenon　in　the　feedback　operation　phase　of　the　motor.　In　this　paper,　a　three-phase　inverter　bridge　motor　drive　circuit　is　constructed　to　study　the　load-side　contactor　breaking　voltage　characteristics　under　different　conduction　stages　of　the　power　electronic　switch.　Through　simulation,　it　is　found　that　the　superposition　of　multiple　power　supply　voltages　is　the　cause　of　contactor　breaking　failure　under　the　dynamic　change　of　the　topology　and　source-load　property　of　the　power　electronic　switch.　Finally,　a　new　contactor　selection　idea　is　proposed,　which　is　of　guiding　significance　for　further　optimizing　the　contactor　structure　and　improving　the　contactor　breaking　capacity.　©　Beijing　Paike　Culture　Commu.　Co.,　Ltd.　2025.