A device for reducing a voltage difference between two ends of a first switch component, comprising a power supply system, wherein the power supply system comprises a power converter (100, 100a) and a switch mechanism, each phase of three phases of an output end of the power converter (100, 100a) is configured to be connected to a downstream circuit being an alternating current power network by using the switch mechanism, the power converter (100, 100a) is configured to perform electric energy conversion, and the switch mechanism comprises a first switch component (K1, K3, K5) and a second switch component (K2, K4, K6) in each phase that are connected in series; the device further comprises: a controller; a passive component; a first capacitor configured to be connected with its first end to a neutral point N of the alternating current power network; a first bus connection line (Bus+) and a second bus connection line (Bus-) connected to an input end of the power converter (100, 100a); a grounded class Y-capacitor consisting of a second, a third and a fourth capacitor each connected to a second end of the first capacitor, wherein the second capacitor is connected to the first bus connection line (Bus+), the third capacitor is connected to the second bus connection line (Bus-) and the fourth capacitor is connected to a connection point (Bus_N), wherein a fifth capacitor is connected between the connection point (Bus_N) and the first bus connection line (Bus+) and a sixth capacitor is connected between the connection point (Bus_N) and the second bus connection line (Bus-), the fifth capacitor and the sixth capacitor equally dividing a direct current bus voltage, wherein two ends of the first switch component in only one phase (K1, K3, K5) of the output end of the power converter (100, 100a) are connected in parallel to the passive component; and the controller is configured to: control the second switch components of all phases (K2, K4, K6) to be turned on, and when a voltage difference between the two ends of the first switch component in the one phase is less than a preset voltage, control the first switch components of all phases (K1, K3, K5) to be turned on. a controller; a passive component; a first capacitor configured to be connected with its first end to a neutral point N of the alternating current power network; a first bus connection line (Bus+) and a second bus connection line (Bus-) connected to an input end of the power converter (100, 100a); a grounded class Y-capacitor consisting of a second, a third and a fourth capacitor each connected to a second end of the first capacitor, wherein the second capacitor is connected to the first bus connection line (Bus+), the third capacitor is connected to the second bus connection line (Bus-) and the fourth capacitor is connected to a connection point (Bus_N), wherein a fifth capacitor is connected between the connection point (Bus_N) and the first bus connection line (Bus+) and a sixth capacitor is connected between the connection point (Bus_N) and the second bus connection line (Bus-), the fifth capacitor and the sixth capacitor equally dividing a direct current bus voltage, wherein two ends of the first switch component in only one phase (K1, K3, K5) of the output end of the power converter (100, 100a) are connected in parallel to the passive component; and the controller is configured to: control the second switch components of all phases (K2, K4, K6) to be turned on, and when a voltage difference between the two ends of the first switch component in the one phase is less than a preset voltage, control the first switch components of all phases (K1, K3, K5) to be turned on.