Abstract: A switching power supply with overvoltage protection includes a soft start circuit, a rectifying circuit, a filter capacitor, a main supply, an auxiliary supply and a monitoring circuit. When the input voltage is higher than the predetermined protection voltage, a first electric control switch is turned off, and the main power circuit of the switching power supply is shut off. At the moment, the actuation and release of the second electric control switch is controlled so as to control the input power supply to intermittently charge the power supply module such that the output voltage downstream of the rectifying circuit inside the power supply is controlled in a safe range. For instance, the second electric control is turned on when the output voltage is lower than a certain value, and is turned off when the output voltage is higher than a certain value.

Abstract: A bistable contactor drive circuit includes a series branch comprising a first relay coil and a control signal source is connected to a power supply. A third normally closed contact and an eighth normally opened contact of the first relay are connected to a positive electrode of the power supply. A first normally opened contact and a sixth normally closed contact are connected to a negative electrode of the power supply, a second movable contact is connected to a positive electrode of the bistable contactor coil, and a seventh movable contact thereof is connected to a seventh movable contact of a second relay. A negative electrode of the bistable contactor coil is connected to a second movable contact of the second relay. Other connections in the circuit provide for operation of the bistable contactor drive circuit.

Abstract: An improved inductance-voltage clamping full-bridge soft-switch circuit including a full-bridge converter, a transformer, an output rectifying unit, an inductor, a clamping resistor, a capacitor, a first clamping diode, and a second clamping diode. The inductor includes a first winding used as an auxiliary inductor and a second winding used for clamping. A capacitor is connected in parallel with the clamping resistor connected in series.

Abstract: A switching power supply with overvoltage protection includes a soft start circuit, a rectifying circuit, a filter capacitor, a main supply, an auxiliary supply and a monitoring circuit. When the input voltage is higher than the predetermined protection voltage, a first electric control switch is turned off, and the main power circuit of the switching power supply is shut off. At the moment, the actuation and release of the second electric control switch is controlled so as to control the input power supply to intermittently charge the power supply module such that the output voltage downstream of the rectifying circuit inside the power supply is controlled in a safe range. For instance, the second electric control is turned on when the output voltage is lower than a certain value, and is turned off when the output voltage is higher than a certain value.

Abstract: A bistable contactor drive circuit is provided. A series branch comprising a first relay coil and a control signal source is connected to a power supply. A third normally closed contact and an eighth normally opened contact of the first relay are connected to a positive electrode of the power supply, a first normally opened contact and a sixth normally closed contact are connected to a negative electrode of the power supply, a second movable contact is connected to a positive electrode of the bistable contactor coil, and a seventh movable contact thereof is connected to a seventh movable contact of a second relay. A negative electrode of the bistable contactor coil is connected to a second movable contact of the second relay.