Abstract: Disclosed is a soft switch control circuit and a flyback converter, comprising a primary edge part and a secondary edge part, and obtaining a trigger pulse signal according to a pre-turning on signal of a main switch transistor before the main switch transistor is turned on. The trigger pulse signal is transmitted to the secondary edge part by an isolation module to control the switch at a secondary edge circuit to conduct, to reduce source-drain voltage of the main switch circuit of the primary edge, to make the main switch transistor to turn on when the source-drain voltage is near zero voltage. The switch of the secondary edge circuit is a synchronous rectifying switch transistor or a discharge switch transistor connected at two ends of the synchronous rectifying switch transistor.

Abstract: A biochar is produced by co-pyrolysing an aquatic plant enriched with heavy metals with a clay mineral, and the aquatic plants themselves have high enrichment and adsorb heavy metals in contaminated water; heavy metals are in situ adsorbed, and are coated or enriched in the biochar, therefore extending the migration time of heavy metals, which are also very stable; attapulgite and montmorillonite as clay minerals are loaded in the biochar during the preparing process; heavy metals contained in the biochar play a catalytic role, and synergy with activated attapulgite, therefore increasing the reliability of the biochar, and effectively reducing the ecological effectiveness and potential risk of heavy metals in the biochar.

Abstract: Disclosed is a protection circuit of a flyback converter and a control method. The protection circuit comprises: an active discharge module, for providing a discharge path between a first current terminal and a second current terminal of a switch transistor in a resonance circuit, and controlling turning-on and turning-off of the discharge path according to a discharge enable signal; in the normal work state of the flyback converter, the discharge path is disconnected, the resonance circuit works, before the flyback converter is restarted, the discharge path is turned on for a predetermined time period to release charges stored in the resonance circuit, and the resonance current after the flyback converter is restarted is reduced to the safe work current of the second switch transistor. The resonance current is discharged before the flyback converter is restarted, thus reducing the resonance current and enhancing system stability and security.

Abstract: Disclosed is a protection circuit of a flyback converter and a control method. The protection circuit comprises: an active discharge module, connected to at least one end of a first capacitor in a resonance circuit of the flyback converter to provide a discharge path, and controlling turning-on and turning-off of the discharge path according to the discharge enable signal; in a normal work state, the discharge path is disconnected, the first capacitor works as a resonance capacitor; before the flyback converter is restarted, the discharge path is turned on for a predetermined time period to release charges of the first capacitor, a resonance current after the flyback converter is restarted is reduced to a safe work current of the second switch transistor. Charges stored in the first capacitor can be discharged to release before the flyback converter is restarted to reduce the resonance current and enhance system stability and security.

Abstract: A control method and control circuit of a switched-mode power supply, and the switched-mode power supply are provided. An operating mode of the switched-mode power supply is controlled in a first mode and a second mode according to an output feedback signal of the switched-mode power supply. One operating period of the first mode includes a switch period of a boundary conduction mode (BCM), and one operating period of the second mode includes N switch periods of BCMs and a switch period of a discontinuous conduction mode (DCM). The auxiliary switch transistor is turned on once to discharge a parasitic capacitor of the main switch transistor when the switched-mode power supply enters the next operating period from one operating period of the current second mode before the next operating period starts or the switched-mode power supply enters the first mode from the current second mode before the first mode starts.

Abstract: A clamping switch abnormality detection method, a clamping switch abnormality detection circuit and a switch circuit are provided, wherein an active clamping flyback circuit includes a clamping switch, a main switch and a transformer. When a clamping switch control signal is active, a switching node voltage or a voltage on an auxiliary winding or an magnetizing inductor current is detected, and when the switching node voltage or the voltage on the auxiliary winding or the magnetizing inductor current oscillates, or the switching node voltage is less than a first voltage threshold or the voltage on the auxiliary winding is less than a second voltage threshold, the clamping switch is abnormal or a clamping switch driving circuit is abnormal. The switching node is a common node of the transformer and the main switch, and the transformer includes a primary winding, a secondary winding and the auxiliary winding.

Abstract: An active clamping flyback circuit and a control method are disclosed, comprising a flyback circuit, a clamping circuit and a clamping control circuit. The active clamping flyback circuit comprises a transformer, a main transistor, and a freewheeling diode or a synchronous rectifier, an output feedback circuit is coupling to an auxiliary winding of the transformer and outputs a feedback voltage through a divided voltage The clamping circuit comprises a first capacitor and a first transistor coupling in series, In a discontinuous conduction mode, the clamping control circuit starts timing from a turn-off time of the first transistor, and ends timing until the feedback voltage is reduced to zero voltage, to obtain a first time, The clamping control circuit adjusts a turn-off moment of next switching cycle of the first transistor so that the first time of the next switching cycle is close to a first threshold.

Abstract: A clamping switch abnormality detection method, a clamping switch abnormality detection circuit and a switch circuit are provided, wherein an active clamping flyback circuit includes a clamping switch, a main switch and a transformer. When a clamping switch control signal is active, a switching node voltage or a voltage on an auxiliary winding or an magnetizing inductor current is detected, and when the switching node voltage or the voltage on the auxiliary winding or the magnetizing inductor current oscillates, or the switching node voltage is less than a first voltage threshold or the voltage on the auxiliary winding is less than a second voltage threshold, the clamping switch is abnormal or a clamping switch driving circuit is abnormal. The switching node is a common node of the transformer and the main switch, and the transformer includes a primary winding, a secondary winding and the auxiliary winding.

Abstract: An active clamping flyback circuit is disclosed, comprising a flyback circuit, a clamping circuit and a clamping control circuit, wherein the flyback circuit comprises a transformer, a main transistor, and a freewheeling diode or a synchronous rectifier, an output feedback circuit is coupling to an auxiliary winding of the transformer and outputs a feedback voltage through a divided voltage; the clamping circuit comprises a first capacitor and a first transistor coupling in series, one end of the first capacitor is coupling to a high voltage end, one end of the first transistor is coupling to a common end of the main transistor and a primary winding of the transformer; the clamping control circuit adjusts a turn-off time of next switching cycle of the first transistor so that the first time of the next switching cycle is close to a first threshold.