The invention relates to a synchronous rectifier (16) for integration into a power source (10) in order to provide a direct current, in particular in a cube or ashlar-shaped unit of a heavy-current transformer (12), comprising circuit elements (24), an actuation circuit (17) for actuating the circuit elements (24) and a supply circuit (48), wherein a printed circuit board (35) with conductor tracks and connection surfaces is provided for receiving electronic components. For reduction of losses and improvement of efficiency, the circuit elements (24), the actuation circuit (17) and the supply circuit (48) are arranged on the circuit board (35) for the autonomous operation thereof, wherein several openings (37), which are arranged in parallel and in series, are provided on the circuit board (35) for receiving protrusions (36) of a contact plate (29), above which openings (37) the circuit elements (24) are arranged and are connected or soldered and can be contacted with the protrusions (36) of the contact plate (29).

A resistance spot welded joint is formed by resistance-spot-welding a plurality of steel sheets including at least one high strength steel sheet. The high strength steel sheet has a specific chemical composition, and the microstructure of a nugget edge region includes ferrite at an area fraction of 1% or more with respect to the total area of the nugget edge region. The hardness Hv of a softest portion of the nugget edge region and the hardness Hvm of a central portion of the nugget satisfy the relation 0.90Hvm>Hv, and the hardness Hvh of a HAZ softened region and the hardness Hvm of the central portion of the nugget satisfy the relation 0.90Hvm>Hvh.

A flat, electrically and thermally conductive flat surface group is formed in the common connection region 32 of the secondary coil 13. The flat conductive surface group is directly and mechanically joined to the connecting surfaces of the first conductor plate 42, the second conductor plate 44, and the third conductor plate 46, respectively. The first conductor plate 42, the second conductor plate 44, and the third conductor plate 46 cover the entire common connection region 32. The annular first conductor plate 42 occupies the maximum area. The refrigerant can be circulated in the annular cavity provided inside the first conductor plate 42 to efficiently cool the whole.

Components of an electrical resistance welding system include a DC power supply, an energy storage assembly, a switch, and an electrical resistance welding assembly configured to weld a work piece. The system may be free of any transformer which permits the system to operate in an infinite number of variable voltages between a minimum and maximum system setting. The variable voltage control permits greater operability of the electrical resistance welding system by creating a specific weld voltage dependent on parameter, such as a dimension, of the work piece that is to be welded.

Provided is a spot welding method capable of reliably welding a metal sheet laminate while suppressing occurrence of expulsion. In the spot welding method, a pulse current is applied in a first current application step and a second current application step by a DC chopping control method. In the DC chopping control method, a pulse waveform of the pulse current is generated by switching between current application and current application stop to a pair of electrodes 12 and 22 by a current switch 28, a peak current value of the pulse current in the first current application step is set to a value A1 equal to that of the pulse current in the second current application step, and a power of the pulse current in the first current application step is set to a value larger than that of the pulse current in the second current application step.

Provided is a spot welding method capable of performing current control that makes a rising slope of waveform constant even in a case where pulse-shaped waveforms overlap with each other. The spot welding method includes, for a welding current L10: setting a target rise current value P for each predetermined PWM pulse when the welding current L10 increases toward a peak current range R1; and setting, as a first target current value A, a target rise current value P that is larger than and the closest to a rise start current value S in a case where an effective value L14 of the welding current reaches a set welding current L23 while the welding current is decreasing toward a bottom current PB.

Components of an electrical resistance welding system include a DC power supply, an energy storage assembly, a switch, and an electrical resistance welding assembly configured to weld a work piece. The system may be free of any transformer which permits the system to operate in an infinite number of variable voltages between a minimum and maximum system setting. The variable voltage control permits greater operability of the electrical resistance welding system by creating a specific weld voltage dependent on parameter, such as a dimension, of the work piece that is to be welded.

Components of an electrical resistance welding system include a DC power supply, an energy storage assembly, a switch, and an electrical resistance welding assembly configured to weld a work piece. The system may be free of any transformer which permits the system to operate in an infinite number of variable voltages between a minimum and maximum system setting. The variable voltage control permits greater operability of the electrical resistance welding system by creating a specific weld voltage dependent on parameter, such as a dimension, of the work piece that is to be welded.

Components of an electrical resistance welding system include a DC power supply, an energy storage assembly, a switch, and an electrical resistance welding assembly configured to weld a work piece. The system may be free of any transformer which permits the system to operate in an infinite number of variable voltages between a minimum and maximum system setting. The variable voltage control permits greater operability of the electrical resistance welding system by creating a specific weld voltage dependent on parameter, such as a dimension, of the work piece that is to be welded.

Components of an electrical resistance welding system include a DC power supply, an energy storage assembly, a switch, and an electrical resistance welding assembly configured to weld a work piece. The system may be free of any transformer which permits the system to operate in an infinite number of variable voltages between a minimum and maximum system setting. The variable voltage control permits greater operability of the electrical resistance welding system by creating a specific weld voltage dependent on parameter, such as a dimension, of the work piece that is to be welded.