Power supply device, joining system, and electric processing method

A power supply device that supplies an output current to an electric processing device which performs electric processing on workpieces, the power supply device comprising:

• a first power supply;
• a magnetic energy recovery switch that receives a current supplied from the first power supply, and converts the received current into the output current;
• and
• a control unit that controls the magnetic energy recovery switch such that an electric current frequency of the output current includes a first electric current frequency and a second electric current frequency which are different from each other within a one-time electric processing time using the electric processing device,
• wherein the magnetic energy recovery switch includes
• a bridge circuit in which a first reverse conducting semiconductor switch and a fourth reverse conducting semiconductor switch are arranged in series in a first path such that conduction directions when the first and fourth reverse conducting semiconductor switches are switched off are reverse directions each other, a second reverse conducting semiconductor switch and a third reverse conducting semiconductor switch are arranged in series in a second path such that conduction directions when the second and third reverse conducting semiconductor switches are switched off are reverse directions each other, and the conduction directions of the first reverse conducting semiconductor switch and the third reverse conducting semiconductor switch when the first and third reverse conducting semiconductor switches are switched off are the same, and
• a capacitor that is connected between a region of the first path which is located between the first reverse conducting semiconductor switch and the fourth reverse conducting semiconductor switch and a region of the second path which is located between the second reverse conducting semiconductor switch and the third reverse conducting semiconductor switch,
• the magnetic energy recovery switch is disposed between the first power supply and the electric processing device, and
• the control unit controls the electric current frequency within the one-time electric processing time by controlling an ON time and an OFF time of at least one of a pair including the first reverse conducting semiconductor switch and the third reverse conducting semiconductor switch and a pair including the second reverse conducting semiconductor switch and the fourth reverse conducting semiconductor switch, or controls the electric current frequency and a current value of the output current within the one-time electric processing time by controlling the current supplied from the first power supply, and the ON time and the OFF time of at least one of the pair including the first reverse conducting semiconductor switch and the third reverse conducting semiconductor switch and the pair including the second reverse conducting semiconductor switch and the fourth reverse conducting semiconductor switch.