| 摘要 |
PROBLEM TO BE SOLVED: To immediately break the supply of a normal electric current even in the halfway time of an AC wave when such a situation happens that the supply of a normal electric current should be interrupted before the termination of a predetermined time of supplying the electric current in a joining or a reflow-soldering of metallic members where an electric current having an AC wave form is used. SOLUTION: A controlling part 32 operates a continuous switching at an inverter frequency only for switching elements (22 and 26) on the positive pole side while keeping switching elements (24 and 28) on the negative pole side off at every unit energizing period of an odd number among plural unit energizing periods which compose a set energizing time, and operates a continuous switching at the inverter frequency only for the switching elements (24 and 28) on the negative pole side while keeping the switching elements (22 and 26) on the positive pole side off at every unit energizing period of an even number. Thus, a secondary electric current 12 having the current form of a near trapezium flows in the secondary circuit of a power supply unit, in the positive pole direction in every unit energizing period of an odd number, and in the negative pole direction in every unit energizing period of an even number. When a breaking signal WS of the electric current is inputted during the time of the normal energizing, the controlling part 32 interrupts the switching control of an inverter 16 and immediately stops the supply of the normal electric current.
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