Power source device for electric discharge machine

A power supply device for an electric discharge machine, comprising:

• a current supply unit for supplying a pulsed current to an electrode gap constituted by a workpiece and an electrode, which are opposed to each other with a predetermined gap, for electric-discharge machining a workpiece, and
• a current regeneration unit for regenerating the current, wherein
• the current supply unit comprises:
• a first DC power supply for applying a first voltage which generates the current to the electrode gap and which is connected in parallel with the electrode gap,
• a first switching element which is arranged between the electrode and a side of a first pole of the first DC power supply and which is turned on while the first voltage is being applied to the electrode gap, and
• a second switching element which is arranged between the workpiece and a side of a second pole of the first DC power supply and which is turned on while the first voltage is being applied to the electrode gap, and
• the current regeneration unit comprises:
• a capacitive element which is arranged between a first connection point between the electrode and the first switching element and a second connection point between the workpiece and the second switching element, and
• a third switching element which is arranged between a third connection point between the first connection point and a first side of the first DC power supply and a fourth connection point between the second connection point and one side of the capacitive element and which is turned on when the voltage of the capacitive element exceeds a preset second voltage which is higher than the first voltage during regeneration of the current so as to maintain the voltage of the capacitive element at the second voltage.