Power conversion device and press apparatus

A press apparatus comprising:

• a bolster where a target workpiece is placed;
• a slide arranged to face the bolster across the target workpiece;
• a servomotor configured to control a distance between the bolster and the slide by moving the slide;
• and
• a power conversion device configured to include a voltage-doubling rectifier circuit and an inverter circuit, and control the servomotor,
• wherein the voltage-doubling rectifier circuit includes:
• a rectifier circuit configured to rectify, and thus, convert an input alternating-current voltage into a direct-current voltage;
• a DC-link capacitor configured to include first and second capacitors that are connected in series between paired output nodes, and configured to, in a second rectification mode, retain the direct-current voltage substantially having a double voltage in a first rectification mode as an output voltage of the paired output nodes;
• a switching element configured to, in the second rectification mode, connect a common connection node between the first and second capacitors to a predetermined node so that each of the first and second capacitors is individually charged;
• a first current detector circuit configured to detect a switching current flowing in the switching element;
• a second current detector circuit configured to detect a load current flowing in the servomotor;
• and
• a controller circuit configured to, in a mode switching period from the first rectification mode to the second rectification mode, control the switching of the switching element, based on the switching current and the load current, and
• the inverter circuit converts the output voltage of the paired output nodes into an alternating-current voltage to control the servomotor by using the alternating-current voltage.