Power conversion device

A power conversion device comprising:

• a chopper that converts a first DC voltage supplied from a DC power supply into a second DC voltage and supplies the second DC voltage to a DC load;
• a capacitor that stabilizes the second DC voltage;
• a current detector that detects an output current of the DC power supply;
• and
• a control circuit that, based on a detection result by the current detector, estimates a temperature increase value of the capacitor every time a predetermined time period elapses, and stops an operation of the chopper when the estimated temperature increase value is higher than an upper limit value, wherein
• the control circuit includes:
• a storage that stores information indicating a relationship among the output current of the DC power supply, a time constant of a temperature increase of the capacitor, and a temperature increase saturation value of the capacitor;
• a computation unit that, based on the detection result by the current detector and contents stored in the storage, calculates an estimated temperature increase value of the capacitor every time the predetermined time period elapses;
• and
• a controller that controls the chopper such that an inter-terminal voltage of the capacitor becomes equal to a reference voltage when the estimated temperature increase value is lower than the upper limit value, and stops the operation of the chopper when the estimated temperature increase value is higher than the upper limit value.