Power supply device and method of operating device

A method of operating a power supply device,

• the device comprising:
• a first switching leg in which a series circuit of a first switching element and a second switching element is connected between DC terminals;
• a second switching leg in which a series circuit of a third switching element and a fourth switching element is connected between the DC terminals;
• a first capacitor leg in which a series circuit of a first capacitor and a second capacitor is connected between the DC terminals;
• a second capacitor leg in which a series circuit of a third capacitor and a fourth capacitor is connected between AC terminals and in which a connection point of the third and fourth capacitors and a connection point of the first and second capacitors are connected by a neutral point connection line;
• a first inductor connected between a connection point of the first and second switching elements and one of the AC terminals;
• a second inductor connected between a connection point of the third and fourth switching elements and another of the AC terminals;
• a controller configured to control the first to fourth switching elements;
• an AC power supply and a load connected between the AC terminals and the connection point of the third and fourth capacitors, the AC power supply and the load in parallel to each other;
• and
• a DC power supply connected between the DC terminals, and
• the method comprising a step of:
• operating the switching elements of the first and second switching legs by the controller in a normal operation state of supplying power from the AC power supply to the load, so as to charge the first and second capacitors to a voltage higher than a voltage crest value of the AC power supply by using power of the AC power supply.