AUXILIARY POWER SUPPLY DEVICE AND METHOD FOR CONTROLLING AUXILIARY POWER SUPPLY DEVICE

An auxiliary power supply device includes a storage circuit having a first electrical double layer capacitor and a second electrical double layer capacitor connected in series between a first node and a second node, a first switch element having a first terminal coupled to the first node, and a second terminal, a first discharging resistor provided between the second terminal and a fourth node, a second discharging resistor provided between the fourth node and ground, a second switch element having a third terminal coupled to a third node between the first electrical double layer capacitor and the second electrical double layer capacitor, and a fourth terminal coupled to the fourth node, and a measurement controller, and the measurement controller performs a procedure to compute a capacitance value of the storage circuit as a first process, and a procedure to connect the first switch element and connect the second switch element as a second process.