Abstract: A power conversion system that performs power conversion between a power supply and a load includes a pair of input ends, a pair of output ends, reactor, diode, switch, capacitor, current sensor, and control unit. The control unit is configured to perform a diagnostic process to diagnose deterioration of the capacitor. The diagnostic process includes a switching process to add an alternating-current component that fluctuates at a predetermined frequency to a voltage applied from the power supply to a series circuit of the reactor and the capacitor, by repeatedly turning on and off the switch, a specifying process to specify the phase difference or gain which an alternating-current component that appears in the current measured by the current sensor has, relative to the added alternating-current component, and a determining process to determine whether the phase difference or gain specified by the specifying process is within a normal range.

Abstract: An electrically operated valve system includes: a first switching element and a second switching element connected in series to an electric power supply; a third switching element and a fourth switching element connected in series to the electric power supply; diodes; a coil connected between a first middle point and a second middle point, the coil being wired such that a valve opens when the second switching element and the third switching element are opened and the first switching element and the fourth switching element are closed; a shutoff switch configured to shut off a path between a positive electrode of the first switching element and the electric power supply; and a capacitor connected at one end of the capacitor between the shutoff switch and the first switching element and connected at the other end of the capacitor to the negative electrode of the electric power supply.

Abstract: An electrically operated valve system includes: a first switching element and a second switching element connected in series to an electric power supply; a third switching element and a fourth switching element connected in series to the electric power supply; diodes; a coil connected between a first middle point and a second middle point, the coil being wired such that a valve opens when the second switching element and the third switching element are opened and the first switching element and the fourth switching element are closed; a shutoff switch configured to shut off a path between a positive electrode of the first switching element and the electric power supply; and a capacitor connected at one end of the capacitor between the shutoff switch and the first switching element and connected at the other end of the capacitor to the negative electrode of the electric power supply.