| 摘要 |
According to one embodiment, there is provided a power supply circuit (14) including a power conversion unit (21), a current regulator (23), a controller (22), and a controller power supply (24). The power conversion unit (21) converts an AC voltage with a controlled conduction angle, supplied through a power supply path (26a), into a different voltage and supplies the converted voltage to a load (12). The current regulator (23) includes a branch path (27) connected to the power supply path (26a) and switches between a first state in which a part of a current flowing through the power supply path (26a) flows to the branch path (27) and a second state in which a current flowing to the branch path (27) is lower than that of the first state. The controller (22) detects a conduction angle of the AC voltage and controls the switching of the current regulator (23) based on the detected conduction angle. The controller power supply (24) is connected to the branch path (27), converts a supplied voltage into a driving voltage and supplies the driving voltage to the controller (22). The controller (22) switches the current regulator (23) to the second state in at least a part of a conduction period of the detected conduction angle and switches the current regulator (23) to the first state in a blocking period of the detected conduction angle. |
