Power supply unit capable of reducing possibility of overcurrent and current shortage

A power supply unit comprising:

• a power supply;
• and
• a converter, wherein:
• the converter is configured to perform at least one operation selected from a group consisting of boosting and stepping down of an output voltage of the power supply;
• the converter includes a reactor in which n-phase coils are magnetically coupled to each other (where n is an integer of 2 or more), n-phase switches each connected to a corresponding one of the n-phase coils, and a control unit;
• the control unit is configured to control duty cycles of the n-phase switches;
• the control unit is configured to monitor a value of current flowing through the n-phase coils;
• the control unit is configured to perform phase switching control in a case where the control unit determines that a first operation condition is satisfied, the phase switching control including phase switching from in phase to out of phase in a case where the n-phase switches are being driven in phase, and phase switching from out of phase to in phase in a case where the n-phase switches are being driven out of phase;
• and
• the first operation condition is that, when an inlet voltage and an outlet voltage of the converter have predetermined voltage values, the converter is operated in a discontinuous mode in a case where the n-phase switches are being driven in phase, and the converter is operated in a continuous mode in a case where the n-phase switches are being driven out of phase, the discontinuous mode being a mode having a period in which the value of current flowing through the n-phase coils is zero during one cycle of duty cycle control, and the continuous mode being a mode having no period in which the value of current flowing through the n-phase coils is zero during one cycle of the duty cycle control.