Bidirectional power supply device

A bidirectional power supply device comprising:

• a power supply circuit including a coil and a switching element connected in an H bridge connection by a plurality of arms;
• and
• a control unit that controls operations of an upper arm switching element and a lower arm switching element in one arm of the power supply circuit in accordance with a polarity of an alternating current at one end and controls operations of the upper arm switching element and the lower arm switching element in the other arm of the power supply circuit so that a coil current flowing through the coil becomes a target current in a first mode in which an AC power supply is connected to one end of the power supply circuit and a DC load is connected to the other end of the power supply circuit or a second mode in which an AC load is connected to the one end of the power supply circuit and a DC power supply is connected to the other end of the power supply circuit,
• wherein the control unit is configured such that, as the other arm drive signal for driving the upper arm switching element and the lower arm switching element in the other arm,
• the control unit compares a first threshold signal waveform obtained by adding a ramp signal in a direction approaching zero to an arithmetic current value in an initial stage of each control cycle of the switching elements with the coil current using an arithmetic current waveform having a larger absolute value than an absolute value of a target current waveform and generates the other arm drive signal that switches between a period until the coil current matches the first threshold signal waveform from the initial stage of the control cycle and a period until the initial stage of the next control cycle after the coil current matches the first threshold signal waveform, in one of the first mode and the second mode, and
• the control unit compares a second threshold signal waveform obtained by adding the ramp signal in a direction separated from zero to the arithmetic current value in the initial stage of each control cycle with the coil current using an arithmetic current waveform having a smaller absolute value than the absolute value of the target current waveform and generates the other arm drive signal that switches between a period until the coil current matches the second threshold signal waveform from the initial stage of the control cycle and a period until the initial stage of the next control cycle after the coil current matches the second threshold signal waveform, in the other one of the first mode and the second mode.