Charge and discharge circuit, control method for charge and discharge circuit, control device for charge and discharge circuit, and direct power converter

A method for controlling a charge and discharge circuit in a direct power converter, said direct power converter including:

• a first power supply line;
• a second power supply line to which a potential lower than a potential applied to said first power supply line is applied;
• a rectifying circuit having an input side to which a single-phase AC voltage is applied, and an output side to be connected to said first and second power supply lines;
• said charge and discharge circuit that is provided between said first and second power supply lines and is closer to said output side of said rectifying circuit;
• and
• an inverter that receives a DC voltage that is a voltage between said first and second power supply lines,
• said rectifying circuit including:
• a diode rectifier that performs single-phase full-wave rectification;
• a first capacitor to be connected between said first and second power supply lines directly or indirectly through said diode rectifier;
• and
• a first reactor to be connected in series with said first power supply line or said second power supply line directly or indirectly through said diode rectifier, said first reactor being more distant from said inverter than said first capacitor is, and
• said charge and discharge circuit including:
• a buffer circuit including a second capacitor provided between said first and second power supply lines, said buffer circuit discharging said second capacitor at a controllable duty ratio;
• and
• a booster circuit that boosts a rectified voltage output by said rectifying circuit to charge said second capacitor,
• said method reducing a DC current to be input to said booster circuit more as a voltage across said first reactor is higher.