Double step-down chopper circuit

A double step-down chopper circuit comprising:

• a first input smoothing capacitor and a second input smoothing capacitor connected in series between a first node connected to a positive electrode of an input power supply and a second node connected to a negative electrode of the input power supply;
• a first switching element disposed between the first node and a third node;
• a second switching element disposed between a fourth node to which one end of a load is connected and the second node;
• a first freewheeling diode disposed between a fifth node between the first input smoothing capacitor and the second input smoothing capacitor and the third node;
• a second freewheeling diode disposed between the fifth node and the fourth node;
• a reactor disposed between a sixth node to which the other end of the load is connected and the third node;
• an output smoothing capacitor disposed between the sixth node and the fourth node;
• a phase difference correction control unit to determine, based on a difference between a voltage of the first input smoothing capacitor and a voltage of the second input smoothing capacitor, a difference between a current flowing through the first switching element and a current flowing through the second switching element, or a difference between a reactor current when a gate signal of the first switching element is turned on and a reactor current when a gate signal of the second switching element is turned on, an amount of correction of a difference between a phase of switching of the first switching element and a phase of switching of the second switching element;
• and
• a switching control unit to switch the first switching element and the second switching element based on the amount of correction.