Abstract: An inverter device (1), including a first inverter (10), and a second inverter (20) connected in parallel to the first inverter. Both the first and second inverters (10, 20) are three-level inverters. The first and second inverters (10, 20) generate first and second output voltages (V1, V2) using the voltage (Vc) at the connection point between a first capacitor (C1) and a second capacitor (C2) connected in series and evenly allocating a power supply voltage (Vin). A control circuit (40) duty-controls the second inverter at high frequency, when the second inverter (20) switches the level of the second output voltage (V2).

Abstract: A DC power supply system includes a DC power supply and a secondary battery for backing up the DC power supply. When a voltage of the DC power supply is lower than a voltage of the secondary battery, the DC power system adds an extra voltage to the voltage of the DC power supply to provide an input voltage to the secondary battery higher than the voltage of the secondary battery by using an electric power of the secondary battery, and the secondary battery is charged.

Abstract: An electric power supply apparatus, which enables a driving frequency of a switching circuit connected to a primary side of a transformer constant and output of a secondary side variable, comprises a transformer (5), a series circuit of two first switching elements (Q1, Q2) connected between terminals of a direct current power supply (2), an LC resonant circuit connected between both ends of one of the first switch element (Q2) and a primary winding (Np) of the transformer (5), bidirectional switch elements (Q3, Q4) connected to secondary windings (Ns1, Ns2) of the transformer (5) and having a rectification function and a phase control function, and a control circuit for inputting gate driving signals having a phase difference into the first switch elements (Q1, Q2) and the second switch elements (Q3, Q4).

Abstract: An inverter device (1), including a first inverter (10), and a second inverter (20) connected in parallel to the first inverter. Both the first and second inverters (10, 20) are three-level inverters. The first and second inverters (10, 20) generate first and second output voltages (V1, V2) using the voltage (Vc) at the connection point between a first capacitor (C1) and a second capacitor (C2) connected in series and evenly allocating a power supply voltage (Vin). A control circuit (40) duty-controls the second inverter at high frequency, when the second inverter (20) switches the level of the second output voltage (V2).

Abstract: An electric power supply apparatus, which enables a driving frequency of a switching circuit connected to a primary side of a transformer constant and output of a secondary side variable, comprises a transformer (5), a series circuit of two first switching elements (Q1, Q2) connected between terminals of a direct current power supply (2), an LC resonant circuit connected between both ends of one of the first switch element (Q2) and a primary winding (Np) of the transformer (5), bidirectional switch elements (Q3, Q4) connected to secondary windings (Ns1, Ns2) of the transformer (5) and having a rectification function and a phase control function, and a control circuit for inputting gate driving signals having a phase difference into the first switch elements (Q1, Q2) and the second switch elements (Q3, Q4).

Abstract: A DC power supply system includes a DC power supply and a secondary battery for backing up the DC power supply. When a voltage of the DC power supply is lower than a voltage of the secondary battery, the DC power system adds an extra voltage to the voltage of the DC power supply to provide an input voltage to the secondary battery higher than the voltage of the secondary battery by using an electric power of the secondary battery, and the secondary battery is charged.