Power system-interconnected inverter device

摘要

In a power-system-interconnected inverter device, PI control circuits obtain voltage correction values in directions reducing the current errors on the basis of current errors serving as differences between target current values and detection values. Multiplexers provide modulation circuits with voltage target values corrected by the voltage correction values being added to voltage detection values. The modulation circuits provide gate signals for switch elements in multilevel circuits. In addition, a sign circuit provides gate signals for switch elements in a bridge clamping circuit.

主权项

1. A power-system-interconnected inverter device comprising:
a first three-level circuit including first, second, third and fourth preceding-stage switch elements connected in series between a first input end of a direct-current power supply and a neutral point and a first charging and discharging capacitor including a first end that is connected to a connection point between the first preceding-stage switch element and the second preceding-stage switch element and a second end that is connected to a connection point between the third preceding-stage switch element and the fourth preceding-stage switch element; a second three-level circuit including fifth, sixth, seventh and eighth preceding-stage switch elements connected in series between a neutral point and a second input end of the direct-current power supply and a second charging and discharging capacitor including a first end that is connected to a connection point between the fifth preceding-stage switch element and the sixth preceding-stage switch element and a second end that is connected to a connection point between the seventh preceding-stage switch element and the eighth preceding-stage switch; a bridge clamping circuit including first, second, third and fourth subsequent-stage switch elements bridge-connected to first, second, third and fourth terminals wherein a first end is connected to a connection point between the second preceding-stage switch element and the third preceding-stage switch element and a second end is connected to a connection point between the sixth preceding-stage switch element and the seventh preceding-stage switch element; a first inductor connected between a first output end and a connection point between the first subsequent-stage switch element and the second subsequent-stage switch element in the bridge clamping circuit; a second inductor connected between a second output end and a connection point between the third subsequent-stage switch element and the fourth subsequent-stage switch element in the bridge clamping circuit; a detection unit arranged to detect an output current and an output voltage of a single-phase three-wire power system having a U-phase and a W-phase; an amplification unit arranged to amplify a current error serving as an error of the output current with respect to a current target value of a substantially sinusoidal wave; a voltage correction value obtaining unit arranged to obtain a voltage correction value in a direction reducing the current error; a voltage target value obtaining unit arranged to obtain a voltage target value by superimposing the voltage correction value on a detection value of the output voltage; a PWM-modulation unit arranged to obtain a PWM-modulated signal of the voltage target value; a switch element drive unit arranged to drive the first, second, third and fourth preceding-stage switch elements and the fifth, sixth, seventh and eighth preceding-stage switch elements based on the PWM-modulated signal; and a switch unit arranged to switch a state of the bridge clamping circuit based on a sign of the voltage target value.