| 摘要 |
<p>The present invention relates to a unit type inverter which applies a three-level inverter circuit using a bidirectional switch capable of performing a balance of the output currents of each unit in a parallel operation. The present invention establishes a current balance control method by a PWM pulse pattern including the bidirectional switch connected to a neutral pole (M) of DC power supply and simplifies a current control circuit. The present invention installs an output current detector in each three-level inverter unit. The present invention calculates an average value of the output currents of the whole unit and the deviation of current values of each unit by connecting each output to a connection line through resistance and detecting the voltage of both ends of a resistor. The present invention balances the output currents of each inverter unit by delaying the increase of an IGBT on-pulse according to the deviation. [Reference numerals] (1a) Connecting wire A;(1b) Connecting wire B;(DL1,DL2,DL3,DL4) ON delay;(LC) Local control circuit;(LM1,SM2) Bottom value zero;(MC) Main control device;(UN1) Unit 1;(UN2) Unit 2;(UN3) Unit 3</p> |
