| 摘要 |
PURPOSE:To prevent the breakdown of a switching element of the inverter, and to obtain stable operation by using an overcurrent control pulse width modulation system, employing a gate turn-off type thyristor as the switching element and mounting an overcurrent protective circuit. CONSTITUTION:DC voltage is obtained by means of a rectifying circuit consisting of diodes D7-D12 and a capacitor C from input terminals R, S, T connected to a commercial three-phase AC power supply. The bridge inverter is constituted in such a manner that the terminals J, K of a two terminal circuit 1 for protecting overcurrents are connected to a DC supply line, and a parallel circuit of the gate turn-off type thyristors GTO1-GTO6 and feedback diodes D1-D6 is connected between the terminal K at the output side of the two terminal circuit 1 and three-phase AC output terminals U, V, W. Each gate turn-off type thyristor GTO1-GTO6 is severally controlled by means of ignition control circuits A1-A6. |
