| 摘要 |
<p>PURPOSE:To improve the reliability of a main circuit and entire auxiliary power system, by dropping the AC voltage set up at an AC terminal of a PWM inverter of a main power circuit and by obtaining necessary source voltage. CONSTITUTION:A smoothing capacitor connected in parallel between a starter 4 and a PWM inverter 2 is divided into two, 51 and 52, which are mutually connected in series. The primary winding of an auxiliary transformer 71 is connected between a connecting point A of smoothing capacitors 51 and 52 and an AC terminal B of the first arm of a main PWM inverter 2. Similarly, the primary winding of an auxiliary transformer 72 is connected between the above-mentioned connecting point A and an AC terminal C of the second arm of the main PWM inverter 2; so is with an auxiliary transformer 73 between the connecting point A and an AC terminal D of the three-phase arm thereof. An auxiliary power unit 8 is further connected to the secondary windings of each transformer 71-73, from the output terminals of which necessary power source is obtained.</p> |
