| 摘要 |
<p>PURPOSE:To enable the commutation of a commutating circuit even at a low voltage time by providing primary side voltage detecting means of a chopper and a VVVF inverter and operating a limiter which reduces the output of the inverter proportionally to the primary voltage. CONSTITUTION:A chopper 104 receives a DC voltage through a pantograph 1, thereby driving by an induction motor 9 a compressor for an AC cooler. A voltage detector 110 detects the primary voltage of the chopper 10, and an output limiter setting circuit 111 determines the output limit value of a VVVF inverter 108 is response to the detected voltage. When the voltage of a power source is decreased by less than -20%, the output of the inverter 108 and hence the current limit value of the chopper 104 is lowered proportionally to the voltage of the power source, thereby remedying against the decrease in the commutation capacity. In other words, a VVVF controller 112 is controlled to lower the output frequency and the output voltage, thereby reducing the output of the inverter 108. Thus, a small commutating circuit allows to enable to commutate in the total variation range of the power source voltage, thereby obtaining the power source which has less commutation loss.</p> |
