| 摘要 |
<p>PURPOSE:To prevent elements in an inverter from being damaged due to a large current by opening the contact of a relay circuit when the output value of a current detector exceeds a predetermined value. CONSTITUTION:The output signal of potentiometer 21 is input as a slip frequency omegas to an adder 70 to be added to the output omegar of an F/V converter 69, and the adder outputs a synchronous rotation frequency omega1. The frequency omega1 is converted to quantized sinusoidal waves of four types having a frequency corresponding to the value of the frequency omega1, and output as a synchronous rotation frequency omega1. The waves omega1 are converted to quantized 3-phase primary current commands of four types having a frequency corresponding to the value of the frequency omega1, and further converted to an analog 3-phase primary current command. When an accelerator pedal is released, an analog switch 71 is closed to supply the output omegar of the converter 69 as a subtracting element to an adder/subtractor 72 to regeneratively operate it. On the other hand, when the output voltage of a CT 76 in a shortcircuit protecting unit 73 becomes a set value or higher, the contact of the relay circuit 74 is opened.</p> |
