| 摘要 |
PURPOSE:To stabilize a control operation of a DC bus type AC variable speed apparatus by measuring the amplitude of a starting current at the time of rising the apparatus and the rising time of a DC voltage to calculate the smoothing condenser value of a load, and regulating the gain of a voltage controller in response to the value. CONSTITUTION:A DC power is supplied through a DC power source 2 for obtaining a constant DC voltage from a 3.phase AC power source 1, a reactor 3, smoothing condensers 4-1-4-n to voltage type inverters 5-1-5-n, converted to an AC of variable voltage and variable frequency to drive induction motors IM. In this case, a comparator 11 for detecting the rise up to a rated DC voltage, a DC current detector 12, an integrator 13, a gain regulator 14 and a voltage controller 15 are provided, and the gain of the controller 15 is regulated to a gain reversely proportional to the output of the integrator. Thus, an optimum voltage control state is held irrespective of a load condition to be able to perform a stable control operation.
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