DIGITAL STARTING DEVICE OF ALTERNATING CURRENT MOTOR

摘要

PURPOSE: A digital starting device of an AC(Alternating Current) motor is provided to improve the control function for the AC motor by gradually increasing an AC source voltage to be applied to the AC motor. CONSTITUTION: A synchronous circuit unit(201) outputs a synchronous pulse synchronizing with a zero potential of AC power voltage which is operating power applied to an AC motor. A tooth wave generating unit(202) generates a tooth wave signal having the same period with the synchronous pulse generated from the synchronous circuit unit(201). When an output signal of a digital control unit is a high signal, a delay signal unit(203) reverses the high signal to generate slowly reduced signal within a predetermined period. A comparing circuit unit(204) compares the tooth wave signal of the tooth wave generating unit(202) with the output signal of the delay signal unit(203). If the tooth wave signal is higher than the output signal of the delay circuit unit(203), the comparing circuit unit(204) outputs a high level signal, and otherwise it outputs a low level signal. An AC motor driving unit(109) applies the AC power to the AC motor according to the signal outputted from the comparing circuit unit(204).