Patent ID: 8508905

Claim:
A coil-driving apparatus of an electronic magnetic contactor, the coil-driving apparatus comprising: a voltage detecting unit comprising an input power processing unit for converting an input power to a direct current power and an input voltage detecting unit for detecting a voltage level of the direct current power; and a driving control unit for controlling a current flowing through a coil via based on a difference between the detected voltage level and a pre-set reference voltage level, wherein the driving control unit comprises: an operation control unit for performing a suction operation when the comparing unit generates the suction signals, the operation control unit comprising: a comparing unit for comparing the detected voltage level with the pre-set reference voltage level and generating control signals and the suction signals in response to the comparison, and a time determining unit for determining a time period to maintain the generated suction signals; an integral PWM controller for outputting PWM signals such that the current flowing through the coil is controlled in response to the generated control signals; and a switching unit for switching the current flowing through the coil in response to the output PWM signals such that the current is conducted or blocked; and wherein: the integral PWM controller is is further for receiving a feedback of the current flowing through the coil for outputting the PWM signals such that the current is constant even when a source is overvoltaged; and the integral PWM controller comprises: a control voltage level controlling unit for controlling a pulse width of the output PWM signals according to the difference between the detected voltage level and the pre-set reference voltage level, a sawtooth generation unit for outputting sawtooth signals for a predetermined period while the control voltage level controlling unit operates, a PWM output unit for comparing the signals output by the control voltage level controlling unit to the output sawtooth signals and outputting the PWM signals in response to the comparison, an overvoltage prevention unit for suppressing a signal level of the signal output by the control voltage level controlling unit, and a temperature compensating unit for compensating for the suppressed signal level of the signals output by the control voltage level controlling unit in response to temperature changes.