Patent ID: 7518330

Claim:
A protect-control device capable of limiting current for reducing noise resulting from switchover of a motor comprising: a power source; a motor coil set constituting a motor; a driving unit being electrically connected to the power source and the motor coil and providing a driving level to pass through the motor coil for driving the motor; a sensing unit being electrically connected to the motor coil set and having a first resistance with a first resistant value and a second resistance with second resistant value; a control unit being electrically connected to the power source, the driving unit and the sensing unit and providing a first PWM output end and a second PMW output end to supply a PWM signal with a duty cycle to the driving unit for the driving unit being capable of driving the motor; and a Hall component being electrically connected to the control unit, detecting a positive voltage signal and a negative voltage signal from the motor and sending said positive and negative voltage signals to the control unit; wherein the sensing unit provides a preset reference level, which is regulated with a change of said first and second resistant values respectively, detects said driving level, compares said driving level to said preset reference level and outputs an identifying signal to the control unit; and the control unit adjusts said driving level based on said identifying signal for an output signal of the driving unit being capable of maintaining a basic duty cycle, which is much less than the duty cycle of the PMW signal, such that a frequency of a noise resulting from the motor is greater than 25 KHZ, which is not perceived by the human ears.