Patent ID: 6465983
Filing Date: 2002-10-15
Classification: H02J,Y02T

Abstract:
A current controlling and overcurrent protection device for controlling a current flow from at least one secondary cell to a motor, said device including a switching means for allowing a current, corresponding to a duty factor of a pulse for a PWM control, to flow to the motor; current detecting means for detecting the current flowing to the motor and for outputting this detection result; duty factor calculating means for calculating a duty factor, corresponding to a current value instruction, for adjusting the current flowing to the motor, such that the detection result of the current detecting means is coincident with a target current value which should flow to the motor; and a pulse generating means for generating a pulse for said PWM control having the duty factor calculated by the duty factor calculating means and for providing the pulse for said switching means, the overcurrent protection being provided by limit calculating means for dividing a limit current value, which can be discharged from the secondary cell, by a dividing value comprised of one of said target current value and the detection result of the current detecting means and means for outputting the division result as a limit value of the said duty factor; and selection means for comparing the duty factor calculated by the duty factor calculating means with said limit value, said selection means providing the duty factor calculated by the duty factor calculating means for the pulse generating means if the duty factor is less than the limit value and providing said limit value for said pulse generating means if said duty factor is greater than said limit value.