Patent ID: 7158360
Filing Date: 2007-01-02
Classification: H01F,H01H

Abstract:
1. A solenoid drive circuit comprising: a DC power source; a switching element and a solenoid connected in series to the DC power source; a PWM controller for supplying drive signals (S a control circuit for producing command signals (S said control circuit comprising a detector for discerning current flow through said detector to produce electric signals that corresponds to level of the current flow through said solenoid; an amplifier for amplifying the electric signals from said detector; an integrator for integrating the amplified output (S an operational comparator for comparing the detected current values from the integrator and a target current value and producing command values (S a reset circuit for resetting output of the integrator; and a retention circuit connected between the integrator and the operational comparator for receiving and preserving the detected current value from said integrator; wherein said retention circuit samples the detected current value from said integrator before said reset circuit resets the output of the integrator each time the PWM controller generates at least one of the successive drive signals (S said operational comparator receives the detected current value preserved in the retention circuit to compare the detected current value with the target current value; and said PWM controller provides the control terminal of the switching element with the drive signal (S