Patent ID: 6055359
Filing Date: 2000-04-25
Classification: H02P

Abstract:
A control circuit for energizing a DC motor having a motor armature connected betweena first terminal and a second terminal, comprising;a DC armature voltage source having a positive rail and a negative rail, said positive rail being coupled to the first terminal of the DC motor;a first switch connected in series with the motor armature, said first switch having a first contact connected to the second terminal of the DC motor and a second contact;a pulse width modulator operatively coupled to said first switch controlling an on time and off time of said first switch to control the average voltage across the motor armature, said pulse width modulator having a current sensing input;a second switch having a first contact coupled to said first switch second contact, and a second contact, said second switch being controlled by said pulse width modulator;a current sense resistor coupled between said first switch second contact and said voltage source negative rail; anda resistor/capacitor (RC) parallel combination having a first end coupled to said second switch second contact and a second end coupled to said voltage source negative rail, said RC combination first end being coupled to the current sensing input of said pulse width modulator.