Variable duty cycle pulse width modulated motor control system
First Claim
Patent Images
1. A control system for controlling an electric motor coupled to a load, said motor having a coil, comprising:
- direct current supply voltage means;
reference voltage means;
oscillator means operable at a first frequency;
a pulse width modulator circuit reset by said oscillator means at a fixed interval of time, and inversely responsive to said direct current supply voltage and directly responsive to said reference voltage for producing a variable duty cycle, pulse width modulated voltage;
commutating circuit means coupled to said coil for reversibly coupling said direct current supply voltage means to said coil at a second frequency lower than said first frequency; and
control circuit means commutated by said commutating circuit means for coupling said variable duty cycle, pulse width modulated voltage to said commutation circuit means to control the electrical power coupled from said direct current supply voltage means to said coil.
1 Assignment
0 Petitions
Accused Products
Abstract
A control system for controlling a direct current powered motor in which the direct current voltage, which may not be constant, is reversibly commutated across the coil or winding of the motor during the predetermined commutation time intervals and chopped at high frequency during each commutation time interval by a variable duty cycle, pulse width modulated voltage, in which the width of each voltage pulse, determined by a reference voltage, is varied as an inverse function of the magnitude of the direct current voltage which exists during each voltage pulse interval.
28 Citations
18 Claims
-
1. A control system for controlling an electric motor coupled to a load, said motor having a coil, comprising:
-
direct current supply voltage means; reference voltage means; oscillator means operable at a first frequency; a pulse width modulator circuit reset by said oscillator means at a fixed interval of time, and inversely responsive to said direct current supply voltage and directly responsive to said reference voltage for producing a variable duty cycle, pulse width modulated voltage; commutating circuit means coupled to said coil for reversibly coupling said direct current supply voltage means to said coil at a second frequency lower than said first frequency; and control circuit means commutated by said commutating circuit means for coupling said variable duty cycle, pulse width modulated voltage to said commutation circuit means to control the electrical power coupled from said direct current supply voltage means to said coil. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
-
-
16. A motor control system for controlling the electrical power coupled to the coil of an electromagnetic device from a supply of direct current voltage, comprising:
-
commutating circuit means for reversibly coupling said supply of direct current voltage, in equal intervals of time, to said coil; means for producing a reference voltage indicative of electrical power; means responsive to said reference voltage and to said direct current voltage for producing a variable duty cycle, pulse width modulated voltage of substantially constant magnitude, having pluralities of pulses in each of said intervals of time and in which the pulse width is directly proportional to said reference voltage and inversely proportional to the voltage magnitude of said direct current voltage; and means for coupling said pulse width modulated voltage to said commutating circuit means for interrupting said direct current voltage coupled to said coil at the frequency of said voltage pulses and for the time interval between the voltage pulses, for controlling the electrical power coupled to said coil. - View Dependent Claims (17, 18)
-
Specification