Stepper motor drive system

Claim 1

A method for dynamically controlling the damping of a stepper motor having motor phase windings on salient poles and also having means for controlling the application of currents to predetermined phase windings, said method including: generating a clock signal; generating a reference signal in predetermined phase and frequency relationship with said clock signal, said reference signal being at a maximum magnitude at a time proximate to said clock signal and decreasing continuously in magnitude at subsequent times until power to one of said predetermined phase windings is switched between ON and OFF; sensing the current including current flowing through said one of said predetermined phase windings but not including current flowing through phase winding for a pole next adjacent in operation to a pole of said one phase winding for deriving a sense signal thereof; comparing for equality in amplitude said reference signal with said sense signal for deriving an equality information thereof; switching the power applied to said one of said predetermined phase windings ON and OFF alternatively, using the information provided by said clock signal for switching one way and said quality information for switching the other way.

Claim 2

A method for dynamically controlling the damping of a stepper motor having motor phase windings on salient poles and also having means for controlling the application of currents to predetermined phase windings, said method including: generating a clock signal; generating a reference signal in predetermined phase and frequency relationship with said clock signal, said reference signal being at a maximum magnitude at a time proximate to said clock signal and decreasing continuously in magnitude at subsequent times until power to one of said predetermined phase windings is switched between ON and OFF; sensing the current including current flowing through said one of said predetermined phase windings but not including current flowing through phase winding for a pole next adjacent in operation to a pole of said one phase winding for deriving a sense signal thereof; comparing for equality in amplitude said reference signal with said sense signal for deriving an equality information thereof; switching the power applied to said one of said predetermined phase windings ON and OFF alternatively, using the information provided by said clock signal for switching one way and said quality information for switching the other way.

Claim 9

A system for dynamically controlling the damping of a stepper motor having one winding per phase or a set of windings connected together into a single phase winding for each of its phases, said system comprising: a power supply; a power stage for selectively connecting said sets of winding to said power supply; sensing means connected to said power stage for sensing phase currents and for deriving a sense signal thereof representative of the current of one phase; a clock signal generator for generating a clock signal; a voltage reference generator connected to said clock signal for generating a reference signal in predetermined frequency and phase relationship with said clock signal, said reference signal being at a maximum magnitude at a time proximate to said clock signal and decreasing continuously in magnitude at subsequent times until power to the winding of said one phase is switched between ON and OFF; a predrive control processing unit provided with: comparing means for comparing said sense signal and said reference signal and for deriving an equality information thereof; and switching means for switching the connection between said winding of said one phase and said power supply ON and OFF based on the information provided by said clock signal and said equality in amplitude information.

Claim 10

A system for dynamically controlling the damping of a stepper motor having one winding per phase or a set of windings connected together into a single phase winding for each of its phases, said system comprising: a power supply; a power stage for selectively connecting said sets of winding to said power supply; sensing means connected to said power stage for sensing phase currents and for deriving a sense signal thereof representative of the current of one phase; a clock signal generator for generating a clock signal; a voltage reference generator connected to said clock signal for generating a reference signal in predetermined frequency and phase relationship with said clock signal, said reference signal being at a maximum magnitude at a time proximate to said clock signal and decreasing continuously in magnitude at subsequent times until power to the winding of said one phase is switched between ON and OFF; a predrive control processing unit provided with: comparing means for comparing said sense signal and said reference signal and for deriving an equality information thereof; and switching means for switching the connection between said winding of said one phase and said power supply ON and OFF based on the information provided by said clock signal and said equality in amplitude information.

Claim 19

A method for controlling the damping of a stepper motor having motor phase windings, power supply means and switching means for connecting only one of said motor phase windings to said power supply means, said method including: generating a clock signal; generating sense signals by sensing the currents flowing into only said one of said motor phase windings; using said clock signal for switching said switching means one way; generating a reference signal in phase with said clock signal, said reference signal being at a maximum magnitude at a time proximate to said clock signal and decreasing continuously in magnitude at subsequent times until said switching means is switched the other way; comparing for equality in amplitude said reference signal with said sense signal for generating an equality information therefrom; using said equality information for switching said switching means the other way.

Claim 20

A method for controlling the damping of a stepper motor having motor phase windings, power supply means and switching means for connecting only one of said motor phase windings to said power supply means, said method including: generating a clock signal; generating sense signals by sensing the currents flowing into only said one of said motor phase windings; using said clock signal for switching said switching means one way; generating a reference signal in phase with said clock signal, said reference signal being at a maximum magnitude at a time proximate to said clock signal and decreasing continuously in magnitude at subsequent times until said switching means is switched the other way; comparing for equality in amplitude said reference signal with said sense signal for generating an equality information therefrom; using said equality information for switching said switching means the other way.