Method and arrangement for controlling a stepping motor
First Claim
1. A method for controlling a stepping motor comprising a winding and a rotor magnetically coupled to said winding, said rotor being subjected to a resisting torque variable between a minimum and a maximum value, said method comprising:
- applying a driving pulse to said winding each time that said rotor is to turn by one step;
measuring a first quantity of electrical energy converted into mechanical energy by said motor from the beginning of said driving pulse;
comparing said first quantity with a reference energy which is substantially equal to the quantity of electrical energy that said motor must convert into mechanical energy for said rotor to turn by just one step when said resisting torque has said minimum value;
measuring the time required for said first quantity to equal said reference energy;
determining an optimum duration of said pulse as a function of said measured time, wherein said optimum duration is the duration for which the first quantity is substantially equal to the quantity of electrical energy that the motor has to convert into mechanical energy for said rotor to turn by just one step in overcoming the resisting torque said rotor is actually subjected to during said driving pulse; and
interrupting said driving pulse at the end of said optimum duration.
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Accused Products
Abstract
The method of this invention includes measuring the quantity Eme of electrical energy converted into mechanical energy by the motor during a driving pulse, determining the time required for said quantity of energy to attain a reference value Eref and interrupting the driving pulse as a function of such time.
The arrangement includes means for measuring said quantity Eme of energy, means for determining the time required for such quantity of energy to attain such reference value Eref and means for effecting interruption of the driving pulse as a function of such time.
21 Citations
18 Claims
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1. A method for controlling a stepping motor comprising a winding and a rotor magnetically coupled to said winding, said rotor being subjected to a resisting torque variable between a minimum and a maximum value, said method comprising:
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applying a driving pulse to said winding each time that said rotor is to turn by one step; measuring a first quantity of electrical energy converted into mechanical energy by said motor from the beginning of said driving pulse; comparing said first quantity with a reference energy which is substantially equal to the quantity of electrical energy that said motor must convert into mechanical energy for said rotor to turn by just one step when said resisting torque has said minimum value; measuring the time required for said first quantity to equal said reference energy; determining an optimum duration of said pulse as a function of said measured time, wherein said optimum duration is the duration for which the first quantity is substantially equal to the quantity of electrical energy that the motor has to convert into mechanical energy for said rotor to turn by just one step in overcoming the resisting torque said rotor is actually subjected to during said driving pulse; and interrupting said driving pulse at the end of said optimum duration. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An arrangement for controlling a stepping motor comprising a winding and a rotor magnetically coupled to said winding, said rotor being subjected to a resisting torque variable between a minimum and a maximum value, said arrangement comprising:
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means for applying a driving pulse to said winding each time that said rotor is to turn by one step; means for measuring a first quantity of electrical energy converted into mechanical energy by said motor from the beginning of said driving pulse; means for comparing said first quantity with a reference energy which is substantially equal to the quantity of electrical energy that said motor must convert into mechanical energy for said rotor to turn by just one step when said resisting torque has said minimum value; means for measuring the time required for said first quantity to equal said reference energy; means for determining an optimum duration of said driving pulse as a function of said measured time, wherein said optimum duration is the duration for which the first quantity is substantially equal to the quantity of electrical energy that the motor has to convert into mechanical energy for said rotor to turn by just one step in overcoming the resisting torque said rotor is actually subjected to during said driving pulse; and means for interrupting said driving pulse at the end of said optimum duration. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A method for measuring a first quantity of electrical energy converted into mechanical energy by a stepping motor comprising a winding and a rotor magnetically coupled to said winding, said electrical energy being converted during a driving pulse which is applied to said winding, said method comprising:
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producing a periodic sampling signal defining a plurality of sampling instants, two consecutive sampling instants being separated by a period equal to the period of said sampling signal; measuring a current flowing through said winding; adjusting the current flowing through said winding during said driving pulse to a reference current by connecting said winding to a power source at each sampling instant when said current flowing in said winding is less than said reference current and disconnecting said winding from said source and short circuiting said winding at each sampling instant when said flowing current is equal to or greater than said reference current; and calculating a first expression as follows;
space="preserve" listing-type="equation">Eme.sub.0x =U·
I.sub.ref ·
Δ
·
C1.sub.x -R·
I.sup.2.sub.ref ·
Δ
·
C2.sub.xin which Eme0x is said first quantity; U is the voltage of said power source; Iref is the value of said reference current; R is the ohmic resistance of said winding; Δ
is the duration of said period of the sampling signal;C1x is a first number equal to the number of sampling instants at which said winding is connected to said power source between an instant t1 and an instant tx, said instant t1 being the first sampling instant when said current flowing through said winding is equal to or greater than said reference current and said instant tx being any sampling instant subsequent to said instant t1 ; and C2x is a second number equal to the total number of sampling instants between the beginning of said driving pulse and said instant tx. - View Dependent Claims (14, 15)
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16. An arrangement for measuring a first quantity of electrical energy converted into mechanical energy by a stepping motor comprising a winding and a rotor magnetically coupled to said winding, said electrical energy being converted during a driving pulse which is applied to said winding, said arrangement comprising:
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a power source; means for producing a periodic sampling signal defining a plurality of sampling instants, two consecutive sampling instants being separated by a period equal to the period of said sampling signal; means for measuring a current flowing through said winding; means responsive to said sampling signal for connecting said winding to said power source at each sampling instant when said current flowing in said winding is less than a reference current and for disconnecting said winding from said source and short circuiting said winding at each sampling instant when said flowing current is equal to or greater than said reference current; and means for calculating a first expression as follows;
space="preserve" listing-type="equation">Eme.sub.0x =U·
I.sub.ref ·
Δ
·
C1.sub.x -R·
I.sup.2.sub.ref ·
Δ
·
C2.sub.xin which Eme0x is said first quantity; U is the voltage of said power source; Iref is the value of said reference current; R is the ohmic resistance of said winding; Δ
is the duration of said period of the sampling signal;C1x is a first number equal to the number of sampling instants at which said winding is connected to said power source between an instant t1 and an instant tx, said instant t1 being first sampling instant when said current flowing through said winding is equal to or greater than said reference current and said instant tx being any sampling instant subsequent to said instant t1 ; and C2x is a second number equal to the total number of sampling instants between the beginning of said driving pulse and said instant tx. - View Dependent Claims (17, 18)
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Specification