Deceleration during mains break
First Claim
1. A method for stopping sectional drive controllably in connection with a fault situation in the supplying mains, the sectional drive comprising a plurality of inverters (4) which are supplied by a DC voltage intermediate circuit (3) supplied by the mains (1), a plurality of electric motors (5) which are controlled by the inverters with speed and/or torque control and which are used for implementing speed and tightness reference values of the strip in the sectional drive, the tightness reference value being predetermined motor-specifically or motor-group-specifically, characterized by the method comprising, before stopping the sectional drive, an implementing step in which an estimate (T) of the time needed for stopping the sectional drive motors is determined, whereby the method comprises, in connection with a fault situation in the mains, the steps of detecting a fault situation in the supplying mains;
- forming a deceleration reference value for the motors for stopping the motors within a predetermined time;
controlling the speed of the speed-controlled sectional drive motors on the basis of the deceleration reference value;
controlling the torque of the torque-controlled sectional drive motors on the basis of a predetermined tightness reference value;
determining the magnitude (u) of the DC voltage of the DC voltage intermediate circuit (3);
comparing the magnitude (u) of the DC voltage with a predetermined voltage limit (Udc); and
altering the deceleration reference value on the basis of the magnitude of the DC voltage in such a way that when the determined DC voltage (u) is lower than the voltage limit (Udc), the deceleration of the motors is increased, or in such a way that when the DC voltage (u) is higher than the voltage limit (Udc), the deceleration is decreased to stop the sectional drive in a controllable manner, maintaining the tightness reference value of the strip.
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Accused Products
Abstract
A method and an arrangement for stopping sectional drive controllably in connection with a fault situation in the supplying mains, the sectional drive comprising a plurality of inverters (4) which are supplied by a DC intermediate circuit (3) supplied by the mains (1), a plurality of electric motors (5) which are controlled by inverters with speed and/or torque control and which are used for implementing speed and tightness reference values of the strip in the sectional drive system, the tightness reference value being predetermined motor-specifically or motor-group-specifically. Prior to stopping the sectional drive, the method comprises the implementing step of predetermining an estimate (T) of the time needed for stopping the motors, whereby the method comprises the steps, in connection with a fault situation, of detecting a fault situation in the supplying mains, forming a deceleration reference value for the motors for stopping the motors within a predetermined time, controlling the speed of the speed-controlled motors in the sectional drive on the basis of the deceleration reference value, controlling the torque of the torque-controlled motors in the sectional drive on the basis of the predetermined tightness reference value, determining the magnitude of the DC voltage intermediate circuit (3) and altering the deceleration reference value on the basis of the magnitude of the DC voltage.
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Citations
9 Claims
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1. A method for stopping sectional drive controllably in connection with a fault situation in the supplying mains, the sectional drive comprising a plurality of inverters (4) which are supplied by a DC voltage intermediate circuit (3) supplied by the mains (1), a plurality of electric motors (5) which are controlled by the inverters with speed and/or torque control and which are used for implementing speed and tightness reference values of the strip in the sectional drive, the tightness reference value being predetermined motor-specifically or motor-group-specifically, characterized by the method comprising, before stopping the sectional drive, an implementing step in which an estimate (T) of the time needed for stopping the sectional drive motors is determined, whereby the method comprises, in connection with a fault situation in the mains, the steps of
detecting a fault situation in the supplying mains; -
forming a deceleration reference value for the motors for stopping the motors within a predetermined time;
controlling the speed of the speed-controlled sectional drive motors on the basis of the deceleration reference value;
controlling the torque of the torque-controlled sectional drive motors on the basis of a predetermined tightness reference value;
determining the magnitude (u) of the DC voltage of the DC voltage intermediate circuit (3);
comparing the magnitude (u) of the DC voltage with a predetermined voltage limit (Udc); and
altering the deceleration reference value on the basis of the magnitude of the DC voltage in such a way that when the determined DC voltage (u) is lower than the voltage limit (Udc), the deceleration of the motors is increased, or in such a way that when the DC voltage (u) is higher than the voltage limit (Udc), the deceleration is decreased to stop the sectional drive in a controllable manner, maintaining the tightness reference value of the strip. - View Dependent Claims (2, 3, 4, 5)
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6. An arrangement for stopping sectional drive controllably in connection with a fault situation of the supplying mains, the sectional drive comprising a plurality of inverters (4) that receive their supply from a DC voltage intermediate circuit (3) supplied by the mains (1), a plurality of electric motors (5) that are controlled with inverters in a speed-controlled or torque-controlled manner and that are used for implementing the speed reference value and tightness reference value of the strip of the sectional drive, whereby the tightness reference value is predetermined motor-specifically or motor-group-specifically, characterized in that the arrangement comprises
means (2) for detecting a fault situation in the mains; -
first control means (6) for controlling the speed of the speed-controlled motors;
second control means (6) for controlling the torque of the torque-controlled motors on the basis of a predetermined tightness reference value;
a voltage-measuring member (2) in order to determine the DC voltage of the DC voltage intermediate circuit;
tightness-determining means arranged to determine the tightness of the material strip of the sectional drive; and
a memory and processing member (7) arranged to store the estimate (T) of the time needed for stopping the motors of the sectional drive, to form a deceleration reference value for the motors for stopping the motors within a predetermined time, to compare the magnitude of the DC voltage with a predetermined voltage limit, and to alter the deceleration reference value, depending on the magnitude of the DC voltage. - View Dependent Claims (7, 8, 9)
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Specification