摘要:
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.
摘要:
An apparatus and process for detecting rotor position for improved motor start-up. The apparatus detects a target equilibrium position of the rotor using a fixed gain amplifier, window comparator and slope detector circuitry. The window comparator circuitry qualifies the peaks of the back EMF signal. Slope detector circuitry pinpoints the peak of the back EMF signal qualified by the window comparator. The technique utilizes the steps of energizing the phase windings of said motor, detecting the target equilibrium position, and then accelerating the motor through a commutation process.