Method and device for controlling an electric motor
First Claim
1. A method for controlling a sensorless electric motor, comprising:
- measuring a motor current and a motor voltage during a sensorless open-loop control mode of operation of the motor,determining a speed and a torque of the electric motor from the measured motor current and the measured motor voltage,computing a moment of inertia of the electric motor and determining a control torque from the calculated moment of inertia,associating the control torque with a torque control value determined by a controller from a speed deviation from a speed setpoint value, andsupplying the control torque as a torque setpoint value to a control element for setting the motor current or the motor voltage,wherein during a sensorless open-loop control mode of operation the control element receives as input variable a control torque generated from a predefined moment of inertia, as long as the speed of the electric motor is below a minimum speed.
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Accused Products
Abstract
A method and device for controlling an electric motor, in particular a machine tool drive, wherein during a sensorless open-loop control mode of operation of the electric motor the speed and the torque are determined from the motor current and the motor voltage, and the moment of inertia of the electric motor torque are determined from the determined motor current and the determined motor voltage, wherefrom then a control torque is determined, which is then associated with an open-loop torque control value and supplied as the torque setpoint value to a control element for setting the motor current and/or the motor voltage in the open-loop mode of operation. As long as the speed is below a minimum speed, the control element receives as input variable a control or pilot control torque generated from a predefined moment of inertia for a sensorless closed-loop control mode of operation of the electric motor.
9 Citations
12 Claims
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1. A method for controlling a sensorless electric motor, comprising:
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measuring a motor current and a motor voltage during a sensorless open-loop control mode of operation of the motor, determining a speed and a torque of the electric motor from the measured motor current and the measured motor voltage, computing a moment of inertia of the electric motor and determining a control torque from the calculated moment of inertia, associating the control torque with a torque control value determined by a controller from a speed deviation from a speed setpoint value, and supplying the control torque as a torque setpoint value to a control element for setting the motor current or the motor voltage, wherein during a sensorless open-loop control mode of operation the control element receives as input variable a control torque generated from a predefined moment of inertia, as long as the speed of the electric motor is below a minimum speed. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A device for controlling a sensorless electric motor, comprising:
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a measuring device measuring a motor current and a motor voltage, a functional module determining a speed and a torque as well as a moment of inertia of the electric motor from the measured motor current and from the measured motor voltage, an open-loop controller determining a torque control value from a speed deviation from a speed setpoint value, a pilot controller for generating a control torque s a function of the moment of inertia, and a control element which receives from the pilot controller as input variable a control torque generated from a predefined moment of inertia and which sets at least one of the motor current and the motor voltage in a open-loop control mode of operation of the electric motor, as long as the speed of the electric motor is below a minimum speed. - View Dependent Claims (9, 10)
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11. A machine tool drive comprising an electric motor controlled by:
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measuring a motor current and a motor voltage during a sensorless open-loop control mode of operation of the motor, determining a speed and a torque of the electric motor from the measured motor current and the measured motor voltage, computing a moment of inertia of the electric motor and determining a control torque from the calculated moment of inertia, associating the control torque with a torque control value determined by a controller from a speed deviation from a speed setpoint value, and supplying the control torque as a torque setpoint value to a control element for setting the motor current or the motor voltage, wherein during a sensorless open-loop control mode of operation the control element receives as input variable a control torque generated from a predefined moment of inertia, as long as the speed of the electric motor is below a minimum speed.
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12. A machine tool drive comprising a sensorless electric motor and having a device for controlling a sensorless electric motor, the device comprising:
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a measuring device measuring a motor current and a motor voltage, a functional module determining a speed and a torque as well as a moment of inertia of the electric motor from the measured motor current and from the measured motor voltage, an open-loop controller determining a torque control value from a speed deviation from a speed setpoint value, a pilot controller for generating a control torque s a function of the moment of inertia, and a control element which receives from the pilot controller as input variable a control torque generated from a predefined moment of inertia and which sets at least one of the motor current and the motor voltage in a open-loop control mode of operation of the electric motor, as long as the speed of the electric motor is below a minimum speed.
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Specification