Control system for an electric motor

Patent metadata

Field	Value
Publication number	US-9806647-B2
Application number	US-201615043937-A
Country	US
Kind code	B2
Filing date	Feb 15, 2016
Priority date	Feb 17, 2015
Publication date	Oct 31, 2017
Grant date	Oct 31, 2017

Abstract

A control system for an electric motor comprising a stator having a plurality of stator coils and a rotor movable along the stator comprises a position detection device and a coil monitoring device. In this case, the position detection device is designed to generate position data representing a position of the rotor along the stator, and the coil monitoring device is designed to generate coil data representing a status of one or a plurality of the stator coils. The control system furthermore comprises a safety device designed to carry out a coordination between the coil data and the position data. Moreover, the safety device is designed to cause the electric motor to be transferred to a safe state if an error has been discovered during the coordination.

First claim

The invention claimed is:

1. A control system for a linear electric motor comprising
a stator having a plurality of stator coils and a rotor movable along the stator,
wherein the control system is designed to control current sources of an energization device of a drive comprising the linear electric motor such that a current signal driving the rotor is only applied to said stator coils in an energization region in a vicinity of the rotor and such that the energization region shifts concomitantly with the rotor moving along the stator,
wherein the control system comprises a position detection device and a coil monitoring device,
wherein the position detection device is designed to generate position data representing a position of the rotor along the stator,
wherein the coil monitoring device is designed to generate coil data representing a status of one or a plurality of the stator coils,
wherein the control system comprises a position determining module designed to determine a rotor position on the basis of the position data,
wherein the control system comprises a safety device designed to carry out a coordination between the coil data and the position data,
wherein the safety device comprises a position calculation module designed to determine an energization position of the rotor within the energization region on the basis of the coil data,
wherein the safety device comprises a position comparison module designed to compare the rotor position with the energization position in the context of the coordination, and
wherein the safety device is designed to cause the linear electric motor to be transferred to an emergency shutdown if an error has been discovered during the comparison between the rotor position and the energization position.

2. The control system of claim 1 ,
wherein the safety device comprises a current pattern comparison module designed to compare the coil data with predefined setpoint coil data in the context of the coordination,
wherein the error comprises an error discovered during the comparison between the coil data and the predefined setpoint coil data.

3. The control system of claim 2 ,
wherein the current pattern comparison module is designed to determine a force on the rotor on the basis of the coil data and to compare the force with a predefined setpoint force,
wherein the error comprises an error discovered during the comparison between the force and the predefined setpoint force, and
wherein the predefined setpoint force is dependent on the position of the rotor.

4. The control system of claim 1 ,
wherein the safety device comprises a speed calculation module and a speed comparison module,
wherein the speed calculation module is designed to calculate a speed of the rotor on the basis of the position data and/or on the basis of the coil data,
wherein the speed comparison module is designed to compare the speed of the rotor with a predefined setpoint speed,
wherein the error comprises an error discovered during the comparison between the speed and the setpoint speed, and
wherein the predefined setpoint speed is dependent on the position of the rotor.

5. The control system of claim 1 , wherein the coil data represent a coil current through one of the stator coils of the linear electric motor.

6. The control system of claim 1 , wherein the coil data represent a voltage drop across one of the stator coils of the linear electric motor.

7. The control system of claim 1 , wherein the coil data represent an activation state of one of the stator coils of the linear electric motor.

8. The control system of claim 1 , wherein the safety device is embodied by means of safe functional components of the control system.

9. The control system of claim 1 , wherein the control system is designed to apply a proximity current signal to at least one of the stator coils if the rotor of the linear electric motor is situated in the vicinity of the stator coil, wherein the proximity current signal exerts no drive force on the rotor.

10. A drive system having:
a linear electric motor comprising a stator having a plurality of stator coils and a rotor movable along the stator,
an emergency shutdown apparatus designed to carry out a transfer of the linear electric motor to an emergency shutdown, and
a control system, wherein the control system is designed to control current sources of an energization device of a drive comprising the linear electric motor such that a current signal driving the rotor is only applied to said stator coils in an energization region in a vicinity of the rotor and such that the energization region shifts concomitantly with the rotor moving along the stator,
wherein the control system comprises a position detection device and a coil monitoring device,
wherein the position detection device is designed to generate position data representing a position of the rotor along the stator,
wherein the coil monitoring device is designed to generate coil data representing a status of one or a plurality of the stator coils,
wherein the control system comprises a position determining module designed to determine a rotor position on the basis of the position data,
wherein the control system comprises a safety device designed to carry out a coordination between the coil data and the position data,
wherein the safety device comprises a position calculation module designed to determine an energization position of the rotor within the energization region on the basis of the coil data,
wherein the safety device comprises a position comparison module designed to compare the rotor position with the energization position in the context of the coordination, and
wherein the safety device is connected to the emergency shutdown apparatus of the drive and designed to cause the emergency shutdown apparatus to carry out the emergency shutdown of the linear electric motor if an error has been discovered during the comparison between the rotor position and the energization position.

11. The drive system of claim 10 , wherein the stator coils and a signal detection unit of the position detection device of the control system are arranged in a stationary manner with respect to one another and are integrated into a housing of the stator.

12. The drive system of claim 10 , wherein the drive is designed to transmit the coil data by means of a secure data transmission channel via a data transmission medium connecting the stator to an operating device of the control system, wherein the control system is designed to transmit position data and coil data via the data transmission medium.

13. A method for controlling a linear electric motor of a drive, the linear electric motor comprising a stator having a plurality of stator coils and a rotor movable along the stator, wherein the method comprises:
controlling current sources of an energization device of the drive such that a current signal driving the rotor is only applied to said stator coils in an energization region in the vicinity of the rotor and such that the energization region shifts concomitantly with the rotor moving along the stator,
generating position data representing the position of the rotor along the stator, generating coil data, representing the status of one or a plurality of the stator coils,
determining an energization position of the rotor within the energization region on the basis of the coil data,
carrying out a coordination between the coil data and the position data,
comparing the position of the rotor with the energization position in the context of the coordination, and
causing the electric motor to be transferred to an emergency shutdown if an error has

Assignees

• Beckhoff Automation Gmbh

Inventors

• Prüssmeier Uwe
• Achterberg Jan

Classifications

• H02P6/12 Primary

  Monitoring commutation; Providing indication of commutation failure · CPC title

• H02K41/031

  of the permanent magnet type · CPC title

• H02P6/006

  Controlling linear motors · CPC title

• H02P29/0241

  the fault being an overvoltage · CPC title

• H02P29/024

  Detecting a fault condition, e.g. short circuit, locked rotor, open circuit or loss of load · CPC title