Braking method for an electric motor

Patent metadata

Field	Value
Publication number	US-11114958-B2
Application number	US-201716649548-A
Country	US
Kind code	B2
Filing date	Sep 25, 2017
Priority date	Sep 25, 2017
Publication date	Sep 7, 2021
Grant date	Sep 7, 2021

Abstract

An electric motor connected to a switching device is braked from an active operating state by actuating a semiconductor switch arranged in parallel with an electromechanical switch to reduce a current intensity in the electromechanical switch, opening the electromechanical switch, blocking the semiconductor switch for an adjustable period, determining a resulting torque of the electric motor, and determining an actuation time for braking the electric motor based on the resulting torque and actuating the semiconductor switch at the actuation time. The resulting torque is opposite a present direction of rotation of the electric motor at the actuation time. The semiconductor switch is turned on for an adjustable actuation period. Also disclosed are a computer program product and a soft starter configured to implement the described method.

First claim

The invention claimed is:

1. A method for braking an electric motor connected to a switching device from an active operating state, said method comprising:
a) actuating at least one semiconductor switch, which is arranged in parallel with an electromechanical switch, to reduce a current intensity in the electromechanical switch;
b) opening the electromechanical switch;
c) turning-off the at least one semiconductor switch for an adjustable period;
d) determining a resulting torque of the electric motor; and
e) determining an actuation time for braking the electric motor based on the resulting torque and actuating the at least one semiconductor switch at the actuation time,
wherein the resulting torque is opposite a present direction of rotation of the electric motor at the actuation time.

2. The method of claim 1 , wherein, in step e), the at least one semiconductor switch is turned on for an adjustable actuation period.

3. The method of claim 1 , wherein the actuation time corresponds to a time after which the resulting torque opposite the present direction of rotation is produced for an adjustable minimum period.

4. The method of claim 1 , wherein the actuation time is determined based on an algorithm and/or a table of values.

5. The method of claim 1 , wherein steps d) and/or e) are repeated until the electric motor reaches an adjustable desired speed.

6. The method of claim 1 , wherein the at least one semiconductor switch comprises semiconductor switches arranged in pairs, the method further comprising, in a further step f), actuating the semiconductor switches arranged in pairs with a selectable constant ignition angle for further braking.

7. The method of claim 1 , wherein the electric motor is constructed as a permanent magnet synchronous motor.

8. The method of claim 1 , wherein the at least one semiconductor switch is implemented as a thyristor or an anti-parallel thyristor pair.

9. A computer program product embodied in a non-transitory computer-readable storage medium and comprising computer commands which, when stored hi a memory of a switching device and executed by the switching device, causes the switching device to output actuation commands to at least one semiconductor switch and to receive and process measured values, by:
a) actuating the at least one semiconductor switch, which is arranged in parallel with an electromechanical switch, to reduce a current intensity in the electromechanical switch;
b) opening the electromechanical switch;
c) turning-off the at least one semiconductor switch for an adjustable period;
d) determining a resulting torque of the electric motor; and
e) determining an actuation time for braking the electric motor based on the resulting torque and actuating the at least one semiconductor switch at the actuation time,
wherein the resulting torque is opposite a present direction of rotation of the electric motor at the actuation time.

10. The computer program product of claim 9 , wherein the switching device is a soft starter.

11. A system comprising a first computer program product embodied in a non-transitory computer-readable storage medium and executed in a switching device, and a second computer program product embodied in a non-transitory computer-readable storage medium and executed in a superordinate control device, each of the first and second computer program products comprising computer commands which interact to cause the switching device to output actuation commands to at least one semiconductor switch and to receive and process measured values, by:
a) actuating at least one semiconductor switch, which is arranged in parallel with an electromechanical switch; to reduce a current intensity in the electromechanical switch;
b) opening the electromechanical switch;
c) turning-off the at least one semiconductor switch for an adjustable period;
d) determining a resulting torque of the electric motor; and
e) determining an actuation time for braking the electric motor based on the resulting torque and actuating the at least one semiconductor switch at the actuation time,
wherein the resulting torque is opposite a present direction of rotation of the electric motor at the actuation time.

12. The system of claim 11 , wherein the superordinate control device is implemented as a programmable logic controller, an installation master computer, a handheld device or a computer cloud.

13. A soft starter for controlling an electric motor, comprising:
a semiconductor switch and an electromechanical switch connected in parallel with the semiconductor switch arranged in at least one phase,
an internal control unit designed to actuate the semiconductor switch and the electromechanical switch, and
a computer program product embodied in a non-transitory computer-readable storage medium and comprising computer commands which, when stored in a memory of the soft starter and executed by the soft starter, causes the soft starter to output actuation commands to the semiconductor switch and to receive and process measured values, by:

a) actuating the semiconductor switch, which is arranged in parallel with an electromechanical switch, to reduce a current intensity in the electromechanical switch;
b) opening the electromechanical switch;
c) turning-off the at least one semiconductor switch for an adjustable period;
d) determining a resulting torque of the electric motor; and
e) determining an actuation time for braking the electric motor based on the resulting torque and actuating the at least one semiconductor switch at the actuation time,
wherein the resulting torque is opposite a present direction of rotation of the electric motor at the actuation time.

14. An electric motor arrangement, comprising:
an electric motor; and
a soft starter connected to the electric motor controlling the electric motor, wherein the soft starter comprises a first memory storing computer commands of a first computer program product embodied in a non-transitory computer-readable storage medium and executing the computer commands, the soft starter being connected to a superordinate control device having a second memory in which a second computer program product embodied in a non-transitory computer-readable storage medium and having computer commands is stored for execution by the superordinate control device, with the first and second computer program products interacting to cause the soft starter to output actuation commands to at least one semiconductor switch and to receive and process measured values, by:
a) actuating at least one semiconductor switch, which is arranged in parallel with an electromechanical switch, to reduce a current intensity in the electromechanical switch;
b) opening the electromechanical switch;
c) turning off the at least one semiconductor switch for an adjustable period;
d) determining a resulting torque of the electric motor; and
e) determining an actuation time for braking the electric motor based on the resulting torque and actuating the at least one semiconductor switch at the actuation time,

wherein the resulting torque is opposite a present direction of rotation of the electric motor at the actuation time.

Assignees

• Siemens Ag

Inventors

• Nannen Hauke
• Zatocil Heiko

Classifications

• H02P3/24 Primary

  by applying DC to the motor · CPC title

• H02P6/182

  using back-emf in windings · CPC title

• H02P3/18 Primary

  for stopping or slowing an AC motor · CPC title