Switching device for controlling energy supply of a downstream electric motor

Patent metadata

Field	Value
Publication number	US-9954464-B2
Application number	US-201214442459-A
Country	US
Kind code	B2
Filing date	Nov 19, 2012
Priority date	Nov 19, 2012
Publication date	Apr 24, 2018
Grant date	Apr 24, 2018

Abstract

A switching apparatus includes an energy store and two measuring devices connected to the control apparatus, the energy store being connected in series between the supply connection and the power supply via the first measuring device, the control apparatus can ascertain if the supply voltage attached to the primary side of the power supply falls short of a first voltage threshold value and, via the second measuring device, if the supply voltage of the power supply attached to the secondary side of the power supply falls short of a second voltage threshold value, the control apparatus evaluates the time between falling short of the first voltage threshold value and falling short of the second voltage threshold value.

First claim

The invention claimed is:

1. A switching device, comprising:
a control unit;
a supply connection;
a power supply unit; and
a first current path, incorporating a first electro-mechanical switch and, connected in series with the first switch, a circuit incorporating a second electro-mechanical switch in parallel with a semiconductor switch, wherein the control unit is configured to output a switching signal for the first switch, for the second switch and for the semiconductor switch, wherein the supply connection is linked to the power supply unit and the control unit is configured to draw the energy for the switching signals through the power supply unit, wherein the switching device incorporates an energy store and two measurement devices linked to the control unit, wherein the energy store is connected in between the supply connection and the power supply unit, so that an energy supply for the switching device effected through the supply connection is buffered internally within the device by way of the energy store, wherein the control unit is configured to determine by way of the first measurement device any drop in the supply voltage, present at the primary side of the power supply unit, below a first voltage threshold value, wherein the control unit is configured to determine by way of the second measurement device any drop in the supply voltage, present at the secondary side of the power supply unit below a second voltage threshold value, wherein the control unit is designed to evaluate the duration of the time from when the voltage drops below the first voltage threshold value up until when the voltage drops below the second voltage threshold value and emits a signal if the time between the fall below the first voltage threshold value up until the fall below the second threshold value falls below a critical time value.

2. The switching device of claim 1 , wherein the control unit is designed such that, if it determines that the voltage on the primary side of the power supply unit has dropped below the first voltage threshold value, the control unit is configured to use the energy in the energy store and is configured to:
switch the semiconductor switch to be electrically conducting and then opens the second switch, and
subsequently switch the semiconductor switch to be electrically non-conducting, and then opens the first switch.

3. The switching device of claim 1 , wherein the control unit is designed to determine, by way of the first measurement device, the voltage on the primary side of the power supply unit and determines the critical time value as a function of the voltage determined.

4. The switching device of claim 1 , wherein the energy store is configured to be charged up through the supply connection.

5. The switching device of claim 1 , wherein the energy store is designed to ensure the output of the switching signals required for the switching and subsequent switching.

6. The switching device of claim 1 , wherein the switching device incorporates a second current path, which incorporates a first electro-mechanical switch and, connected in series with the first switch, a circuit incorporating a second electro-mechanical switch in parallel with a semiconductor switch, wherein the control unit is configured to output a switching signal for the first switch, for the second switch and for the semiconductor switch in the second current path, wherein the control unit is designed to, if the energy supply which is monitored by way of the measurement device drops into a critical range, the control unit is configured to use the energy in the energy store and is configured to:
switch the semiconductor switch in the second current path to be electrically conducting and then opens the second switch in the second current path,
subsequently switch the semiconductor switch in the second current path to be electrically non-conducting, and then opens the first switch in the second current path.

7. The switching device of claim 1 , wherein the control unit is designed to, in the subsequent switching, switch the semiconductor switch into the electrically non-conducting state as the current for the energy it feeds passes through zero.

8. A system for the safe operation of an electric motor, comprising:
the switching device of claim 1 ;
a supply source; and
a switching mechanism, wherein the switching mechanism is connected into the supply line from the supply source to the supply connection of the switching device in such a way that, by actuating the switching mechanism, a supply of energy effected from the supply source to the switching device is interrupted.

9. A method for a switching device including a control unit, a supply connection, a power supply unit and a first current path, wherein the first current path incorporates a first electro-mechanical switch and, connected in series with the first switch, a circuit incorporating a second electro-mechanical switch in parallel with a semiconductor switch, wherein the control unit is configured to output a switching signal for the first switch, for the second switch and for the semiconductor switch, wherein the supply connection is linked to the power supply unit and the control unit is configured to draws the energy for the switching signals through the power supply unit, wherein the switching device incorporates an energy store and two measurement devices linked to the control unit, wherein the energy store is connected in between the supply connection and the power supply unit, so that an energy supply for the switching device effected through the supply connection is buffered internally within the device, the method, comprising:
determining, via the first measurement device, any drop in the supply voltage, present at the primary side of the power supply unit, below a first voltage threshold value; and
determining, via the second measurement device, any drop in the supply voltage, present at the secondary side of the power supply unit, below a second voltage threshold value;
evaluating, at the control unit, a duration of the time from when the voltage drops below the first voltage threshold value up until when the voltage drops below the second voltage threshold value; and
emitting a signal, from the control unit, if the time between the fall below the first voltage threshold value up until the fall below the second threshold value falls below a critical time value.

10. The method for the switching device of claim 9 wherein, after determining that the voltage on the primary side of the power supply unit has dropped below the first voltage threshold value, the control unit, using the energy in the energy store, automatically:
switching the semiconductor switch to be electrically conducting and then opening the second switch; and
subsequently switching the semiconductor switch to be electrically non-conducting, and then opening the first switch.

11. The method for the switching device of claim 9 , wherein the control unit determines by way of the first measurement device the voltage on the primary side of the power supply unit and determines the critical time value as a function of the voltage determined.

12. The method for the switching device of claim 9 wherein, in the subsequent switching, the control unit switches the semiconductor switch into the electrically non-conducting state as the current for the energy it feeds passes through zero.

13. The method for the switching device of claim 10 wherein, in the subsequent switching, the control unit switches the semiconductor switch into the electrically non-conducting state as the current for the energy it feeds passes through zero.

Assignees

• Siemens Ag

Inventors

• Fritsch Andreas
• Kuhla Hubert

Classifications

• H02P1/022 Primary

  Security devices, e.g. correct phase sequencing · CPC title

• H02P3/02

  Details {of stopping control} · CPC title

• H01H9/542 Primary

  Contacts shunted by static switch means · CPC title

• H02P1/023

  Protection against sparking of contacts or sticking together · CPC title

• H02M2001/0006

  Electricity · mapped topic