SWITCHING STATE OF A MECHANICAL SWITCH

• US 20180136284A1
• Filed: 11/16/2017
• Published: 05/17/2018
• Est. Priority Date: 11/17/2016
• Status: Active Grant

• Current Assignee: LISA Draxlmaier GmbH
• Original Assignee: LISA Draxlmaier GmbH
• Inventors: MAYER, Florian
• Granted Patent: US 10,209,311 B2
• Time in Patent Office: Days
• CPC Class Codes: B60W 10/26 for electrical energy, e.g. batteries or capacitors
• CPC Class Codes: G01R 31/006 on road vehicles, e.g. automobiles or trucks testing of ignition installations peculiar to internal combustion engines F02P17/00
• CPC Class Codes: G01R 31/3274 Details related to measuring, e.g. sensing, displaying or computing; Measuring of variables related to the contact pieces, e.g. wear, position or resistance measuring contact resistance G01R27/205
• CPC Class Codes: G01R 31/3275 Fault detection or status indication
• CPC Class Codes: G01R 31/3277 of low voltage devices, e.g. domestic or industrial devices, such as motor protections, relays, rotation switches
• CPC Class Codes: G01R 31/382 Arrangements for monitoring battery or accumulator variables, e.g. SoC

Abstract

A circuit for monitoring a switching state of a mechanical switch is provided that includes a first mechanical switch configured to couple a high-voltage power storage device to a load, a measuring device that measures a voltage characteristic at the first mechanical switch, the measuring device is being connected to the first mechanical switch via a first measuring resistor such that a voltage drop at the first mechanical switch is measurable over a period of time, an insulation-monitoring unit having a first switchable resistor that can be switched in during measuring such that a voltage divider formed by two or more insulation resistors (R_iso+, R_iso−) of the high-voltage power storage device is modified, and an evaluation device that compares the measured voltage characteristic at the first mechanical switch with a predefined threshold value so that the switching state of the first mechanical switch can be determined.

Claims

1. A circuit for monitoring a switching state of a mechanical switch, the circuit comprising:

a first mechanical switch configured to couple a high-voltage power storage device to a load;

a measuring device configured to measure a voltage characteristic at the first mechanical switch, wherein the measuring device is capable of being switched to the first mechanical switch via a first measuring resistor such that a voltage drop at the first mechanical switch is measurable over a period of time;

an insulation-monitoring unit having a first switchable resistor, wherein the first switchable resistor is capable of being switched in during the measurement of the voltage characteristic at the first mechanical switch, wherein a voltage divider formed by two or more insulation resistors (R_iso+, R_iso−

) of the high-voltage power storage device is modifiable by the switching in; and

an evaluation device configured to compare the measured voltage characteristic at the first mechanical switch with a predefined threshold value such that the switching state of the first mechanical switch is determined.

2. The circuit according to claim 1, wherein the evaluation device supplies a signal based on the comparison, wherein the signal indicates that the first mechanical switch is open when the predefined threshold value is exceeded, and/or with the signal indicates that the first mechanical switch is closed when the predefined threshold value is undershot.

3. The circuit according to claim 1, wherein the insulation-monitoring unit further comprises a second switchable resistor, wherein the second switchable resistor is capable of being switched in during the measurement of the voltage characteristic at the first mechanical switch, wherein a voltage divider formed by the two or more insulation resistors (R_iso+, R_iso−

) of the high-voltage power storage device is modifiable by the switching in.

4. The circuit according to claim 3, wherein the first and the second resistors of the insulation-monitoring unit are alternately switchable.

5. The circuit according to claim 3 further comprising a second mechanical switch configured to couple the high-voltage power storage device to the load.

6. The circuit according to claim 5, wherein the measuring device is connectable to the second mechanical switch via a third measuring resistor such that a voltage drop at the second mechanical switch is measurable over a period of time.

7. The circuit according to claim 3 further comprising a supply line and a ground conductor, wherein the first switchable resistor is switchably connected to the supply line and the second switchable resistor is switchably connected to the ground conductor.

8. The circuit according to claim 3, wherein the first and the second switchable resistors are connected in series, with an equipotential predominating between the first and the second switchable resistors.

9. The circuit according to claim 1, wherein at least one of the measuring device and the insulation-monitoring unit is arranged between the high-voltage power storage device and the load and is parallel connected to the high-voltage power storage device and the load.

10. The circuit according to claim 9, wherein the first or the first and the second mechanical switches are arranged between the measuring device and the load, wherein the load is disconnected from the high-voltage power storage device, the insulation-monitoring unit, and the measuring device when the first and/or second mechanical switch is open.

11. The circuit according to claim 10, wherein the connection from the high-voltage power storage device and the load is in the following order:

high-voltage power storage device;

insulation-monitoring unit;

measuring device;

first or first and second mechanical switch; and

load.

12. The circuit according to claim 1 further comprising a second mechanical switch configured to couple the high-voltage power storage device to the load.

13. The circuit according to claim 12, wherein the first or the first and the second mechanical switches are arranged between the measuring device and the load, wherein the load is disconnected from the high-voltage power storage device, the insulation-monitoring unit, and the measuring device when the first and/or second mechanical switch is open.

14. The circuit according to claim 12, wherein the connection from the high-voltage power storage device and the load is in the following order:

high-voltage power storage device;

insulation-monitoring unit;

measuring device;

first or first and second mechanical switch; and

load.

15. A method for monitoring a switching state of a mechanical switch, the method comprising the steps of:

measuring a voltage characteristic at a first mechanical switch, the first mechanical switch configured to couple a high-voltage power storage device to a load, wherein a voltage drop at the first mechanical switch is measured over a period of time;

switching in a first switchable resistor of an insulation-monitoring unit during the measurement of the voltage characteristic at the first mechanical switch, wherein a voltage divider formed by at least two insulation resistors (R_iso+, R_iso−

) of the high-voltage power storage device is modified by the switching in of the first switchable resistor; and

determining the switching state of the first mechanical switch based on the measured voltage characteristic at the first mechanical switch, wherein determining the switching state includes comparing the measured voltage characteristic at the first mechanical switch with a predefined threshold value.

16. The method according to claim 15 further comprising the step of:

supplying a signal indicating that the first mechanical switch is open if the predefined threshold value is exceeded and/or indicating that the first mechanical switch is closed if the predefined threshold value is undershot.

17. The method according to claim 16 further comprising the step of:

alternating the switching in of the first switchable resistor and of a second switchable resistor of the insulation-monitoring unit.

18. The method according to claim 15 further comprising the step of:

alternating the switching in of the first switchable resistor and of a second switchable resistor of the insulation-monitoring unit.

19. The method according to claim 15 further comprising the step of:

measuring a voltage characteristic at a second mechanical switch, the second mechanical switch configured to couple a high-voltage power storage device a load, wherein a voltage drop at the second mechanical switch is measured over a period of time.

20. The method according to claim 15 further comprising the steps of:

alternating the switching in of the first switchable resistor and of a second switchable resistor of the insulation-monitoring unit; and

measuring a voltage characteristic at a second mechanical switch, the second mechanical switch configured to couple a high-voltage power storage device a load, wherein a voltage drop at the second mechanical switch is measured over a period of time.