Electronic device, system and method for insulation resistance measurements with functions of self-diagnosis and diagnosis of insulation loss with respect to ground of an energized electrical apparatus

Patent metadata

Field	Value
Publication number	US-10175288-B2
Application number	US-201615378922-A
Country	US
Kind code	B2
Filing date	Dec 14, 2016
Priority date	Dec 18, 2015
Publication date	Jan 8, 2019
Grant date	Jan 8, 2019

Abstract

An electronic device for the diagnosis of insulation loss of an energized electrical apparatus, with respect to a ground. The device includes a first resistance-switch group and a second resistance-switch group, connectable or disconnectable in a controlled manner, and also a first measurement circuit and a second measurement circuit, arranged in parallel to the first and second resistance-switch groups, respectively. The first and second measurement circuits include respective first and second detection circuits, first and second charge modulation circuits and first and second partition resistors (RBminus, RBplus). The first and second charge modulation circuits allow a dynamic “switching” measurement technique. Moreover, a method is described for measuring the insulation resistances (RIminus, RIplus) of an energized electrical apparatus with respect to ground, in which the method is carried out by a device according to the invention. Finally, a self-diagnosis method of device is described.

First claim

The invention claimed is:

1. The electronic device for the diagnosis of insulation loss, with respect to a ground of an energized electrical apparatus having a negative terminal and a positive terminal, through the measurement of a negative terminal insulation resistance (RI minus ) present between said negative terminal and said ground, and a positive terminal insulation resistance (RI plus ) present between said positive terminal and said ground, the device including:
a first device terminal and a second device terminal, suitable to be connected, respectively, to the negative and positive terminals of the energized electrical apparatus;
a first resistance-switch group, comprising a first sample resistance (RS minus ) adapted to be connected or disconnected in a controlled manner between the first device terminal and the ground by a first sample resistance insertion switch (S minus );
a first measurement circuit, arranged between the first device terminal and the ground, in parallel to the first resistance-switch group;
a second resistance-switch group, comprising a second sample resistance (RS plus ) adapted to be connected or disconnected in a controlled manner between the second device terminal and the ground by a second sample resistance insertion switch (S plus );
a second measurement circuit, arranged between the second device terminal and the ground, in parallel to the second resistance-switch group;
wherein the first measurement circuit comprises:
a first detection circuit, comprising at least a first resistor (R 2 ) and a first capacitor (C 1 ) arranged mutually in parallel, so that at the ends of the first capacitor (C 1 ), after the first device terminal is connected to the energized electrical apparatus and reaches a first steady state, there is a first detection voltage (VC minus ) depending on the negative voltage (V minus ) of the energized electrical apparatus; the first detection circuit further comprising a first voltage meter (U minus );
a first charge modulation circuit, arranged in parallel to the first detection circuit, and comprising a first modulation resistance (R 1 ) and a first modulation switch (SW 1 ), arranged in series with the first modulation resistance (R 1 ) and adapted to be controlled by a first driving signal (V SW-minus ), so that, when the first device terminal is connected to the energized electrical apparatus, the first capacitor (C 1 ) is partially discharged and recharged, respectively, during each closing and opening period of the first modulation switch (SW 1 ), so that the first detection voltage (VC minus ) oscillates between a first detection voltage maximum value (VC minus-MAX ) and a first detection voltage minimum value (VC minus-MIN ), around a first detection voltage intermediate value (VC minus ) representative of the negative voltage (V minus ) of the energized electrical apparatus;
a first partition resistor (RB minus ) connected between the first device terminal and the first detection circuit, so that the first partition resistor (RB minus ) and the first detection circuit are arranged mutually in series;
and wherein the second measurement circuit comprises:
a second detection circuit, comprising at least a second resistor (R 6 ) and a second capacitor (C 2 ) arranged mutually in parallel, so that at the ends of the second capacitor (C 2 ), after the second device terminal is connected to the energized electrical apparatus and reach a second steady state, there is a second detection voltage (VC plus ) depending on the positive voltage (V plus ) of the energized electrical apparatus; the second detection circuit further comprising a second voltage meter (U plus );
a second charge modulation circuit, arranged in parallel to the second detection circuit, and comprising a second modulation resistance (R 5 ) and a second modulation switch (SW 2 ), arranged in series with the second modulation resistance (R 5 ) and adapted to be controlled by a second driving signal (V SW-plus ), so that, when the second device terminal is connected to the energized electrical apparatus, the second capacitor (C 2 ) is partially discharged and recharged, respectively, during each closing and opening period of the second modulation switch (SW 2 ), so that the second detection voltage (VC plus ) oscillates between a second detection voltage maximum value (VC plus-MAX ) and a second detection voltage minimum value (VC plus-MIN ), around a second detection voltage intermediate value (VC plus ) representative of the positive voltage (V plus ) of the energized electrical apparatus;
a second partition resistor (RB plus ) connected between the second device terminal and the second detection circuit, so that the second partition resistor (RB plus ) and the second detection circuit are arranged mutually in series;
wherein said first voltage meter (U minus ) is configured to provide the first detection voltage (VC minus ) under both opening and closing conditions of the first resistance-switch group switch (S minus ), in which conditions the first sample resistance (RS minus ) is connected and disconnected, respectively;
and wherein said second voltage meter (U plus ) is configured to provide the second detection voltage (VC plus ) under both opening and closing conditions of the second resistance-switch group switch (S plus ) in which conditions the second sample resistance (RS plus ) is connected and disconnected, respectively.

2. The device according to claim 1 , comprising:
a first device switch (M minus ), adapted to connect or disconnect in a controlled manner the first terminal of the device to/from the negative terminal of the energized electrical apparatus;
a second device switch (M plus ), adapted to connect or disconnect in a controlled manner the second terminal of the device to/from the positive terminal of the energized electrical apparatus.

3. The device according to claim 1 , wherein:
the first detection circuit further comprises a third resistor (R 3 ) connected between the parallel of the first resistor (R 2 ) and first capacitor (C 1 ) and the ground;
the second detection circuit further comprises a fourth resistor (R 7 ) connected between the parallel of the second resistor (R 6 ) and second capacitor (C 2 ) and the ground.

4. The device according to claim 1 , wherein the first measurement circuit and the second measurement circuit have an identical circuit structure and have electrical parameters of corresponding resistors and capacitors respectively identical.

5. The device according to claim 1 , wherein:
each of said first device switch (M minus ) and second device switch (M plus ) comprises an electromechanical switch, and wherein
each of said first modulation switch (SW 1 ) and second modulation switch (SW 2 ) comprises a respective solid state electronic switch.

6. The device according to claim 1 , wherein each of said first voltage meter (U minus ) and second voltage meter (U plus ) comprises a respective operational amplifier.

7. An electronic system for the diagnosis of the insulation loss of an energized electrical apparatus, comprising an electronic device according to claim 1 , and further comprising a control device, wherein the control device is configured to:
generate and provide to the first modulation switch (SW 1 ) said first driving signal (V SW-minus );
generate and provide to the second modulation switch (SW 2 ) said second driving signal (V SW-plus ),
receive the first detection voltage (VC minus ) from the first voltage meter (U minus ) and the second detection voltage (VC plus ) from the second voltage meter (U plus );
determine a first value of first detection voltage (VC 1 minus ), under condition of disconnection of the first sample resistance (RS minus ), and determine a second value

Assignees

• Magneti Marelli Spa

Inventors

• Pritelli Danilo
• Suglia Rosanna
• Aurilio Gianluca
• Cerutti Alessandro
• Ciampolini Franco

Classifications

• G01R27/18 Primary

  Measuring resistance to earth {, i.e. line to ground} · CPC title

• H01G2/00

  Details of capacitors not covered by a single one of groups H01G4/00-H01G11/00 · CPC title

• G01N1/00

  Sampling; Preparing specimens for investigation · CPC title

• G01R19/16566

  Circuits and arrangements for comparing voltage or current with one or several thresholds and for indicating the result not covered by subgroups G01R19/16504, G01R19/16528, G01R19/16533 · CPC title

• G01R31/006

  on road vehicles, e.g. automobiles or trucks (testing of ignition installations peculiar to internal combustion engines F02P17/00) · CPC title