Device for detecting a defect in insulation

Patent metadata

Field	Value
Publication number	US-9606165-B2
Application number	US-201314090473-A
Country	US
Kind code	B2
Filing date	Nov 26, 2013
Priority date	Jun 1, 2011
Publication date	Mar 28, 2017
Grant date	Mar 28, 2017

Abstract

An electrical power supply includes DC source outputting Vm and a device that detects insulation defects in the DC source. The device includes input terminals connected to the source's terminals, impedances Z1 and Z2 connected in series between the input terminals, where Z1=Z2=Z and Vm/Imax<z<(3/2)*Vm/Imax, wherein Imax is a maximum insulation defect current defined by a standardized safety threshold, and a current-detection circuit connected between ground and an intermediate point between the impedances. The current-detection circuit includes a microcontroller that receives a voltage proportional to the defect current originating from the intermediate point, the input terminal being connected by Z3 to a power supply with Vcc<Vm, the input terminal being connected to ground by way of Z4. The microcontroller is configured to determine amplitude of an insulation defect as a function of the voltage applied to the input terminal, wherein Z*Vcc/(4*Vm)<(Z3,Z4)<Ztmax=Z*Vcc/2Vm.

First claim

Having described the invention, and a preferred embodiment thereof, what is claimed as new, and secured by Letters Patent is:

1. An apparatus comprising an electrical power supply device, said electrical power supply comprising a DC voltage source capable of providing a voltage sufficient to induce electrocution, said DC voltage source being configured to apply a nominal voltage V m between terminals thereof, and a device for detecting an insulation defect of said DC voltage source, wherein said device comprises first and second input terminals connected to said terminals of said voltage source, first and second impedances connected in series between said first and second input terminals, said first and second impedances each having an impedance value Z of between Z min and Z max , wherein Z min =V m /I max and Z max =1.5*V m /I max , wherein Imax is a maximum insulation defect current defined by a standardized safety threshold, and a current-detection circuit connected between an electrical ground and an intermediate point between said first and second impedances, wherein said current-detection circuit further comprises a microcontroller comprising an input terminal configured to receive a voltage proportional to said insulation defect current originating from said intermediate point, said input terminal being connected by a third impedance to a power supply with a voltage level V cc at least ten times lower than said voltage level of said DC voltage source, said input terminal being connected to said electrical ground by way of a fourth impedance, said microcontroller being configured to determine an amplitude of said maximum insulation defect current as a function of said voltage applied to said input terminal, wherein said third and fourth impedances each have an impedance value Z t of between Z tmin and Z tmax , wherein Z tmin =Z*V cc /(4*V m ) and Z tmax =Z*V cc /2 V m .

2. The apparatus of claim 1 , wherein said first and second impedances are selected so as to be traversed by a maximum current of less than 3.5 mA when one of said terminals of said DC voltage source is short-circuited to said electrical ground.

3. The apparatus of claim 1 , further comprising a first breaker connected in series with said first impedance between said first input terminal and said intermediate point, a second breaker connected in series with said second impedance between said second input terminal and said intermediate point, and a control circuit configured to simultaneously keep one of said first and second breakers open and an other of said first and second breakers closed.

4. The apparatus of claim 1 , further comprising a first diode connected in parallel with said third impedance and a second diode connected in parallel with said fourth impedance.

5. The apparatus of claim 1 , wherein said third and fourth impedances are substantially identical resistors.

6. The apparatus of claim 1 , further comprising a fifth impedance connected in parallel with said third impedance and having a lower impedance value than said third impedance, a sixth impedance connected in parallel with said fourth impedance and having a lower impedance value than said fourth impedance, a first breaker connected in series with said fifth impedance, and, a second breaker connected in series with said sixth impedance.

7. The apparatus of claim 6 , further comprising a control circuit configured to transiently and simultaneously close said first and second breakers.

8. The apparatus of claim 7 , wherein said control circuit is configured to determine that said amplitude of said maximum insulation defect current exceeds a threshold and to transiently close said first and second breakers when a crossing of said threshold is determined.

9. The apparatus of claim 7 , wherein said microcontroller is configured to generate a signal proportional to said voltage of said intermediate point and to provide said control circuit with said generated signal.

10. The apparatus of claim 1 , wherein said voltage level of said power supply is less than 25 V.

11. The apparatus of claim 1 , wherein said first and second impedances have an impedance value of greater than or equal to 100 kΩ.

12. The apparatus of claim 1 , wherein said first and second impedances are substantially identical resistors.

13. The apparatus of claim 1 , wherein said DC voltage source comprises a battery having terminals, said apparatus further comprising an inverter comprising a DC interface and an AC interface, wherein said terminals of said battery are connected to said DC interface, and wherein an electric motor is connected to said AC interface.

14. The apparatus claim 13 , wherein a voltage across said terminals of said battery is greater than 100 V.

Assignees

• Commissariat Energie Atomique

Inventors

• Chatroux Daniel
• Carcouet Sebastien
• Dauchy Julien

Classifications

• B60L58/18

  of two or more battery modules · CPC title

• B60L50/51

  characterised by AC-motors · CPC title

• B60L2240/547

  Voltage · CPC title

• B60L58/21

  having the same nominal voltage · CPC title

• B60L2270/145

  Structure borne vibrations · CPC title