Method and device for short circuit or open load detection
View Patent ↗A method or apparatus is provided for detecting an error condition associated with a load (R L ) or a connection (P) to the load (R L ). The load (R L ) may comprise an energy storing element (Cext). During a first diagnosis phase, it is determined whether the load (R L ) or the connection (P) to the load (R L ) is in a normal operation condition or in an error condition. If the load (R L ) or the connection (P) to the load (R L ) is in an error condition, during a second diagnosis phase it is determined whether the error condition is an open load condition, short circuit condition to ground or a short circuit condition to a power supply. When the load is in a starting state before the first diagnosis phase, the method or apparatus may further comprise carrying out, after the second diagnosis phase, a resetting phase for resetting the load to the starting state.
1. A method for detecting an error condition associated with a load (R L ) or a connection (P) to the load (R L ) comprising:
during a first diagnosis phase determining whether the load (R L ) or the connection (P) to the load (R L ) is in a normal operation condition or in an error condition, and
if the load (R L ) or the connection (P) to the load (R L ) is in an error condition, during a second diagnosis phase determining whether the error condition is an open load condition, short circuit condition to ground or a short circuit condition to a power supply,
wherein the second diagnosis phase comprises changing a first parameter associated with the load in an attempt to escape from said error condition.
2. A method according to claim 1 , wherein changing a first parameter comprises changing the polarity of a current flowing in or out the load (R L ).
3. A method according to claim 1 , wherein changing a first parameter comprises changing the amplitude of a current flowing in or out the load (R L ).
4. A method according to claim 2 , wherein changing a first parameter furthermore comprises changing the amplitude of a current flowing in or out the load (R L ).
5. A method according to claim 3 , wherein changing the amplitude of the current is such that the amplitude of the current is larger than a minimum level, said minimum level being defined by formula:
I
DiagMin
=
Δ
V
·
A
ext
t
wherein ΔV is a reference voltage, A ext is a memory value of an energy storing element present in the load (R L ) and t is the time between the change of the amplitude of the current and a moment of measuring a voltage.
6. A method according to claim 1 , the load (R L ) being in a starting state before the first diagnosis phase, the method further comprising carrying out, after the second diagnosis phase, a resetting phase for resetting the load (R L ) to the starting state.
7. A method according to claim 1 , wherein the first diagnosis phase comprises monitoring whether a second parameter associated with the load (R L ) is below a first pre-determined low level or is above a second pre-determined high level, and if so, reporting that the load (R L ) is in an error condition.
8. A method according to claim 7 , wherein monitoring a second parameter comprises monitoring a current flowing in or out the load (R L ) or a voltage drop across the load (R L ).
9. A method according to claim 6 , wherein the resetting phase comprises changing a third parameter associated with the load (R L ).
10. A method according to claim 9 , wherein changing a third parameter comprises changing a current flowing in or out the load (R L ).
11. An error detection apparatus for detecting an error condition associated with a load (R L ) or a connection (P) to the load (R L ) comprising:
first diagnosis means for determining whether the load (R L ) or the connection (P) to the load (R L ) is in a normal operation condition or in an error condition and
second diagnosis means for, if the load (R L ) or the connection (P) to the load (R L ) is in an error condition, determining whether the error condition is an open load condition, a short circuit condition to ground or a short circuit condition to power supply and
wherein the second diagnosis means comprises means for changing a first parameter associated with the load (R L ) in an attempt to escape from said error condition.
12. An error detection apparatus according to claim 11 , wherein said means for changing a first parameter comprises means for changing the polarity of a current flowing in or out the load (R L ).
13. An error detection apparatus according to claim 11 , wherein said means for changing a first parameter comprises means for changing the amplitude of a current flowing in or out the load (R L ).
14. An error detection apparatus according to claim 12 , wherein said means for changing a first parameter furthermore comprises means for changing the amplitude of a current flowing in or out the load (R L ).
15. An apparatus according to claim 11 , wherein the load (R L ) comprises an energy storing element (C ext ).
16. An apparatus according to claim 11 , for detecting an error condition on the load (R L ) in a starting state, the apparatus further comprising resetting means for resetting the load (R L ) to the starting state.
17. An apparatus according to claim 11 , wherein the first diagnosis means comprises means for monitoring whether a second parameter associated with the load (R L ) is below a first pre-determined low level or is above a second pre-determined high level, and reporting means for reporting that the load (R L ) is in an error condition.
18. An apparatus according to claim 17 , wherein the second parameter is a current flowing in or out the load (R L ) or a voltage drop across the load (R L ).
19. An apparatus according to any of claims 16 , wherein the resetting means comprises means for changing a third parameter associated with the load (R L ).