HV relay sticking control system and method

A high voltage relay sticking control system for a vehicle having at least one contactor, a high voltage battery pack interfacing with the contactor and a weld diagnostic detection system interfacing with the high voltage battery pack and the contactor includes an increment counter adapted to interface with the contactor, the high voltage battery pack and the weld diagnostic detection system. The increment counter is adapted to transmit at least one set of coil power cycles through the contactor if a weld exists at the contactor. A high voltage relay sticking control method is also disclosed.

FIELD

Illustrative embodiments of the disclosure generally relate to electric vehicles. More particularly, illustrative embodiments of the disclosure generally relate to an HV (high voltage) relay sticking control system and method which reopens HV battery contactors by cycling coil power through the contactors.

BACKGROUND

Electric vehicles including hybrid electric vehicles (HEVs) may include a high voltage battery pack which may be electrically connected to a pair of contactors. A high voltage bus may electrically interface with the contactors, and the vehicle electrical system may electrically interface with the high voltage bus. When the vehicle is turned off, the contactors are opened and the battery is electrically uncoupled from the high voltage bus. When the vehicle is turned on, the contactors are closed and the battery is electrically coupled to the high voltage bus.

Under some circumstances, a contact weld may occur at one or both of the contactors, causing the contactor to “stick” or remain closed. This may result in undesired flow of electrical current in the battery circuit or vehicle electrical system.

Accordingly, an HV (high voltage) relay sticking control system and method which reopens HV battery contactors by cycling coil power through the contactors is needed.

SUMMARY

Illustrative embodiments of the disclosure are generally directed to a high voltage relay sticking control system for a vehicle having at least one contactor, a high voltage battery pack interfacing with the contactor and a weld diagnostic detection system interfacing with the high voltage battery pack and the contactor. An illustrative embodiment of the high voltage relay sticking control system includes an increment counter adapted to interface with the contactor, the high voltage battery pack and the weld diagnostic detection system. The increment counter is adapted to transmit at least one set of coil power cycles through the contactor if a weld exists at the contactor.

Illustrative embodiments of the disclosure are further generally directed to a high voltage relay sticking control method for a vehicle having at least one contactor. An illustrative embodiment of the method includes detecting a weld at the at least one contactor and transmitting at least one set of coil power cycles through the at least one contactor.

DETAILED DESCRIPTION

Referring initially toFIGS. 1 and 3, an illustrative embodiment of a high voltage (HV) relay sticking control system is generally indicated by reference numeral120inFIG. 1. An exemplary electric vehicle which is suitable for implementation of the HV relay sticking control system120is generally indicated by reference numeral100inFIG. 1. In some embodiments, the electric vehicle100may be a hybrid vehicle (HEV) such as a plug in hybrid electric vehicle (PHEV), for example and without limitation. A block diagram of an exemplary increment counter122which is suitable for implementation of the HV relay sticking control system100is shown inFIG. 3.

The electric vehicle100may include a high voltage battery pack102which supplies electrical power to a vehicle electrical system114. A positive contactor108and a negative contactor110may be electrically connected to a positive terminal104and a negative terminal106, respectively, of the high voltage battery pack102. A high voltage bus112may be electrically connected to the positive contactor108and the negative contactor110. The vehicle electrical system114may be electrically connected to the high voltage bus112.

When the ignition of the electric vehicle100is turned off, the positive contactor108and the negative contactor110are open to prevent flow of electrical current from the high voltage battery pack102to the vehicle electrical system114through the high voltage bus112. When the ignition of the electric vehicle100is activated, the positive contactor108and the negative contactor108close. Accordingly, electrical current flows from the high voltage battery pack102to the vehicle electrical system114through the positive contactor108, the negative contactor110and the high voltage bus112, respectively, for operation of the electric vehicle100.

A weld diagnostic detection system116may be electrically connected to the high voltage battery pack102, the positive contactor108and the negative contactor110. In the event that the weld diagnostic detection system116determines that a “weld” exists at the positive contactor108or the negative contactor110, meaning that the positive contactor108or negative contactor110is stuck or has failed to open upon previous deactivation of the vehicle ignition, the weld diagnostic detection system116detects which of the positive contactor108and the negative contactor110is stuck, such as in the conventional manner. A vehicle controller118may interface with the weld diagnostic detection system116and the vehicle electrical system114.

The HV relay sticking control system120may include an increment counter122. The increment counter122may electrically interface with the high voltage battery pack102, the positive contactor108, the negative contactor110and the weld diagnostic detection system116. In the event that it detects a weld at the positive contactor108or the negative contactor110, the weld diagnostic detection system116notifies the increment counter122. In response, the increment counter122may be adapted to initiate and sustain at least one set126(FIG. 3) of multiple coil power cycles124in which electrical current is transmitted in cycles from the high voltage battery pack102through the stuck positive contactor108or negative contactor110. Therefore, the coil power cycles124may reopen the stuck positive contactor108or negative contactor110.

The increment counter122may be adapted to notify the weld diagnostic detection system116after each set126of coil power cycles124is transmitted through the stuck positive contactor108or negative contactor110. In response, the weld diagnostic detection system116may be adapted to recheck the stuck or open status of the positive contactor108or negative contactor110after each set126of coil power cycles124. In the event that the weld diagnostic detection system116determines that the positive contactor108or negative contactor110is no longer stuck, the vehicle controller118may initiate ignition of the electric vehicle100such as via the vehicle electrical system114. On the other hand, in the event that it determines that the positive contactor108or negative contactor110remains stuck, the weld diagnostic detection system116may again notify the increment counter122. In response, the increment counter122may initiate and sustain a subsequent set126of the coil power cycles124through the stuck positive contactor108or negative contactor110.

The increment counter122may be adapted to count the number of sets126of coil power cycles124which are transmitted through the stuck positive contactor108or negative contactor110as responses to notifications from the weld diagnostic detection system116that the positive contactor108or negative contactor110remains stuck. Therefore, in the event that the weld diagnostic detection system116notifies the increment counter122that the positive contactor108or negative contactor110remains stuck after a predetermined number of sets126of the power cycles124(such as 3 sets, for example and without limitation) has been transmitted through the stuck positive contactor108or negative contactor110, the increment counter122may be adapted to terminate further transmission of coil power cycles124through the positive contactor108or negative contactor110.

Referring next toFIG. 2, a block diagram of an illustrative embodiment of an HV relay sticking control method200for a vehicle is shown. The method200may start at block202. At block204, weld detection at a positive contactor or a negative contactor may be carried out. At block206, the vehicle may proceed to start if a weld is not detected at one of the contacts at block204and the method200may then end at block208.

In the event that a weld is detected at block204, weld diagnostics processes may be carried out at block210. At block212, the number of sets of coil power cycles which have been transmitted through the stuck positive contactor or negative contactor may be counted. In the event that the number of transmitted sets of coil power cycles is equal to or less than a predetermined number such as 0-3, for example and without limitation), a first or subsequent set of coil power cycles may be transmitted through the stuck positive contactor or negative contactor in an attempt to open the contactor at block214. Weld detection may then again be carried out at block204. On the other hand, in the event that the number of transmitted sets of coil power cycles is greater than the predetermined number, further transmission of coil power cycles may be terminated and the method may end at block208.