High voltage interlock system and control strategy

A High Voltage Interlock Loop (HVIL) system and Control Strategy is provided for an alternative fuel vehicle including an electric, a hybrid electric, or a fuel cell vehicle. Generally, the HVIL system having associated logic including an HVIL circuit is provided to allow the vehicle to operate in either a high voltage (HV) or power mode powered by a power source or a HVIL interrupt mode based on an operational state of the HVIL system. When HVIL circuit fails shorted high, low or open, a Diagnostic Trouble Code (DTC) is set and the Service Soon Lamp is illuminated to indicate to a service technician that additional safety precautions need to be taken when servicing the HV system. The HV contactors may or may not be activated providing HV to the vehicle when HV is not expected to be present at connectors and HV devices.

FIELD OF THE INVENTION

The present invention generally relates to a high-voltage interlock and relates more specifically to a high-voltage interlock having a monitoring system.

BACKGROUND OF THE INVENTION

Modern vehicles often include many high-voltage electrical devices. High voltage devices may present challenges not present in conventional lower voltage systems. In the event of a vehicle accident or vehicle component failure, a short-circuited high voltage system may sustain heavy damage because of the relatively high voltage levels. Another concern is undesired contact with high voltage levels, either directly or indirectly, by a vehicle user or other persons.

Existing high voltage interlocks do provide a degree of safety for users anticipating contact with a high voltage electrical system, such as maintenance personnel, but may not provide protection in situations where a user inadvertently contacts a high voltage electrical system.

While existing devices suit their intended purposes, what is needed is a system that allows monitoring the High Voltage Interlock Loop (HVIL) with respect to wiring failures. This allows alerting the service personnel of a wiring failure system that needs additional precautions prior to servicing the high voltage system.

SUMMARY

A High Voltage Interlock Loop (HVIL) system and Control Strategy is provided for an alternative fuel vehicle such as an electric, a hybrid electric, or a fuel cell vehicle. Generally, the HVIL system having associated logic including an HVIL circuit is provided to allow the vehicle to operate in either a high voltage (HV) or power mode powered by a power source or a HVIL interrupt mode based on an operational state of the HVIL system.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1illustrates an exemplary fuel cell vehicle and includes the HVIL control system10and strategy in accordance with one embodiment of the present invention.

The present invention can be used, however, with any hybrid electric systems without deviating from the scope of the present invention, including vehicles powered by internal combustion engines, series hybrid electric vehicles (SHEV), parallel hybrid electric vehicles (PHEV), and electric vehicles that use a high voltage power source in combination with a vehicle battery.FIG. 1illustrates an electrical diagram of the HVIL control system in accordance with one embodiment of the invention.

Exemplary fuel cell vehicle10includes electrically operated or controlled components including fuel cell154, transmission16, and vehicle battery220. These components operate with a planetary gear set24in the transmission, a motor/generator26, an inverter28within the IPT72, that powers a differential axle38(at the output of the transmission) and the vehicle wheels40. The IPT72controls and monitors the torque output of engine14and motor/generator26. Fuel cell154, transmission16, and VSC78cooperate to form a system for the vehicle10, as is shown and discussed in further detail inFIG. 1.

Vehicle system controller78(VSC) controls all aspect of vehicle operation. VSC78monitors vehicle operation and controls vehicle10. VSC78generates and transmits signals to the vehicle components. The components operate as instructed by VSC78. VSC78may control each component independently and collectively to control vehicle operation.

In one embodiment of the invention, vehicle10includes HVIL monitor and control module microprocessor86. HVIL monitor and control module microprocessor86provides HVIL control logic through an inertia switch192, a plurality of HV accessory connectors193, and a HV contactors relay194to one or more HV contactors182,184.

In the embodiment of the invention illustrated inFIG. 1, the HVIL control system10includes two HV contactors182,184. In other embodiments of the invention, one or more HV contactors may be included.

In one embodiment of the invention, illustrated inFIG. 1the control module86and associated control logic may reside within the VSC78.

In one embodiment of the invention, the HVIL module86may be in operative communication with the VSC78but may reside in a separate location from the VSC78.

In an embodiment of the invention, VSC78includes an associated HVIL activation switch80, the HVIL activation switch80in signal communication with the VSC78and adapted to selectively couple or decouple a vehicle battery220from the VSC78. The high voltage interlock system logic is in electrical communication with a vehicle system controller (VSC) and may be integrally formed as a sub-module within the VSC.

Signals from a HVIL212source signal are input into the inertia switch192. The HVIL source212becomes the HVIL Out214continuing on to the power distribution box206and components associated therewith when an inertia switch192is closed or not triggered. The HVIL Out214is then input into the HV connectors193and becomes the HVIL sense signal204when monitoring for breaks in the HVIL source212and the HVIL sense signal204. The HVIL source212and HVIL sense signal204are the same signal when the inertia switch192is closed and when the HV connectors193are mated with the activated HV contactors relay194, and thus cooperate to form HVIL circuit224that provides vehicle battery220power to the HV contactors182,184. VSC78can control operation of power sensed and distributed within the vehicle10based on the operation of the HVIL circuit.

FIG. 1illustrates an exemplary fuel cell vehicle10. Fuel cell vehicles include components similar to those to be described below with respect to vehicles having internal combustion engines.

The fuel cell vehicle10illustrated inFIG. 1includes fuel cell154and a traction motor/generator26. Fuel cell154replaces a conventional engine, but it is similarly controlled by VSC78. The traction motor/generator26, powered by inverter28and gearing24is controlled by VSC78. Inverter28and motor/generator26operate on power provided from the high voltage bus160. High voltage bus160receives power from Fuel Cell154. DC/DC converter162receives power inputs from HV power bus160, and supplies 12V to the vehicle low voltage electrical system and recharges the 12V battery220. Fuel cell154further includes air conditioning compressor68and associated controller70, air module66and HV water pump52.

FIG. 1illustrates a high voltage interlock control system10and strategy for use in a vehicle having a HVIL module86in accordance with one embodiment of the invention.

The HVIL control system10includes a VCS78in signal communication with a plurality of signal lines including a HVIL source line212output from the VCS78to an HVIL out line214when inertia switch192is closed and an inertia sense line216in further communication with an Energy Management Module (EMM)23when the inertia switch192is tripped, and a HVIL sense line204in further signal communication with a HV contactors controller relay194, power distribution box206(PDB), and using the CAN network protocol218is in further operative communication with an IPT interface202, a torque controller222, and other vehicle systems.

The VSC78provides a source for the HVIL circuit224and operates to control the HVIL system and monitor for nonconforming HVIL operating conditions.

In an embodiment of the invention, the HVIL circuit224is in further operative communication with an Energy Management Module23that monitors for high voltage battery readings, wherein for the HV power supply154to power the modules in signal communication with the PDB206, the HVIL sense line204input must be high and the inertia sense line216must be low.

In another embodiment of the invention, if the VSC78uses power from the vehicle battery220, the VSC78may not need to monitor the HVIL circuit224for HV battery readiness, and wherein the EMM23reads the inertia sense line216input.

The PDB206control communications between the VSC78, the IPT interface202, an auxiliary battery220, and a power supply154via a HV bus160in communication218with a plurality of modules including an air module66, an A/C compressor68, and a HV water pump54.

Operation of the HVIL10control system depends upon a HV contactors controller194, shown inFIG. 1as a relay operating as a switch, shown inFIG. 1as not activated, whereas the HV contactors182,184are not triggered or opened, thereby suppressing power from the HV bus160to selected vehicle systems or components. As the HV contactors controller relay194is activated by the HVIL Sense204circuit, the HV contactors182,184are closed in a normal vehicle operation mode, the HV power supply154then provides power to the selected vehicle components54,66,68as disclosed herein and as shown inFIG. 1when the HV contactors182,184are triggered or closed. The HV contactors182,184are normally open relays operating as single pole single throw switches as shown inFIG. 1.

The inertia switch192is provided in communication with the VCS78and the EMM23. The inertia switch192trips when an inertia event occurs, thereby forming a connection between the HVIL source line212and an inertia sense line216. The inertia switch192operates in an opposite switching state from the switching state of the HV controller194, when the inertia switch192trips, the inertia sense line216communicates a second digital input164into the EMM23, wherein the second digital input164has an associated second pull-down resistor176that is input into the EMM23and toggles between a high or a low/open state depending upon the operating mode of the HVIL circuit224, and in particular, the state of the inertia sense line216.

In the embodiment of the invention illustrated inFIG. 1, IPT72includes associated IPT microprocessor202, the IPT microprocessor202in signal communication with the VSC78.

A first digital input160has an associated pull-down resistor170input into the VSC78and EMM23and is connected to the HVIL sense line204that toggles between a high or a low/open state depending upon the operating mode of the HVIL circuit224, and in particular, the state of the HVIL inertia sense line204.

The HVIL circuit224powers the HV Contactors182,184in accordance with commands received from the VSC78.

The HVIL circuit224includes the HVIL source line212that is enabled by the VSC78and that powers the HV contactors182,184to close until an HV contactor open event occurs; an HVIL sense line204that is at the same potential as the HVIL source line212if the inertia sense switch192is not tripped, or closed if the HVIL sense circuit204is not broken; an inertia sense line216that is at the same potential as the HVIL source line212output from the VSC78if the inertia sense switch192is tripped or closed. The VSC78is in signal communication with a CAN system218for vehicle communications and provides a protocol check for the HVIL control system10. The HVIL circuit224includes the HVIL source line212as an output from the VSC78into a plurality of HVIL related modules including an air module66, an A/C compressor68, an associated A/C compressor controller70, and a HV water pump52; and the HVIL sense line204as an output from the plurality of HVIL related modules into both the VSC78and an HV contactors controller relay194.

The HVIL out line214is at the same potential as the HVIL source line212if the inertia switch192is not tripped, however, the HVIL out line214is not monitored by the HVIL control system10.

FIG. 3illustrates a flowchart of a HVIL control strategy and method230using the HVIL control system10to perform a plurality of options based upon a particular vehicle operation mode.

Initially, the HVIL source212is monitored by the VSC78, control module microprocessor86prior to activating the HVIL activation switch80(231), for a short to 12V (232). If the HVIL source212is low (233), then the HVIL Source is assumed not shorted high (234) and is ready for activation. If the HVIL source212is high (235), then the HVIL source212is assumed shorted and a DTC is set. The HVIL activation switch80is then activated (236) and the vehicle can be operated.

In an embodiment of the invention, the HVIL sense204is then monitored (237). If the HVIL sense line204input is low (239), then the HVIL source212and/or HVIL sense204is either open or shorted low, wherein a DTC is also set (240). If the HVIL sense line204input is high (238), the system is OK and no action is required (241).

In an embodiment of the invention, when the VSC78senses a low input from the HVIL sense line204, then one of four events has occurred, indicating an event selected from: an HVIL open circuit, a local open circuit, a tripped inertia switch, or a short to ground.

If an HVIL open circuit is detected, then the HV contactors182,184are opened and thus, the HV bus160is suppressed from the fuel cell154. The VCS78confirms HV operational status from the CAN218.

If a local open circuit is detected, then the HV contactors182,184could be open or closed and the potential of the HV bus160is high, exists.

The VCS78checks the HVIL circuit224operational status from the CAN218. Additionally, the status of other modules within the vehicle may be checked from the CAN including, but not limited to: HVIL sense line204and inertia sense line216.

In another embodiment of the invention, the EMM23reads inputs from the inertia switch192, and determines if the inertia switch192is tripped or closed.

In another embodiment of the invention, the VCS78determines if a short to ground in HVIL source line212of the HVIL circuit224exists when the vehicle is being driven. A fuse48associated with the HV contactors controller194may be blown if a short to ground exists and thus, the HV contactors182,184will open, thereby decoupling the 12V battery220from the HVIL circuit224.

The HVIL sense signal204is a logic signal inputting either a high or a low input into the VCS78from the HVIL sense line204or indirectly from the HVIL circuit224, wherein the HVIL sense signal204provides control to the HV contactors relay194that provides power the HV contactors182,184. The HV contacts182,184will not be powered by the auxiliary battery220when the HVIL circuit224is broken.

FIG. 2illustrates a logic table300indicating operating states of the vehicle and in particular the HVIL control system10.

A logic table shown inFIG. 2illustrates states of monitoring the HVIL Source212before and after the HVIL activation switch80is applied. This indicates whether the HVIL Source212is shorted to 12V. Upon activation of the HVIL activation switch80, the HVIL Sense204is monitored using the first digital input160associated with the HVIL sense line204input into the VSC78. The level of the HVIL Sense204with respect to the HVIL Source212indicates possible failure conditions to the HVIL circuit.