FAULT DETECTION IN A MULTIPLE HIGH-VOLTAGE BUS SYSTEM

Abstract

Vehicle bus system (18) comprising: first and second contactors configured to share a first terminal (20) of a battery (14), wherein the first contactor (44) is configured to energize a first load (34) when closed, and the second contactor (46) is configured to energize a second load (36) when closed, and a controller (16) programmed to, after issuing a command to close the first and second contactors (44, 46), precharge a second terminal (21) of the battery (14) in response to a first voltage across the first contactor (44) exceeding a first threshold in the closed state, and to start upon a second voltage across the second protector (46) that exceeds a second threshold value in the closed state and to generate an alert and to prevent a start of the precharge in response to at least one of the first and second voltages being lower than the corresponding first and second threshold values in the closed state.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to systems and methods for performing fault detection in a multiple high voltage (HV) bus system STATE OF THE ART

[0002] A hybrid or electric vehicle may be equipped with at least one traction battery configured to provide power for propulsion. The traction battery may also provide power to other vehicle electrical systems. For example, the traction battery may transfer power to high-voltage loads, such as compressors and electric heaters. In another example, the traction battery may provide power to low-voltage loads, such as a 12V auxiliary battery.

[0003] Document CN 1 02 416 882 A discloses a power distribution box for an electric vehicle with a main circuit and a vehicle controller, wherein the main circuit comprises a battery input terminal, a pair of charging input terminals for connecting a charger, a pair of main motor output terminals for connecting to a main motor controller, and a pair of electrical accessory output terminals for connecting to electrical accessories. The vehicle controller is provided for controlling a connection of a main contactor, a charging contactor, a pre-charging contactor, and an electrical accessory contactor of the main circuit.

[0004] JP 2010-230 678 A discloses an apparatus for diagnosing an abnormality in a power supply circuit, comprising a power supply that supplies power to a load, and a circuit switch that is arranged between the power supply and the load and connects and disconnects the power supply.

[0005] US 8 575 940 B2 discloses a power supply device installed in a hybrid car, electric vehicle or fuel cell vehicle and supplying electrical energy to a drive electric motor for operating the vehicle, and a method for detecting the non-contact state of a load connected to the power supply device.

[0006] The publication KR 10 2013 126 146 A discloses a method for diagnosing relay faults which can shorten the time required to check for the burnout of a main relay in an electric vehicle or hybrid vehicle. SUMMARY

[0007] A vehicle bus system includes a controller programmed to, upon issuing a command to close a pair of contactors configured to share a battery terminal and each configured to energize a load when closed, initiate a pre-charge of another terminal in response to voltages across the contactors exceeding respective closed-state thresholds, and to generate a notification and prevent initiation of the pre-charge in response to one of the voltages being lower than the respective closed-state threshold.

[0008] A method includes, after issuing a command by a controller to close a pair of contactors configured to share a battery terminal and each configured to energize a load when closed, initiating a precharge of another terminal in response to voltages across the contactors exceeding respective closed-state thresholds, and generating a notification and preventing initiation of the precharge in response to one of the voltages being lower than the respective closed-state threshold.

[0009] A vehicle bus controller comprises input channels configured to receive signals indicative of voltages across a pair of contactors configured to share a battery terminal and each configured to energize a load when closed, output channels configured to provide a command to close the contactors, a command to start precharging another traction battery terminal, and a notification, and control logic configured, after issuing the command to close the contactors, to generate the command to start precharging another terminal in response to the voltages being higher than corresponding thresholds in the closed state and to generate the notification in response to one of the voltages being lower than the corresponding threshold in the closed state for a period of time,which is longer than a closing delay of the corresponding contactor. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a block diagram of a plug-in hybrid electric vehicle (PHEV) illustrating typical powertrain and energy storage components; Fig. 2A is a block diagram illustrating a contactor arrangement for a single high-voltage bus system; Fig. 2B is a circuit diagram illustrating a contactor; Fig. Figure 3 is a graphic illustrating a sequence of commands for a single high-voltage bus system; Fig. 4 is a block diagram illustrating a contactor arrangement for a multiple high-voltage bus system; Fig. 5 is a diagram illustrating a sequence of commands for a multiple high-voltage bus system; and Fig. 6A-6B are flowcharts illustrating an algorithm for performing fault detection in a multiple high-voltage bus system. DETAILED DESCRIPTION

[0010] Embodiments of the present disclosure are described herein. It should be understood, however, that the disclosed embodiments are merely examples, and that other embodiments may take various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art how to variously employ the present invention.It will be apparent to one of ordinary skill in the art that various features illustrated and described with reference to one of the figures may be combined with features illustrated in one or more other figures to produce embodiments not explicitly illustrated or described. The combinations of illustrated features provide representative embodiments for typical applications. However, various combinations and modifications of the features consistent with the teachings of the present disclosure may be desired for particular applications or implementations.

[0011] Fig. 1 illustrates an exemplary plug-in hybrid electric vehicle (PHEV) system 10. A plug-in hybrid electric vehicle 12, hereinafter vehicle 12, may include at least one traction battery or battery pack 14. The battery pack 14 includes a battery controller 16 and may be configured to receive an electrical charge via a charging session at a charging station connected to a power grid. In one example, the power grid may include a device that harnesses renewable energy, such as a photovoltaic (PV) solar panel or a wind turbine.

[0012] The battery pack 14 may include one or more battery cells (not shown), such as electrochemical cells, capacitors, or other types of energy storage device implementations. The battery cells may be configured and configured in any suitable configuration to receive and store electrical energy for use in operating the vehicle 12. Each cell may provide a same or different nominal voltage threshold. The battery cells may further be configured in one or more arrays, sections, or modules, further connected in series or parallel.

[0013] The battery pack 14 may further include a bussed electric center (BEC) 18 electrically connected to the battery cells, such as via positive and negative battery terminals 20, 21. As described with respect to at least the Fig. 2A-5, the BEC 18 may be in communication with the battery controller 16 and may include a plurality of connectors and switches that enable the supply and removal of electrical energy to and from the battery pack 14.

[0014] The battery controller 16 is electrically connected to the BEC 18 and controls the flow of energy between the BEC 18 and the battery cells. For example, the battery controller 16 may be configured to monitor and manage the temperature and state of charge of each of the battery cells. The battery controller 16 may command the BEC 18 to open or close a plurality of switches in response to the temperature or state of charge in a given battery cell reaching a predetermined threshold.

[0015] The battery controller 16 may communicate with one or more vehicle controllers 38, such as, but not limited to, an engine control module (ECM) and a powertrain control module (TCM), and may command the BEC 18 to open or close a plurality of switches in response to a predetermined signal from the one or more vehicle controllers 38.

[0016] The vehicle 12 may further include one or more electric machines 22 mechanically connected to a hybrid transmission 24. The electric machines 22 may be capable of operating as a motor or as a generator. Furthermore, the hybrid transmission 24 is mechanically connected to an internal combustion engine 26. The hybrid transmission 24 is also mechanically connected to a drive shaft 28, which is mechanically connected to the wheels 30.

[0017] The electric machines 22 can provide propulsion and deceleration capability when the internal combustion engine 26 is turned on or off using energy stored in the battery pack 14, such as via the BEC 18. The electric machines 22 also function as generators and can provide fuel economy benefits by recovering energy that would normally be lost as heat in the friction braking system. The electric machines 22 can also provide reduced pollutant emissions because the vehicle 12 can operate in electric mode under certain conditions.

[0018] The battery pack 14 typically provides a high-voltage direct current output. The BEC 18 of the battery pack 14 may be electrically connected to an inverter system controller (ISC) 32. The ISC 32 is electrically connected to the electric machines 22 and provides the capability for bidirectional transfer of power, such as via the BEC 18, between the battery pack 14 and the electric machines 22. In one example, the electric machines 22 and other components of the vehicle 12 that supply and / or receive power to and from the battery pack 14 may define a primary load 34 of the battery pack 14.

[0019] In a motor mode, the ISC 32 may convert the DC output provided by the battery pack 14 into a three-phase AC output, as may be required for proper functionality of the electric machines 22. In a regenerative mode, the ISC 32 may convert the three-phase AC output from the electric machines 22, which act as generators, into the DC voltage required by the battery pack 14. Although Fig. 1 illustrates a typical plug-in hybrid electric vehicle, the description herein is equally applicable to a pure electric vehicle. In a pure electric vehicle, e.g., a battery electric vehicle (BEV), the hybrid transmission 24 may be a transmission connected to the electric machines 22, and the internal combustion engine 26 may not be present. In one example, the main load 34 of the battery pack 14 in the BEV may include the electric machines 22 and the transmission.

[0020] In addition to providing power for propulsion capability, the battery pack 14 may provide power to other vehicle electrical systems (generally shown as auxiliary loads 36). For example, the battery pack 14 may transfer power to high-voltage loads 32, such as compressors and electric heaters. In another example, the battery pack 14 may provide power to low-voltage loads, such as a 12V battery. In such an example, the vehicle 12 may include a DC / DC converter module (not shown) that converts the high-voltage DC output of the battery pack 14 into a low-voltage DC supply compatible with the low-voltage loads. The various components discussed may have one or more associated controllers to control and monitor the operation of the components. The controllers may be connected via a serial bus (e.g.,Controller Area Network (CAN)) or via discrete conductors.

[0021] Now referring to Fig. 2A shows an exemplary arrangement 40 of the BEC 18 for transferring power to and from the main load 34. The arrangement 40 may include a main fuse 42 that protects the main load 34 from being exposed to excessive electrical current. The BEC 18 may include a positive main contactor 44 electrically connected to the positive terminal 20 of the battery pack 14 and a negative main contactor 46 electrically connected to the negative terminal 21 of the battery pack 14.

[0022] As in Fig. 2B, each of the positive and negative main contactors 44, 46 may define an electromechanical device 62 including an inductor 63 and a relay 64, wherein energizing the inductor 63 causes the relay 64 to close, and de-energizing the inductor 63 causes the relay 64 to open. In one example, a time delay may occur between a first time when the BEC 18 energizes terminals of the relay 64 and a second time when the relay 64 actually closes and connects the load to the source. The time delay may be, for example, between 10 ms and 50 ms, or another threshold.The amount of delay a given contactor will experience may be affected by one or more characteristics, such as, but not limited to, design and manufacturer specifications, manufacturing processes and materials, testing, contactor age and / or cycle counting, and so on.

[0023] With reference to Fig. 2A, the voltage across the positive main contactor 44 at the reference points V POS and V TOP 48, 50 and the voltage across the negative main contactor 46 at the reference points V NEG and V BOT52, 54 are measured. In one example, closing the positive and negative main contactors 44, 46 enables the flow of electrical energy to and from the battery cells of the battery pack 14. In such an example, the battery controller 16 may command the BEC 18 to open or close the main contactors 44, 46 in response to receiving a signal from the one or more vehicle controllers 38, e.g., ECM, TCM, and so forth, indicating a request to start or stop the transfer of electrical energy between the main load 34 and the battery pack 14.

[0024] The BEC 18 may further include a precharge circuit 56 configured to control a power supply process to the positive terminal 20. In one example, the precharge circuit 56 may include a precharge resistor 58 connected in series with a precharge contactor 60. The precharge circuit 56 may be electrically connected in parallel with the positive main contactor 44. When the precharge contactor 60 is closed, the positive main contactor 44 may be open and the negative main contactor 46 may be closed, allowing electrical energy to flow through the precharge circuit 56 and control a power supply process to the positive terminal 20.

[0025] In one example, the battery controller 16 may command the BEC 18 to close the positive main contactor 44 and open the precharge contactor 60 in response to sensing that the voltage across the positive and negative terminals 20, 21 has reached a predetermined threshold. The transfer of electrical energy between the main load 34 and the battery pack 14 may then proceed via the positive and negative main contactors 44, 46. For example, the BEC 18 may support the transfer of electrical energy between the battery pack 14 and the ISC 32 during either a motoring or a generator mode via a direct connection to conductors of the positive and negative main contactors 44, 46.

[0026] In Fig. 3, an exemplary graphical representation 66 of several commands issued by the battery controller 16 to the BEC 18 that operate the positive and negative main contactors 44, 46 and the precharge contactor 60 is shown. The graphic 66 has an x-axis 68 representing time measured in milliseconds and a y-axis 70 representing bus voltage measured in volts. The battery controller 16 may provide the BEC 18 with a time t 1 72, e.g. t 1 = 0ms, command the negative main contactor 46 to close and the BEC 18 at a time t 2 74, e.g. t 2 = 10 ms, to close the precharge contactor 60. In one example, the BEC 18 may cause the one or more contactors to close by energizing their respective induction coils.

[0027] The negative main contactor 46 can be switched on at a time t 3 76 close and the pre-charging contactor 60 can be closed at a time t 478. The battery controller 16 can determine that the bus voltage of V 1 , e.g. V 1 = 0V, at a time t 5 to V 2 at a time t 6 in response to the closing of both the negative main contactor 46 and the pre-charge contactor 60. The battery controller 16 may, in response to determining that the bus voltage has reached a predetermined threshold and / or at a time t 7 80 command the BEC 18 to close the positive main contactor 44. In one example, the battery controller 16 may command the BEC 18 to close the positive main contactor 44 a predetermined period of time after determining that the bus voltage has reached a predetermined threshold. The positive main contactor 44 may be closed at a time t 8 82. The battery controller 16 can determine that the bus voltage of V 3 to V 4 , where |V4 - V 3 | = δV, in response to the closing of the positive main contactor 44.

[0028] In another example, the battery controller 16 may enable power transfer to high-voltage loads, such as compressors and electric heaters, via a direct connection to the positive and negative main contactors 44, 46. In yet another example, the battery controller 16 may command power transfer to low-voltage loads, such as a 12V auxiliary battery, via a DC / DC converter (not shown) connected to the positive and negative main contactors 44, 46.

[0029] Now referring to Fig. 4 shows an exemplary arrangement 84 of the BEC 18 for transferring energy between the main load 34 and the battery pack 14 and between the auxiliary loads 36 and the battery pack 14. In addition to the exemplary arrangement 40 of Fig. 2A, the assembly 84 may include an auxiliary fuse 86 that protects the auxiliary loads 36 from being exposed to excessive electrical current. The BEC 18 may further include an auxiliary contactor 88 electrically connected to the negative terminal 21 of the battery pack 14. In one example, the auxiliary contactor 88 may include the electromechanical device 62 previously described with respect to Fig. 2B was described.

[0030] The voltage across the auxiliary contactor 88 can be measured at the reference points V AUx and V BOT90, 54 are measured. In one example, closing the positive and negative auxiliary contactors 44, 88 enables the flow of electrical energy between the auxiliary loads 36 and the battery pack 14. In such an example, the battery controller 16 may command the BEC 18 to open or close the auxiliary contactor 88 in response to receiving a signal from the one or more vehicle controllers 38, e.g., ECM, TCM, and so forth, indicating a request to start or stop the transfer of electrical energy between the main loads 36 and the battery pack 14.

[0031] As previously mentioned regarding Fig. 2B, a time delay may occur between a first time when the battery controller 16 commands the BEC 18 to close the conductor, e.g., by energizing an induction coil of the contactor, and a second time when the conductor actually closes and connects the load to the source. The extent of the delay associated with a given contactor may be influenced by one or more characteristics, such as, but not limited to, design and manufacturer specifications, manufacturing processes and materials, testing, age of the contactor and / or cycle count, and so forth. Furthermore, in a high-voltage system including multiple high-voltage buses connecting multiple electrical loads, such as the assembly 84 of Fig. 4, energize, time delays vary among the multiple contactors due to varying cycle counts and other variables.

[0032] In Fig. 5, an exemplary graphical representation 92 of several commands issued by the battery controller 16 to the BEC 18 is shown, which actuate the negative main and auxiliary contactors 46, 88 and the pre-charge contactor 60. The graphic 92 has an x-axis 94 representing time measured in milliseconds and a y-axis 96 representing bus voltage measured in volts. The battery controller 16 may, at a time t 9 98, e.g. t 9 = 0ms, command the negative main and auxiliary contactors 46, 88 to close and the BEC 18 at a time t 10 100, e.g. t 10 = 10 ms, to close the precharge contactor 60. In one example, the BEC 18 may cause the one or more contactors to close by energizing their respective induction coils.

[0033] The negative main contactor 46 can be switched on at a time t 11102 close and the pre-charging contactor 60 can at a time t 12 104. The battery controller 16 can determine that the bus voltage of V 1 at a time t 13 in response to the closing of both the negative main contactor 46 and the precharge contactor 60. In one example, the auxiliary contactor 88 may be closed at a time t 14 106 or a predetermined period of time after the bus voltage has started to decrease from V 1 Thus, the bus voltage can reach a predetermined threshold V 3 have been reached when the auxiliary contactor 88 is switched on at a time t 14 106 has closed.

[0034] With reference to Fig. 6A and Fig. 6B, a diagnostic method 108 for performing multiple high-voltage bus system fault detection is shown. The method 108 may begin at block 110, where the battery controller 16 receives a signal indicating a request to close the negative main and auxiliary contactors 46, 88. In one example, the battery controller 16 may receive a request to close the negative main and auxiliary contactors 46, 88 from the one or more vehicle controllers 38 in response to a request to start the vehicle 12.

[0035] At block 112, the battery controller 16 determines whether the negative main contactor 46 is open. In one example, the battery controller 16 determines whether the negative main contactor 46 is open by determining whether an absolute value of a difference between the reference points V NEG and V BOT52, 54 is less than a predetermined threshold value, e.g., 20 V. The battery controller 16 determines at block 114 whether a lapsed time t 1VERGANGEN longer than a predetermined period of time in response to determining at block 112 that the negative main contactor 46 is closed, e.g., a difference (or an absolute value of a difference) between the reference points V NEG and V BOT 52, 54 is greater than a predetermined threshold.

[0036] In an example, a past time t 1VERGANGENa period of time that has elapsed since the battery controller 16 received a signal at block 110 indicating a request to close the negative main and auxiliary contactors 46, 88. In another example, the battery controller 16 may set a predetermined period of time using one or more factors that affect the opening time of the negative main contactor 46, such as, but not limited to, design and manufacturer specifications, manufacturing processes and materials, contactor life test results, expected opening period for a given age, and / or cycle count of the contactor. The battery controller 16 may proceed to block 112 in response to determining at block 114 that an elapsed time t 1VERGANGEN shorter than a predetermined period.

[0037] The battery controller 16 reports an error at block 116 in response to determining at block 114 that a lapsed time t 1VERGANGEN longer than a predetermined period of time. In one example, the battery controller 16 may transmit to the one or more vehicle controllers 38 a signal indicating a diagnostic fault detected at the negative main contactor 46. In another example, the battery controller 16 and / or the one or more vehicle controllers 38 may set a diagnostic trouble code (DTC) indicating a negative main contactor fault. The one or more vehicle controllers 38 may further display an indication to a user of the vehicle 12 that a contactor fault has been detected. The battery controller 16 may then exit method 108 and prevent the pre-charge from starting.

[0038] At block 118, the battery controller 16 determines whether the auxiliary contactor 88 is open in response to determining at block 112 that the negative main contactor 46 is open. In one example, the battery controller 16 determines whether the auxiliary contactor 88 is open by determining whether a difference (or an absolute value of a difference) between the reference points V AUx and V BOT 90, 54 is less than a predetermined threshold value, e.g., 20 V. The battery controller 16 determines at block 120 whether a lapsed time t 2VERGANGEN longer than a predetermined period of time, in response to determining at block 118 that the auxiliary contactor 88 is closed, e.g., a difference between the reference points V AUx and V BOT 90, 54 is greater than a predetermined threshold.

[0039] In an example, a past time t 2VERGANGENa period of time that has elapsed since the battery controller 16 received a signal at block 110 indicating a request to close the negative main and auxiliary contactors 46, 88. In another example, the battery controller 16 may set a predetermined period of time using one or more factors that affect the opening period of the auxiliary contactor 88, such as, but not limited to, design and manufacturer specifications, manufacturing processes and materials, contactor life test results, expected opening period for a given age, and / or cycle count of the contactor. The battery controller 16 may proceed to block 118 in response to determining at block 120 that an elapsed time t 2VERGANGEN shorter than a predetermined period.

[0040] The battery controller 16 reports an error at block 122 in response to determining at block 120 that a lapsed time t 2VERGANGEN longer than a predetermined period of time. In one example, the battery controller 16 may transmit to the one or more vehicle controllers 38 a signal indicating a diagnostic fault detected at the auxiliary contactor 88. In another example, the battery controller 16 and / or the one or more vehicle controllers 38 may set a DTC indicating an auxiliary contactor fault. The one or more vehicle controllers 38 may further display an indication to a user of the vehicle 12 that a contactor fault has been detected. The battery controller 16 may then exit method 108 and prevent the pre-charge from starting.

[0041] At block 124, the battery controller 16 transmits a signal to the BEC 18 instructing the negative main and auxiliary contactors 46, 88 to close in response to determining at block 118 that the auxiliary contactor 88 is open, e.g., a difference between the reference points V AUx and V BOT 90, 54 is less than a predetermined threshold. The battery controller 16 at block 126 determines whether the negative main contactor 46 is closed. In one example, the battery controller 16 determines whether the negative main contactor 46 is closed by determining whether a difference (or an absolute value of a difference) between the reference points V NEG and V BOT 52, 54 is greater than a predetermined threshold value, e.g., 20 V. The battery controller 16 determines at block 128 whether a elapsed time t 3VERGANGENlonger than a predetermined period of time, in response to determining at block 126 that the negative main contactor 46 is open, e.g., a difference between the reference points V NEG and V BOT 52, 54 is less than a predetermined threshold.

[0042] In an example, a past time t 3VERGANGENa period of time that has elapsed since the battery controller 16 transmitted a signal at block 124 indicating a request to close the negative main and auxiliary contactors 46, 88. In another example, the battery controller 16 may set a predetermined period of time using one or more factors that affect the closing time of the negative main contactor 46, such as, but not limited to, design and manufacturer specifications, manufacturing processes and materials, contactor life test results, expected open period for a given age, and / or cycle count of the contactor. The battery controller 16 may return to block 126 in response to determining at block 128 that an elapsed time t 3VERGANGEN shorter than a predetermined period.

[0043] The battery controller 16 reports an error at block 130 in response to determining at block 128 that a lapsed time t 3VERGANGEN longer than a predetermined period of time. In one example, the battery controller 16 may transmit to the one or more vehicle controllers 38 a signal indicating a diagnostic fault detected at the negative main contactor 46. In another example, the battery controller 16 and / or the one or more vehicle controllers 38 may set a DTC indicating a negative main contactor fault. The one or more vehicle controllers 38 may further display an indication to a user of the vehicle 12 that a contactor fault has been detected. The battery controller 16 may then exit method 108 and prevent the pre-charge from starting.

[0044] At block 132, the battery controller 16 determines whether the auxiliary contactor 88 is closed in response to determining at block 126 that the negative main contactor 46 is closed. In one example, the battery controller 16 determines whether the auxiliary contactor 88 is closed by determining whether a difference (or an absolute value of a difference) between the reference points V AUx and V BOT 90, 54 is greater than a predetermined threshold, e.g., 20 V. The battery controller 16 determines at block 134 whether a lapsed time t 4VERGANGEN longer than a predetermined period of time, in response to determining at block 132 that the auxiliary contactor 88 is open, e.g., a difference between the reference points V AUx and V BOT 90, 54 is less than a predetermined threshold.

[0045] In an example, a past time t 4VERGANGENa period of time that has elapsed since the battery controller 16 transmitted a signal at block 124 indicating a request to close the negative main and auxiliary contactors 46, 88. In another example, the battery controller 16 may set a predetermined period of time using one or more factors that affect the closing time of the auxiliary contactor 88, such as, but not limited to, design and manufacturer specifications, manufacturing processes and materials, contactor life test results, expected open period for a given age, and / or cycle count of the contactor. The battery controller 16 may proceed to block 132 in response to determining at block 134 that an elapsed time t 4VERGANGEN shorter than a predetermined period.

[0046] The battery controller 16 reports an error at block 136 in response to determining at block 134 that a lapsed time t 4VERGANGEN longer than a predetermined period of time. In one example, the battery controller 16 may transmit to the one or more vehicle controllers 38 a signal indicating a diagnostic fault detected at the auxiliary contactor 88. In another example, the battery controller 16 and / or the one or more vehicle controllers 38 may set a DTC indicating an auxiliary contactor fault. The one or more vehicle controllers 38 may further display an indication to a user of the vehicle 12 that a contactor fault has been detected. The battery controller 16 may then exit method 108 and prevent the pre-charge from starting.

[0047] At block 138, the battery controller 16 transmits a signal to the BEC 18 instructing the precharge contactor 60 to close in response to determining at block 132 that the auxiliary contactor 88 is closed, e.g., a difference between the reference points V AUx and V BOT 90, 54 is greater than a predetermined threshold. At this point, the method 108 may end. In one example, the method 108 may be repeated in response to receiving a signal indicating a request to close the negative main and auxiliary contactors 46, 88 or in response to another notification or request. The method 108 provides that each of the elapsed times t 1VERGANGEN , t 2VERGANGEN , t 3VERGANGEN and t 4VERGANGENmay be different or the same as the rest. Similarly, method 108 provides that a predetermined period of time necessary for a relay of a given contactor to open may be different or the same as a predetermined period of time necessary for the relay to close.

[0048] The battery controller 16 may transmit a signal to the BEC 18 indicating a command to close the positive main contactor 44 a predetermined period of time after commanding the BEC 18 to close the pre-charge contactor 60. In yet another example, the battery controller 16 may transmit a signal to the BEC 18 indicating a command to close the positive main contactor 44 a predetermined period of time after determining that the pre-charge contactor 60 is closed.

[0049] The processes, methods, or algorithms disclosed herein may be deliverable to or implemented by a processing device, controller, or computer, which may include any existing programmable electronic control unit or dedicated electronic control unit. Likewise, the processes, methods, or algorithms may be stored as data and instructions executable by a controller or computer in many forms, including, but not limited to, information permanently stored on non-writable storage media, such as read-only memory devices, and information modifiably stored on writable storage media, such as floppy disks, magnetic tapes, compact discs, RAM devices, and other magnetic and optical media. The processes, methods, or algorithms may also be implemented in a software-executable object.Alternatively, the processes, methods, or algorithms may be implemented in whole or in part using suitable hardware components, such as application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), state machines, controllers, or other hardware components or devices, or a combination of hardware, software, and firmware components.

[0050] The terms used in the specification are for the purpose of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the disclosure. As previously described, the features of various embodiments may be combined to form other embodiments of the invention that may not be explicitly described or illustrated. However, while various embodiments have been described as providing advantages or being preferred with respect to one or more desired characteristics over other prior art embodiments or implementations, it will be apparent to one of ordinary skill in the art that trade-offs may be made between one or more characteristics or features to achieve the desired overall system characteristics, depending on the particular application and implementation.These features may include, but are not limited to, cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, maintainability, weight, manufacturability, ease of assembly, etc. Thus, embodiments described as less desirable than other embodiments or prior art implementations with respect to one or more characteristics are not outside the scope of the disclosure and may be desirable for certain applications. Key to symbols

[0051] Fig. 2A PRC CON pre-charging contactor PRC RES precharge resistor Battery Terminals Battery terminals Main Fuse Main Load Main Consumer MC + Positive main contactor MC - Negative main contactor

[0052] Fig. 2B Source Source Load consumer Coil coil

[0053] Fig. 3 Bus Voltage (V) Bus Voltage (V) Time (ms) Time (ms) MC - Closed Negative main contactor closed PRC Closed Pre-charging contactor closed MC + Closed Positive main contactor closed CMD MC - Command to negative main contactor CMD PRC command to pre-charging contactor CMD MC + command to positive main contactor

[0054] Fig. 4 Aux Fuse auxiliary fuse Aux Loads auxiliary loads PRC CON pre-charging contactor PRC RES precharge resistor Main Fuse Main contactor Main Load Main Consumer Aux - Auxiliary contactor - MC + Positive main contactor MC - Negative main contactor

[0055] Fig. 5 Bus Voltage (V) Bus Voltage (V) MC Closed Main contactor closed PRC Closed Pre-charging contactor closed AUX closed Auxiliary contactor closed Time (ms) Time (ms) CMD AUX, MC - Command to auxiliary contactor and negative main contactor CMD PRC command to pre-charging contactor

Claims

[1] Vehicle bus system (18) comprising: first and second contactors configured to share a first terminal (20) of a battery (14), wherein the first contactor (44) is configured to energize a first load (34) when closed, and the second contactor (46) is configured to energize a second load (36) when closed, and a controller (16) programmed to, after issuing a command to close the first and second contactors (44, 46), precharge a second terminal (21) of the battery (14) in response to a first voltage across the first contactor (44) exceeding a first threshold in the closed state, and upon a second voltage across the second contactor (46) exceeding a second closed state threshold, to initiate and generate a notification and prevent initiation of the precharge in response to at least one of the first and second voltages being lower than the corresponding first and second closed state thresholds. [2] The system (18) of claim 1, wherein the controller (16) is further programmed to generate the notification and prevent the start of the precharge in response to one of the first and second voltages exceeding a respective first or second threshold in the open state prior to issuing the command to close the first and second contactors (44, 46). [3] The system (18) of claim 2, wherein the controller (16) is further programmed to generate the notification and prevent the start of the precharge in response to one of the first and second voltages exceeding the respective first or second threshold in the open state for a period of time longer than respective first and second open delays defining the first and second contactor ages, the first and second cycle counts of the first and second contactors (44, 46), or the age of the battery (14). [4] The system (18) of claim 3, wherein the respective first and second opening delays defining the first and second contactor ages, the first and second cycle counts, or the age of the battery (14) are the same. [5] The system (18) of claim 1, wherein the controller (16) is further programmed to generate a notification and prevent the start of the precharge in response to one of the first and second voltages being lower than the corresponding first or second closed state threshold for a period of time longer than respective first and second closing delays after issuing the command to close the first and second contactors (44, 46). [6] The system (18) of claim 5, wherein the controller (16) is further programmed to modify the respective first and second closing delays defining the first and second contactor ages, the cycle count, or the age of the battery (14). [7] The system (18) of claim 5, wherein the respective first and second closing delays associated with the first and second contactors (44, 46) are the same. [8] Procedure comprising: after issuing a command by a controller (16) to close first and second contactors (44, 46) which are arranged to share a first terminal (20) of a battery (14) and are each configured to energize a load (34) when closed, starting a pre-charge of a second terminal (21) in response to voltages across the contactors (44, 46) being higher than corresponding threshold values ​​in the closed state, and generating a notification and preventing a start of the pre-charge in response to one of the voltages being lower than the corresponding threshold value in the closed state. [9] The method of claim 8, further comprising generating the notification by the controller (16) and preventing the start of the precharge in response to one of the voltages being higher than a threshold in the open state prior to issuing the command to close the contactors (44, 46). [10] The method of claim 9, further comprising generating the notification by the controller (16) and preventing the start of the pre-charge in response to one of the voltages being higher than the threshold in the open state for a period of time longer than respective open delays defining the respective first and second contactor ages, the first and second cycle counts of the first and second contactors (44, 46), or the age of the battery (14). [11] The method of claim 10, wherein the respective opening delays defining the first and second contactor ages, the first and second cycle counts, or the age of the battery (14) are the same. [12] The method of claim 8, further comprising generating the notification by the controller (16) and preventing the start of the precharge in response to one of the voltages being lower than the corresponding closed state threshold for a period of time longer than respective closing delays after issuing the command to close the first and second contactors (44, 46). [13] The method of claim 12, further comprising modifying, by the controller (16), the respective closing delays defining a first and second contactor age, first and second cycle counts of the first and second contactors (44, 46), or an age of the battery (14). [14] The method of claim 12, wherein the closing delays of the first and second contactors (44, 46) are the same. [15] Vehicle bus control (16) comprising: Input channels configured to receive first and second signals indicative of first and second voltages across first and second contactors (44, 46), the first and second voltages configured to share a first terminal (20) of a traction battery (14), and the first and second contactors (44, 46) configured to energize a load (34) when closed; Output channels configured to provide a command to close the first and second contactor (44, 46), provide a command to start a pre-charge of a second terminal (21) of the traction battery (14) and provide a notification; and control logic configured, after issuing the command to close the first and second contactors (44, 46), to generate the command to start a pre-charge of the second terminal (21) in response to the first and second voltages being higher than corresponding first and second threshold values ​​in the closed state, and to generate the notification in response to one of the first and second voltages being lower than the corresponding first or second threshold value in the closed state for a period of time longer than a corresponding first or second closing delay associated with the first and second contactors (44, 46), respectively. [16] The controller (16) of claim 15, wherein the first and second closing delays are the same. [17] The controller (16) of claim 15, wherein the control logic is further configured to generate the notification and prevent the start of the precharge in response to one of the first and second voltages exceeding a first or second threshold in the open state for a period of time longer than a corresponding first or second opening delay of the first or second contactor (44, 46) prior to issuing the command to close the first and second contactors (44, 46).

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