Electrified Vehicle Powertrain Monitoring Systems

Abstract

A control system for a vehicle includes a controller. The controller is configured to open a traction battery contactor based on an electrical potential between a high voltage cable and a chassis continuously exceeding a magnitude threshold for at least a predefined duration. The controller is further configured to selectively open the contactor based on data obtained from the electrical potential during time periods, each of which is defined by the time that the electrical potential exceeds and then falls below the magnitude threshold, not exceeding the predefined duration.

Description

Technical Field

[0001] The present application generally relates to a monitoring system for an electrified vehicle powertrain having an isolated high voltage system configured to detect intermittent ground faults. Background Art

[0002] Electrified vehicles (EVs), including hybrid electric vehicles (HEVs) and battery electric vehicles (BEVs), rely on traction batteries to provide power to traction motors for propulsion, and rely on power inverters between them to convert direct current (DC) power to alternating current (AC) power. A typical AC traction motor is a three-phase motor that can be powered by 3 sinusoidal signals, each driven with 120 degrees of phase separation. The traction battery is configured to operate and provide current within a specific voltage range. However, by operating within a different voltage range, typically at a voltage greater than the traction battery terminal voltage, improvements in motor performance can be achieved. Similarly, the current requirements for driving the vehicle motor are often referred to as high current. The traction battery may alternatively be referred to as a high voltage battery, and the components of the electric drive (e.g., traction motors, inverters, converters, batteries, converters, etc.) are referred to as high voltage electrical systems or high voltage powertrains. Along with the high voltage electrical system is a low voltage electrical system, which typically operates at a nominal voltage of 12V. The low voltage electrical system provides power for many vehicle systems such as radios, navigation systems, vehicle controllers, and the like. Low voltage electrical systems typically use conductors for the positive low voltage and the vehicle chassis to carry the negative low voltage, while high voltage electrical systems have dedicated conductors for carrying both positive and negative high voltages. Summary of the invention

[0003] A control system for a vehicle includes a controller. The controller is configured to open a traction battery contactor based on an electrical potential between a high voltage cable and a chassis continuously exceeding a magnitude threshold for at least a predefined duration. The controller is further configured to selectively open the contactor based on data obtained from the electrical potential during time periods, each of which is defined by the time that the electrical potential exceeds and then falls below the magnitude threshold, not exceeding the predefined duration.

[0004] A vehicle fault detection method includes opening a traction battery contactor in response to an electrical potential between a high voltage cable and a chassis continuously exceeding a magnitude threshold for at least a predefined duration. The method also includes selectively opening the contactor in response to data obtained from the electrical potential during time periods, each defined by the time the electrical potential exceeds and then falls below the magnitude threshold, not exceeding the predefined duration.

[0005] The vehicle includes a contactor and a controller. The contactor couples a traction battery to an electric machine via a high voltage cable. The controller is configured to selectively open the contactor in response to the vehicle being stopped and frequency domain data obtained from a detected potential between the high voltage cable and the chassis during time periods each defined by the time the potential exceeds and then falls below a magnitude threshold, not exceeding a predefined duration. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 is an illustration of an electrified vehicle having an intermittent ground / isolation fault detection monitoring system.

[0007] Figure 2 is a diagram of a hybrid vehicle showing a typical powertrain including a variable voltage variable frequency converter and energy storage components.

[0008] Figure 3 is a flow chart of an intermittent ground / isolation fault detection monitoring system.

[0009] Figure 4 is a schematic diagram of a ground / isolation fault detection system.

[0010] Figure 5 is a schematic diagram of a leakage detection system for grounding / isolation fault detection. DETAILED DESCRIPTION

[0011] Embodiments of the present disclosure are described herein. However, it should be understood that the disclosed embodiments are merely examples, and other embodiments may take various forms and alternative forms. The drawings are not necessarily drawn to scale; some features may be exaggerated or minimized to show the details of specific components. Therefore, the specific structural details and functional details disclosed herein should not be interpreted as being restrictive, but merely as a representative basis for teaching those skilled in the art to adopt the present invention in different ways. As will be understood by those of ordinary skill in the art, the various features shown and described with reference to any one of the accompanying drawings may be combined with the features shown in one or more other drawings to produce embodiments that are not explicitly shown or described. The combination of features shown provides representative embodiments for typical applications. However, various combinations and modifications of features consistent with the teachings of the present disclosure may be desired for specific applications or implementations.

[0012] Electrified vehicles typically have both high-voltage subsystems and low-voltage systems. The high-voltage subsystem may include a traction battery, a DC-DC converter, a DC-AC inverter, and a motor. The low-voltage system may include: a low voltage (auxiliary battery or 12-volt battery); an engine starter; vehicle accessories such as power seats, power windows, power doors, power locks, and window defrosters; and vehicle control modules and subsystems, including anti-lock brakes, airbags, safety systems, adaptive steering systems, adaptive cruise control, radiator fans, distributors, in-vehicle entertainment systems, telecommunications units, instrument clusters, vehicle displays, and other low-voltage components. In most vehicle implementations, the low-voltage system is not isolated from the chassis because the chassis is used as a return path for the current. This is achieved by isolating the positive voltage using insulators such as insulated wires and cables while shorting the negative terminal of the battery with the vehicle chassis. This uses the chassis as a return path, thereby reducing the need for insulated wires and cables for all negative voltages. However, in most hybrid or electric vehicle implementations, the high-voltage system is electrically isolated because the chassis is not used to short both the negative and positive voltages. The high voltage system is configured so that both the negative terminal and the positive terminal are isolated, typically using both an insulated negative cable and an insulated positive cable. For this reason, the high voltage subsystem is referred to as being in high impedance or ungrounded (floating) relative to the chassis (or ground). For this reason, the potential of the negative or positive wire or cable can be significantly greater or less than the vehicle chassis or ground. To prevent accidental discharge, electric / hybrid drive vehicles use an insulation monitoring system or ground fault detection system to check and monitor the integrity of the high voltage (HV) system (including the insulation of wires, cables, and components).

[0013] Insulation monitoring systems, also known as ground / isolation fault detection systems, typically monitor leakage current through the system and convert the leakage into a signal (e.g., a signal indicating a voltage read by a controller) to determine whether a ground fault exists. Conventional ground / chassis fault detection systems work well for solid ground faults (i.e., the ground fault is continuous). However, in some applications, such as vehicles subject to harsh environments (i.e., vibration / shake, temperature changes, salt / water spray, debris, cable wiring and components, etc.), HV cables, busbar insulation, and other components may be damaged so that specific points / areas may not have a firm / consistent contact with the chassis. This intermittent contact with the chassis can cause the controller to be configured to ignore intermittent short circuits as noise. Here, intermittent ground faults are stored and analyzed to detect patterns that match vehicle operation. The patterns can indicate faults that may not be detected by traditional methods and systems, and can be used to capture potential faults before any major problems occur.

[0014] Examples of analysis include converting a time domain signal to a frequency domain signal so that events occurring at frequencies generally corresponding to the speed of the vehicle, harmonics of the vehicle speed, the speed of an internal combustion engine (ICE), harmonics of the ICE speed, or the speed of an electric machine can indicate a fault associated with the operation of the vehicle. One way to convert a time domain signal to a frequency domain signal is to perform a Fourier transform on the time domain signal. Another way is to perform a bandpass filter or filter bank. Additionally, the system can be configured to adjust the sampling time to correspond to the frequency of interest.

[0015] Figure 1A vehicle having a high voltage system configured to detect intermittent faults is shown. Here, the controller is configured to detect intermittent ground / chassis faults by receiving intermittent ground / chassis fault data in step 2. The data may be a continuous signal, such as an amplitude signal continuously received by the controller. The controller may be configured with a comparator so that if the amplitude exceeds an amplitude threshold, a record is generated. The record may include a peak amplitude and a pulse duration. If the pulse duration exceeds the pulse threshold, the system may output a ground / chassis fault. Based on the ground / chassis fault, the high voltage switch may be disengaged, thereby disconnecting the traction battery from other high voltage components. However, if the pulse is less than the pulse duration, a characteristic is stored by the controller in step 4. The characteristic includes the speed of the vehicle, the speed of the internal combustion engine (ICE), the speed of the motor, the amplitude of the fault signal, the waveform of the fault signal, the integral of the fault signal, and the operating mode of the vehicle. The characteristic stored in box 4 is analyzed by the controller in step 6. The controller may determine the response (e.g., frequency response or harmonics) of the vehicle speed, the speed of the ICE, the fault signal, or the vehicle motion based on the characteristic. This includes comparing the characteristic (e.g., the fault signature) with a predetermined pattern as shown in box 10. The vehicle motion frequency response is the frequency response of the vehicle traveling along the roadway. For example, the vehicle motion frequency response may be caused by tire imbalance, periodic humps or potholes in the roadway, etc. The vehicle motion frequency response may be based on signals from modules such as an electronic stability control module or an active suspension control module. The above frequency response is analyzed to determine whether movements such as periodic vibrations or sudden jolts correspond to intermittent chassis faults. Together with the frequency response, the operating mode of the vehicle may also be used to calculate fault characteristics such as the fault frequency as shown in box 8. Then, the controller will operate the vehicle based on the comparison of boxes 8 and 10 as shown in box 12. The operation of the vehicle described in box 12 includes opening the contactor to disable the high voltage system so that the traction battery is disconnected from other high voltage components. The operation also includes starting the internal combustion engine (ICE) to convert the vehicle propulsion power from the motor to the ICE. The operation may also include maintaining the contactor in a closed position so that the battery still powers the high voltage system, and also starting the ICE so that the system is in a ready state, thereby transitioning from being propelled by the motor to being propelled by the ICE.

[0016] Figure 2An electrified vehicle 112 that may be referred to as a plug-in hybrid electric vehicle (PHEV) is shown. The plug-in hybrid electric vehicle 112 may include one or more motors 114 mechanically coupled to a hybrid transmission 116. The motor 114 may be capable of operating as a motor or a generator. In addition, the hybrid transmission 116 is mechanically coupled to an engine 118. The hybrid transmission 116 is also mechanically coupled to a drive shaft 120, which is mechanically coupled to wheels 122. When the engine 118 is turned on or off, the motor 114 can provide propulsion and deceleration capabilities. The motor 114 can also act as a generator and can provide fuel economy benefits by recovering energy that is usually lost as heat in a friction braking system. The motor 114 can also reduce vehicle emissions by allowing the engine 118 to operate at a more efficient speed and allowing the hybrid electric vehicle 112 to operate in an electric mode while the engine 118 is shut down under certain conditions. The electrified vehicle 112 may also be a battery electric vehicle (BEV). In a BEV configuration, the engine 118 may not exist. In other configurations, the electrified vehicle 112 may be a full hybrid electric vehicle (FHEV) without plug-in capability.

[0017] The traction battery or battery pack 124 stores energy that can be used by the motor 114. The vehicle battery pack 124 can provide a high voltage direct current (DC) output. The traction battery 124 can be electrically coupled to one or more power electronics modules 126. One or more contactors 142 can isolate the traction battery 124 from other components when open, and connect the traction battery 124 to other components when closed. The power electronics module 126 is also electrically coupled to the motor 114 and provides the ability to transfer energy bidirectionally between the traction battery 124 and the motor 114. For example, the traction battery 124 can provide a DC voltage, and the motor 114 can function with three-phase alternating current (AC) operation. The power electronics module 126 can convert the DC voltage into a three-phase AC current to operate the motor 114. In the regenerative mode, the power electronics module 126 can convert the three-phase AC current from the motor 114 acting as a generator into a DC voltage compatible with the traction battery 124.

[0018] The vehicle 112 may include a variable voltage converter (VVC) 152 electrically coupled between the traction battery 124 and the power electronics module 126. The VVC 152 may be a DC / DC boost converter configured to increase or step up the voltage provided by the traction battery 124. By increasing the voltage, current requirements may be reduced, resulting in a reduction in wiring size for the power electronics module 126 and the motor 114. Additionally, the motor 114 may operate with better efficiency and lower losses.

[0019] In addition to providing energy for propulsion, the traction battery 124 can also provide energy for other vehicle electrical systems. The vehicle 112 may include a DC / DC converter module 128 that converts the high voltage DC output of the traction battery 124 into a low voltage DC power source compatible with low voltage vehicle loads. The output of the DC / DC converter module 128 may be electrically coupled to an auxiliary battery 130 (e.g., a 12V battery) to charge the auxiliary battery 130. The low voltage system may be electrically coupled to the auxiliary battery 130. One or more electrical loads 146 may be coupled to the high voltage bus. The electrical load 146 may have an associated controller that operates and controls the electrical load 146 as needed. Examples of the electrical load 146 may be a fan, an electric heating element, and / or an air conditioning compressor.

[0020] The electrified vehicle 112 may be configured to recharge the traction battery 124 from an external power source 136. The external power source 136 may be a connection to an electrical outlet. The external power source 136 may be electrically coupled to a charger or electric vehicle supply equipment (EVSE) 138. The external power source 136 may be a distribution network or grid provided by an electric utility company. The EVSE 138 may provide circuitry and controls to regulate and manage energy transfer between the power source 136 and the vehicle 112. The external power source 136 may provide DC or AC power to the EVSE 138. The EVSE 138 may have a charging connector 140 for plugging into a charging port 134 of the vehicle 112. The charging port 134 may be any type of port configured to transfer power from the EVSE 138 to the vehicle 112. The charging port 134 may be electrically coupled to a charger or an onboard power conversion module 132. The power conversion module 132 may regulate the power supplied from the EVSE 138 to provide the appropriate voltage and current levels to the traction battery 124. The power conversion module 132 may interface with the EVSE 138 to coordinate the transfer of power to the vehicle 112. The EVSE connector 140 may have pins that mate with corresponding recesses of the charging port 134. Alternatively, the various components described as being electrically coupled or connected may transfer power using wireless inductive coupling.

[0021] One or more wheel brakes 144 may be provided for decelerating the vehicle 112 and preventing the movement of the vehicle 112. The wheel brakes 144 may be hydraulically actuated, electrically actuated, or some combination thereof. The wheel brakes 144 may be part of a braking system 150. The braking system 150 may include other components for operating the wheel brakes 144. For simplicity, the figure shows a single connection between the braking system 150 and one of the wheel brakes 144. Connections between the braking system 150 and other wheel brakes 144 are implied. The braking system 150 may include a controller for monitoring and coordinating the braking system 150. The braking system 150 may monitor the braking components and control the wheel brakes 144 to achieve vehicle deceleration. The braking system 150 may respond to driver commands and may also operate autonomously to achieve features such as stability control. The controller of the braking system 150 may implement a method that applies the requested braking force when requested by another controller or sub-function.

[0022] The electronic modules in the vehicle 112 can communicate via one or more vehicle networks. The vehicle network can include multiple channels for communication. One channel of the vehicle network can be a serial bus, such as a controller area network (CAN). One of the channels of the vehicle network can include an Ethernet network defined by the Institute of Electrical and Electronics Engineers (IEEE) 802 series of standards. Additional channels of the vehicle network can include discrete connections between modules and can include power signals from the auxiliary battery 130. Different signals can be transmitted on different channels of the vehicle network. For example, a video signal can be transmitted on a high-speed channel (e.g., Ethernet), while control signals can be transmitted on the CAN or can be discrete signals. The vehicle network can include any hardware and software components that facilitate the transmission of signals and data between modules. The vehicle network is not in Figure 2 1, but it may be implied that the vehicle network may be connected to any electronic modules present in the vehicle 112. A vehicle system controller (VSC) 148 may be present to coordinate the operation of the various components.

[0023] Typically, the VVC 152 is configured as a boost converter. The VVC 152 may include an input terminal that may be coupled to a terminal of the traction battery 124 via a contactor 142. The VVC 152 may include an output terminal coupled to a terminal of the power electronics module 126. The VVC 152 may be operated so that a voltage at the output terminal is greater than a voltage at the input terminal. The vehicle 112 may include a VVC controller that monitors and controls electrical parameters (e.g., voltage and current) at various locations within the VVC 152. In some configurations, the VVC controller may be included as part of the VVC 152. The VVC controller may determine an output voltage reference value. The VVC controller can be based on electrical parameters and voltage reference values The VVC 152 is controlled by a control signal that is sufficient to cause the VVC 152 to achieve the desired output voltage. In some configurations, the control signal may be implemented as a pulse width modulation (PWM) signal, wherein the duty cycle of the PWM signal varies. The control signal may operate at a predetermined switching frequency. The VVC controller may use the control signal to command the VVC 152 to provide the desired output voltage. The specific control signal that operates the VVC 152 may be directly related to the amount of boost that the VVC 152 will provide.

[0024] refer to Figure 2 , the VVC 152 can boost or "step up" the voltage potential of the power provided by the traction battery 124. The traction battery 124 can provide high voltage (HV) DC power. In some configurations, the traction battery 124 can provide a voltage between 150 volts and 400 volts. The contactor 142 can be electrically coupled in series between the traction battery 124 and the VVC 152. When the contactor 142 is closed, the HV DC power can be transferred from the traction battery 124 to the VVC 152. The input capacitor can be electrically coupled in parallel with the traction battery 124. The input capacitor can reduce any voltage and current ripple. The VVC 152 can receive the HV DC power and boost or "step up" the voltage potential of the input voltage according to the duty cycle. Typically, the output capacitor is electrically coupled between the output terminal of the VVC 152 and the input of the power electronics module 126 to stabilize the bus voltage and reduce the voltage and current ripple at the output of the VVC 152.

[0025] Figure 3 300 is a flow chart of an intermittent ground fault detection monitoring system. Here, the controller is configured to detect intermittent ground / chassis faults by receiving intermittent ground / chassis fault data in step 302. The data can be a continuous signal, such as an amplitude signal continuously received by the controller. The controller can be configured with a comparator so that if the amplitude exceeds an amplitude threshold, a record is generated. The record can include a peak amplitude and a pulse duration. If the pulse duration exceeds the pulse threshold, the system can output a ground / chassis fault. In another embodiment, the fault detection signal can be sampling at least one voltage indicating a voltage difference between a vehicle chassis and a high voltage potential through an analog-to-digital (A / D) converter. The sampling rate can be adjusted based on characteristics in step 304, such as vehicle speed, rotational speed of a motor, or data from a suspension system.

[0026] Based on the detection of a ground / chassis fault (i.e., the voltage difference exceeds both the magnitude threshold and the duration period threshold), the high voltage switch may be disengaged, thereby disconnecting the traction battery from the other high voltage components. The predefined duration (e.g., duration period threshold) may generally be calculated because time is equal to 1 divided by frequency, or in other words, time=1 / frequency. For example, a motor rotating at 3000 revolutions per minute (RPM) may generate a pulse period of 20 ms (3000 RPM equals 50 revolutions per second, and 1 / 50=0.020). Thus, the predefined period may be set constant, or may vary as the rotational speed of the motor, wheels, or internal combustion engine changes. In another embodiment, if the vehicle is running when the ground / chassis / isolation fault is detected, the high voltage switch may not be opened immediately, but after the vehicle stops and if the fault is still detected, the controller will inhibit the vehicle from restarting.

[0027] Another indication of an intermittent ground fault is that the fault signal disappears completely but reappears after the car begins to run. However, if the pulse is less than the pulse duration, the characteristics are stored by the controller in step 306. The characteristics include the speed of the vehicle, the speed of the internal combustion engine (ICE), the speed of the motor, the amplitude of the fault signal, the waveform of the fault signal, the integral of the fault signal, and the operating mode of the vehicle. The characteristics stored in box 306 are analyzed by the controller in step 308. The analysis may include converting the time domain signal to a frequency domain signal. The conversion may include performing a Fourier transform, a fast Fourier transform (FFT), a bandpass filter, a filter bank, an average, a weighted average, or other digital signal processing (DSP) algorithm. The controller may determine the response (e.g., frequency response or harmonics) of the vehicle speed, the speed of the ICE, the fault signal, or the vehicle motion based on the characteristics. This includes comparing the characteristics (e.g., the fault signature) with a predetermined pattern as shown in box 310. The vehicle motion frequency response is the frequency response of the vehicle traveling along the roadway. For example, the vehicle motion frequency response may be due to tire imbalance, periodic humps or potholes in the roadway, etc. The vehicle motion frequency response may be based on signals from modules such as an electronic stability control module or an active suspension control module. The frequency response is analyzed to determine whether movements such as periodic vibrations or sudden jolts correspond to intermittent chassis faults. Along with the frequency response, the vehicle's operating mode may also be used to calculate fault characteristics such as fault frequencies as shown in box 312. The controller then operates the vehicle based on a comparison of boxes 310 and 312 as shown in box 314. The operation of the vehicle described in box 314 includes opening a contactor to disable the high voltage system so that the traction battery is disconnected from other high voltage components. The operation also includes starting an internal combustion engine (ICE) to convert vehicle propulsion power from the motor to the ICE. The operation may also include maintaining the contactor in a closed position so that the battery still powers the high voltage system, and also starting the ICE so that the system is in a ready state, thereby transitioning from being propelled by the motor to being propelled by the ICE.

[0028] Figure 44 is a schematic diagram of a ground fault detection system 400. Here, a power source 402, such as a battery, causes current to flow to a load 406 via a contactor 404. The current flows equally and oppositely via a current transformer 408 so that under a no-fault condition, the current flowing in each direction is equal and opposite, and a detection circuit 414 does not detect a fault. The circuit may have a test circuit including a resistor 410 and a momentary contact switch 412. When the momentary switch 412 is pressed, the test circuit is operated, and current bypasses the current transformer in one direction but not in the other direction, so that the currents are now unequal. The current differential of the detection circuit 414 is detected via the windings on the transformer. When a fault is detected, the circuit 414 opens the contactor 404.

[0029] Figure 5 5 is a schematic diagram of a chassis fault detection system 500. Here, a power source 502, such as a traction battery for a vehicle, is used to provide power to a load 522. In this system, both the negative voltage bus and the positive voltage bus are isolated and can "float" relative to a fixed potential such as a chassis ground or an earth ground. When the voltage buses are isolated, the voltage difference between the positive voltage bus or the negative voltage bus and the ground can be easily manipulated. Here, two contactors 504 and 506 are used to engage a string of series resistors 508, 510, 512, and 514. The resistor chain includes a connection to the chassis ground 516 so that the resistor divider is located above the chassis ground 516 and the resistor divider is located below the chassis ground 516. For the high-side resistor divider, resistor R1 508 and resistor R2 510 divide the voltage difference between the positive DC bus voltage and the chassis ground 516. If resistor R1 508 is much larger than resistor R2 510, the voltage across resistor R2 510 will be much smaller than the voltage across resistor R1 508. The voltage across resistor R2 510 can then be measured by a high-side voltmeter 518. Similarly, for the low-side resistor divider, resistor R3 512 and resistor R4 514 divide the voltage difference between the positive DC bus voltage and chassis ground 516. If resistor R4 514 is much larger than resistor R3 512, the voltage across resistor R3 512 will be much smaller than the voltage across resistor R4 514. The voltage across resistor R3 512 can then be measured by a low-side voltmeter 520. If the battery 502 is a high voltage (e.g., 200 V) and the high side resistor divider and the low side resistor divider divide the high voltage equally, it is still not practical to have a separate resistor divider to equally subdivide the voltage because the voltage between the chassis ground and the positive bus voltage will still be 100 V, and the voltmeter may then be required to measure up to 100 V. However, by making the external resistors (508 and 514) larger than the measurement resistors (510 and 512), large voltage excursions can be reduced.

[0030] Here, when a chassis fault occurs, the voltage offset between chassis ground and the positive and negative bus voltages changes. For example, if there is a chassis fault between the positive high voltage bus and the chassis, the voltage measured by voltmeter V1 518 will decrease and the voltage measured by voltmeter V2 520 will increase. When the chassis fault is removed, the series resistor chain will behave like a simple resistor divider so that if the high side resistor divider and the low side resistor divider are equal, the voltages measured by voltmeters V1 518 and V2 520 will return to being equal.

[0031] In one embodiment, the contactor is not immediately opened, but a flag is set so that when the vehicle is stopped or the vehicle is in an ignition-off state, if a fault is confirmed, the vehicle is prohibited from starting and a notification is output to the owner / operator (e.g., asking the driver to check the vehicle). Further based on the fault frequency characteristics, the location of the fault can be obtained. For example, a component mounted on the transmission may have a different fault frequency characteristic than a chassis mounted component or an ICE mounted component.

[0032] The control logic or function performed by the controller can be represented by a flowchart or similar diagram in one or more figures. These figures provide representative control strategies and / or logic, which can be implemented using one or more processing strategies such as event-driven, interrupt-driven, multi-tasking, multi-threading, etc. To this end, the various steps or functions shown can be performed in parallel in the sequence shown, or omitted in some cases. Although not always explicitly shown, it will be recognized by those of ordinary skill in the art that one or more of the steps or functions shown can be repeatedly performed according to the specific processing strategy used. Similarly, the processing sequence is not necessarily required to achieve the features and advantages described herein, but is provided for ease of illustration and description. The control logic can be implemented primarily in software executed by a microprocessor-based vehicle, engine and / or powertrain controller (such as a controller). Of course, depending on the specific application, the control logic can be implemented in software, hardware, or a combination of software and hardware in one or more controllers. When implemented in software, the control logic can be provided in one or more computer-readable storage devices or media, which have storage data representing codes or instructions executed by a computer to control a vehicle or its subsystems. The computer-readable storage device or medium may include one or more of several known physical devices that utilize electrical, magnetic, and / or optical storage to retain executable instructions and associated calibration information, operating variables, and the like.

[0033] The process, method or algorithm disclosed herein can be provided / implemented by a processing device, a controller or a computer, which can include any existing programmable electronic control unit or a dedicated electronic control unit. Similarly, the process, method or algorithm can be stored as data and instructions that can be executed by a controller or a computer in many forms, including but not limited to information permanently stored on non-writable storage media such as read-only memory (ROM) devices and information that can be modified and stored on writable storage media such as floppy disks, tapes, compact disks (CDs), random access memory (RAM) devices and other magnetic and optical media. The process, method or algorithm can also be implemented in a software executable object. Alternatively, the process, method or algorithm can 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 combinations of hardware, software and firmware components.

[0034] Although exemplary embodiments are described above, these embodiments are not intended to describe all possible forms covered by the claims. The words used in the specification are descriptive rather than limiting, and it should be understood that various changes can be made without departing from the spirit and scope of the present disclosure. As described above, the features of the various embodiments can be combined to form other embodiments of the present invention that may not be explicitly described or illustrated. Although various embodiments may have been described as providing advantages or being superior to other embodiments or prior art implementations relative to one or more desired characteristics, it is recognized by those of ordinary skill in the art that one or more features or characteristics can be compromised to achieve the desired overall system properties, depending on the specific application and implementation. These properties may include, but are not limited to, cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, maintainability, weight, manufacturability, ease of assembly, etc. For this reason, embodiments described as being less ideal than other embodiments or prior art implementations in terms of one or more characteristics are also within the scope of the present disclosure and may be ideal for specific applications.

[0035] According to the present invention, there is provided a control system for a vehicle, the control system having a controller configured to open a traction battery contactor based on the electrical potential between the high voltage cable and the chassis continuously exceeding a magnitude threshold for at least a predefined duration, and to selectively open the contactor based on data obtained from the electrical potential during time periods, the time periods each being defined by the time the electrical potential exceeds and then falls below the magnitude threshold, not exceeding the predefined duration.

[0036] According to one embodiment, the controller is further configured to selectively output a fault indication based on the data.

[0037] According to one embodiment, the indication identifies a location on the vehicle associated with the fault.

[0038] According to one embodiment, the controller is further configured to selectively open the contactor based on vehicle speed.

[0039] According to one embodiment, the amplitude threshold is based on vehicle speed or motor rotation speed.

[0040] According to one embodiment, the predefined duration is based on the motor rotation speed.

[0041] According to one embodiment, the data is frequency domain data.

[0042] According to one embodiment, the controller is further configured to obtain data via Fourier transformation or bandpass filtering.

[0043] According to the present invention, a vehicle fault detection method is: in response to the potential between the high voltage cable and the chassis continuously exceeding a magnitude threshold for at least a predefined duration, opening the traction battery contactor; and selectively opening the contactor in response to data obtained from the potential during respective time periods, each of which is defined by the time that the potential exceeds and then falls below the magnitude threshold, not exceeding the predefined duration.

[0044] According to one embodiment, the invention is also characterized by selectively outputting a fault indication based on the data.

[0045] According to one embodiment, the indication identifies a location in the vehicle associated with the fault.

[0046] According to one embodiment, the selective opening is also based on vehicle speed.

[0047] According to one embodiment, the amplitude threshold is based on vehicle speed or motor rotation speed.

[0048] According to one embodiment, the predefined duration is based on the motor rotation speed.

[0049] According to one embodiment, the data is frequency domain data.

[0050] According to one embodiment, the invention is also characterized by obtaining data via Fourier transformation or bandpass filtering.

[0051] According to the present invention, there is provided a vehicle having: a contactor coupling a traction battery to an electric machine via a high voltage cable; and a controller configured to selectively open the contactor in response to the vehicle being stopped and frequency domain data obtained from a detected electrical potential between the high voltage cable and the chassis during time periods each defined by the time the electrical potential exceeds and then falls below a magnitude threshold, not exceeding a predefined duration.

[0052] According to one embodiment, the controller is further configured to selectively output a fault indication in response to the vehicle movement and the frequency domain data.

[0053] According to one embodiment, the indication identifies a location within the vehicle associated with the fault.

[0054] According to one embodiment, the controller is further configured to open the contactor in response to the electrical potential continuing to exceed the magnitude threshold for at least a predefined duration.

Claims

1. A control system for a vehicle, the control system comprising: A controller, the controller being configured to: opening the traction battery contactor based on the electrical potential between the high voltage cable and the chassis continuously exceeding a magnitude threshold for at least a predefined duration, and The traction battery contactors are selectively opened based on data obtained from the electrical potential during respective time periods, the time periods each being defined by the time the electrical potential exceeds and then falls below the amplitude threshold, not exceeding the predefined duration. 2 . The system of claim 1 , wherein the controller is further configured to selectively output a fault indication based on the data.

3. The system of claim 2, wherein the indication identifies a location on the vehicle associated with the fault.

4. The system of claim 1 wherein the controller is further configured to selectively open the traction battery contactor based on vehicle speed.

5. The system of claim 1, wherein the amplitude threshold is based on vehicle speed or motor rotation speed.

6. The system of claim 1, wherein the predefined duration is based on motor rotation speed.

7. The system of claim 1, wherein the data is frequency domain data.

8. The system of claim 1, wherein the controller is further configured to obtain the data via Fourier transform or bandpass filtering.

9. A vehicle fault detection method, the method comprising: in response to the electrical potential between the high voltage cable and the chassis continuously exceeding the magnitude threshold for at least a predefined duration, opening the traction battery contactor, and The traction battery contactor is selectively opened in response to data obtained from the electrical potential during respective time periods, the time periods each being defined by the time the electrical potential exceeds and then falls below the magnitude threshold, not exceeding the predefined duration.

10. The method of claim 9, further comprising selectively outputting a fault indication based on the data.

11. The method of claim 10, wherein the indication identifies a location in the vehicle associated with the fault.

12. The method of claim 9 wherein said selectively disconnecting is further based on vehicle speed.

13. The method of claim 9, wherein the amplitude threshold is based on vehicle speed or motor rotation speed.

14. The method of claim 9, wherein the predefined duration is based on motor rotation speed.

15. The method of claim 9, wherein the data is frequency domain data.

Images