Vehicle system and insulation loss detection method

Abstract

A vehicle and related system and monitoring method are provided for detecting insulation loss on one side of a power converter. In one embodiment, a method involves monitoring a normalized voltage input to a power conversion module coupled to a motor, in response to the normalized voltage exceeding a diagnostic activation threshold, determining a first number of instances for which a range between consecutive extremums of the normalized voltage exceeds an insulation loss range threshold within a diagnostic time window, and automatically initiating a remedial action when the first number is greater than the insulation loss detection threshold.

Description

[0001] The technical field relates generally to vehicle systems and, more particularly, to diagnostics for vehicle electrical systems. Background Art

[0002] Advances in technology have led to substantial changes in motor vehicle design. In particular, electric motors (or motors) are increasingly being used in the automotive industry due to the electrification of automotive drive systems. Electric and / or hybrid vehicles utilize electric motors as a primary or supplemental source of torque in the automotive drive system. In electric and / or hybrid vehicles, the electric motor is typically powered by a rechargeable energy source (such as a battery), using one or more power conversion modules to generate the desired alternating current signal on the stator windings of the electric motor.

[0003] Electric motors are expected to operate for long periods of time with high reliability under extreme operating conditions. However, over time, the operating stresses applied to the motor may degrade the condition of the stator windings or otherwise render the motor inoperable. For example, mechanical shock or stress may cause the rotor to deform or otherwise cause a conductive object to strike or contact the stator windings and cause intermittent insulation loss or short circuits on the alternating current (AC) side. Therefore, it is desirable to quickly detect and accurately diagnose insulation loss in electric motors to extend the service life of electrical components, reduce downtime for maintenance, and maintain vehicle availability. Summary of the invention

[0004] An apparatus for a vehicle and related methods and vehicle systems are provided. In an exemplary embodiment, a method for monitoring an electric motor in a vehicle includes: monitoring, by a control module, a normalized voltage of a power conversion module coupled to the electric motor, in response to the normalized voltage exceeding a diagnostic activation threshold, determining a first number of instances in which a range between consecutive extreme values ​​of the normalized voltage exceeds an insulation loss range threshold within a diagnostic time window after detecting that the normalized voltage exceeds the diagnostic activation threshold, and automatically initiating a remedial action when the first number is greater than an insulation loss detection threshold.

[0005] In one or more embodiments, the method detects an alternating current (AC) insulation loss event after verifying that respective averages associated with respective instances of consecutive extreme values ​​of a normalized voltage are within a threshold of a normalized voltage value, wherein automatically initiating remedial action involves automatically providing an indication of the AC insulation loss event. In one embodiment, automatically providing an indication involves a control module automatically generating a diagnostic code associated with the electric motor.

[0006] In one or more embodiments, the method detects a direct current (DC) insulation loss event when a difference between corresponding average values ​​associated with corresponding instances of consecutive extreme values ​​of the normalized voltage and the normalized voltage value is greater than a threshold, wherein automatically initiating remedial action involves automatically providing an indication of the DC insulation loss event.

[0007] In one or more embodiments, monitoring the normalized voltage involves obtaining a measured voltage of a reference node associated with a voltage bus coupled between the energy source and the power conversion module relative to a ground reference node, and dividing the measured voltage by a direct current (DC) voltage associated with the energy source to obtain the normalized voltage.

[0008] In one or more embodiments, the method involves extracting instances of consecutive extreme values ​​of the normalized voltage during a diagnostic time window, wherein respective instances of the consecutive extreme values ​​include respective maximum values ​​of the normalized voltage and respective minimum values ​​of the normalized voltage. In one embodiment, the method subtracts respective minimum values ​​of the normalized voltage from respective maximum values ​​of the normalized voltage to obtain respective range values ​​associated with respective instances of the consecutive extreme values, wherein determining a first number of instances involves incrementing a counter when the respective range value is greater than an insulation loss range threshold. In an embodiment, automatically initiating a remedial action involves automatically initiating a remedial action when the value of the counter is greater than an insulation loss detection threshold.

[0009] In one or more embodiments, monitoring the normalized voltage involves determining an intermediate group voltage between a node of a voltage bus coupled between the energy source and the power conversion module and a vehicle chassis ground reference voltage node, dividing the intermediate group voltage by a direct current (DC) voltage associated with the energy source to obtain a normalized intermediate group voltage, and monitoring the normalized intermediate group voltage. In one embodiment, determining a first number of instances involves counting a first number of instances when a range between a corresponding pair of peaks and valleys of the normalized intermediate group voltage is greater than an insulation loss range threshold within a diagnostic time window. In an embodiment, automatically initiating a remedial action involves automatically providing an indication of an alternating current (AC) insulation loss event when a first number of instances of a range between a corresponding pair of peaks and valleys of the normalized intermediate group voltage is greater than an insulation loss range threshold within a diagnostic time window, the first number being greater than an AC insulation loss detection threshold number.

[0010] Also provided is an apparatus for a non-transitory computer-readable medium having executable instructions stored thereon that, when executed by a processor, cause the processor to provide a monitoring service to a power conversion module coupled to an electric motor of a vehicle in response to a normalized voltage exceeding a diagnostic activation threshold, the monitoring service being configurable to monitor the normalized voltage, determine a first number of instances in which a range between consecutive extreme values ​​of the normalized voltage exceeds an insulation loss range threshold within a diagnostic time window after detecting that the normalized voltage exceeds the diagnostic activation threshold, and automatically initiate a remedial action when the first number is greater than an insulation loss detection threshold.

[0011] In one or more embodiments, the monitoring service may be configured to detect an alternating current (AC) insulation loss event after verifying that respective average values ​​associated with respective instances of consecutive extreme values ​​of a normalized voltage are within a threshold of the normalized voltage value, wherein automatically initiating remedial action involves automatically providing an indication of the AC insulation loss event.

[0012] In one or more embodiments, the monitoring service may be configured to detect a direct current (DC) insulation loss event when respective average values ​​associated with respective instances of consecutive extreme values ​​of a normalized voltage are greater than a normalized voltage value by more than a threshold, wherein automatically initiating remedial action involves automatically providing an indication of the DC insulation loss event.

[0013] In one or more embodiments, the monitoring service may be configured to extract instances of consecutive extreme values ​​of the normalized voltage during the diagnostic time window, wherein respective instances of the consecutive extreme values ​​include respective maximum values ​​of the normalized voltage and respective minimum values ​​of the normalized voltage. In one embodiment, the monitoring service may be configured to subtract respective minimum values ​​of the normalized voltage from respective maximum values ​​of the normalized voltage to obtain respective range values ​​associated with respective instances of the consecutive extreme values, wherein determining the first number of instances involves incrementing a counter when the respective range value is greater than an insulation loss range threshold.

[0014] A vehicle system is also provided that includes an electric motor, a direct current (DC) voltage bus including a reference voltage node, a power conversion module coupled between the DC voltage bus and the electric motor, and a control module coupled to the power conversion module to provide a monitoring service. The monitoring service may be configured to monitor a normalized voltage to the power conversion module, the normalized voltage relating to a relationship between a measured voltage at the reference voltage node and a DC voltage associated with the DC voltage bus, determine a first number of instances in which a range between consecutive extreme values ​​of the normalized voltage exceeds an insulation loss range threshold within a diagnostic time window after detecting that the normalized voltage exceeds the diagnostic activation threshold in response to the normalized voltage exceeding the diagnostic activation threshold, and automatically initiate a remedial action when the first number is greater than an insulation loss detection threshold.

[0015] In one or more embodiments, the vehicle system includes an output device coupled to the control module, wherein the remedial action involves the monitoring service, and the monitoring service provides a user notification via the output device. In one or more embodiments, the output device is a dashboard indicator, and the user notification is implemented as illumination or activation of the dashboard indicator.

[0016] In one or more implementations, a vehicle system includes an energy source coupled to a DC voltage bus, wherein the DC voltage is an output voltage associated with the energy source. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Exemplary aspects will be described below with reference to the following drawings, wherein like reference numerals represent like elements, and wherein:

[0018] Figure 1 is a block diagram illustrating an electrical system suitable for use with a vehicle, the electrical system being configurable to support a monitoring service for detecting insulation loss on an alternating current (AC) side of the electrical system, according to various embodiments;

[0019] Figure 2 is a diagram showing a method suitable for use according to one or more embodiments described herein. Figure 1 A flow chart of an exemplary loss of insulation (LOI) detection process for an embodiment of a monitoring service in a vehicle electrical system of FIG.

[0020] Figure 3 It is a combination Figure 2 An exemplary embodiment of the LOI detection process depicts Figure 1 A graph of the normalized midpack voltage in an electrical system of FIG. DETAILED DESCRIPTION

[0021] The following detailed description is merely exemplary in nature and is not intended to limit application and use. In addition, there is no intention to be bound by any express or implied theory presented in the previous technical field, the invention content or the following specific embodiments. As used herein, the term module refers to any hardware, software, firmware, electronic control component, processing logic and / or processor device, alone or in any combination, including but not limited to: application-specific integrated circuits (ASICs), electronic circuits, processors (shared, dedicated or groups) and memories that execute one or more software or firmware programs, combinational logic circuits and / or other suitable components that provide the described functions.

[0022] Figure 1 An exemplary embodiment of an electrical system 100 suitable for use with a motor vehicle 150 is depicted. The illustrated electrical system 100 includes, but is not limited to, an energy source 102, a power conversion module 104, an electric motor 106, a control module 108, and at least one output device 110. In the illustrated embodiment, the control module 108 is coupled to the power conversion module 104 and generates commands for operating the power conversion module 104 in a manner that results in desired operation of the electric motor 106 in response to commands received from a driver of the vehicle 150 (e.g., via an accelerator pedal, a brake pedal, a cruise control system, a collision avoidance system, etc.). In an exemplary embodiment, voltage sensors are coupled to respective nodes 112, 114 corresponding to respective power supply rails of a direct current (DC) voltage bus used to provide power from the energy source 102 to the power conversion module 104 to obtain voltage measurements associated with the respective voltage nodes 112, 114, the voltage measurements being indicative of voltage inputs to the power conversion module 104. As described in more detail below, in an exemplary embodiment, loss of insulation (LOI) monitoring service at the control module 108 monitors the corresponding voltages of the nodes 112, 114 referenced to a chassis or other ground voltage to detect and diagnose loss of AC insulation (ACLOI) at the motor 106 on the AC side of the electrical system 100 or otherwise between the power conversion module 104 and the motor 106.

[0023] The energy source 102 (or power source) generally represents a component in the vehicle 150 that is capable of providing a direct current (DC) voltage to the power conversion module 104 to operate the motor 106. Depending on the embodiment, the energy source 102 can be implemented as a battery, a fuel cell, a rechargeable high-voltage battery pack, a supercapacitor, or another suitable energy source known in the art. In other embodiments, the energy source 102 can be implemented as an output of a DC-DC converter, a rectifier, a voltage regulator, or other circuit, module, or component that receives input power from another source. That is, in an exemplary embodiment, the energy source 102 is implemented as one or more rechargeable batteries that are configured to provide a desired DC voltage for operating the motor 106.

[0024] The power conversion module 104 generally represents a component in the vehicle 150 that is coupled between the energy source 102 and the motor 106 to convert the DC power from the energy source 102 into alternating current (AC) power for driving the motor 106. In this regard, in an exemplary embodiment, the power conversion module 104 is implemented as a power inverter having one or more phase legs, wherein each phase leg corresponds to a respective phase of the motor 106. Typically, the switches of the phase legs are modulated (opened or closed) at a particular switching frequency and duty cycle to produce an AC voltage across its associated phase of the stator windings of the motor 106, which in turn produces torque-producing current in these stator windings and operates the motor 106. For purposes of explanation and not limitation, the power conversion module 104 may alternatively be referred to herein as an inverter module or a power inverter; however, the subject matter described herein is not necessarily limited to DC-AC power converters.

[0025] In one exemplary embodiment, the motor 106 is implemented as an induction motor, however, the subject matter described herein should not be construed as limited to use with any particular type of motor. In other embodiments, the motor 106 may be implemented as an interior permanent magnet (IPM) motor, a synchronous reluctance motor, or another suitable motor known in the art. Although not described herein, the subject matter described herein should not be construed as limited to use with any particular type of motor. Figure 1 , but the motor 106 may include a transmission integrated therein such that the motor 106 and the transmission are mechanically coupled to at least some of the wheels of the vehicle 150 via one or more drive shafts such that the speed of the motor 106 (e.g., the rotational speed of the rotor) affects the speed of the vehicle 150.

[0026] In an exemplary embodiment, the vehicle 150 is implemented as an automobile, and depending on the embodiment, the vehicle 150 can be any of a variety of different types of automobiles, such as a sedan, a wagon, a truck, or a sport utility vehicle (SUV), and can be two-wheel drive (2WD) (i.e., rear-wheel drive or front-wheel drive), four-wheel drive (4WD), or all-wheel drive (AWD). In an exemplary embodiment, the vehicle 150 is implemented as a fully electric vehicle, a plug-in hybrid vehicle, etc. However, in various embodiments, the vehicle 150 can be implemented as a fuel cell vehicle (FCV) or another suitable alternative fuel vehicle, and / or the vehicle 150 can also include any of a variety of different types of engines or combinations, such as gasoline or diesel fuel combustion engines, "flexible fuel vehicle" (FFV) engines (i.e., using a mixture of gasoline and alcohol), gaseous compound (e.g., hydrogen, natural gas, propane, etc.) fuel engines, and / or combustion / motor hybrid engines.

[0027] In an exemplary embodiment, the output device 110 generally represents a component associated with the vehicle 150 that is capable of providing one or more user notifications or alerts to the driver or other user associated with the vehicle 150. For example, in some embodiments, the output device 110 may include or otherwise be implemented as one or more lights, indicators, or other elements on the dashboard of the vehicle 150. In other embodiments, the output device 110 may be implemented as an electronic display device that is located on the vehicle 150 or otherwise associated with another system on the vehicle 150, such as, for example, any kind of infotainment module, a navigation head unit, or another similar or suitable unit resident on the vehicle 150, which may be integrated into the dashboard or other console within the passenger compartment of the vehicle 150. That is, in other embodiments, the output device 110 may be implemented as an electronic device associated with the vehicle owner or other user associated with the vehicle 150 that is separate and distinct from the vehicle 150, but is communicatively coupled to the control module 108 via a communication network, such as a smart phone, a mobile computer (e.g., a tablet computer, a laptop computer, or a netbook computer), a wearable computing device (e.g., a smart watch, smart glasses, smart clothing), etc.

[0028] Still reference Figure 1, the control module 108 generally represents the hardware, firmware, software and / or other components of the electrical system 100 that are appropriately configured to operate the power conversion module 104 to provide electrical power to the motor 106 while monitoring the voltage of the corresponding DC voltage bus nodes 112, 114 to detect insulation loss on the AC side of the electrical system 100 (e.g., at the motor 106 or between the power conversion module 104 and the motor 106). According to an embodiment, the control module 108 may include or be implemented as any custom or commercially available processor, a central processing unit (CPU), a graphics processing unit (GPU), an auxiliary processor of several processors associated with the control module 108, a semiconductor-based microprocessor (in the form of a microchip or chipset), any combination thereof, or any device generally for executing instructions. In practice, the control module 108 may include processing logic that is configurable to perform functions, techniques, and processing tasks associated with the operation of the vehicle electrical system 100, as described in more detail below.

[0029] In an exemplary embodiment, the steps of the method or algorithm described in conjunction with the embodiments disclosed herein may be directly embodied in hardware, firmware, a software module executed by the control module 108, or any practical combination thereof. In an exemplary embodiment, the control module 108 includes or otherwise accesses a data storage element, memory, or any other short-term or long-term storage medium or other suitable non-transitory computer-readable device or medium capable of storing programming instructions executed by the control module 108, which may include volatile and non-volatile storage in read-only memory (ROM), random access memory (RAM), keep-alive memory (KAM), flash memory, registers, hard disk, removable disk, magnetic or optical mass storage, and / or the like. The computer-executable programming instructions, when read and executed by the control module 108, cause the control module 108 to perform, support, generate, or otherwise provide a monitoring service that monitors the voltage at the DC voltage bus nodes 112, 114 to detect AC insulation loss and perform the various tasks, operations, functions, and processes described herein.

[0030] Figure 2 An exemplary loss of insulation (LOI) detection process 200 is depicted, which is suitable for implementation by monitoring a service associated with a control module that controls the operation of an electric motor using a power conversion device. For illustrative purposes, the following description may refer to the above combined Figure 1 Although portions of the LOI detection process 200 may be performed by different elements of the vehicle system, for purposes of explanation, the subject matter may be described herein primarily in the context of the LOI detection process 200 being primarily performed by a monitoring service at the control module 108 .

[0031] The LOI detection process 200 is initialized or otherwise begins at 202 by calculating or otherwise determining normalized intermediate group voltages (measured relative to a vehicle chassis ground reference voltage) for the positive and negative rails of a DC voltage bus used to power a power conversion device, and monitoring the normalized intermediate group voltages to detect when at least one of the normalized intermediate group voltages satisfies a diagnostic activation threshold for insulation loss detection at 204. In this regard, the LOI monitoring service at the control module 108 continuously monitors the normalized intermediate group voltages for deviations from a normal operating range that may indicate insulation loss on the AC side of the electrical system 100. In an exemplary embodiment, the LOI monitoring service calculates or otherwise determines the normalized positive intermediate group voltage by obtaining a positive reference voltage measurement from a voltage sensor associated with the DC voltage bus positive reference node 112 indicating the voltage of the DC voltage bus positive reference node 112 relative to a chassis or ground reference voltage, and then dividing the absolute value of the positive reference voltage measurement by the voltage difference between the positive and negative DC voltage bus reference nodes 112, 114 (e.g., the reference DC voltage output by the energy source 102). Thus, the normalized positive intermediate group voltage may correspond to a relative percentage or distribution of battery group voltages that are above (or positive relative to) the chassis or ground voltage. In a similar manner, the normalized negative intermediate group voltage is calculated by obtaining a negative reference voltage measurement from a voltage sensor associated with the DC voltage bus negative reference node 114 indicating the voltage of the DC voltage bus negative reference node 114 relative to a chassis or ground reference voltage, and then dividing the absolute value of the negative reference voltage measurement by the cumulative voltage difference between the positive and negative DC voltage bus reference nodes 112, 114. Thus, the normalized negative intermediate pack voltage may correspond to a relative percentage or distribution of battery pack voltages that are below (or negative relative to) chassis or ground voltage.

[0032] After determining the normalized positive intermediate pack voltage and the normalized negative intermediate pack voltage, the LOI detection process 200 compares the normalized intermediate pack voltage values ​​to one or more activation thresholds or other criteria for initiating diagnostic monitoring to confirm whether an excursion or deviation in the normalized intermediate pack voltage is attributable to an ACLOI condition. For example, in one embodiment, the LOI detection process 200 monitors the normalized intermediate pack voltages to detect when one of the normalized intermediate pack voltages drops below a lower threshold of 0.2 (or 20% of the battery pack voltage) or exceeds an upper threshold of 0.8 (or 80% of the battery pack voltage). In this regard, the diagnostic activation thresholds may be selected to accommodate voltage transient fluctuations due to active isolation or other processes or operations that may cause a relative voltage change between the DC voltage bus nodes 112, 114 and the ground or chassis reference voltage node.

[0033] In response to detecting a normalized intermediate group voltage that satisfies the diagnostic activation threshold, the LOI detection process 200 monitors the corresponding normalized intermediate group voltage over a diagnostic time window to identify and extract consecutive voltage extreme value pairs (cycle maximums or peaks, and cycle minimums or valleys) within the diagnostic window at 206. To identify and extract the peaks and valleys, the LOI monitoring service at the control module 108 analyzes consecutive samples of the corresponding voltage nodes 112, 114 to determine whether the difference between the samples is greater than a threshold voltage difference (e.g., to mitigate noise), and adds the normalized voltage value to a temporary array or buffer when the difference from the previous sample in the array is greater than the threshold voltage difference, and discards the normalized voltage sample when the difference is less than the threshold voltage difference. Once the normalized voltage sample values ​​in the temporary array or buffer indicate an extreme value or change in the electrical cycle, the LOI monitoring service stores or otherwise maintains the minimum or maximum value as the corresponding peak or valley extreme value within the diagnostic window. For example, in one embodiment, the temporary array may be configured to maintain the three most recent normalized voltage samples that exceed a threshold voltage difference relative to a previous sample, wherein when the buffered normalized voltage value indicates an extreme value and a corresponding change in electrical cycle direction, a second or intermediate normalized voltage sample value corresponding to the extreme value is then stored or maintained as a corresponding peak or valley within the diagnostic window. In this manner, the LOI monitoring service at the control module 108 extracts a first set of peak and valley normalized voltage extreme values ​​for the positive DC voltage bus reference node 112 and a second set of peak and valley normalized voltage extreme values ​​for the DC voltage bus negative reference node 114.

[0034] Still reference Figure 2 , after extracting the normalized voltage extremes of the corresponding intermediate group voltages of the positive and negative rails of the DC voltage bus, the LOI detection process 200 calculates or otherwise determines the average and range values ​​of the corresponding peak and valley pair extremes within the diagnostic window at 208, and detects the occurrence of the ACLOI condition based on the corresponding average and range values ​​at 210. In this regard, in an exemplary embodiment, the LOI detection process 200 performs a rainflow range mean analysis to determine when to mature the diagnosis of the ACLOI event based on the number of corresponding range values ​​greater than the diagnostic threshold that exceed the LOI range detection threshold. When the number of range values ​​exceeding the LOI range detection threshold within the diagnostic window is less than the diagnostic threshold, the LOI detection process 200 determines that the LOI condition does not exist and resumes monitoring the normalized intermediate group voltage to restart the subsequent diagnostic window at 202 and 204. In this manner, the LOI detection process 200 avoids false alarms or false triggering of LOI notifications due to noise or other transients.

[0035] In one or more embodiments, for each pair of consecutive peak and valley normalized voltage extremes of the DC voltage bus positive reference node 112, the LOI monitoring service at the control module 108 may calculate a corresponding range value associated with the corresponding peak and valley pair by subtracting the extracted normalized valley voltage value from the extracted normalized peak voltage value, and calculate a corresponding average value associated with the corresponding peak and valley pair by averaging the corresponding extracted normalized valley voltage value and the corresponding extracted normalized peak voltage value. In an exemplary embodiment, the LOI detection process 200 identifies an ACLOI condition by counting the number of corresponding peak-valley pairs having an associated range value greater than an ACLOI range threshold and detecting an ACLOI condition when the number of corresponding peak-valley pairs exceeding the ACLOI range threshold within the diagnostic window is greater than an ACLOI detection threshold. For example, in one embodiment, the LOI monitoring service at the control module 108 detects an ACLOI condition when two or more peak-valley pairs associated with the corresponding DC voltage bus reference nodes 112, 114 have an associated range value greater than 0.8 (or 80% of the battery pack voltage).

[0036] In some embodiments, the average value associated with the corresponding peak-valley pair is utilized to verify or otherwise confirm that the range value associated with the corresponding peak-valley pair indicates an LOI condition. For example, when the average value associated with the corresponding peak-valley pair is within the LOI verification threshold of the normalized intermediate group voltage value of 0.5 (or 50% of the battery group voltage), then a DCLOI is not detected because the normalized positive intermediate group voltage and the negative intermediate group voltage are symmetrical about the value of 0.5 during normal conditions. However, even if the average value is consistent with a normal state on the DC side of the electrical system 100 (e.g., where the respective voltages of the positive and negative DC voltage reference nodes are equidistant from the chassis or ground reference voltage node), the range value associated with the corresponding peak-valley pair may also be considered to indicate an ACLOI condition. However, when the average value associated with the corresponding peak-valley pair deviates from the normalized intermediate group voltage value of 0.5 by more than the LOI verification threshold, the LOI detection process 200 may classify or otherwise characterize the corresponding peak-valley pair as indicating a DC insulation loss (DCLOI) condition, and it may fail to increment the ACLOI counter. In this regard, in some embodiments, when the number of corresponding peak-valley pairs having range values ​​exceeding the ACLOI range threshold, the LOI monitoring service at the control module 108 can detect an AC LOI condition. In this manner, the corresponding range values ​​associated with the corresponding peak-valley pairs can be used to detect the ACLOI condition, and the average values ​​associated with the corresponding peak-valley pairs can be used to classify the LOI condition as a DCLOI event.

[0037] Still reference Figure 2In an exemplary embodiment, after detecting the LOI condition, the LOI detection process 200 automatically initiates one or more remedial actions at 212. In one or more embodiments, in response to detecting the ACLOI event, the LOI monitoring service at the control module 108 automatically generates or otherwise provides an indication of the LOI event, for example, by setting an ACLOI diagnostic flag to a value indicating the ACLOI event, or otherwise automatically initiates the generation of a maintenance code or diagnostic code associated with the motor 106 to provide a corresponding notification to a user via the output device 110 to inspect the AC side of the motor 106 or the electrical system 100 during the next maintenance event. Additionally or alternatively, the LOI monitoring service at the control module 108 may automatically initiate the generation of a user notification via the output device 110 that alerts a driver or other operator of the vehicle 150 of a potential maintenance issue (e.g., by illuminating a check engine light or one or more dashboard indicators) to expedite maintenance on the vehicle 150. In some embodiments, the LOI monitoring service may also cause the control module 108 to implement an alternate control mode when operating the power conversion module 104 and / or the motor 106 to mitigate any potentially harmful effects of the ACLOI condition (e.g., a safe mode, a limp home mode, etc.). In this regard, it should be appreciated that there are many different potential combinations of remedial actions and corresponding schemes, thresholds, and / or logic rules for generating such remedial actions, and the subject matter described herein is not intended to be limited to any particular implementation. Additionally, it should be appreciated that the LOI monitoring service at the control module 108 automatically generates or otherwise provides an indication of an LOI event in response to detecting a DCLOI event in a similar manner (e.g., by setting a DCLOI diagnostic flag, generating a DCLOI diagnostic code, etc.).

[0038] Figure 33 is a graph 300 depicting a relationship between a normalized positive intermediate group voltage 302 associated with the DC voltage bus positive reference node 112 and a normalized negative intermediate group voltage 304 associated with the DC voltage bus negative reference node 114 relative to time within an exemplary embodiment of the LOI detection process 200. When the normalized positive intermediate group voltage 302 drops below a diagnostic initiation threshold lower limit 308 (e.g., 0.2) and the normalized negative intermediate group voltage 304 exceeds a diagnostic initiation threshold upper limit 306 (e.g., 0.8) at a time point 310, the LOI monitoring service at the control module 108 initiates a diagnostic monitoring window (e.g., at 204). Thereafter, the LOI monitoring service at the control module 108 identifies and extracts a valley 312 corresponding to the lower extreme value of the normalized positive intermediate group voltage 302, followed by a peak 314 corresponding to the lower extreme value of the normalized positive intermediate group voltage 302, and a peak 316 corresponding to the upper extreme value of the normalized negative intermediate group voltage 304, followed by a valley 318 corresponding to the lower extreme value of the normalized negative intermediate group voltage 304 (e.g., at 206 of the LOI detection process 200). It should be noted that during normal operating conditions, the normalized positive intermediate group voltage 302 and the normalized negative intermediate group voltage 304 would be expected to be symmetrical about a midpoint or median value of 0.5 in the absence of any LOI conditions.

[0039] The monitoring service at the control module 108 determines that the difference between the peak-valley pair 312, 314 associated with the normalized positive intermediate group voltage 302 (e.g., 0.93) is greater than the ACLOI range threshold (e.g., 0.8), and increments the ACLOI detection counter (e.g., at 208 of the LOI detection process 200). Similarly, when the difference between the peak-valley pair 316, 318 associated with the normalized negative intermediate group voltage 304 (e.g., 0.93) is greater than the ACLOI range threshold (e.g., 0.8), the LOI monitoring service at the control module 108 increments the ACLOI detection counter. When the value of the ACLOI detection counter, which tracks the number of ACLOI range excursion events within the diagnostic window, is greater than or equal to the ACLOI detection threshold (e.g., 2), the LOI monitoring service at the control module 108 detects the occurrence of an ACLOI event at time 310 (e.g., at 210 of the LOI detection process 200). In this regard, similarly, when the LOI monitoring service verifies that the average of the positive reference DC peak-to-valley pair 312, 314 and the average of the negative reference DC peak-to-valley pair 316, 318 are both within a threshold of 0.5 of the normalized intermediate group voltage, the LOI monitoring service at the control module 108 classifies the LOI event as a DCLOI event and accordingly initiates one or more remedial actions in response to the DCLOI event (e.g., at 212 of the LOI detection process 200).

[0040] It should be appreciated that the LOI detection process 200 can quickly and accurately diagnose a short circuit or other insulation loss on the AC side of the electrical system (e.g., at the motor 106 or between the power conversion module 104 and the motor 106) by monitoring voltage measurements on the DC side of the electrical system 100. By comparing the positive-chassis and negative-chassis intermediate group voltages to calibrable voltage thresholds and analyzing the range and average calculated from the extreme values ​​of the intermediate group voltages during the diagnostic window, the LOI detection process 200 is able to distinguish true ACLOI events from active insulation or insulation loss on the DC side. By reliably diagnosing ACLOI events, costs associated with misdiagnosing or failing to diagnose problems are reduced. For example, the lack of accurate diagnosis of ACLOI events may result in false triggering of DC-side diagnostic events and undesirable maintenance costs and downtime, such as performing replacement or other maintenance on the energy source 102, power conversion module 104, or other DC-side components (e.g., contactors or other components) when an ACLOI condition or other fault condition actually exists in the motor 106 or otherwise on the AC side. Additionally, the driver or other vehicle operator may be notified of an ACLOI event at an earlier stage to allow the driver or other vehicle operator to take remedial action to prolong operation of the vehicle 150 before the ACLOI condition progresses.

[0041] For the sake of brevity, conventional techniques related to vehicle electrical systems, motors, power converters, and other functional aspects of the systems (and the individual operating components of the systems) may not be described in detail herein. In addition, the connecting lines shown in the various figures included herein are intended to represent exemplary functional relationships and / or physical connections between the various elements. It should be noted that many alternative or additional functional relationships or physical connections may exist in embodiments of the present subject matter.

[0042] As used herein, the word "exemplary" means "serving as an example, instance, or illustration." Thus, any implementation described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other implementations. All implementations described herein are exemplary implementations provided to enable persons skilled in the art to make or use the invention, rather than to limit the scope of the invention, which is defined by the claims.

[0043] Those skilled in the art will appreciate that the various illustrative logic blocks, modules, circuits and algorithm steps described in conjunction with the embodiments disclosed herein may be implemented as electronic hardware, computer software or a combination of the two. Some embodiments are described above in terms of functions and / or logic block components (or modules) and various processing steps. However, it should be understood that such block components (or modules) may be implemented by any number of hardware, software and / or firmware components configured to perform a specified function. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits and steps have been generally described above with respect to their functionality. Whether such functions are implemented as hardware or software depends on the specific application and the design constraints imposed on the entire system. Those skilled in the art may implement the described functions in different ways for each specific application, but such implementation decisions should not be interpreted as causing departure from the scope of the invention.

[0044] When implemented in software or firmware, the various elements of the system described herein are basically code segments or instructions that perform various tasks. A program or code segment can be stored in a processor-readable medium, or transmitted by a computer data signal embodied in a carrier wave through a transmission medium or a communication path. "Computer-readable medium", "processor-readable medium" or "machine-readable medium" may include any medium capable of storing or transmitting information. Examples of processor-readable media include electronic circuits, semiconductor memory devices, ROMs, flash memory devices, erasable ROMs (EROMs), floppy disks, CD-ROMs, optical disks, hard disks, optical fiber media, radio frequency (RF) links, etc. Computer data signals may include any signal that can be propagated through a transmission medium (such as an electronic network channel, optical fiber, air, electromagnetic path or RF link). Code segments may be downloaded via computer networks such as the Internet, intranets, LANs, etc.

[0045] In this document, relational terms such as first and second, etc. may be used solely to distinguish one entity or action from another entity or action, without necessarily requiring or implying any actual such relationship or order between such entities or actions. Numerical ordinals such as "first," "second," "third," etc. simply represent different singles out of a plurality, and do not imply any order or sequence unless specifically defined by the claim language. The order of the text in any claim does not mean that the processing steps must be performed in a temporal or logical order according to such order, unless it is specifically defined by the language of the claim. The processing steps may be interchanged in any order without departing from the scope of the invention, as long as such interchange does not contradict the claim language and is logically consistent.

[0046] In addition, the foregoing description may refer to an element or node or feature that is "connected" together. As used herein, unless otherwise expressly stated, "connection" means that an element / node / feature is directly or indirectly connected to another element / node / feature (or is directly or indirectly communicated with another element / node / feature), and is not necessarily mechanically connected. For example, two elements can be physically, electronically, logically or in any other way connected to each other by one or more additional elements. Therefore, although the accompanying drawings can depict an exemplary arrangement of elements directly connected to each other, additional intermediate elements, devices, features or parts may be present in the embodiment of the depicted theme. In addition, some terms may also be used only for reference purposes in this article, and are therefore not intended to be restrictive.

[0047] Although at least one exemplary aspect has been presented in the foregoing specific embodiments, it should be understood that there are a large number of variations. It should also be understood that one or more exemplary aspects are merely examples and are not intended to limit the scope, applicability or configuration of the present disclosure in any way. On the contrary, the foregoing detailed description will provide a convenient roadmap for those skilled in the art to implement one or more exemplary aspects. It should be understood that the function and arrangement of elements may have different variations without departing from the scope of the present disclosure set forth in the attached claims and their legal equivalents.

Claims

1. A method for monitoring an electric motor in a vehicle, the method comprising: monitoring, by the control module, a normalized voltage of a power conversion module coupled to the electric motor; responsive to the normalized voltage exceeding a diagnostic activation threshold, determining a first number of instances in which a range between consecutive extreme values ​​of the normalized voltage exceeds an insulation loss range threshold within a diagnostic time window after detecting that the normalized voltage exceeds the diagnostic activation threshold; as well as When the first number is greater than an insulation loss detection threshold, remedial action is automatically initiated.

2. The method of claim 1 , further comprising detecting an alternating current (AC) insulation loss event after verifying that respective averages associated with respective instances of the consecutive extreme values ​​of the normalized voltage are within a threshold of a normalized voltage value, wherein automatically initiating remedial action comprises automatically providing an indication of the AC insulation loss event.

3. The method according to claim 2, wherein: Automatically providing the indication includes the control module automatically generating a diagnostic code associated with the electric motor.

4. The method according to claim 1, further comprising: A direct current (DC) insulation loss event is detected when a difference between a normalized voltage value and respective average values ​​associated with respective instances of the consecutive extreme values ​​of the normalized voltage is greater than a threshold, wherein automatically initiating remedial action includes automatically providing an indication of the DC insulation loss event.

5. The method of claim 1 , wherein monitoring the normalized voltage comprises: obtaining a measured voltage of a reference node associated with a voltage bus relative to a ground reference node, the voltage bus being coupled between an energy source and the power conversion module; as well as The measured voltage is divided by a direct current (DC) voltage associated with the energy source to obtain the normalized voltage. 6 . The method of claim 1 , further comprising extracting instances of consecutive extreme values ​​of the normalized voltage during the diagnostic time window, wherein respective instances of the consecutive extreme values ​​include respective maximum values ​​of the normalized voltage and respective minimum values ​​of the normalized voltage.

7. The method of claim 6, further comprising subtracting a respective minimum value of the normalized voltage from a respective maximum value of the normalized voltage to obtain a respective range value associated with a respective instance of the continuous extreme value, wherein determining a first number of instances comprises incrementing a counter when the respective range value is greater than the insulation loss range threshold.

8. The method according to claim 7, wherein: Automatically initiating a remedial action includes: automatically initiating a remedial action when the value of the counter is greater than the insulation loss detection threshold.

9. The method of claim 1 , wherein monitoring the normalized voltage comprises: determining an intermediate group voltage between nodes of a voltage bus coupled between an energy source and the power conversion module; dividing the intermediate group voltage by a direct current (DC) voltage associated with the energy source to obtain a normalized intermediate group voltage; as well as Monitor the normalized middle group voltage.

10. A vehicle system comprising: Electric motor; a direct current (DC) voltage bus including a reference voltage node; a power conversion module coupled between the DC voltage bus and the electric motor; as well as A control module coupled to the power conversion module to provide a monitoring service, wherein the monitoring service can be configured to: monitoring a normalized voltage of the power conversion module, the normalized voltage comprising a relationship between a measured voltage of a reference voltage node and a DC voltage associated with the DC voltage bus; In response to the normalized voltage exceeding a diagnostic activation threshold, determining a first number of instances in which a range between consecutive extreme values ​​of the normalized voltage exceeds an insulation loss range threshold within a diagnostic time window after detecting that the normalized voltage exceeds the diagnostic activation threshold; and When the first number is greater than an insulation loss detection threshold, remedial action is automatically initiated.

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