Electric vehicle maintenance equipment
Patent Information
- Application Number
- JP2026523581
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2024-10-14
- Filing Date
- 2024-10-17
- Publication Date
- 2026-10-30
Smart Images
Figure 2026536579000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to an electric vehicle of the type that uses a battery pack for storing electricity used to supply power to the vehicle. This includes both hybrid vehicles and pure electric vehicles. More specifically, the present invention relates to maintenance and diagnosis of electrical components and systems such as battery packs that are used in conjunction with electric vehicles.
Background Art
[0002] Conventionally, vehicles have used internal combustion engines as their power source. However, electrically driven vehicles have come into widespread use. Such vehicles can provide improved fuel efficiency and can be operated using alternative energy sources.
[0003] Some types of electric vehicles are driven entirely using electric motors and electricity. Other types of electric vehicles include an internal combustion engine. The internal combustion engine can be used to generate electricity and to assist the power supplied by the electric motor. These types of vehicles are known as "hybrid" electric vehicles.
[0004] Operation of an electric vehicle requires a power source capable of supplying a large amount of electric power. Typically, electric vehicles store electricity in a large battery pack composed of a plurality of batteries. These batteries may be formed by a large number of individual cells, or may themselves be individual cells, depending on the configuration of the batteries and the battery pack. These packs are large, can be expensive to replace, and can be difficult to access and maintain. Furthermore, it is desirable to test the safety of the vehicle and its components.
[0005] Dr. Keith S. Champlin and Midtronics, Inc. of Willowbrook, Illinois have pioneered the development of various techniques for testing batteries, electric vehicles, hybrid vehicles, and vehicle electrical systems, including multiple techniques for measuring battery dynamic parameters such as battery dynamic conductance, as well as other techniques. These techniques are documented in numerous U.S. patents, such as U.S. Patent No. 3,873,911 (Champlin, March 25, 1975), U.S. Patent No. 3,909,708 (Champlin, September 30, 1975), U.S. Patent No. 4,816,768 (Champlin, March 28, 1989), U.S. Patent No. 4,825,170 (Champlin, April 25, 1989), and U.S. Patent No. 4,881,0 U.S. Patent No. 38 (Champlin, issued November 14, 1989), U.S. Patent No. 4,912,416 (Champlin, issued March 27, 1990), U.S. Patent No. 5,140,269 (Champlin, issued August 18, 1992), U.S. Patent No. 5,343,380 (issued August 30, 1994), U.S. Patent No. 5,572,136 (issued November 5, 1996), U.S. Patent No. 5,574,355 (November 1996) (Issued on the 12th), U.S. Patent No. 5,583,416 (Issued December 10, 1996), U.S. Patent No. 5,585,728 (Issued December 17, 1996), U.S. Patent No. 5,589,757 (Issued December 31, 1996), U.S. Patent No. 5,592,093 (Issued January 7, 1997), U.S. Patent No. 5,598,098 (Issued January 28, 1997), U.S. Patent No. 5,656,920 (Issued August 12, 1997), U.S. Japanese 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[Overview of the project]
[0006] The present invention includes a battery pack maintenance device for performing maintenance on the battery pack of a hybrid vehicle and / or an electric vehicle (generally referred to herein as an electric vehicle). Input / output circuits for communicating with circuits within the battery pack and / or the vehicle's circuits may be provided.
[0007] A maintenance device is provided that is coupled to the electrical circuit of an electric vehicle and performs maintenance on the battery, the maintenance device including an electrical connector configured to be coupled to the vehicle's electrical circuit. A measurement circuit is coupled to the electrical connector. A controller is coupled to the measurement circuit and configured to collect relevant information from the measurement circuit and make diagnostic decisions in response.
[0008] An apparatus for safety testing of electrical components in an electric vehicle includes a low-voltage data connector configured to connect to the data port of the electric vehicle. The test connector is configured to connect a test signal to the electrical component of the electric vehicle, and a test signal source having a signal generator is connected to a voltage divider. The voltage divider generates a test signal and a monitor signal, and a measurement circuit is connected to the monitor signal and its low-voltage data connector. The measurement circuit identifies leakage current based on the monitor signal.
[0009] In one embodiment, an apparatus for safety testing of electrical components in an electric vehicle is provided, which optionally includes a low-voltage data connector configured to be coupled to a data port of the electric vehicle. The test connector is configured to couple a test signal to the electrical components of the electric vehicle. A test signal source having a signal generator is coupled to a voltage divider. The voltage divider generates a test signal and a monitor signal. A measurement circuit is coupled to the monitor signal, and a controller is coupled to the measurement circuit. The controller detects leakage current based on the monitor signal.
[0010] This summary of the invention is provided to introduce in a simplified manner a selection of several concepts that will be further described in the embodiments for carrying out the invention described below. This summary of the invention is not intended to identify any important or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. The claimed subject matter is not limited to embodiments that resolve any or all of the disadvantages pointed out in the background art. [Brief explanation of the drawing]
[0011] [Figure 1] Figure 1 is a simplified block diagram showing a battery maintenance device according to the present invention connected to an electric vehicle.
[0012] [Figure 2] Figure 2 is a more detailed block diagram of the battery maintenance device shown in Figure 1.
[0013] [Figure 3] Figure 3 is a simplified circuit diagram of a battery maintenance device used to determine the failure or deterioration of insulation or other components within a vehicle, using a small AC signal source.
[0014] [Figure 4]Figure 4 is a simplified block diagram of a maintenance device for exploring electrical resistance between two test points, such as between a PE connection in a vehicle's charging port and an electrical ground point inside the vehicle. [Modes for carrying out the invention]
[0015] Embodiments of this disclosure will be described more thoroughly below with reference to the accompanying drawings. Elements identified by the same or similar reference numerals refer to the same or similar elements. Some elements may not be shown in each of the drawings for the sake of simplicity.
[0016] Various embodiments of this disclosure can be embodied in many different forms and should not be construed as being limited to any particular embodiment described herein. Rather, these embodiments are provided to make this disclosure thorough and complete and to adequately convey the scope of this disclosure to those skilled in the art.
[0017] Maintenance of vehicles with internal combustion engines is a well-known technique. Procedures for servicing the vehicle's internal combustion engine, drivetrain, battery (which is generally used to start the vehicle and operate the electrical equipment within the vehicle), and fuel storage and distribution systems are known. In contrast, the widespread use of electric vehicles is a relatively new phenomenon, and there is a continuing need for improved procedures for performing maintenance on the batteries of such vehicles.
[0018] The apparatus of the present invention can be used to test the electrical systems of electric vehicles or to provide other maintenance and diagnostics to the battery packs of such vehicles. Generally, this work can be problematic for several reasons. Firstly, different types of electric vehicles use different types of electrical systems and battery packs. The configuration, voltage, and connections of such electrical systems and packs vary considerably. Furthermore, the vehicle itself typically includes "intelligence" to control charging and discharging, in addition to monitoring the state of the battery pack. Furthermore, some battery packs themselves also include "intelligence" to control charging and discharging, in addition to monitoring the state of the battery pack. The apparatus of the present invention can interface with the data bus of the vehicle and / or the data bus of the battery pack to control and monitor the operation of the battery pack and electrical systems. The battery pack and / or electrical systems may be difficult to access physically, and it may be difficult to obtain an electrical connection to the electrical system or battery pack. Furthermore, in one embodiment, the apparatus also includes a charging function for use when charging some or all of the cells of the battery pack in order to make the battery pack usable.
[0019] Electric vehicles typically include "contactors," which are electrically operated relays (switches) used to selectively couple the high voltage from the battery pack to the vehicle's charging port or a powerful electric motor used in the vehicle's drivetrain. To access the battery pack from a position on the vehicle, these contactors must be closed to complete the electrical circuit. However, the vehicle and / or battery pack control electronics typically disconnect (open) the contactors when the electric motor or charging port is not in use, for safety purposes, to isolate the battery pack from the vehicle. Therefore, in one embodiment, the present invention communicates with the electric vehicle or battery pack controller, or directly with the contactors, to close the contactors, thereby providing access to the high voltage of the battery pack. When communicating with the vehicle's control system, the device of the present invention can provide the vehicle system with information indicating that it is appropriate to close the contactors. Therefore, fault indications or other errors, including errors related to the vehicle having been in an accident, must be suppressed. Instead, information indicating that it is appropriate to close the contactors is provided to the vehicle system by the battery pack maintenance device.
[0020] Furthermore, in many cases, it is important to assess the safety of electric vehicles in service. For example, in some regions, conventional vehicles with internal combustion engines are subject to mandatory annual safety inspections. This may include checking brakes, suspension, exterior lighting, etc. This is similar to emissions testing but is related to safety. In addition, in some regions, vehicles cannot be sold without obtaining a safety certificate.
[0021] Figure 1 is a simplified block diagram showing the maintenance / diagnostic device 100 coupled to an electric vehicle 102. The vehicle 102 is shown in a simplified block diagram and includes a battery pack 104 used to power the vehicle 102, including supplying power to the vehicle's motor 106. The vehicle 102 includes a vehicle controller 108 coupled to the vehicle's data bus 110. The controller 108 receives information about the vehicle's operation via a sensor 112 and controls the vehicle's operation via an output 114. Furthermore, the battery pack 104 is shown optionally including its own controller 120, which monitors the operation of the battery pack 104 using a battery pack sensor 122.
[0022] During operation, the electric vehicle 102 is controlled by the controller 108 based on input from the driver, for example, via the operator input / output 109. The operator input / output 109 may include outputs related to the operation of the vehicle, such as accelerator pedal input, brake input, input indicating the position of the steering wheel, information related to a desired gear ratio for the drivetrain, speed, charge information, amount of energy remaining in the battery pack 104, and diagnostic information. The controller 108 can control the operation of the electric motor 106 to propel the vehicle and can also monitor and control other systems of the vehicle 102. The controller 120 of the battery pack 104 can be used to monitor the operation of the battery pack 104. For example, the sensor 122 may include a temperature sensor configured to disconnect the battery of the battery pack if a threshold temperature is exceeded. Other exemplary sensors include current sensors or voltage sensors that can be used to monitor the charge level of the battery pack 104. Figure 1 also shows the contactor relay 130 of the vehicle 102, which is used to selectively disconnect the battery pack 104 from the system of the vehicle 102 as described above. For example, the controller 108 can provide a signal to close the contactor 130, thereby connecting the battery pack 104 to the electrical system of the vehicle 102.
[0023] The device 100 includes a main unit 150 coupled to the vehicle via a low-voltage junction box 152 and a high-voltage junction box 154. These junction boxes 152, 154 are optional, and other techniques may be used to couple the maintenance device 100 to the vehicle 102. The maintenance device 100 includes a memory 164 containing programming instructions used, for example, by a microprocessor 160, as well as the microprocessor 160 and an input / output circuit 162. The input / output circuit 162 can be used for user input, output, remote input, output, and both input and output to and from the vehicle 102. The maintenance device 100 includes a controllable load 170 for use when discharging the battery pack 104. A charging source 171 is also optionally provided and can be used, for example, in situations where it is desirable to charge the battery pack 104 in order to perform maintenance on the battery pack 104. The high-voltage junction box 154 is used to provide an electrical connection between the terminals of the battery pack 104 and the maintenance device main unit 150. Using this connection, the battery in the battery pack 104 can be discharged using the load 170 or charged using the charge source 171. Similarly, the low-voltage junction box 152 is used by the battery pack maintenance device 100 to connect to the low-voltage system of the electric vehicle 102. Such a system includes the vehicle's data bus 110, sensor 112, output 114, etc. Through this connection, as described above, the maintenance device 100 can collect information about the state of the system in the vehicle 102, including the battery pack 104, and can control the operation of the system in the vehicle 102. Similarly, through this connection, the output from sensor 112 can be modified or altered, thereby providing the modified sensor output to the controller 108. This can be used, for example, to cause the controller 108 to receive information indicating that the vehicle 102 or the battery pack 104 is in a different state than what sensor 112 is actually sensing. For example, this connection can be used to close contactor 130, thereby providing an electrical connection to the battery pack 104.Furthermore, the low-voltage junction box 152 can be used to couple to the controller 120 and / or the sensor 122 of the battery pack 104. The junction boxes 152, 154 are coupled to the vehicle 102 by using suitable connectors. The specific connector used can be selected based on the particular type of the vehicle 102 and the types of connections available to the operator. For example, an OBDII connection can be used to couple to the vehicle's data bus 110. Other plugs or adapters may be used to couple to the sensor 112 or the output 114. A specific type of plug may be available for coupling the high-voltage junction box 154 to the battery pack 104. If no available contactors are present, or they are inaccessible, or they do not respond, in one configuration, the coupling can be performed using clips or other types of clamp-on or selectively connectable contactors.
[0024] The vehicle 102 includes a data port 133, such as an OBDII port. This allows the device 100 to communicate with the vehicle's data bus. In such a configuration, a data connector 135 for connecting to the data port 133 is provided.
[0025] In one configuration, the high-voltage connection to the vehicle is made via the vehicle charging port 123, and the apparatus 100 includes a suitably configured charging plug 121. The vehicle 102 includes an additional contactor 131 that is used to selectively couple the battery pack 104 to the charging port 123. Some charging ports also include a data connection. In such a configuration, the data port 133 may be included in the charging port 123. Furthermore, some configurations enable data transmission over the same wires that are used to provide the charging connection.
[0026] Figure 2 is a simplified block diagram of a battery pack maintenance apparatus 100 according to an exemplary embodiment of the present invention. The apparatus includes a microprocessor 160 that operates in accordance with instructions stored in a memory 164. A power supply is used to supply power to the apparatus. The power supply 180 may be coupled to an AC power source, such as a wall outlet or other high-power power source, for use in charging the battery pack 104 of the vehicle 102. Further, when the apparatus 100 is used only for discharging the vehicle battery pack 104, the power supply 180 may be coupled to a DC power source such as a 12-volt battery. For example, many electric vehicles include a standard 12-volt vehicle battery in addition to the battery pack 104. This 12-volt vehicle battery may be used to supply power to the maintenance apparatus 100. The microprocessor communicates with an operator using an operator input / output 182. Other input / output circuitry 184 is provided for use in physically connecting to a data communication link such as RS232, a USB connection, or Ethernet (registered trademark). Wireless input / output circuitry 186 is also optionally provided for use in communicating according to wireless technologies such as Wi-Fi technology, Bluetooth (registered trademark), and Zigbee (registered trademark). A low-voltage input / output circuit 190 is provided for use in communicating with the data bus of the vehicle 108, the data bus of the battery pack 104, or receiving other inputs or providing outputs to the vehicle 102. Examples include the CAN communication protocol, OBDII, and the like. Further, contact closure or other voltage inputs or outputs may be applied to the vehicle using the low-voltage input / output circuit 190. Figure 2 also shows an operator cutoff switch 192 that can be actuated to immediately disconnect the high voltage control unit 170 from the battery 104 using a disconnect switch 194. Other circuit configurations may be used to implement this cutoff function. This configuration allows the operator to perform an emergency cutoff, or otherwise immediately disconnect the apparatus 100 from the battery as desired.
[0027] The low-voltage junction box 152 also provides a power output if desired. This power can be used, for example, to supply power to the components of vehicle 102 when vehicle 102 loses power. This could be useful, for example, to supply power to the vehicle 102's controller 108 so that it can collect information from the vehicle and control various components of the vehicle, such as the contactor 130.
[0028] In one configuration, the connection between the high-voltage control circuit 170 and the high-voltage junction box 154 is via a Kelvin connector. This can be used to eliminate the voltage drop that occurs when a large current is drawn through the wiring, thereby providing more accurate voltage measurements. The actual connection between the junction box 154 and the battery pack 104 does not need to be a Kelvin connection if the distance between the junction box 154 and the battery pack 104 is short enough that the voltage drop across the connection leads is negligible. Isolation circuits such as fuses may be provided in the junction box 154 to prevent the application of high voltage or high current to the maintenance device 100, thereby protecting the circuits within the device. Similarly, the low-voltage junction box 152 and / or low-voltage input / output 190 may include isolation circuits such as optical isolators, inductors for providing inductive coupling, or other techniques. The low-voltage junction box 152 may also optionally include user outputs and / or inputs 196. For example, this may be a display observable by the operator. Examples of displays include light-emitting diode (LED) displays or individual light-emitting diodes (LEDs), which provide an indication to the operator regarding the functional operation of a low-voltage junction box, vehicle, or battery pack. This can be used to visually inform the operator about the various functions performed by the low-voltage junction box and the voltage detected by the low-voltage junction box. Visual outputs and / or inputs 198 may be provided on the high-voltage junction box 154.
[0029] Appropriate high-voltage and low-voltage junction boxes 154 and 152 can be selected based on the specific vehicle 102 or battery pack 104 being inspected. Similarly, junction boxes 152 and 154 can be selected based on the types of connections available in a particular situation. For example, if the vehicle is damaged, it may be impossible to connect to the battery pack 104 by available connectors. Instead, a junction box 154 can be used that includes connection probes that can be directly connected to the battery pack 104. Furthermore, if such connections are unavailable or damaged, connectors can be provided for connecting to individual cells or batteries within the battery pack 104.
[0030] The use of low-voltage and high-voltage junction boxes 152 and 154 is advantageous for several reasons. The junction boxes can be used to provide standardized connections to the circuits of the maintenance device 100. From the junction boxes 152 and 154, dedicated connectors can be provided for use in different types of vehicles and / or battery packs. Similarly, different types of junction boxes 152 and 154 can be used for different vehicles and / or battery packs. The junction boxes 152 and 154 allow a single set of cable connections to extend between the device 100 and remote locations. This results in better cable management, ease of use, and improved accuracy.
[0031] In addition to being used as a load for discharging the battery, the high-voltage control circuit may optionally include a charging function for use when charging the battery.
[0032] When the device 100 is coupled to the vehicle 102 that has been involved in an accident, the device can perform various tests on the vehicle 102 to determine the condition of the vehicle and the battery. For example, in one embodiment, the device 100 detects leakage between the positive and negative terminals of the battery pack 102 and the ground or chassis of the vehicle 102.
[0033] During the discharge of the vehicle battery pack 104, data can be collected from the battery pack. For example, the battery pack typically includes sensors 122, such as voltage sensors, current sensors, and temperature sensors, which are positioned to collect data from various locations within the battery pack. This information can be acquired by the maintenance device 100 via coupling to the data bus 110. During discharge, the discharge can be controlled using any abnormal parameters measured by the sensors. For example, if the battery pack 104 is experiencing excessive heat, the discharge rate can be reduced until the battery temperature returns to an acceptable level. If any of the internal temperature sensors in the battery pack are not functioning, the temperature of the battery pack can be detected using an external battery pack temperature sensor. Similarly, if a cell in the pack is experiencing an abnormally high discharge current, the discharge rate can be reduced. Furthermore, if such data cannot be acquired because a sensor is damaged, or because the data bus is damaged or inaccessible, the maintenance device 100 can automatically enter a slow / safe discharge state to ensure that the battery is not damaged.
[0034] Some electric vehicles include what is called a “pre-charge contactor.” The pre-charge contactor can be used to charge the vehicle’s capacity at a slow and controlled rate before the main contactor 130 shown in Figure 1 is engaged. This prevents excessive current discharge from the battery pack when the main contactor is activated and the pack is directly coupled to the vehicle’s load, including the vehicle’s traction module used to control the vehicle’s electric motors.
[0035] In another embodiment, some or all of the information acquired during the test is retrieved and stored for later access in, for example, memory 164 shown in Figure 1. This information may be retrieved to other devices, such as a USB drive or similar, or transmitted via a network connection. This information may be downloaded from the vehicle 102's controller 108 and may also be information related to how the vehicle battery pack 104 was discharged and taken out of use.
[0036] In one configuration, the voltage sensor 232 is used to detect leakage current in a discharging battery. The device can also monitor battery cell voltage and temperature to ensure that no dangerous conditions occur during discharge.
[0037] The input / output circuit 190 can be used to connect to the vehicle's data bus via an OBDII connection to collect information such as VIN, software and hardware version numbers. The device can communicate with the Battery Electronic Control Unit (ECU) using any suitable protocol, including CAN, LIN, or others, to obtain specific battery information and discharge protocols. The device can be connected as a slave unit to other repair shop equipment components using either a wired connection or a wireless connection such as Bluetooth® or Wi-Fi. Reverse polarity protection and overvoltage protection can be provided. Other safety techniques for potential, temperature, and axis point can be fully interlocked to prevent operation of the unit. In one configuration, the input / output 184 may include a barcode scanner that can be used to obtain specific information such as battery type or serial number, and vehicle identification number. In another exemplary configuration, the input / output circuit 184 may include a remote temperature sensor that can be electrically coupled to the discharger to report the battery temperature. This is useful if the internal battery temperature sensor is damaged or inoperable. The device is expandable to allow multiple controllable loads 100 to be connected in parallel. Relay contacts can also be provided and are available externally to control various circuits on a discharging battery pack. Various circuits on the battery pack can be monitored using additional voltage sensing connections, such as those provided by the junction box 152.
[0038] Other exemplary configurations include a high-voltage DC-DC converter, such as power supply 180 shown in Figure 2. In such a configuration, the high-voltage output from the battery pack can be converted to a lower DC voltage for use in supplying power to the device.
[0039] As described above, in some configurations, the present invention can be configured to measure the dynamic parameters of the vehicle's electrical components. In such configurations, a forcing function is applied to the electrical components, and dynamic parameters such as dynamic conductance, resistance, and admittance can be determined based on changes in voltage across the battery pack and the current flowing through the battery pack. The forcing function can be any type of function having a time-varying mode, including an AC signal or a transient signal.
[0040] Different types of junction boxes and connecting cables can be used based on the specific type of vehicle and battery pack being serviced. The microprocessor can provide information to the operator to prompt them to use the appropriate junction box or cable. This can be based on the operator entering the Vehicle Identification Number (VIN) into the microprocessor, or on other identification information, including an identification number associated with the battery pack. During battery pack discharge, the microprocessor can also provide the operator with information indicating the remaining time until discharge is complete. The microprocessor 160 can also detect whether the correct junction box and cable are connected to the specific battery pack and vehicle equipment and battery pack being serviced. If incorrect wiring or junction box is used, information can be provided to the operator.
[0041] As described above, the device 100 may include multiple connectors for use when connecting the low-voltage junction box 152 and / or the high-voltage junction box 154 to the vehicle 102 and / or battery pack 104. This allows the device 100 to be easily modified to interact with different types of batteries or vehicles simply by selecting the appropriate connector. In one configuration, the connector includes some identifier that can be read by the device 100, so that the microprocessor 160 and the device 100 can receive information and thereby identify the type of connector in use. This allows the microprocessor 100 to know what kind of information or tests may be available through the various connectors. In another example, the operator inputs information related to the type of connector being used to the microprocessor 160 using the operator input / output 182 shown in Figure 2. In another exemplary embodiment, the microprocessor 160 may receive information identifying the type of vehicle or battery on which maintenance is being performed. This information may be input by the operator using the operator input / output 182, or by other means such as communication with the vehicle's data bus, scanning a barcode, or other types of input. Based on this information, the microprocessor can provide an output to the operator using operator input / output 182, which informs the operator of what type of interconnection cable should be used to connect the low-voltage junction box 152 and / or the high-voltage junction box 154 to the vehicle and / or battery pack.
[0042] The operator input / output 182 may include a display along with a keypad input or a touchscreen. The input can take various forms, such as a menu-driven format in which the operator progresses through a series of menus while selecting various options and configurations. Similarly, the operator input / output 182 can be used by the microprocessor 160 to allow the operator to progress through maintenance procedures step by step. In one configuration, the memory 164 is configured to receive user identification information that identifies the operator using the device. This can be input, for example, via the operator input / output 182, and allows information related to the maintenance being performed to be associated with information that identifies a particular operator. Additional information that can be associated with maintenance data includes tests performed on the vehicle and / or battery, record information, processes performed in accordance with the maintenance, date and time information, geographical location information, environmental information including temperature, test conditions, and other arbitrary desired information. This information can be stored in the memory 164 for simultaneous or subsequent transmission to other devices or locations for further analysis. The memory 164 can also store program instructions, battery parameters, vehicle parameters, test or maintenance information or procedures, and other information. These programming instructions can be updated, for example, using input / output 184 or 186 via a USB flash drive, SD card, or other memory device, or by any other means as desired. This makes it possible to modify the device 100, for example, when a new type of vehicle or battery pack configuration is provided, or when new testing or maintenance procedures are desired.
[0043] As discussed herein, the maintenance device 100 can be used to test aspects of the vehicle 102 that are related to safety. Low-voltage connections 152 can be coupled to the vehicle's data bus, for example, via an OBDII connection or a low-voltage connection of the charging input, and high-voltage connections can be coupled to various points in the vehicle's powertrain or to a high-voltage connection of the vehicle's charging input via connectors or probes. When testing the vehicle for aspects related to safety, an initial assumption can be made that the vehicle is safe, and a series of tests are performed to determine whether this assumption is false. If any of the tests are performed, the vehicle is determined to be unsafe. This is essentially a logical OR function. Any of the failed tests may raise doubts about the vehicle's safety. The OR function can be divided into two categories: 1) data that the vehicle computer (or electronic control unit (ECU)) can recognize and report, and 2) data that can be identified externally independently by the maintenance device 100. This can also be used to ensure that the safety determination is unbiased. The output provides the vehicle's "state of safety" or "(SOS)".
[0044] The maintenance device 100 can operate as a scan tool connected to the vehicle's data port. Examples of parameters that may raise safety concerns requiring further investigation include: • Absolute battery voltage below a specified threshold. • Individual cell voltage below a predetermined threshold. • The standard deviation of cell voltage that exceeds a predetermined threshold. • Cell voltage exceeding a specified threshold [MAX-MIN]. • Cell conductance below a certain value. Note that this may not be directly reported by the ECU, but can be calculated using virtual conductance techniques such as monitoring the current through the cell and the voltage across the cell. • Cell conductance standard deviation exceeding a predetermined threshold. • Faults reported by the ECU. • Any cell that does not report data. • Any temperature sensor that does not report data. • Any current or voltage sensors that are not reported. • The airbags deployed. • Internal leakage current failure. • Other safety-related parameter identifier (parameter ID: PID) values.
[0045] External verification devices such as maintenance device 100 are • Any leakage current value from the battery pack to the vehicle chassis can be reported due to one of the following: • Dielectric breakdown or dielectric degradation • Leakage of electrolyte solution • Bursting cell • Mechanical failure of internal components • Contamination inside the battery pack • Defective seal • Water intrusion • Structural damage to the pack
[0046] Some of these parameters can be measured with a scan tool, but according to the present invention, a safety determination is made based on the values or combinations of values by, for example, a microprocessor 160. These parameters can be processed by a rule set to arrive at a safety determination. To measure leakage current, the device 100 can determine the impedance to ground at any other point in the circuit that is coupled to a battery terminal, such as B+, B-MSD, or auxiliary port of a battery pack 104. In this measurement, the location of the fault relative to the test point is irrelevant. An adapter that is accepted at the CCS DC charging point can be provided, which sends a command to close the contactor and is tested from one terminal. Some battery packs have internal leakage circuits, but these can be unreliable and insufficient for safety testing.
[0047] Another aspect of the present invention relates to measuring the electrical insulation of a component. Insulation is conventionally measured by a test known as the HIPOT test (representing high potential). This is primarily used to verify the integrity of the insulation system in AC wiring. A voltage with a coefficient significantly higher than the operating voltage of the system is selected and applied to each conductor against another component, such as a vehicle chassis. Ideally, there should be no conduction. However, in practice, there is always some high-resistance electrical path, and the actual insulation is greater than a certain selected number of megohms. This is considered a non-destructive test in that the insulation is not damaged as a result of this test. The present invention includes verifying the insulation of an AC charging port using either this method or a small-signal AC-based forcing function.
[0048] Regarding battery systems, leakage is not visible to the test equipment as long as the applied potential does not exceed the battery string voltage, regardless of the presence of any leakage paths. However, at this voltage level, the test is a destructive test. Therefore, this test of insulation safety actually causes degradation of the system. This is due to the delicate nature of battery cells. They are not simple insulation systems, but complex systems with electrolyte, separators, electrodes, and other components. Exceeding the voltage across the cell terminals causes separator destruction, which leads to failure. This method is used as a sampling inspection of separator integrity during cell manufacturing, but those cells are discarded after the test procedure. In this situation, leakage can be detected without exceeding the battery voltage using a small-signal AC forcing function. The AC signal passes through the cell, thereby raising both the anode and cathode simultaneously.
[0049] In one embodiment, a low-frequency, small AC voltage is generated. The frequency can be selected as desired, but is preferably within the extremely low frequency (ELF) range. In specific configurations, 50 Hz or 100 Hz is used. However, other frequencies may be used as desired. This signal can be applied to a tuning circuit (voltage divider) and capacitively coupled into a battery string. The output of the voltage divider is monitored between the voltage divider and the coupling capacitor. When the circuit is "loaded" on the battery side due to the presence of insulation resistance, the test apparatus can monitor the degradation of the drive signal and solve the resulting equations for the unknown insulation resistance. Furthermore, this configuration is not sensitive to where leakage is located within the high-voltage string. Although specific configurations are described herein, any configuration can be used to generate the test signal and monitor signal.
[0050] The measuring device can test for leaks in available circuits via the charging port, or via any other point in the system that allows access or electrical probe or electrical connection. This may be done at a manual safety shutoff point that provides access to a separate half or section of the battery system. Other locations may also be accessible, for example, via any high-voltage accessory port such as an AC compressor.
[0051] Vehicles generally have two types of charging ports: one that accepts AC power only (single-phase or three-phase), and another that accepts both AC and DC power.
[0052] The measurement system can test all types of connections. AC connections can be tested by either the AC signaling method disclosed herein or by the conventional HIPOT test. DC charging connections can only be tested using the AC signaling model.
[0053] Electric vehicle charging connectors vary considerably depending on the manufacturer and region. One preferred connection is a standard unit with a North American Charging System (NACS) connector. This type of connector is preferred because it provides AC and DC connectivity along with data communication in a very compact form. Adapters can be used to convert this to J1772, CCS1, CCS2, or other connector standards. In other configurations, part-specific units with appropriate connectors can be provided. The main assembly is the same, but customized connectors can be housed in storage areas within the housing of the device 100.
[0054] Furthermore, the AC or DC charging contactor 131 can be instructed to close. For example, if element 121 is configured as a charging plug, communication with the vehicle can be achieved using a data connection. For example, the contactor 131 can be instructed to close using a control pilot pin, for example, using the HomePlug Green PHY protocol. Such a configuration enables data communication via the power connection.
[0055] Some vehicles have vehicle-to-grid charging connections. In such configurations, the vehicle does not expect a charger to be connected to the charging port, but instead receives a line voltage AC input. However, most vehicles do not have this capability, in which case the vehicle must be instructed to close the contactors in the absence of a charger. One way to implement this in some vehicles is to simply communicate with the vehicle computer to indicate that a charger is connected. Once the contacts are closed, there is no way for the vehicle to detect this because the vehicle sees the same voltage both inside and outside the vehicle, since the voltage is all generated by the vehicle battery. Another technique that can be used to instruct the contactors to close is to generate a high-voltage reference at a low current level (not enough to charge, but enough for the vehicle to read the voltage). Once the contactors are closed, they remain closed.
[0056] Element 121 can be configured as an electrical connector configured to connect to various standard connectors in the vehicle 102, such as the battery pack 104, the internal DC-DC converter in the vehicle 102, the charging port 123, or other components. Element 121 can also be configured as a probe, allowing an operator to manually contact the probe 121 at various locations within the vehicle 102. For example, the probe 121 can be used to probe various points along the string of batteries that make up the battery pack 104. A display in the operator input / output can be used to instruct the operator on where to place the probe, through textual instructions and / or images.
[0057] Figure 3 is a simplified block diagram of apparatus 100 showing a circuit used to test the resistance between components in an electric vehicle 102 that should be highly electrically isolated, particularly between components that are part of the vehicle 102's charging and power systems. Element 123 is shown as a charging port and includes multiple charging connections for illustrative purposes. However, any charging technique or standard can be implemented on port 123. Port 123 shows DC battery charging connections B+ and B-, along with AC charging connections L1, L2 and L3. AC charging may be via single-phase or multi-phase AC signals. A neutral connection N is shown along with ground or earth potential PE. When charging using DC charging signals applied to the B+ and B- connections, a large amount of charge can be directly transferred to the battery pack 104 at high voltage and high current. AC charging can also be applied to the vehicle 102 using the L1, L2 and L3 connections. However, AC charging requires the use of an AC-DC converter in the vehicle 102 to convert the AC charging signals into DC charging signals suitable for application to the battery pack 104. Therefore, AC charging is typically performed at a slower charging speed than that possible with DC charging. Furthermore, in Figure 3, the element 121 configured as a charging plug and the high-voltage junction box 154 are shown as a single component. However, this is not a mandatory requirement. Preferably, the charging plug is selectable by the operator, thereby allowing a specific plug to be selected to connect to the charging port 123 of a particular type of vehicle.
[0058] In the configuration shown in Figure 3, the device 100 is shown to include a controller or microprocessor 160, input / output circuits 162, and memory 164. A low-voltage AC test signal source 220 is provided, controlled by the microprocessor 160, and provides an AC test signal to an RC network formed by capacitors 222 and resistors 224 that form a voltage divider. The AC signal generated by the signal source 220 is also referred to herein as a forcing function. The AC signal provided by the signal source 220 may be any particular form including a sine wave, a square wave, or other waveform shape, and may also include a simple transient signal in some configurations. The AC test signal is coupled to capacitors 222 and resistors 224 that generate a monitor signal applied to one of the input connections of the charging port 123, using a controllable switch 226 operating under the control of the microprocessor 160. Switch 262 allows the AC signal to be coupled to any one of several inputs in the charging port 123. The charging plugs 154 / 121 are also connected to the PE connection of the vehicle 102, which is coupled to the electrical ground of the device 100. The measurement circuit is provided by a differential amplifier 230, which is arranged to measure the voltage difference between the AC test signal and the monitor signal appearing on the opposite side of an RC circuit formed by resistors 224 and capacitors 222. The voltage difference is supplied to an analog-to-digital converter 232, which provides a digital signal to the microprocessor 160.
[0059] During operation, switch 226 is moved to selectively couple a monitor signal generated by the AC test signal to one of the connections in the charging port 123. The AC signal from the AC source 220 is then applied to the connection through capacitor 222 and resistor 224. If there is any leakage current between the AC input connection and the ground provided by the PE connection, an AC current will flow through resistor 224 and capacitor 222. This causes a voltage drop across resistor 224 and capacitor 222, which is detected by differential amplifier 230. This differential signal is converted into a digital signal for microprocessor 160 using digital-to-analog converter 232. If the measured resistance is greater than the maximum resistance threshold, the microprocessor 160 can indicate to the operator via input / output circuit 162 that there is a potential short circuit or insulation fault in the vehicle 102.
[0060] When the charging contactor 131 shown in Figure 1 is open, the insulation test will only test the connection from the charging port 123 to the contactor 131. Furthermore, if, for example, an AC signal is applied through AC connections L1 to L3, it may also be possible to test the insulation of the AC-DC converter inside the vehicle, depending on the vehicle configuration. However, when the contactor 121 is closed, the insulation test can be performed along the entire length of the connection from the charging port 123 to the battery pack 104, as well as inside the battery pack 104 and to the devices to which the battery pack 104 is connected. If desired, the system can also perform a HIPOT test using the high-voltage circuit discussed in relation to Figures 1 and 2.
[0061] The specific frequency of the AC signal from the AC source can be selected as desired. However, typically, the signal is of a relatively low frequency, e.g., below 100 Hz, and may be selected based on the geographical region of the specific implementation or use.
[0062] The microprocessor 160 can also use data collected from the AC signal test to determine how much leakage current will occur at high voltages. For example, if the AC signal is a 1-volt signal, it can easily determine how much current will leak if the applied voltage is 1000 volts or more. This makes it possible to simulate the HIPOT test without actually applying high voltages.
[0063] The connection provided by element 154 / 121 may be in the form of a probe. In this configuration, the probe 154 / 121 can be applied to various locations and test points within the vehicle. For example, any point along the battery string of pack 104 can be probed. Similarly, other locations or test points within the vehicle 102, such as contactors 130, 131, motor 106, AC-DC or DC-AC converters within the vehicle, can be tested.
[0064] Figure 4 shows another operating mode of the maintenance device 100 used to identify faulty grounding connections within the vehicle 102. In this configuration, Kelvin connections 300 and 302 are used to determine the conductance between grounding points that should be electrically connected to each other. Kelvin connection 300 includes a drive connection 300A and a sensing connection 300B. Similarly, Kelvin connection 302 includes a drive connection 302A and a sensing connection 302B. Kelvin connection 300 is connected to the PE connection of charging port 123 through charging ports 154 / 121. Kelvin connection 302 is configured as a test probe that can be electrically connected by the operator to various grounding points. An AC signal source 220 provides an AC forcing function applied to the drive connection 300A for connection to the test point, and to the drive connection 302A for connection to grounding points such as the PE of plug 123. Any voltage difference between the two Kelvin connections 300 and 302 is detected by a differential amplifier 306 using sensing connections 300B and 302B. This difference signal output from amplifier 306 is connected to digital-to-analog converter 232 and provided to microprocessor 160 for evaluation.
[0065] In this configuration, the operator uses the test probe 302 to connect to various grounding points within the vehicle 192, including the vehicle chassis, battery electrical ground, motor or contactor electrical ground, etc. The connections 302A and 302B of the probe 302 may be push-pin connectors or similar. Kelvin connections allow for the measurement of even small resistances between two contact points. If the measured resistance is greater than the maximum resistance threshold, the microprocessor 160 can provide the operator with an indication via the input / output circuit of a potential safety issue and that components of the vehicle 102 are not properly grounded.
[0066] In one configuration, the charging plug 154 / 121 includes multiple exposed connectors, thereby allowing the operator to connect to any assumed charging port configuration or other electrical connectors using jumper wires. These connections can be used to directly connect to battery strings in the battery pack 104, other locations in the electric powertrain including contactors 130, 131, and other connections that provide data, such as proximity pilot connections or control pilot connections. This also makes it possible to test vehicles with non-standard charging ports 123. The insulation and ground fault tests discussed in relation to Figures 3 and 4 can be used in combination with data collected using the data connections 135 / 133 shown in Figure 1. For example, the OBDII connection can be used to read data identifying faults in the battery, electrical components, electrical ground, or other devices in the vehicle. Based on this determination, the microprocessor 160 can instruct the operator to perform specific tests on specific components or test points of the vehicle using the AC forcing function provided by the AC signal source 220. This makes it possible to identify dielectric breakdown or degradation, electrolyte leakage, ruptured cells in the battery pack 104, other mechanical damage to internal components, contamination in the battery pack 104, seal failure, water ingress into components of the vehicle 102, structural damage to the battery pack 104, or other potential safety-related issues.
[0067] While the present invention has been described with reference to preferred embodiments, those skilled in the art will recognize that modifications can be made in form and detail without departing from the spirit and scope of the invention. Although specific embodiments describe increasing load or current, it should be understood that the change in applied load or drawn current can be either an increase or a decrease.
Claims
1. A device for safety testing of electrical components in electric vehicles, A low-voltage data connector configured to be connected to the data port of the electric vehicle, A test connector configured to couple a test signal to the electrical components of the electric vehicle, A test signal source having a signal generator and coupled to a voltage divider, wherein the voltage divider generates the test signal and the monitor signal, A measurement circuit coupled to the monitor signal, A device comprising: a low-voltage data connector and a controller coupled to the measurement circuit and configured to identify leakage current based on the monitor signal.
2. The apparatus according to claim 1, wherein the test signal includes an AC forcing function.
3. The apparatus according to claim 1, wherein the measurement circuit includes a differential amplifier for measuring the difference between the test signal and the monitor signal.
4. The apparatus according to claim 1, wherein the voltage divider comprises a resistor and a capacitor.
5. The apparatus according to claim 1, wherein the test connector comprises a charging plug configured to connect to the charging port of the vehicle.
6. The apparatus according to claim 1, wherein the test connector includes a plurality of connectors, each configured to be coupled to an electrical connector of the vehicle.
7. The apparatus according to claim 6, further comprising a switch configured to selectively couple the monitor signal to at least one of the plurality of connectors.
8. The apparatus according to claim 1, wherein the test connector includes a connection to the electrical ground of the vehicle.
9. The apparatus according to claim 8, wherein the electrical grounding includes a PE connection.
10. The apparatus according to claim 1, further comprising a digital-to-analog converter that couples the monitor signal to the controller.
11. The apparatus according to claim 1, wherein the controller is further configured to close the contactor of the vehicle.
12. The apparatus according to claim 11, comprising connection to the data bus of the vehicle, wherein the controller communicates via the data bus.
13. The apparatus according to claim 1, comprising connection to the data bus of the vehicle, wherein the controller communicates via the data bus.
14. The apparatus according to claim 13, wherein the controller is configured to receive diagnostic information from a data connection to the vehicle.
15. The apparatus according to claim 14, wherein the controller is configured to instruct an operator to perform a leakage current test on the vehicle based on the diagnostic information.
16. The apparatus according to claim 1, wherein the test connector provides a Kelvin connection.
17. The apparatus according to claim 16, wherein the resistance between the electrical ground and the Kelvin connection is measured.
18. The apparatus according to claim 17, wherein the Kelvin connection is configured as a probe.
19. The apparatus according to claim 18, wherein the controller instructs the operator on where to place the probe.
20. The apparatus according to claim 16, wherein the Kelvin connection is configured to be coupled to the PE connection of the vehicle.
21. The apparatus according to claim 16, wherein the Kelvin connection receives an AC forcing function.
22. The apparatus according to claim 16, comprising a differential amplifier configured to detect the voltage difference between the Kelvin connection detection connections.
23. The apparatus according to claim 12, wherein the battery voltage of the battery pack is acquired via the data bus.
24. The apparatus according to claim 12, wherein diagnostic information is acquired via the data bus.
25. The apparatus according to claim 12, wherein leakage current fault information is acquired via the data bus.